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Heavy Duty Racing – Featured Customer

Heavy Duty Racing is a manufacturing company based in Stafford, VA, that specializes in motocross, off-road motorcycle suspension, and 2-stroke engine modification. Its owner, Peter Payne, grew up racing motorcycles. Later in life, he even taught classes on how to race. Simply, Motocross and motorcycles became Peter’s passion.

Peter always looked for ways to enhance his motorcycle’s engine, but quickly realized that no shops in his area could design what he was looking for. To get access to the parts he would need, he would have to rely upon companies from far away, and would oftentimes be forced to wait more than three weeks for them to arrive. Because of this, Peter decided he would need to take part manufacturing into his own hands. He purchased a manual lathe, allowing him to make modifications to his two-stroke engines exactly how he wanted them. Quickly thereafter, Heavy Duty Racing was born.

Peter discussed with us his love of racing, how he first got into machining, the parts his shop has designed, and tips and tricks for new machinists.

How did you get started in machining?

Since I was a kid I have been riding motorcycles and racing motocross. I went to a tech school in the ’80s and learned diesel technologies. When I realized nobody in this area could help design the engines I wanted to make, I decided I needed to learn how to do it myself. I have a friend, George, who is a retired mold and die maker that also worked on motorcycle engines, I asked him for some advice on how to get started. George ended up teaching me all about machining and working on engines. I really learned from failures, by trying new things, and doing it every day. I started Heavy Duty Racing in 1997 and we have been modifying and designing the highest performing engines since then.

What machines and softwares are you using in your shop?

We currently have a Thormach PCNC 1100 and a Daluth Puma CNC Lathe (we call it The Beast, it’s angry and grumpy but it gets the job done). We also have a Bridgeport Mill, Manual Lathe, and a Tiggwell. When we were choosing software to use, they had to be easy and quick to learn. We weighed our options and decided to use Autodesk Fusion 360 about 5 years ago. We mostly machine cast iron and steel since most engines are made from those materials.

What sets Heavy Duty Racing apart from the competitors?

We have a small hands-on approach and treat every part with care. We don’t have a cookie-cutter process so we are very flexible when it comes to customer needs. Since each part is different, we don’t have set prices and have custom quoting on each part. We value our customers and tailor every build to the rider, based on the weight, fuel, and skill level of the rider. We make unique components for each rider so they can have the best experience when they hop on their bike. We are just focused on letting people do what they love.

What is the coolest project you have worked on?

In 2016, MX Tech Suspension in Illinois gave us the opportunity to build an engine for them to display at their event. We got to go to California to watch them demo the engine in front of thousands of people. It was very nerve-racking to watch it live but the experience was amazing. The engine was later featured on the cover of Motocross Action magazine. It was very cool to see something we dedicated so much hard time toward get that much recognition.

Why is high qualtiy tooling important to you?

We are making really difficult machine parts so we need tools that can last. Micro 100 tooling lasts and does the job. The thread mills we use are 3-4 mm and 14 mm and they last longer than any competition out there. The thread mills do not chip like the competition and the carbide is super strong. Breaking a tool is not cheap, so to keep one tool in the machine for how long we have has really saved me in the long run. We found Micro 100 one day looking through our distributor’s catalog and decided to try some of their boring bars. After about 5 holes, we realized that these tools are the best we have ever used! Micro has had everything I’ve been looking for in stock and ready to ship, so we have yet to need to try out their custom tools.

Most engine tolerances are no more than .005” taper. You need the tooling to hold tight tolerances, especially in engines. Just like with tooling, minimizing vibration is key to getting the engine to last longer. We need tight tolerances to maintain high quality and keep engines alive.

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

The same advice I’ve given to my son: Don’t be ashamed to start from the bottom and learn from the ground, up. Everybody wants to make cool projects, but you need to learn what is going on around you to master the craft. Learn the processes and follow the steps. It’s very easy to break a tool, ruin a part, or even hurt yourself. Don’t be scared of quality tools! Buying the cheap stuff will help you with one job, but the quality tools last and will save you in multiple situations.

Follow Heavy Duty Racing on Instagram, and go check out their website to see more about them!

Hybrid Machining – Featured Customer

Located in Holland, MI, Hybrid Machining uses machining skills combined with 3 different 3D printing technologies to manufacture complex projects. Hybrid Machining is a manufacturing company that can take the customer’s design from start to finish, allowing customers to dictate their path. Rather than focusing on a single product, Hybrid has listened to customer needs and presented solutions that, in many cases, customers didn’t know were possible. Jeff Robinson, the owner, took some time out of his day to answer some questions about Hybrid Machining.

How did you get into manufacturing?  

I started working in an architectural shop during my high school years.  I quickly realized that there was a more advanced part of the industry that I was missing out on. Therefore, I started researching CNC Routing.  I fell in love with the technology and have been studying it ever since. 

What sort of machines and materials do you use in your shop?

