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A Nice Gear Tutorial #1

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I'm going to make some gears soon and came across this while brushing-up and refreshing my memory. Of course, the Machinist's Handbook has it all but, this is a very nicely authored and to-the-point tutorial. This is based on Diametral Pitch and not the Module method. I have some other guides based on Module method but need to check the copyright information.

Enjoy...

Ray
 

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Here's some other decent guides. Very "user-friendly". More discussion about "Module" method of dealing with gears.
BTW: Gears are gears but, SAE terminology tends to do measurement by Diametric Pitch and Metric terminology handles things with "Module" methods.

One can be converted to the other. The analogy I think of, is that SAE measures bolts as Threads-Per-Inch and the metric system handles things as Millimeters-per-Thread.

Ray
 

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Hi Ray.
I am also getting into gear cutting soon. I just got myself a Vertex BS-0 dividing head20180404_090847.jpg
20180405_115952.jpg
So I am really fresh on gear cutting scene. And in my neck of the woods we mostly work with the metric form but also imperial. So thanks for posting. I am going to go through those.
Michael.
 
Hi Ray.
I am also getting into gear cutting soon. I just got myself a Vertex BS-0 dividing headView attachment 264374
View attachment 264373
So I am really fresh on gear cutting scene. And in my neck of the woods we mostly work with the metric form but also imperial. So thanks for posting. I am going to go through those.
Michael.
Ooooo, nice! Nice indeed! You're going to have fun with that!

Do you have a project in mind or, are you just in the process of teaching yourself something new?

I have 2 things in mind... Someone is requesting that I make two replacement gears and he wants them somewhat hardened if possible. He also wants them to operate quieter. It's nice that this side-job came along because I have always wanted to make a project of my own that needs a good bunch of different gears. The project is a gear rack that synchronizes a mill table and a rotary table. I've never made a worm gear and want to see if I can. So... it's "Gear Season" in Ray's shop ...

Ray
 
Gear season indeed Ray.
Yes to both. I want to start with 4 different size gears for my lathe. It has a metric leadscrew,but can do metric and imperial threads,but I want to be able to do a much coarser thread like 1Tpi so I can use it for grease grooving on shafts. So that would be my firts gear project. And also I want to make a thread dial for my lathe. So in short I will be the test subject for learning something new. But you can do so much with a dividing head. I have been wanting one for a long time.
 
This thread is right on time for me too!! I am working on a milling machine table drive setup using one of the miniature 12v high torque motors to drive. Off the shelf gears that would fit or meet my specs are extremely hard to find and/or expensive to buy.

Thanks for sharing the attachments

Jim
 
Thanks for the information. I have made a couple of gears and, like you, have looked through a lot of information. Your information is very well presented and easy to follow. Thanks!
 
Thank you for sharing the info.. I would like to make a replacement set of gears for my S.B. 9 inch.. Still trying figure out which way to go, single point, hobb, or a set of cutters. But spring time is a ways off yet, and I need to wait on warmer weather.
 
I'm going to make some gears soon and came across this while brushing-up and refreshing my memory. Of course, the Machinist's Handbook has it all but, this is a very nicely authored and to-the-point tutorial. This is based on Diametral Pitch and not the Module method. I have some other guides based on Module method but need to check the copyright information.

Enjoy...

Ray
I have just noticed some "plastic" gears being sold on eBay for SB lathe. Just started to dabble in plastic 3D printing and am having a hard time believing a plastic gear could hold up. Wonder what plastic they are using if indeed they work?
 
@Hit-N-Miss Tom POM / acetal / delrin is common for cut gears, and I've heard of more people lately printing it, though I've also heard that bed adhesion can be tricky. It's on my list to play with but I haven't ordered any yet. I've heard of and seen ABS for printed change gears, which is fine, but you may want to account for a bit of shrinking. Some of the modified PLAs (like PLA+) are probably a reasonable choice too. ABS typically shrinks more uniformly than PLA; PLA tends to shrink differently in Z than in X/Y but for a gear that's actually not a big deal.

I used PLA+ to print some bevel gears. I used 0.1mm layers for the bevel gears for a smoother bevel, but for spur gears I don't think that's valuable. Thinner layers aren't necessarily stronger. I think that 0.3mm layers with a 0.4mm nozzle is common for spur gears for change gears, if memory serves.

Annealing PLA will cause substantial changes, if I remember right it will typically shrink meaningfully in X and Y and expand in Z. This can be measured and pre-scaled against. I've seen multiple reports of annealed PLA being strong and heat-resistant, neither of which is a characteristic I normally associate with PLA. But I'd think that with PLA+ you would be fine without annealing.

For change gears, they shouldn't be under tremendous load. You typically have a clutch or shear pin to protect steel change gears; with essentially disposable plastic gears they will probably fail before a shear pin but should be fine for driving a lead screw.

OpenSCAD's MCAD collection has an involute gear module.
 
@Hit-N-Miss Tom POM / acetal / delrin is common for cut gears, and I've heard of more people lately printing it, though I've also heard that bed adhesion can be tricky. It's on my list to play with but I haven't ordered any yet. I've heard of and seen ABS for printed change gears, which is fine, but you may want to account for a bit of shrinking. Some of the modified PLAs (like PLA+) are probably a reasonable choice too. ABS typically shrinks more uniformly than PLA; PLA tends to shrink differently in Z than in X/Y but for a gear that's actually not a big deal.

I used PLA+ to print some bevel gears. I used 0.1mm layers for the bevel gears for a smoother bevel, but for spur gears I don't think that's valuable. Thinner layers aren't necessarily stronger. I think that 0.3mm layers with a 0.4mm nozzle is common for spur gears for change gears, if memory serves.

Annealing PLA will cause substantial changes, if I remember right it will typically shrink meaningfully in X and Y and expand in Z. This can be measured and pre-scaled against. I've seen multiple reports of annealed PLA being strong and heat-resistant, neither of which is a characteristic I normally associate with PLA. But I'd think that with PLA+ you would be fine without annealing.

For change gears, they shouldn't be under tremendous load. You typically have a clutch or shear pin to protect steel change gears; with essentially disposable plastic gears they will probably fail before a shear pin but should be fine for driving a lead screw.

OpenSCAD's MCAD collection has an involute gear module.
I made my South Bend 10K spur gear out of ABS, not that I needed it, but to see how, or if, it would work. Took 3 tries to get the size right due to shrinkage, but finally got it. So far it has been holding up great. It seems the shrinkage was greater on the inner than the outside dimensions. What came to mind was a foundry ruler that compensates for metal shrinkage. I have taken design measurements then compared them to plastic printed part and so far have not come up with a "constant-factor" for shrinkage. Perhaps too many variables involved.
 
Glad you got it to work!

If you don't have a heated build chamber, ABS will warp and shrink inconsistently as you print it. I should have mentioned that. The heated build chamber I made wasn't great, which is related to my having done more with other filament types. :)
 
Glad you got it to work!

If you don't have a heated build chamber, ABS will warp and shrink inconsistently as you print it. I should have mentioned that. The heated build chamber I made wasn't great, which is related to my having done more with other filament types. :)
Read somewhere that ABS should be printed on a Raft. Once I did that on the 3 tries I did get a consistant flat print. I set Tevo Tornado to .15 layer, 240 on the hot end and 95 on the build plate, fan 30%.
 
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