The gears in my head don't mesh

Suzuki4evr said:
I have measured the gears on the lathe and I used it for reference for the change gears I want to make and it looks like the module are M2.0 if I use the information the members gave me. That being said, I can say this is a metric lathe so it makes sense that the gears would be Module and not DP. In the pic below it shows the gear configuration on the lathe as it is now.
View attachment 319378
Now that I have the module,I will be able to work out the rest. If someone thinks I am missing something, please let me know, but I think I am ons the right course now.
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As benmychree said above, you will need to know the pressure angle. It will be either 14.5º or 20º. This can be rather tricky. The best way is to compare the tooth profile to a known P.A. There are sources online with images which should aid with that.
 
matthewsx said:
This might be an unorthodox approach but how about cutting circles from thin plywood in about the size you think will work and seeing how they fit on the lathe. I'm not any kind of expert but if they fit in the physical space and have the right number of teeth that's all that should matter, right?

Cheers,

John
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I understand the challenges of computing the gears
graham-xrf said:
@Suzuki4evr :
Hi Michael
The final dimensions are precision, but the quick-'n -dirty check with a temporary plywood dummy, or bit of plastic can lead you straight to the correct gear, and remove ambiguity, if you only have the number of teeth.

An obvious question is.. does anything survive of the originals? If you can get at them, you can measure the pitch. Even an approximation may be enough to then figure out the rest of the gear - because the possible combinations are limited.

gear guide.pdf has a table of pitch comparisons on P602, various calculation examples, etc.

If you know, or can measure, the distance between the shaft centres, then the number of possible solutions that have the known number of teeth rapidly become fewer.

p-1930-bg_engineering-info-spur-gears has very complete tables and information about gears on P309 and P311.

Unfortunately, the madly comprehensive gear_guide1.pdf is 21.4MB, and so too large to upload to HM.
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this is what I meant with a mock up. Of course you need the correct pitch, form, and a bunch of other stuff but if you can figure the physical size that should help. Still not an expert and my machinery’s handbook is 2000 miles away ;)
 
Yep, it’s back in Michigan. looks like the experts have arrived :encourage:
 
pressure angle should be 20degrees.https://www.hobby-machinist.com/threads/g4003-change-gear-specs.83304/#post-732305 In this thread I discover and do the math to check pressure angle. You can do the same with a gear from the lathe. It should confirm both module and pressure angle. I learned that bit so I didn't buy the wrong module or pressure angle of cutters. I believe your blanks will be teeth + 2 X module. IE... 50+2x2=104mm blank for the 50 tooth gear. I look forward to seeing your figures and your shiny new gears.
 
Hallo LEEQ.
Well I a bit far away from actually making the gears,because of two things. One is the lockdown we are in and B,I can't order any tool or cutter online now because our Rand vs Dollar are in the dumpster at the moment. But what I can give you is the results on the OD's of the blanks working on Module 2 with 20dgr PA. Gears blanks are as follows :
N66 (OD=136mm)
N55 (OD=114mm)
N95 (OD=194mm)
N57 (OD=118mm)
In DP it is 12.7
I want to thank everyone helping with this. Next up is material to use,I am thinking 1043 (EN8), and to heat treat or not on the gear teeth,but I am leaning towards yes. I don't know if and when they will lift this lockdown, but as soon as I get to knocking out some gears,I will post it.
 
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