Looking at cnc milling tool paths and the lead in, lead out marks that end mill cutters can leave behind. Part design can avoid these slight imperfections
@@vikeskie Engineer that sometimes has to design tooling for their job.I work at a small company and there is no dedicated professional CAD designer so I had to learn it by myself.
See if your local makerspace has one, or if you can help them get one! Sharing a machine is a great way to afford one, and meet a community of interesting people to boot.
The importance of these design-for-manufacture videos cannot be understated. I'm an industrial cnc machinist getting more serious about designing, I appreciate every single one of these videos. If only I can get some engineers to watch these....
As a mechanical engineering student who wants to go into manufacturing design, I can't agree more. I came across this channel by happen stance and love learning all these tricks I otherwise wouldn't know.
I've been doing CAD for a while now and I've literally never thought about any of these imperfections. Seeing the machinist's perspective is fascinating
Another thought-provoking video thanks Adam. I've been experimenting with very shallow approach angles but even then, there's a tiny amount of tool deflection and I can even see a tiny ripple cause by the tool starting to engage and bouncing. EVERYTHING is rubber below a certain scale. Taking a final contour pass at 5 micrometres above a floor step is still a band-aid solution. I'm still a rank beginner, but I'm convinced that designing in machinability is more sensible than finding tricks to avoid poor design choices. More of this please!
Brilliant insights as usual a lot of detail that nobody ever talks about and probably nobody really understands fantastic video as usual can't wait for the next one
This is again a nice one. Even though I do know and use some of these techniques, I learned a lot more that I'd like to try. I do a lot of milling of aluminum parts which are anodized after milling without any processing in between those steps. That means careful planning of milling strategies, not just the lead-in/lead-out transitions but also blending tool paths of different tools, preventing any steps when having multiple setups etc. This also means that I do think of the milling tools and strategies to use during the design phase, sometimes using the imperfect result as a surface finish - but that does come with the challenge of making sure that imperfection is constant over the whole surface of the part.
I split the part into full loops height wise and mill them all the same way. Mill to nominal size directly and make a spring pass without compensation for the tool to relax into the work the same way. By doing so the steps are hardly recognizable. I also put a tiny ch am fer (0.1 mm) on sharp corners and start in the middle of it. Break sharp edges this way and making the start/end invisible. Another strategy I learned is to use the full cutting length of the cutter all the way using adaptive strategies. In the past I would use 1/2 D z height in step size per pass. By doing so this end wears out first and start approaching a conical shape. When blending in top/bottom configurations you end up with a more or less visible transition line. If you use the tool in full cutting height as much as possible the tool wears out more uniform and transitions will look and feel much better during the life of the tool. And, in single part production or a small batch; depending on the function of the finished part some elbow grease in combination with steel wool, scotch rite, high speed de-burring tools and fine sanding paper and the right mindset can make great results too. Maybe some tips here. Adam, your the king here, I just try to add some useful information. I learn a lot from all of your videos. Thank you! Stay safe and all the best! Job
@adamthemamachinist thanks for the video. It should be obvious that your aim in this video is not the machinist but the designer. Some engineers can’t understand/care about the machinists and/or mechanics. Impossible to do a simple repair because of a nut/screw’s bad placement; you have to disassemble the whole piece. On the other hand you have small shops where the staff works as a well oiled machine; better when you are the designer, machinist, mechanic …… sales rep, accountant, ad support tech.
Still watching the video, but I've found that when I lead in on the curved sections with a tiny overlap I often can't see any lead in marks. I experimented with shallower angles for lead-ins on the flat sections and could never get it perfect. But a 35-45 degree leadin/out on a filleted corner seems to work great for what I make. I am loving these videos and learning a lot from them. Appreciate you making them! EDIT: Hah, I was 30 seconds away from you saying the same thing about the corners. Too funny. FWIW, I do this not only on contours but also on chamfers, the same applies.
Thank you for taking the time to share your experience. This is all masters-level stuff and I am barely an apprentice, but I appreciate it just the same.