We currently run a Datron Neo, Fanuc Robodrill, and a CR Onsrud 5-axis Router. We work primarily with wood, plastic, and non-ferrous materials. We currently use Autodesk Fusion 360, FeatureCAM, Powermill, Vectric Aspire, and AlphaCAM for CAM.  For CAD, we run Fusion 360, Inventor, and Solidworks.

When did you start using 3D printing and how has it benefitted you?

I have been 3D printing for just over a year.  It was the first technology that we initiated here at Hybrid Machining, and it has allowed us to provide the best solution to the customer no matter what the requirements are. By expanding into 3D printing, we can help the customer decide which technology will work the best for their part. Many times, we take the “Hybrid” approach and use both additive and subtractive technologies together.

How have you adapted during the Covid-19 outbreak and how has it changed your business?

We started by stopping normal production to form a non-profit called 3DC19 with other local, small business owners with the sole purpose of 3D printing and assembling plastic face shields.  Hybrid Machining became the distribution center for the efforts.  Collectively, we produced and donated 75K articles of PPE to local hospitals, nursing homes, doctor offices, and first responders.  You can learn more about the efforts at www.3DC19.com. We have also been machining a lot of acrylic face guards for customers so that we can help them to get their office staff back to work safely. 

What sets Hybrid Machining apart from the rest of the manufacturing community? 

We have a serious passion for educating our youth and local businesses on the rapid changes currently happening in the manufacturing industry and preparing them for the impact that Industry 4.0 will have on our lives in the future.  We want to produce knowledgeable people just as much as we produce products, and we do this in our unique Learning Lab.  We team up with local schools, vocational schools, and community colleges to help them spread the word about manufacturing.  We also intend to do ‘Lunch and Learns’ with local businesses to help them understand what other manufacturing methods and advanced materials are available on the market today.

What is the coolest project you have had come through the shop?

Many years ago, at my previous shop, we worked on the presidential handrail that the last three presidents stood behind during the inauguration.

Are you using HEM techniques to improve cycle times? 

Yes, we use a couple of the fastest and most nimble machines on the market: the Datron NEO and the Fanuc Robodrill.  We leverage the machine’s tools’ high accelerations and deceleration rates, along with HEM, to drastically reduce cycle times for our customers.  This allows us to be competitive against over-seas importers.

What do you have to lose other than cycle time? You purchased the entire tool, not just the tip, so use it!  You will be surprised how the different the machine will sound and you can get parts done faster with less tool wear.

Why is high quality tool performance important to you?

The tooling is super important to the success of a project because the tool is what is doing the work.  I like to tell people, “Why would you buy a high-end sports car with all bells and whistles and then put crappy tires on it?  All that power and handling is worthless unless you have good tires.”  The same goes for tooling.  You can have a half-million-dollar machine that is super-fast and accurate and yet still produce a terrible part with cheap tooling. 

When was a time that Harvey Tool, Helical Solutions, or Micro 100 saved the day?

Harvey Tool helped me get through some tough composite projects in the past.  Their technical support team was extremely knowledgeable on the subject matter and helped me pick the right tool and parameters to get the job done. 

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

NEVER STOP LEARNING.  Things may be going great at first and you think you have it all figured out, but then a new technology comes and swipes you off your feet.  Spend your spare time studying industry trends, talking to other business leaders, new and old, and preparing for the future.

 Is there anything else you would like to share with the In The Loupe community?

We are extremely thankful that Harvey Tool spends a lot of time developing ‘material-specific’ tooling.  We spend 90% of our time in that section of the catalog.  We recently tested out the new wood cutters and are extremely happy. We pushed these tools at speeds and feeds that are unbelievable.  We also use the Harvey Tool plastic cutters on a regular basis. 

Here at Hybrid Machining, we are blending the lines between routing and milling.  For many decades, the line had been fairly clear. There were certain types of jobs you ran on certain types of machines.  We are blurring those lines and are using the best tools for the jobs.  For instance, we use the 24K RPM spindle on the Robodrill to run it more like a router than a mill.  Therefore, we call it the “RoboRouter”.  We can produce wood and plastic parts at unbelievable speeds while achieving surface finishes that are off the charts.  This is not conventional practice, but the team at Hybrid Machining is willing to blaze the path forward for others to follow.

To check out more about Hybrid Machining go to their website or follow them on social media!

Achieving Success in CNC Woodworking

Developing a Successful Cutting Direction Strategy

There are a number of factors that can affect the machining practices of wood. One that comes up a lot for certain hardwoods is the cutting direction, specifically in relation to the grain pattern of the wood. Wood is an anisotropic material. This means that different material properties are exhibited in different cutting directions. In terms of lumber, there are different structural grades of wood related to grain orientation. If the average direction of the cellulose fibers are parallel to the sides of the piece of lumber, then the grains are said to be straight. Any deviation from this parallel line and the board is considered to be “cross-grain”. Figure 1 below depicts a mostly straight grain board with arrows indicating the different axes. Each of these axes exhibits different sets of mechanical properties. Because of these differences, one must be conscious of the tool path and minimize the amount of cutting forces placed on the cutter in order to maximize its tool life.

