Sprocket generator and CNCing sprockets

Hello CD!

After the competitive season was cancelled, our team has refocused our efforts towards solidifying our current knowledge and also completing several R&D projects over the next eight months. One of those, which I am taking charge of, is cutting sprockets (both #25 and #35) on our CNC. We want to be able to generate sprockets (ideally in in F360), some very large for a turret, so that we can produce them quickly. We currently use Onshape (CAD) and Fusion 360 (CAM). Does anyone have any tips for generating sprockets quickly and cutting them on a CNC?

Thanks,
J Rehagen 6672 Fusion Corps

We constructed a 200 tooth #25 chain sprocket for our turret this use. Designed in Iventor and then used Fusion 360 for CAM.

@GalactechGoat and @Ivan_Lamb Can you weigh in on this? Please help John get moving! Let’s use our collaboration tools to share our knowledge!

You can fairly easily CAD a parametric sprocket using this guide: http://www.gearseds.com/files/design_draw_sprocket_5.pdf

Alternatively, if you know someone with access to Gearteq it is very easy to generate a sprocket.

As for cutting one out, we’ve always cut the profile out with a 4mm endmill and then clean up the contour with an 1/8" endmill.

One tip I have is to use either .1" or .09" (3/32") plate rather then 1/8" plate since then you don’t need to chamfer the teeth.

Not sure how this translates to fusion 360, but to design the sprocket in inventor, we used the sprocket and chain tool in the design accelerator tab that comes up when you are in an assembly. It allows you to specify the chain type, number of teeth, etc and it generates a pair of sprockets and chain. We just had it make the one sprocket we needed and used the project geometry tool to create a new sprocket ipart which we could import into fusion to do the CAM.

3 Likes

Mastercam has a sprocket profile generator tool that I’ve used in the past to pretty good success. Generate the profile sketch, export as a dxf, import the dxf into your cad program to get a sketch, extrude the sketch as your sprocket. Each team has a mastercam license from the virtual kit of parts.

1 Like

@sgeckler @GalactechGoat why not use InventorHSM or InventorCAM or whatever they’re calling it nowadays

I’ve been trying to push the team in the direction of F360 for modeling and it includes pretty much a full CAM package too. No real reason to use two packages except most of our older students are more comfortable modeling in Inventor.

I just like the option F360 brings for collaboration away from our computer network.

Thank you all for your help so far. I looked into downloading other programs but decided I did not want to go down that rabbit hole. I found an add in for F360 that should work (looks like a similar generator to the others people have shown in this thread) but I am not sure what parameters to put in. The drop down has:

  • Pressure Angle (14.5, 20, 25 or custom)
  • diametrical pitch (number of teeth per inch of pitch diameter)
  • number of teeth
  • Backlash (in inches)
  • root fillet radius (which seems to be the inner radius in between teeth)
  • Gear thickness (I know this one)

Does anyone have any guidance on what parameters I need to use?
I looked up ansi spec and for #25 it had a pitch of 0.25 in, which should mean the diametrical pitch is 4? (1/0.25) and for #35 (0.375 in pitch) a diametrical pitch of 2.66666…?

Edit: Just found some ANSI dimensions
For #25 it says the roller diameter max is 0.13 - so should the root fillet radius be 0.13/2 =0.65?
For #35 it says the roller diameter max is 0.2 - so should the root fillet radius be 0.2/2=0.1?
is this correct?

Edit 2: This add in is for gears not sprockets - I do not know how to read lol.

Thanks!

For our 154 tooth sprocket we generated it with the tool built into Solidworks and then brought the dxf into onshape.

do you know what parameters (pressure angle, diametrical pitch, root fillet radius etc) you used?

The only issue I have found with F360 in regards to sprocket and gear generation is purely the lack of documentation. What I have found however, is that gear generation is possible, but I do not know how to use the tool in F360. Other than this issue, I have found that F360 can be a much more powerful CAD/CAM software compared to inventor due to its ability to share files and directly import CAD models from McMaster Carr without having to download and upload like inventor, solid works, pro-e, etc.

Can you post a screen capture of the sprocket tool in whatever CAD package you are using. Chains don’t have a diametral pitch and root fillet radii; that is for gears. I think you are working in a gear generation add-in. Chain should be a lot simpler.

@GalactechGoat can you check fusion for a chain tool?

Yup I misread the title of the tool I was using yesterday… it was a gear generator. I could not find an add in for sprockets. If there is one that would be awesome (and easier than what I am doing right now… writing a custom featurescript in onshape).

Theres a program called sprocketeer that also generates sprocket dxfs. Idk how accurate it is tho.

1 Like

I will check that out. Seems like a decent solution

It doesn’t look like there’s a sprocket tool in fusion or one on the Autodesk app store for fusion. At this point it might be best to watch a YouTube video and learn how to make a sprocket geometry manually. You’ll gain some useful knowledge too!

Yup! I used the link @juju_beans sent to make a sprocket manually this morning and I am now in the process of making it into a featurescript so it will auto update values. http://www.gearseds.com/files/design_draw_sprocket_5.pdf.

Thank you all for the help! I’ve learned a lot.

2 Likes

Anyone have a good reference for the correct bevels/chamfers for a given sprocket pitch?

I mentioned it before, but if you’re looking to make a #25 chain sprocket if you use .1" or .09" thick plate you will not need to chamfer it.

I can vouch for sprocketeer. We used it to make a 120 tooth sprocket this year and it worked flawlessly. We took the DXF and cut the sprocket from .125" Delrin on a laser cutter and then slightly chamfered each tooth and haven’t had any issues yet.