Great video, thanks! For aerospace parts we see the same challenges on pockets with several different floor heights and brackets with thickness steps. Usually the cam department makes happy noises when i explicitly design into the cad model how surfaces are supposed to meet up. Often i do this with 0.1-0.3 mm surface offsets on the negatives bodies that i subtract from my part body to make the pocket. It makes all the mismatches explicit and on a general tolerance of 0.5 mm it falls away in the tolerance band so no need for quality to try to measure them.
Your calling yourself a machinist is why I never call myself a machinist. I've seen machinist and I'm just a guy that can kind a run a mill and a lathe. Thank you for teaching us.
What interests me with this series is that hobbyists like myself on flimsy manual machines often must deal with these sorts of details MORE than pros with super rigid, ball-screw CNC machines.
Great video lots of good information, please can you do a video on work holding on the cnc milling machine and surface grinder explaining how designers can make complex parts easy to hold and minimise distortion
Awesome. Another good video would be talking about similar problems from the machining perspective. Things like how roughing surface finish effects tool deflection on the finish, use of high accuracy modes (fanuc g5.1, not sure about haas), endmill selection, lead radius sizes, etc.
I split the part into full loops height wise and mill them all the same way. Mill to nominal size directly and make a spring pass without compensation for the tool to relax into the work the same way. By doing so the steps are hardly recognizable. I also put a tiny ch am fer (0.1 mm) on sharp corners and start in the middle of it. Break sharp edges this way and making the start/end invisible. Another strategy I learned is to use the full cutting length of the cutter all the way using adaptive strategies. In the past I would use 1/2 D z height in step size per pass. By doing so this end wears out first and start approaching a conical shape. When blending in top/bottom configurations you end up with a more or less visibel transition line. If you you use the tool in full cutting height as much as possible the tool wears out more uniform and transitions will look and feel much better during the life of the tool. Maybe some tips here. Adam, your the king here, I just try to add some useful information. I learn a lot from all of your videos. Thank you! Stay safe and all the best! Job
lots of great tips, thanks man How i imagined 11:04 came to be: Client 1: hey do you know a machinist who does nice 'shafts with protrusion' work at all? Client 2: Hey yeah, i know i guy, heres his number 🤣🤣😂😂 Client 3: Sweet, can i grab his number too?
I split the part in full loops height wise and mill them all the same way. Mill to nominal size direct and make a spring pass without compensation for the tool to relax into the work the same way. By doing so the steps are hardly recognizable. I also put a tiny chamfer (0,1 mm) on sharp corners and start in the middle of it. Break sharp edges this way and making the start/end invisible. Maybe a tip. Best! Job
All good tips, I generally use a mold making endmill and fine step downs to achieve a clean surface. The goal of the video was to address this issue from a design perspective though. How much time and money can be saved on a global scale if we didn’t need to do spring passes and extra cuts to avoid some tool marks
@@adamthemachinist ; I totally agree. For me this is a way to gain satisfaction for the work that I've done. My clients visit my shop before and after the work done. A lot of them are young and inexperienced. I reflect on their design and the consequences it has on the production of the part of parts. By doing so I recognize they appreciate my input and they get better at their job. Progress for both parties.
Another finish issue that drives me nuts is tool swirls on a milled face. Sometimes it'll happen during a straight line move because a chip snags the tool. But the main situations that annoy me are parts that either a facemill doesn't come off a part before jogging to the next pass or a face or pocket that is cut with a square type toolpath. When the machine stops one axis and switches to the other it dwells momentarily leaving a circle swirl. Whereas if it was done with nice sweeping corners so there is never a stop in the machines motion those swirls don't happen. I was just looking at a part this morning done by someone else that did this. It's a roughly 8" square flat face that was faced off with an endmill using a square corner pocket type tool path. Every change in axis left a circle instead of doing a circular type facing tool path so the machine never paused.