Figure 1: Mostly straight grain board with arrows indicating different axes

Cutting perpendicular to the grain is known as cutting “across the grain”. In Figure 1 above, this would be considered cutting in the radial or tangential direction. Cutting parallel to the grain is known as cutting “along the grain” (longitudinally in terms of Figure 1). The closer you are to cutting at 90° to the grain of the wood in any direction, the larger the cutting force will be. For example, a tool with its center axis parallel to the tangential direction and a tool path along the longitudinal direction would have less wear than a tool with the same center axis but moving in the radial direction. The second type of tool orientation is cutting across more grain boundaries and therefore yields greater cutting forces. However, you must be careful when cutting along the grain as this can cause tear-outs and lead to a poor surface finish.

The Proper Formation of Wood Chips

When cutting wood parallel to the grain, there are three basic types of chips that are formed. When cutting perpendicular to the grain, the chip types generally fall into these same 3 categories, but with much more variability due to the wide range in wood properties with respect to the grain direction.

Type 1 Chips

Type 1 chips are formed when wood splits ahead of the cutting edge through cleavage until failure in bending occurs as a cantilever beam. A large force perpendicular to the shear plane is produced, causing the wood ahead of the cutting edge to split, forming this tiny cantilever beam. When the upward force finally exceeds the strength of this tiny beam, it breaks off.  These types of chips cause comparatively little wear compared to types 2 and 3, as the material is splitting before coming in contact with the pointed edge. End mills with either extremely high rake or very low rake angles often produce type 1 chips. This is especially true when machining against grain slopes that are greater than 25°. Woods with moisture content less than 8%form discontinuous chips and are at a higher risk of tear-out.

Type 2 Chips

Type 2 chips are the most desirable of the three types in terms of surface finish. They are a result of material failure along a diagonal shear plane, extending from the cutting edge to the workpiece surface. Type 2 chips form when there is a proper balance between the properties of the wood, cutting parameters, and cutter geometry. Woods with a moisture content between 8% and 20%have a much higher chance of forming continuous type 2 chips while leaving a good surface finish.

Type 3 Chips

The last type of chip forms when the rake angle of a cutter is much too low. In this scenario, the cutting force is almost parallel to the direction of travel. This causes a soft material, such as wood, to be crushed rather than sheared away, leaving a poor surface finish. Generally, the surface left behind looks like tiny bundles of wood elements, a surface defect commonly known as “fuzzy grain.” This type of chip occurs more frequently in softwoods as the crushing situation is compounded in low-density woods.

Figure 2: Different types of wooden chips

Extending Tool Life When Machining Wood

Speeds & Feeds Rules of Thumb

There are several different categories of tool wear that occur when machining wood. General rules of machining still apply as RPM has the greatest influence on wear rate. Over-feeding can increase tool wear exponentially and also cause tool breakage. As with most machining operations, a balance between these two is essential. If you are looking to increase your productivity by increasing your speed, you must increase your feed proportionally in order to maintain a balance that keeps the tool properly engaged in the material.

Proper Management of Heat

When cutting tools are exposed to high heat, they begin to wear even faster, due to corrosion. The cobalt binder within most carbide tools on the market begins to oxidize and break free of the cutting edge. This sets off a chain reaction, as when the binder is removed, the tungsten carbide breaks away, too. Different species of wood and types of engineered wood have different corrosive behaviors at high temperatures. This is the most consistent type of wear that is observed when machining MDF or particleboard. The wear is due to the chlorine and sulfate salts found in adhesives as this accelerates high-temperature corrosion.  As with aluminum, when the silica content of a wood increases, so too does its corrosiveness.

Generally, increased tool wear is observed in wood with high moisture content. This trait is due to the increased electro-chemical wear caused by the extractives in wood., Moisture content in wood includes substances such as resins, sugars, oils, starches, alkaloids, and tannins in the presence of water. These molecules react with the metallic constitutes of the cutting tool and can dull the cutting edge. Carbide is more resistant to this type of wear compared to high-speed steel.

Best Coatings for Extended Tool Life in Wood

If you want a longer-lasting tool that will maintain its sharp cutting edge (and who doesn’t), you may want to consider an Amorphous Diamond coating. This is an extremely abrasive resistant coating meant for non-ferrous operations in which the temperature of the cutting zone does not exceed 750 °F. This coating type is one of Harvey Tool’s thinnest coatings, therefore minimizing the risk of any edge rounding and maximizing this edge’s durability.

Avoiding Common Wood Machining Mishaps

Tear Out

Tear out, sometimes called chipped grain or splintering, is when a chunk of the wood material being machined tears away from the main workpiece and leaves an unappealing defect where it used to be. This is one of the most common defects when machining wood products. There are many different reasons that tear out occurs. Material characteristics are something to be considered. Tear out is more likely to occur if the grain orientation is less than 20°relative to the tool path, the moisture content of the wood is too low, or the density of the wood is too low. Figure 4 shows the grain orientation angle relative to the tool path. In terms of machining parameters, it can also occur if either the chip load, depth of cut, or rake angle is too high.

