Drawing a T5 timing belt pulley

[Anonymous]

I am building a 6 axis robotic arm from Github.  One of the pieces has an 82 tooth T5 timing pulley.  I have tried saving it as an STL using the high option for quality before printing it, but the pulley does not mesh well with the belt.  I am new to CAD and am at a loss as to how to improve the mesh.

One of the other pieces also had a 3d printed pulley that I got a CAD file for and put in as a replacement for the one the original author supplied and it works well.  Unfortunately the biggest pulley I have found to copy is a 60 tooth.

How to you draw a timing belt pulley?

[etfrench]

Compared to a T5N pulley created in Gearotic, your pulley is too large and the tooth depth is too small.  Attached is your file with the Gearotic pulley.  Print a paper copy of the pulleys and compare that to the actual belt before doing the 3d print.

The Gearotic pulley was imported as an stl mesh.  You can use the Sketch|Mesh Tools to convert it to a 3d model.  (The search function isn't working for me, but there are several threads that detail how to do this)

[Anonymous]

The pulley you sent does look like a better match.  

I have  not been able to convert it to a solid body.  Tried several of the methods cited in the forum with no success.

Downloaded the trial version of ReMake (used to be Memento). It uses 100% of my I7 based computer for more than 10 minutes before I gave up on  it.  Tried in both low and high quality exports multiple times with now luck.  Picked the Fusion 360 style .OBJ file for the export.

Any suggestions?

[etfrench · Accepted solution]

Here's a video showing the process:

Updated file attached

[Anonymous]

That was really helpful.  I will print a test using the file you supplied and while its printing try following the video to do it myself.

Thank you very much.

[Anonymous]

The mesh with the belt is really good.

Tried following the video and got to the end and it failed to generate 82 copies of the pattern.  If any one else tries this, note that you need to increase the precision for angles  to 4 decimal places.

[etfrench]

@NicolasXu:The pattern problem looks like another data point this bug: https://forums.autodesk.com/t5/design-validate-document/rectangular-pattern-bug/td-p/6928823

[NicolasXu]

Hi @Anonymous,

Do you mean increasing the Angular precision in Preferences dialog? I tried re-creating the circular pattern based on @etfrench‘s file (T5n_82t_002.f3d), but was not able to reproduce the failure.

Could you attach the file where you saw the problem so I can take a further look?

Here is what I have tried:

Best Regards,

[Anonymous]

Yes, the setting that needs changed is the angular precision in the preferences.  I would attach the file but I deleted it since it was a failure. You were able to insert 82 teeth because you were using the file supplied by @etfrench.  The problem occurs way earlier in his file when he dimensions the angle from the center of the tooth to the line on the left side.  He divides 360/82/2 and gets 2.19512.  My precision was set to one decimal point and it rounded to 2.2 and that makes the tooth segment to large to put in 82 of them.

82*2.2*2=360.8  

82*2.19512*2=359.99968

I am really new to CAD and have gone back and now can't manage to do the mirror step from @etfrench's video to show you.

[NicolasXu]

Thanks for the update, @Anonymous. I got your point.

I tried the default angular precision but was still not able to reproduce it. If you happen to run into it in future, please feel free to post here. We’d like to take a close look and understand the problem.  

Regarding to the precision, if you want to keep the dimension precision, you may want to try working in history-based modeling environment (aka parametric modeling). In this environment, any user-entered expression should be remembered and persisted; the precision setting in Preference dialog only affect the display, not the real value. You can right click on the root node in the browser and select “Capture Design History”, to enter parametric environment. After that, there will be a timeline displayed at the bottom of the application window.

Thanks,