I’ve found in fusion, if you just do a spring pass on a 2D contour the lead in line is basically invisible, also I’d love it if you could discuss surface finish on flat/horizontal faces when milling. This is something I struggle with when making injection moulds unless I can use a carbide tipped cutter like a face mill. If I use an endmill I never get a good finish
hey nice video as always, you could do a video about when to use what metall for wich purpose. we get often customers in our shop that have no idea waht kind of Material is really the best for their application. greetings from germany
There is a radius making the final transition. Usually about 4-5 times bigger than the amount of finish stock. That has a similar effect to a subtle angle entering the cut.
Granted I'm watching on a phone, but when you're holding up parts with examples of bad blending, i literally cannot see what you're talking about. I guess that would make me a pretty laissez-faire customer!
Imagine reaching the point in your CNCfu where you have to take stuff like Machine Thermal Expansion into consideration 😱 That being said... Wouldn't this being an issue essentially mean you're using the wrong machine for the Job? 🤔 Couldn't this be solved by essentially air-conditioning / water cooling the critical parts of the machine? 🤨 Perhaps next a Video about small and or thin Parts Work Holding? 😁
Thermal management is really what it’s all about past a certain level. Having a chilled motion system , cutting fluid , and spindle solves most of these problems. But even odd things like your compressed air being piped in needs controlled when you want that last percentage of thermal consistency
It's not that crazy for a lot of machinists and shops. My main VMC does not have a spindle chiller and if you're running it at 10k (max) for a while it will get warm and grow in Z. Most of what I make doesn't have critical features in Z so I don't have to worry about it very often, but it's not that wild of a concern in general.
*Minimizing Visible Tool Marks in CNC Machining: Design Considerations for Seamless Aesthetics* * *0:18** Lead-in/Lead-out Marks:* Introducing an end mill to a cut creates a lead-in and lead-out, resulting in a small step or mark. While acceptable for many applications, high-end products might require minimizing these marks. * *2:00** Strategic Lead-in Placement:* Placing the lead-in point at a corner or fillet tangent point can effectively hide the transition and minimize visible steps. * *3:19** Challenges with Flat Surfaces:* Blending steps on flat surfaces is challenging as the same tool cutting at different depths deflects differently, making a seamless transition difficult. * *4:29** Design Adaptations for Flat Surfaces:* Instead of flat surfaces with steps, consider incorporating cutouts, large chamfers, or radii to provide a natural blending point and eliminate the need for a potentially visible step. * *6:48** Orientation Changes and Kinematic Errors:* Flipping a part in a multi-axis mill introduces kinematic errors, making it difficult to blend surfaces machined in different orientations. * *7:54** Intentional Steps for Orientation Changes:* Design features with intentional steps between them when they require machining in different orientations to avoid visible mismatches. * *8:39** Micro Features and Blending:* Blending micro features into larger surfaces presents challenges. Using a larger end mill for the primary surface and a micro end mill for the feature might require multiple passes and adjustments. Facing the entire area with the micro end mill could introduce excessive tool wear. * *10:58** Turned Features and Milling:* Blending milled features into turned features (like a shaft with a milled protrusion) is challenging due to inherent differences in surface finish and potential thermal expansion of the lathe or mill. * *12:56** Intentional Steps for Turned/Milled Features:* Design a slight intentional step between turned and milled features to avoid blending issues and simplify machining. * *14:41** Splines and Turned Features:* Similar to other turned/milled combinations, blending splines into a turned diameter can be difficult. Consider an intentional step to separate the features visually and functionally. * *15:15** Surface Finish Differences:* Turned surfaces have a fine thread-like texture, while milled surfaces have a scalloped texture. This inherent difference makes blending them visually challenging, even with minimal size differences. * *16:15** Intentional Steps for Aesthetics:* For high-end parts where aesthetics are paramount, intentional steps might be the best approach to ensure a clean, visually consistent appearance, especially when blending different machining operations or surface textures is involved. I used gemini-1.5-pro-exp-0801 on rocketrecap dot com to summarize the transcript. Cost (if I didn't use the free tier): $0.07 Input tokens: 17189 Output tokens: 562
