FreeCad Tutorial #6 | EASY way to Model a KNURLED Surface for 3D Printing in FreeCAD

[@valdemar7986]

one of those cases when after watching a tutorial one would have more questions then before. thank you, good stuff.

[@LethalDose100]

Nice method, especially compared to some of the more complicated approaches I watched first. With that said, I had an issue generating the subtractive helix. Turns out it was because I missed one fundamental step in the sketch... I didn't toggle construction for the circle and 45 degree line. As a first time user of the software, this was not an obvious thing for me to check. I actually re-watched the video numerous times before I realised my mistake. It might be worth adding an annotation in that section so that other newbies like myself don't make the same mistake. Thanks for the video!

[@calmarcalmar]

Well as a complete novice, you want every .... detail, later you do not want to lose stuff what is obvious to you. Anyway, with tinkering around, you learn too. As a complete novice, maybe you should learn easier stuff beforehand.

[@anoopdsouza6868]

This comment was very helpfull. I too am a novice and was getting an error of wire frame. After fideling around a lot and repeat watching the video multiple times, I checked the commets. Thank you saved me a lot of frustrating time waste.

[@northtexasskies7786]

Thank you! Now I can finally complete my cases for my photography filters.

[@atzimas]

Hello KTEC DESIGNS. Very nice and informative video. As an undergraduate software engineer I can tell you that FreeCAD, as per documentation uses an OpenGL-based 3D API which means that it tries to either offload the calculations to your computer's GPU or, if you are doing this on a computer without a dedicated GPU (eGPU), uses the embedded GPU of your CPU. Now, eGPUs of modern CPUs are generally lower powered components designed, in most cases, for basic display output and are much less powerful than a normal dedicated GPU. In this situation FreeCAD tried to offload the 3D calculations of the model to your computer's GPU and straggled because it's a hefty calculation due to the geometric complexity of the knurled surface. I hope this is informative enough. Keep up the good work!

[@oneman29]

Is there a way to change the settings? Like in blender when rendering, select cpu or gpu

[@macdroid53]

In this case, it is a combination of the OpenGL render after the OpenCascade 3D engine does the calculation. OpenCascade, as most older solid engines, are not using multiple cores. This operation, for solid model math is very compute intensive.

[@macdroid53]

And, no there are no settings to change how the various libraries use the cpu or gpu. You can adjust limited functions of OpenGL in Edit>Preferences, but this changes how OpenGL addresses things like render order mostly.

[@dftdbs1010]

No wonder it is constantly taking a shit on my old laptop haha GPU power is non existant.

[@avongil]

Takes about the same amount of time with a quadro k40000. Commercial packages do this almost instantly. Its a shame, freecad is getting pretty awesome.

[@radpaul2574]

Thank you for the video on this i was able to make my own hand grips at 100mm long. The rendering was a bit of some time but my old computer was able to pull it off. I used the latest FreeCad 1.0 with ease.

[@brucewilliams6292]

Thanks for the video. I do like the way you changed the colors. Subscribed.

[@KTECDesigns]

Thank you!

[@brucewilliams6292]

@@KTECDesigns If you would be so kind, could you do a video on how you changed your colors? Thanks for the video again.

[@samuelgeer4332]

Wow loved watching this

[@anpier926]

Thank you, lots of things learned in your video!

[@na5y]

Just what I wanted! Thank you!

[@calmarcalmar]

beautiful theme/colors there

[@ahmadmohammadi8922]

Thanks. Short and effective.

[@geofelen]

Very informative. Thank you. Is it possible to add a knurl to a tapered shaft? Are there any tutorials showing how?

[@brianprice7020]

Freecad has a lattice 2 workbench as an addon. It is a more in-depth method to do polar and linear arrays. Its computing time is much quicker.

[@KTECDesigns]

Thanks, I’ll try it out. I’ve seen it before but haven’t dabbled with it yet.

[@olafmarzocchi6194]

One of the things which make FreeCAD so difficult to begin with. The same stuff can be done in various workbenches and each one has specific limitations not obvious at the start...

[@KS_Pictures]

Calculation Tip: To get the Turns required I created a calculations sketch (hidden, containing only construction geometry). Create a line at 30° Angle from origin. vertical length of line = part height. Then use a reference constraint to get horizontal length of the angled line. Divide horizontal length by `2*pi*(part diameter/2)` to get the value to use for turn of Subtractive Helix. To get the amount for Polar Pattern I used `[2*pi*(part diameter/2)]/[(knurl depth*2)*1.8]`. This calculated to 29.99 for me so I use 30. If the result is not up to expectations the last value can be increased/decreased slightly to get a better result.

[@KTECDesigns]

I finally found my calculation. I used the distance formula (h = sqrt(a^2 + b^2)) to find the length of the square's hypotenuse (because the square is small, it's roughly equal to the arc length between the coincident points of the square that sit on the cap's circumference). I then used that arc length to find how many instances of the square that I can fit along the cap's circumference. That formula is "pi*D/h". Since this represents squares in sequence end-to-end, I divided the result by 2. So, "h=sqrt(2)" for a square that is 1mm x 1mm, and D=50mm, therefore the circumference "50*pi" divided by the arc length "1.414" is approx. 111. Divide that by two, you get 55.5. Rounded down I ended up with 55 instances.

