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Topic: I've been looking for gears!!!

Im been looking for gears for so long does anyone have or make a matching 10 tooth gear and 100 tooth gear with 2mm drive hole. Diameter needs to be less than 30mm.  I dont have internet on my 3d modeling computer so I cant down load the gear plug in but I can transfer files via thumb drive. Any help would be very helpful

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Re: I've been looking for gears!!!

Inkscape can make gears and then export a dxf.   Make Magazine had a tutorial,  if you Google Inkscape,  gears and Make it should turn up.

3 (edited by pirvan 2014-04-03 03:50:55)

Re: I've been looking for gears!!!

The problem you have is the imposed diameter of 30mm.  Gear sizes are referenced by module, where the module of a gear is the diameter in mm divided by the number of teeth.  In your case the module would be .3.  The problem is that I've tried printing .25 and .3mm module gears before, and the teeth are way too small for the printer to print sharply.

The smallest usable gears I was able to print were with a 1 module.  That would make your large gear 100mm (~4") diameter.

Here is a drawing of a gear set with .5 module

http://www.soliforum.com/misc.php?action=pun_attachment&item=4970

Edit:
P.S.  If you do want to try and print them, I can make and post the STL's, I just need to know the face width (the thickness of the gears), and if you want a hub (so you can use a set screw).

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4 (edited by grob 2014-04-03 05:35:07)

Re: I've been looking for gears!!!

1:10 is a big ratio for gears - and big ratios means worse vibration at speed, poor space usage and weak teeth in the pinion. Also, 10t is pretty small for standard metric module gears, interference kicks in about here - I use it as a bare minimum normally.

Try splitting it into two back-to-back at 2:7 and 7:20. (both as close as possible to 1:sqrt(10), which makes each reduction use very similar sized gears, but also picked for a reason which will become obvious below).

Not sure exactly what this is going into, but for funsies, you could even make the input/output axial by making the tooth count for each pair equal, as per the following working:

  • LCM[ (2+7), (20+7) ] = LCM[9,27] = 27 (use this as initial tooth count for each pair)

  • 2:7 * 3 = 6:21 (total 27)

  • 7:20 * 1 = 7:20 (total 27)

  • Let's multiply by 2 to make that 6t gear turn into a 12t: 12:42 and 14:40

  • For a module 1 the PCD (pitch circle diameter) is m*t = 12, 42, 14, and 40mm. OD of the gear is usually this +2m, so 14,44,16,42mm.

  • The total largest linear outside distance will be (t1+t2+2)*m = (54+2)*1 = 56mm

  • Axle spacing should be (t1+t2)*m/2 = 54*1/2 = 27mm

Thus, by splitting it into two you can do a 1:10 ratio in the same space as pirvan's M0.5 gears, with the nearly-printable M1 tooth size, the input and output coaxial, the smallest gear is a respectable 12t, and the helpful/conventional property that each gear pair shares no prime factors in the tooth count (other than 2) which makes wear very even! smile

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Re: I've been looking for gears!!!

thingiverse has a gear customizer http://www.thingiverse.com/thing:50908

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Re: I've been looking for gears!!!

I had a hard time drawing gears so I went here. http://joostn.github.io/OpenJsCad/gearsdemo.html  It requires google chrome but you just fill out their form for what you need and it gives you an stl. file of the gear. It saved me a lot of work, very cool.