Figure 4: Example of grain orientation angle relative to the tool path

Fuzzy Grain Finish

Fuzzy grain looks like small clumps of wood attached to the newly machined face and occurs when the wood fibers are not severed properly. Low rake or dull cutting tools indent fibers until they tear out from their natural pattern inside, causing type 3 chips to form, resulting in a poor finish. This can be exacerbated by a low feed or depth of cut as the tool is not properly engaged and is plowing material rather than shearing it properly. Softer woods with smaller and lesser amounts of grains are more susceptible to this type of defect. Juvenile wood is known to be particularly liable for fuzzy grain because of its high moisture content.

Figure 5: Example of a fuzzy grain finish

Burn Marks

Burn Marks are a defect that is particularly significant in the case of machining wood, as it is not generally a concern when machining other materials. Dwelling in a spot for too long, not engaging enough of the end mill in a cut, or using dull tools creates an excessive amount of heat through friction, which leaves burn marks. Some woods (such as maple or cherry) are more susceptible to burn marks, therefore tool paths for these types should be programmed sensibly. If you are having a lot of trouble with burn marks in a particular operation, you may want to try spraying the end mill with a commercial lubricant or paste wax. Be careful not to use too much as the excess moisture can cause warping. Increasing your tool engagement or decreasing RPM may also combat burn marks.

Figure 6: Example of burn marks

Chip Marks

Chip marks are shallow compressions in the surface of the wood that have been sprayed or pressed into the surface. These defects can swell with an increase in moisture content, worsening the finish even more. This type of blemish is generally caused by poor chip evacuation and can usually be fixed by applying air blast coolant to the cutting region during the operation.

Raised Grain

Raised grain, another common defect of woods, is when one or more portions of the workpiece are slightly lower than the rest. This blemish is particularly a problem when machining softer woods with dull tools as the fibers will tear and deform rather than be cleanly sheared away. This effect is intensified when machining with slow feeds and the wood has a high moisture content. Variations in swelling and shrinking between damaged and undamaged sections of wood exacerbate this flaw. It’s for this reason that raised grain is a common sight on weather-beaten woods. Work holding devices that are set too tight also have a chance of causing raised grain.

Differentiating Harvey Tool Wood Cutting & Plastic Cutting End Mills

Machinists oftentimes use Plastic Cutting End Mills to machine wood, as this tool has very similar internal geometries to that of an End Mill for Wood. Both tools have large flute valleys and sharp cutting edges, advantageous for the machining of both plastic and wood. The main difference between the Harvey Tool plastic cutters and the woodcutters is the wedge angle (a combination of the primary relief and rake angle). The woodcutter line has a lower rake but still has a high relief angle to maintain the sharpness of the cutting edge. The lower rake is designed to not be as “grabby” as the plastic cutters can be when machining in wood. It was meant to shear wood and leave a quality surface finish by not causing tear-out.

Harvey Tool’s offering of End Mills for Wood includes both upcut and downcut options. The upcut option is designed for milling natural and engineered woods, featuring a 2-flute style and a wedge angle engineered for shearing wood fiber materials without causing tear out or leaving a fuzzy grain finish. The downcut offering is optimized for milling natural and engineered woods and helps prevent lifting on vacuum tables.

For more help on achieving a successful machining operation, or more information on Harvey Tool’s offering of End Mills for Wood, please contact Harvey Tool’s team of engineers at 800-645-5609.

Harvey Performance Company Opens New 79,000-Square-Foot Manufacturing Plant in Gorham

GORHAM, ME (October 13, 2020) – Harvey Performance Company, the parent company of the Harvey Tool, Helical Solutions, and Micro 100 industrial cutting tool brands, last month opened the doors to a new, 79,000-square-foot, state-of-the-art manufacturing facility in Gorham, Maine, to support the tremendous growth and product demand its brands continue to experience.

Harvey Performance Company was quickly outgrowing its Sanford Drive facility in Gorham, Maine, where Helical Solutions products have been manufactured for more than 15 years. The new manufacturing facility, which is just 5 minutes away on Raceway Drive, will become home to Helical Solutions product manufacturing and will serve as an innovation hub for all Harvey Performance Company brands.

“We couldn’t be more excited about this new facility,” said Harvey Performance Company Senior Vice President of Sales Jerry Gleisner. “We’re quite literally opening the doors to countless opportunities for us to serve our customers in ways unmatched in the industry.”

“This new facility is an exciting step for our business, as this investment will create opportunities for us to continue to grow,” said Harvey Performance Company Vice President of Operations Steve Vatcher. “In light of the COVID-19 Pandemic, we worked closely with state and local officials to ensure that the completion of our new facility was done in a way that prioritized the health and safety of all involved. I couldn’t be more proud of how everyone came together to make this facility a reality during these unprecedented times.