[@roncouch]

Yes, very neat indeed! However, KTEC says at the outset quote “ if you’re new to FreeCAD….” and then quickly plunges into the process with little time given to explicitly enumerate the command options selected: following the mouse pointer in order to determine this was nigh on impossible. Yes, I get the principle, but - as the tutor says - I am indeed new to to Freecad, per se, and am finding the command structure - compared with my most familiar Sketchup pro - a little difficult to grasp without explicit guidance. FreeCAD is not, I find, particularly intuitive. I wish I could slow the video down so I could decipher the specific commands used to create this really impressive knurl, especially as I need to model a very similar cap and then create a 3D print from it. But yes, a really cool solution compared to other videos on this subject. PS: after re-running the video a number of times, managed to twig how the helix was generated and the polar array executed….phew!!

[@Appregator]

Threaded screws make huge files and take time to process as well. Lots of computation.

[@trevortjes]

(FreeCAD 0.20) Upon adding the second subtractive helix, the first one got deformed somehow. I thought to fix that by using pitch height for both helixes, but upon waiting 10 minutes for the polar pattern to finish, I got an error that a boolean operation failed. So much for knurled surfaces.

[@the.real.ipatch]

great tutorial. food for thought. could you duplicate your helix patterns to a shorter length, and then apply your polar pattern to the shorter length helixes so you get a more rapid feedback? and then when you get something you like apply to the entire surface.

[@denis_2783]

Very nice video👍🏻👍🏻👍🏻👍🏻👍🏻

[@mecanizadosgrela7380]

,Hello, the video was useful for me.Thanks.

[@ronin2167]

What mode are you running on? I like the colors.

[@freecadantibugs8697]

Very clever

[@MikkoRantalainen]

I would guess it would have been faster to repeat the square and do only two subtractive helix operations. Similar to programming in general, try to minimize the loop count for the most expensive operation.

[@roelofliebenberg2880]

How did you get to the 55 turns in the boolean pattern?

[@pik4chu]

It's the number of times the knurl cut fits into the circumference of the circle so (diameter*pi)/knurl size = number of times it fits

[@daffhead4975]

Nice tutorial. I tried to follow it for another knob. But when i'm trying to make the second helix for the knurls, i get a error, face must be planar. Trying to learn how to use cad by mixing videos and testing for myself. You got any idea what could be my problem?

[@TechieSewing]

I don't understand how the helix settings translated into the diagonal line, and how polar pattern of these lines made final knurling. Seems to just happen but how? The final result does look good.

[@avongil]

Helix is applied as a pitch. Distance in the axis direction per turn. For a 10mm long knob, 1mm pitch would give you 10 turns. 100mm pitch would give you 0.1 turns.

[@nigozeroichi2501]

Awesome, and now I have to get an A axis for my mill 😮‍💨 when will it end, BUT I knew what I was getting into when I when down this rabbit hole😁

[@michaelmelton4726]

Could not get the subtractive helix to do what your video shows. I have watched this video several times and still cannot mimic your process I get "linked object is empty", also the helix parameters do not change when I select the z axis, height, turns,etc ANY tips?

[@yakdaymar6659]

Thank you verry good😍😍😍

[@Sembazuru]

So now I see this after printing some dust caps for some solar filters. It would have been nice to have actual knurls. I used PrusaSlicer fuzzy skin to create a grip on the external surface.

[@infindel]

I keep getting a wire not closed error after trying to make the helix.

[@olafmarzocchi6194]

Why not a polar pattern in the sketch itself?

[@travisjohnston1923]

I have a similar problem as the number of faces increase. I made a plaque and it ended up around 1600 faces and everything I did after I padded the text just ran slower and slower, and I gotta say, from a design POV, knurling creates a multitude of faces.

[@johnernest8109]

It seems that doing Boolean Unions or Cuts in FreeCAD with a lot of intersecting geometries takes a while. I tried a couple of other approaches and it took about the same time. Try cutting in only one direction and see how much less time it takes in comparison.

[@DominionDroneDaily]

When attempting to do the helical cut, I continuously am getting a " wire not closed" error. I've went over all the constraints & it all looks good but still getting the same error. Any suggestions? Thanks in advance

[@hkckoo]

have the same error, not sure what i did wrong. edit: solved it by removing everything from the sketch except for the rectangle and constraining that at neccesary distance from the center of plane

[@Dartheomus]

I followed along, and I have a computer that is overkill for most operations. That said, this sucker still took about 2.5 to 3 minutes to calculate! Really nice trick though! :)

[@rebeltaz123]

You said that you "calculated" that you needed 55 repetitions. Can you explain how you calculated that number?

[@santisis]

You need to calculate the perimeter of the cap as pi*diameter, that's the total length to cover. If your pattern has L length, then the number of repetitions must be the integer number closest to pi*diameter/L.

[@louislaunders364]

Question. Why model a feature like this rather than just use a drawing annotation and callout? It's resource intensive, and in my mind doesn't serve any purpose as knurling is typically not a cnc machined feature.

