11.5 TPI

[jocat54]

Some one made a PDF file that pretty much covers all the TPI. Have used it a couple of times and was accurate for me. Don't remember who or I could give them the credit

 

[Just for fun]

Thanks for the responses and the links. The ELS system would work but it's not that important to go to all that work. I believe I have seen all of the charts that have been produced and there are some combinations that come close, but not exact with the gears I have.

@Funbact I checked out the program GearDFX, that pretty cool. And I do have some other change gears I just didn't get any measurements yet.

With all the question that have come before mine, I was hoping that someone would have a file for a 3D printed gear that they would be willing to share.

I Grizzle one is 10 thousand to large on the bore. And I still need to learn what DP is and how to measure it.

 

[Ken226]

Thanks for the responses and the links. The ELS system would work but it's not that important to go to all that work. I believe I have seen all of the charts that have been produced and there are some combinations that come close, but not exact with the gears I have.

@Funbact I checked out the program GearDFX, that pretty cool. And I do have some other change gears I just didn't get any measurements yet.

With all the question that have come before mine, I was hoping that someone would have a file for a 3D printed gear that they would be willing to share.

I Grizzle one is 10 thousand to large on the bore. And I still need to learn what DP is and how to measure it.

I'd be more than happy to model a gear for you and provide a .STL file for 3d printing, but it isn't possible with what little info has been provided so far.

Awhile back @Chewy was needing a thread dial gear for his pm1226

While we are on gears

We have had several recent posts about gears, so I thought I would add this one. I have a PM 1228 lathe and the thread indicator gear is toast. I did some work on the carriage and noticed the thread indicator was not turning. After taking it off I found that the shaft was seized and the gear...

www.hobby-machinist.com

Assuming yours uses the same gear spec as his thread dial, it's a .91 module (diametral pitch 28) , and 20° pressure angle, but thats just a wild guess. With some luck, maybe he would know if his change gears are the same spec as his thread dial gear.

If you can measure one of your gears and give me the tooth count, outside diameter, thickness, bore diameter and keyway size, it would be easy to calculate module/pitch diameter and produce a .stl file for your 23t/46t change gears.


I sketched one right quick, using 0.91mm module and 23 teeth, but without knowing the thickness, hole diameter and key size, it won't help you much.

Just an FYI, if your gears fit an 18mm shaft with a 4mm key, then a 23T gear isn't going to work for you. I'd recommend going with the 46T instead.

This is the online calculator I use to get the info needed to model gears using Alibre Design:

Gear Dimensions Calculator | Evolvent Design

Calculator to make the right dimensions for a gear or gear blank: calculate gear pitch, outer diameter (OD), root diameter, and clearance.

evolventdesign.com

 

[Ischgl99]

The gears are module, so you will need to use the formulas for an M1.25 gear to determine what size will fit and not the DP formulas .

 

[RJSakowski]

Diametral pitch is calculated by measuring the o.d. of a gear, and dividing that number into the number of teeth + 2. Module is calculated by dividing the o.d. in mm by the (number of teeth + 2). Diametral pitch x mod = 25.4.

When calculating either d.p. or mod, the numbers will be slightly off, due to the o.d. of the gear being slightly less than theoretical but they will be close enough to determine the correct value. The calculations can also help to determine whether a gear is metric or inch. One of the calculations will be significantly different from standard d.p.'s or mod's to make that determination. Asian gears are typically metric while USA old iron gears are inch.

 

[RJSakowski]

https://www.sdp-si.com/products/Gears/Index.php is a good source for gears at a reasonable cost.

 

[RJSakowski]

I have used gear generator.com to create gears. Gears can be downloaded in various file formats.

Involute spur gear generator and simulator

Gear Generator is a tool for creating involute spur gears and download them in SVG format. In addition it let you compose full gear layouts with connetcted gears to design multiple gears system with control of the input/output ratio and rotation speed. Gears can be animated with various speed to...

geargenerator.com

 

[RJSakowski]

One last point and then I'll quit. You also have to know the pressure angle of the gear set in order to purchase or make a gear. Gears are either 14.5º or 20º.

 

[Just for fun]

Thanks guys,

I will get some measurements of the 40T gear today and post them on here.

@Ken226 Thanks for the offer. And I will scratch the 23T gear off the list.

@RJSakowski How do I know what the pressure angle of the gear is?

 

[Ken226]

From the manual on PMs website.

Double check your own manual.