“When it is safe to do so, we look forward to hosting the Gorham community, our neighbors for more than 15 years, at our new home for a ribbon cutting ceremony to share this exciting milestone with us.”

Harvey Performance Company’s New Manufacturing Plant Will:

  • Expand upon its current research and development capabilities to design, test, and manufacture innovative and high performing cutting tools.
  • Accelerate Harvey Performance Company’s new product growth while maintaining its in-stock status and same-day shipping options for all catalog standard items.
  • Host its distributor partners and customers in a state-of-the-art setting that showcases its capabilities.
  • Meet the needs of the market by scaling the size of Harvey Performance Company’s business in the future, through added machines and personnel.
  • Attract, recruit, and retain high-quality employees, engineers, and operators with a high-class work environment.

Rennscot LLC – Featured Customer

David Bamforth is the founder and CEO of Rennscot LLC, a manufacturing company based out of Woburn, Massachusetts, which was created to meet product design demands of both individual and commercial clients. From idea to prototype, and eventually to final product, Rennscot LLC prides itself on its ability to make part ideas come to life. David took some time to talk with us about Rennscot LLC, his company’s machining capabilities, and much more.

What capabilities does your shop have?

We are mostly a mill shop with two verticals and one 5-axis machine. We also have a small bar fed lathe, a larger sub-spindle live-tooling lathe, and some design tools like a Faro Design Scan Arm. We work predominantly with aluminum, but sometimes see brass, stainless, titanium, and steel alloy jobs come through. We use Fusion 360 for everything and currently all 4 of our machines are Haas.

What sets Rennscot LLC apart from the competition?

We are a bit different from most shops because, in addition to machining services, we also offer design services. A lot of our jobs are won because we are a one-stop-shop from idea to producing the final product. Recently we have been making a lot of parts for vehicle restoration. Typically, we are just handed a part and asked to reproduce it.

David, what is your favorite part of your job?

Problem solving and learning new skills. We are a pretty young team and love being challenged by new projects. We also pride ourselves on being pretty innovative with our machining strategies to help reduce lead times and cost for our customers.

Where did your passion for automobiles come from?

Like many, I have always been passionate about cars. I have some great memories of going to car shows with my dad and watching any TV show with a car in it as a kid. Nowadays, I spend my personal time taking our shop development car, a Porsche Cayman, to the track.

What is the coolest product you have made?

We have had some pretty unusual characters bring us some really cool projects. Currently, we are working with a guy from Connecticut on laser scanning a model Mercedes C10 Le Mans car that we will CAD model, so a full-sized car body can be reproduced. It’s a really interesting project, trying to take a 1:43 car and blow it up to full size. Eventually, we will help design and manufacture many of the machined components on this car. Also, we once made a custom billet alternator mount in just 5 days for a 996 Porsche GT3 with a Chevy LS engine in it. We really enjoyed being part of that project and the V8 sounded amazing on track!

What is the most difficult product you have made?

We once worked on an enclosure for a handheld x-ray machine. The part was only about 1”x 1.25” x4” and only had .040” walls all around. The main pocket was machined with our go-to Helical ¼” reduced shank end mill. It also had #0-80 taps all along the top edge of the enclosure, making for a few broken taps! It was a pain to get dialed in but once the process was proved out it was really rewarding to get consistent good parts off the will.

Why is high quality tool performance important to you?

Once we started using high quality end mills, we immediately saw an improvement in tool life and surface finish. We also really enjoy using tools that are backed by a company that puts out so much information and resources to help its customers out.

When was a time that Harvey Tool or Helical products really came through and helped your business?

We have had several moments when we hit a wall while building a process for a new part, and Helical’s phone support helped us find the perfect tool for the process. The combination of great phone support, having such a vast array of product offerings, and all of the tools always being in stock has helped my business tremendously.

Are you guys using High Efficiency Milling (HEM) techniques to improve cycle times?

Always! All our mills are spec’ed with HSM and 12k RPM spindles, and we take full advantage of this with chip breaking roughers. Honestly, we are so young that we have only ever used HEM techniques, so I’m honestly just confused by companies that don’t use it. Not using HEM is like not driving a car on the highway because it’s too fast.

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

Machining is probably the most in demand and most satisfying industries that someone can get into now-a-days. There are a lot of companies that are in demand for green machinists who are just eager to learn. I would recommend putting together and sending out a resume to local shops that shows that you have the ability to take on projects and complete them.

If anyone is interested in learning more about what we do our manufacturing website, rennscotmfg.com is a great resource. Also, check us our on Instagram at @rennscot.