[@keithroberts8568]

I've tried to create your example, but I just can't get it to work. When I create the second subtractiveHelix it wipes out part of the body. Also I tried to polar array just the one subtractive helix and it won't create more than about 15 copies without wiping out the body. I get this error when I array it. Error: one transformed shape does not intersect support. I've messed with it for two days trying different things but nothing works. Any help would be appreciated. Thanks

[@KTECDesigns]

Sorry to hear that. I'm not quite sure what the issue could be. If you send me your model via email, I could see if I could figure out the issue. In general, though, it's a computational intensive operation, so perhaps your computer is struggling to compute the result.

[@roncouch]

Had several attempts at this. Even tried padding my sketch instead of revolving it to produce a solid body, but to no avail: same error message pops up every time. “Wire not closed” when selecting the helix command. Anyone any ideas? Website returns: “There do not seem to be any answers to your search”, or words to that effect.

[@KTECDesigns]

"Wire not closed" could mean that the sketch entities are not closed. By that I mean, the square might not connect together at every corner. You can check this by clicking and dragging each line in the square to see if it is able to move. The same with the vertices of the square. Another thing to make sure is that all other sketch entities besides the square are construction lines. If you are still having issues, you can email me a copy of your model, and I can see if I can find the issue.

[@roncouch]

@@KTECDesigns Success! had another go and encountered an oddity. Attempts to create a fully constrained rectangle/square were frustrated by the vertices not being selectable even with the body made invisible. The solution for me was to (effectively) flip the sketch by padding the body in reverse. Creation of a fully restrained square was then achieved without difficulty and I was able to create the opposing helical grooves and apply the polar array without any further problem. One further point. At the sizes used in your demonstration tutorial - approximately 1mm square - the sketch wasn’t displaying in model space after the constrained sketch was closed. By increasing the size: I used a 20mm square, the sketch was clearly displayed. Of course, at 20mm the results of executing the helix command were somewhat bizarre. However, I eventually settled for 5mm and all was well. Yes, I did maintain the depth of cut at 0.8, the “surplus” body, therefore, had no impact on the final result: it simply increased the visibility of the sketch in model space. It did occur to me that because I elected to use 20 occurrences in the polar array it also avoided the possibility of the larger sketch colliding with itself in the event I had opted for the maximum possible number of grooves? In SketchUp which I use for developing engineering design ideas: currently a sphere turning fixture for a woodturning lathe, I tend to create subtracting volumes, when executing boolean operations, that are (probably) a lot larger than they need to be, but it dies ensure the operation doesn’t miss anything. I fancy, by enlarging the sketch to a “generous” size in this knurling exercise, I was instinctively applying the same logic and successfully too. Would possibly be subject maybe, to the “collision” phenomenon when higher occurrence values are used in the polar arrays. By the way. I appreciate your responding to my plight, thank you.

[@neilweideman2938]

Awesome thanks

[@arctictimberwolf]

You need to slow down your Mouse Movements and make your Pointer more Visible. People can barely see what you are doing.

[@Andreas-gh6is]

One tip: you can calculate the number of polar revolutions in the expression editor by referencing the knob radius, pi and the knurl-thing size.

[@zxcii1817]

would that be: 2 x r x π and then whatever comes out of that divided by the length of the knurl-square?

[@ff-mu6cc]

cool!

[@JordanAnastasio]

I tried to accomplish this on my macbook and failed miserably. Any time he clicked and point to move it I was simply unable to do so. I just wasn't getting the same results whatsoever. Idk...

[@gyllgyllidor6720]

I bet if cut in one direction and after that in second direction it will be much faster

[@channelcadfree]

👍👏

[@stanislavkonstantinov9236]

Nice

[@eiscaer]

Ugh I can't wait for a macro that does this.

[@dftdbs1010]

We need a knurling workbench for freecad, as well as a thread workbench, this sketching shit has to go, when a feature can easily be automated, it should be.

[@keithroberts8568]

There is a Fastener workbench that does all threads.

[@RustyTube]

Why does everybody show how to do this on a cylinder and nothing else? How do you do this on a real thing?

[@KTECDesigns]

This is a real thing, and most shapes that get knurling are cylindrical. This can also be done on a flat surface. If this comment gets enough likes, I’ll do a flat surface example video.

[@RustyTube]

@@KTECDesigns Yes, please do.

[@repeters1]

@@KTECDesigns I was just looking for how to put a knurl pattern on a flat surface. Please let me know if you do decide to do a video on that.

[@Jhfrbcf]

I think it calculates slowly because of python?

[@kozko-xe1xl]

[@JBJHonez]

Your bouncing around the screen back and forth made it a bit hard to follow. Even the speed of what you clicked on was a bit fast for people trying to follow and learn. Had to pause the video a lot and go back and forth

[@JBJHonez]

Worthless because we can’t easily see what model you’re on a such. Can you redo it with less jibber jabber and get to the point. To many back and forth

[@JBJHonez]

A lot of useless talk that’s confusing

[@_droid]

It's slow and uses a ton of memory because Python sucks