We have the following motor as part of our project.
The motor has 4mm shaft and we are having a hard time finding a gear/pinion with 4mm bore size (plus 0.7m and 17T) . We’d appreciate any guidance on this.
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I dont know about an off the shelf pinion, sorry, but have you tried 3d printing one?
I use small gearmotors on a number of projects and have had enormous success with 3d printed pinions and gearsets.
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Hi Riddhi,
Andrew makes an excellent point about 3D printing one! PS: if you turn down the line width in your slicer and flow rate accordingly you an cheat some more resolution into your print 
Another excellent part to pair it with are these universal adapters that let you attach a wider range of parts to the shaft.
Liam
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Oh, and my 3D printed gear tip of the century is to use McMaster Carr. Find the specific gear that you need and they ALL have downloadable STEP files that you can edit in Fusio360 or your modelling software of choice.
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3D printing is a definitely great option for custom gears if you’re not putting the hardware/motor under serious strain/really long life.
I did something very similar printing gears that press-fit into a very similar DC Motor seen here in the project build for the QuadBeest Project.
This was a friction press-fit and I didn’t have any issues with that part of the build.
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Thanks, Andrew,
The link you provided is going to be super useful. Initially, my thought was to get it 3d printed but then I had the same issue on 3d printing sites - cannot find the right bore, module size, and tooth numbers. So went back to looking for an off-the-shelf option. The link you provided looks like has tons of options and I am hopeful of finding my precious there.
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Thanks, Liam, I had a look at the adapters, however, they seem slightly wider in diameter than what I could use. However, they might fit just right for my other projects.
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This was another reason i wanted to get an off-the-shelf metal pinion. However, I am going to give an ABS print a try this time.
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Is your application a slow or high speed use case?
I generally only have slow speed gears so printing in just regular PLA is totally fine, however a couple of my gearboxes are fast and I’ve not really had many issues.
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Hey Andrew,
Very clean prints!! They’re some shmick gears 
Liam
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Thanks again Andrew for the tip. I looked up the site and I found the following as the only relevant option there: McMaster-Carr
It is module 0.8 and my requirement is 0.7. Do you think it may still work?
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it is important to have the modules to match, but if you can print it yourself, just try it 
I see that you want module 0.7 and 17 teeth with a 4mm bore, if you’re printing, ignore the bore as it is trivial to change.
What is the pressure angle and OD that you need for the gear?
Can you find the gear that you are trying to mate it to in McMaster Carr?
Hi Andrew, I thought of answering the pressure angle question by saying “straight angle” 
but the correct answer is that I don’t know the exact term that I should be using so herewith I have attached a picture.
P.S: high-speed use case.
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Ahhhh, the big gear is 3D printed and the pinion has adjustment via the motor, are you after a specific gear ratio or are you after the 17 teeth to replicate what’s there?
0.8 to 0.7 module might not be a big deal as you have adjustment, but wear might be wrong if they dont match.
The only other option is to roll your own 3D model using a gear creation plug-in, then you can get whatever you need.
Ive been able to get by with McMaster Carr for everything as I havent been trying to match to something existing.
Last option is to change the big gear too seeing as it is printed and get the same modulous and size from MC.
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Hi Andrew, thanks again. I might go with 0.8 for now and see if it all works otherwise will get a custom 3d model for the gear. Might even look at changing the motor.
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