How to Optimize Results While Machining with Miniature End Mills

 The machining industry generally considers miniature end mills to be any end mill with a diameter under 1/8 of an inch. This is also often the point where tolerances must be held to a tighter window. Because the diameter of a tool is directly related to the strength of a tool, miniature end mills are considerably weaker than their larger counterparts, and therefore, lack of strength must be accounted for when machining with them. If you are using these tools in a repetitive application, then optimization of this process is key.

Key Cutting Differences between Conventional and Miniature End Mills

Runout

Runout during an operation has a much greater effect on miniature tools, as even a very small amount can have a large impact on the tool engagement and cutting forces. Runout causes the cutting forces to increase due to the uneven engagement of the flutes, prompting some flutes to wear faster than others in conventional tools, and breakage in miniature tools. Tool vibration also impacts the tool life, as the intermittent impacts can cause the tool to chip or, in the case of miniature tools, break. It is extremely important to check the runout of a setup before starting an operation. The example below demonstrates how much of a difference .001” of runout is between a .500” diameter tool and a .031” diameter tool.

The runout of an operation should not exceed 2% of the tool diameter. Excess runout will lead to a poor surface finish.

Chip Thickness

The ratio between the chip thickness and the edge radius (the edge prep) is much smaller for miniature tools. This phenomena is sometimes called “the size effect” and often leads to an error in the prediction of cutting forces. When the chip thickness-to-edge radius ratio is smaller, the cutter will be more or less ploughing the material rather than shearing it. This ploughing effect is essentially due to the negative rake angle created by the edge radius when cutting a chip with a small thickness.

If this thickness is less than a certain value (this value depends of the tool being used), the material will squeeze underneath the tool. Once the tool passes and there is no chip formation, part of the plowed material recovers elastically. This elastic recovery causes there to be higher cutting forces and friction due to the increased contact area between the tool and the workpiece. These two factors ultimately lead to a greater amount of tool wear and surface roughness.

Figure 1: (A) Miniature tool operation where the edge radius is greater than the chip thickness (B) Conventional operation where the edge radius is small than the chip thickness

Tool Deflection

Tool deflection has a much greater impact on the formation of chips and accuracy of the operation in miniature operations, when compared to conventional operations. Cutting forces concentrated on the side of the tool cause it to bend in the direction opposite the feed. The magnitude of this deflection depends upon the rigidity of the tool and its distance extended from the spindle. Small diameter tools are inherently less stiff compared to larger diameter tools because they have much less material holding them in place during the operation. In theory, doubling the length sticking out of the holder will result in 8 times more deflection. Doubling the diameter of an end mill it will result in 16 times less deflection. If a miniature cutting tool breaks on the first pass, it is most likely due to the deflection force overcoming the strength of the carbide. Here are some ways you can minimize tool deflection.

Workpiece Homogeny

Workpiece homogeny becomes a questionable factor with decreasing tool diameter. This means that a material may not have uniform properties at an exceptionally small scale due to a number of factors, such as container surfaces, insoluble impurities, grain boundaries, and dislocations. This assumption is generally saved for tools that have a cutter diameter below .020”, as the cutting system needs to be extremely small in order for the homogeny of the microstructure of the material to be called into question.

Surface Finish

Micromachining may result in an increased amount of burrs and surface roughness when compared to conventional machining. In milling, burring increases as feed increases, and decreases as speed increases. During a machining operation, chips are created by the compression and shearing of the workpiece material along the primary shear zone. This shear zone can be seen in Figure 2 below. As stated before, the chip thickness-to-edge radius ratio is much higher in miniature applications. Therefore, plastic and elastic deformation zones are created during cutting and are located adjacent to the primary shear zone (Figure 2a). Consequently, when the cutting edge is close to the border of the workpiece, the elastic zone also reaches this border (Figure 2b). Plastic deformation spreads into this area as the cutting edge advances, and more plastic deformation forms at the border due to the connecting elastic deformation zones (Figure 2c). A permanent burr begins to form when the plastic deformation zones connect (Figure 2d) and are expanded once a chip cracks along the slip line (Figure 2e). When the chips finally break off from the edge of the workpiece, a burr is left behind (Figure 2f).

Tool Path Best Practices for Miniature End Mills

Because of the fragility of miniature tools, the tool path must be programmed in such a way as to avoid a sudden amount of cutting force, as well as permit the distribution of cutting forces along multiple axes. For these reasons, the following practices should be considered when writing a program for a miniature tool path:

Ramping Into a Part

Circular ramping is the best practice for moving down axially into a part, as it evenly distributes cutting forces along the x, y, and z planes. If you have to move into a part radially at a certain depth of cut, consider an arching tool path as this gradually loads cutting forces onto the tool instead of all at once.

Machining in Circular Paths

You should not use the same speeds and feed for a circular path as you would for a linear path. This is because of an effect called compounded angular velocity. Each tooth on a cutting tool has its own angular velocity when it is active in the spindle. When a circular tool path is used, another angular velocity component is added to the system and, therefore, the teeth on the outer portion of tool path are traveling at a substantially different speed than expected. The feed of the tool must be adjusted depending on whether it is an internal or external circular operation. To find out how to adjust your feed, check out this article on running in circles.

Slotting with a Miniature Tool

Do not approach a miniature slot the same way as you would a larger slot. With a miniature slot, you want as many flutes on the tool as possible, as this increases the rigidity of the tool through a larger core. This decreases the possibility of the tool breaking due to deflection. Because there is less room for chips to evacuate with a higher number of flutes, the axial engagement must be decreased. With larger diameter tools you may be stepping down 50% – 100% of the tool diameter. But when using miniatures with a higher flute count, only step down between 5% – 15%, depending on the size of the diameter and risk of deflection. The feed rate should be increased to compensate for the decreased axial engagement. The feed can be increased even high when using a ball nose end mill as chip thinning occurs at these light depths of cut and begins to act like a high feed mill.

Slowing Down Your Feed Around Corners

Corners of a part create an additional amount of cutting forces as more of the tool becomes engaged with the part. For this reason it is beneficial to slow down your feed when machining around corners to gradually introduce the tool to these forces.

Climb Milling vs. Conventional Milling

This is somewhat of a tricky question to answer when it comes to micromachining. Climb milling should be utilized whenever a quality surface finish is called for on the part print. This type of tool path ultimately leads to more predictable/lower cutting forces and therefore higher quality surface finish. In climb milling, the cutter engages the maximum chip thickness at the beginning of the cut, giving it a tendency to push away from the workpiece. This can potentially cause chatter issues if the setup does not have enough rigidity.  In conventional milling, as the cutter rotates back into the cut it pulls itself into the material and increases cutting forces. Conventional milling should be utilized for parts with long thin walls as well as delicate operations.

Combined Roughing and Finishing Operations

These operations should be considered when micromachining tall thin walled parts as in some cases there is not sufficient support for the part for a finishing pass.

Helpful Tips for Achieving Successful Micromachining Operations

Try to minimize runout and deflection as much as possible.This can be achieved by using a shrink-fit or press-fit tool holder. Maximize the amount of shank contact with the collet while minimizing the amount of stick-out during an operation. Double check your print and make sure that you have the largest possible end mill because bigger tools mean less deflection.

  • Choose an appropriate depth of cut so that the chip thickness to edge radius ratio is not too small as this will cause a ploughing effect.
  • If possible, test the hardness of the workpiece before machining to confirm the mechanical properties of the material advertised by the vender. This gives the operator an idea of the quality of the material.
  • Use a coated tool if possible when working in ferrous materials due to the excess amount of heat that is generated when machining these types of metals. Tool coatings can increase tool life between 30%-200% and allows for higher speeds, which is key in micro-machining.
  • Consider using a support material to control the advent of burrs during a micro milling application. The support material is deposited on the workpiece surface to provide auxiliary support force as well as increase the stiffness of the original edge of the workpiece. During the operation, the support material burrs and is plastically deformed rather than the workpiece.
  • Use flood coolant to lower cutting forces and a greater surface finish.
  • Scrutinize the tool path that is to be applied as a few adjustments can go a long way in extending the life of a miniature tool.
  • Double-check tool geometry to make sure it is appropriate for the material you are machining. When available, use variable pitch and variable helix tools as this will reduce harmonics at the exceptionally high RPMs that miniature tools are typically run at.
Figure 3: Variable pitch tool (yellow) vs. a non-variable pitch tool (black)

Titan Ring Design – Featured Customer

Officially started in 2015, Titan Ring Design is a high quality machine shop that designs rings, as well as mechanical tie clips, art based designs, and freelance custom designs. While working at a machine shop that produced top notch parts for just about every type of field you can imagine, now owner of Titan Ring Design, Trevor Hirschi, noticed that the machining industry is mostly about cranking out a mass quantity of the highest quality parts as quickly as possible. This often resulted in compromised tolerances and part finishes, something Trevor aimed to change. Quality always comes first in his projects.

Whether you are looking for a band for an upcoming wedding, looking to replace or upgrade your current wedding ring, or just want something unique and beautiful, Trevor’s designs are different than anything else. Trevor was able to take the time and answer some questions for us about his business, machining techniques, tooling, and a lot more.

How was Titan Ring Design started?

Titan Ring Designs is a part time, passion/hobby business of mine that I sort of started at the time I was ring shopping for a wedding ring back in 2013. I didn’t like what was available on the market and was inspired by a former Oakley designer to machine my own. I had been introduced to machining in High School at a technical college and had been working as a machinist since graduating in 2007, so I decided to make my own wedding ring. It sort of snowballed into my business in 2015, after finally deciding to make it official with a business license and some sales. Some further work experience in California for McWhinney Designs brought me greater motivation and encouragement to keep going and helped me get to where I am today. I now offer several different CNC Milled [wedding] rings, as well as a mechanical tie clip, some occasional art based designs, and freelance custom design and mill work. I also teach machining full time  at the same tech college I graduated from in my own education and enjoy sharing my knowledge and love for machining with those interested in the career.

What capabilities does your shop have?

Custom Design in CAD/CAM, 3axis CNC Mill work, Small Scale Lathe Work, Tumbling, Finishing, Assembling, 3D Printing/Rapid Prototyping. I cut 6-4 Titanium primarily, but also work with Stainless Steel for fasteners, Aluminum and some Steel for fixtures, and Polycarbonate for prototyping ideas. I teach machining technology full time, so I have access to SolidWorks, MasterCam, Fusion360, and NC Simul. We currently have a Haas OfficeMill 3axis, Levin High Precision Instrument Maker’s Lathe, Prusa i3 MK2S 3D Printer in the shop.

What sets Titan Ring Design apart from the competition?

There are lots of people making interesting rings today, but most are done on lathes. Anyone can make a round part on a lathe. Very few of them make rings on a mill, and I feel that gives the opportunity to be creative and allows you to think outside the box more. I try to stand out in that field by offering something that makes you think about the value of the design process more by interrupting and challenging the norm. I also like to take on work that is outside of jewelry, but still highly design related. Most other ring makers stick with just rings.

What is your favorite part of the job and what other passions do you have?

Making cool stuff! Most machinists only end up making whatever comes through the shop, which can be cool, but most of the time you have no idea what you’re making, just some part for Customer X, Y, or Z. Being a small, design centered business, I get to come up with ideas for what to make next, and most of the time I start out making something that wasn’t ever intended to be marketed, it was simply something I wanted for myself that I found others were interested in too. I discovered machining in high school and fell in love with it when I started making parts for my dirt bikes and truck. I’ve been hooked ever since but I do have other passions. I’ve always had a big interest in LED lighting and flashlights. I’m perpetually working on different ideas for making one of my own, which will happen eventually. I’m also a bit of a health-nut and enjoy being outdoors and spending time with my family.

Who is the most famous contact that you have worked on a project with?

I made a ring for an NFL player once, but I don’t follow football and his name didn’t stick out to me so I’ve forgotten who he was. I also had the privilege of working for McWhinney Designs and made some truly remarkable products in the openable wedding ring niche market. I gained more skill in design, machining, craftsmanship, and engineering while working for Jeff McWhinney. We’re good friends and often work together to help each other when one of us gets stumped on something.

What is the most difficult project you have worked on?

I was commissioned to design from the ground up and machine was a custom set of all-titanium cabinet door handle pulls for a very high end wine cabinet. Each handle was an assembly of 32 pieces, all machined from billet 6-4 Titanium. They required over 400 individual CAM toolpath operations, 35 unique machine setups, and well over 300 hours to complete, including finishing and assembly. More than anything, it was extremely time intensive in programming, set up, and machine time. The design was a fair bit challenging in my mind and initial modeling, but didn’t compete with what it took to actually produce them. I grossly underestimated and underbid the job. But in the end, I really enjoyed making a truly one of a kind, Tour-De-Force product, even if it was completely overkill for its purpose. I enjoy making that kind of stuff, and the lessons you learn from it.

What is your favorite project you have worked on?

It’s really simple and was initially designed just because I wanted it for myself, but I have a mechanical titanium tie clip that I really enjoy making. It’s quite unique in that, as far as I know, to this day, it is the only CNC machined mechanical titanium tie clip you’ll find anywhere in the world. It puts a little bling in your formal attire, for those times you have to go full suit and tie.

Why is high quality tool performance important to you?

Because I cut mostly titanium, tools wear out quickly if you don’t have a rigid set up, the right coolant, proper feeds & speeds, and of course, high quality tooling. Harvey Tool makes such a wide variety of micro tooling that works so well in the industry of making small titanium parts, where I like to fit into. I’ve used a fair spread across Harvey’s offering and have always been impressed with performance and the feeds and speeds guides are top notch too. I had an application that required a .0035” internal corner radius which landed me with a .007” end mill. It’s still hard to comprehend tooling in this league. My machine actually recommends only tooling under 1/4” shank size, so I don’t get into Helical’s range too often. But I’ve used Helical 1/2” end mills extensively at other job shops and they are definitely made for eating metal. I was using another tool brand’s key cutters for some undercut hinges and would wear through them much more often than I thought was reasonable. When I finally decided to try Harvey’s key cutters, I was blown away with how much longer they have lasted me. Truly a game changer!

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

Be creative. Machining is such a rewarding career that has limitless possibilities of what you can achieve. Follow your passion and have fun with it! If you end up in a dead end shop doing something you don’t like, go somewhere else. There are so many shops that need help right now and chances are good that you can find a better shop that suits your style.

Is there anything else you would like to share with the In The Loupe community?

To those machine shops out in industry, do whatever you can to be supportive of your local trade schools that are teaching the upcoming machinist workforce. They really need your support and in turn will bring you the employees you depend on.

Please take the time to check out Titan Ring Designs website or follow them on Instagram @titanringdesigns