GEAR CUTTERS

[Jon Zwicker]

I’m going to be building a Farm Boy engine and I’m wondering if anyone would have a couple of gear cutters they would be willing to sell, I hate to spend a lot of money on new ones just to use them one time. What I need are a
48 pitch 14 1/2 pa number 2 cutter and a
48 pitch 14 1/2 pa number 3 cutter
Thanks Jon

 

[GreenTwin]

I seem to recall several folks making their own gear cutters.
Not sure how pactical it would be.

Seems like they made a single cutter with a shape on it, and the rotated the blank in the lathe, indexing off of one of the gears in the lathe, and moving the carriage to make cuts.

A slow process, but I think it works, and would be ok for one-off gears.

.

 

[krypto]

The 48DP involute gear cutters are in low supply / high demand so you will have trouble sourcing used ones. I ain't givin' mine up.

You have a few options to avoid buying new cutters.

First, you can go metric (0.5). You can get the whole set (1-8) for the cost of one 48DP cutter with some minor changes to the Farm Boy engine. Andrew does that here:



You can make your own 48DP cutters. Clickspring has an excellent video series on shop made cutters.

 

[timo_gross]

Here is a video how to make a nice flycutting style cutter.



You can calculate the button tool diameter with the formulas somewhere in the book "Gears and gear cutting", or you can draw the gear with a cad system and then get the button size by approximating with a circle.

Also sort of viable option and probably very usable, have to look at the complete video.



Greetings Timo

 

[abby]

Hardly a Ridley Scott film , almost 3/4 shows how to make a disc with a hole in it !

 

[MRA]

Apologies if this refers to something already discussed - but the site below, which I found out about via this forum, is good on making your own rack-form hob (video 2 above looks similar). I've made one for making Boxford (USA - SouthBend 9") change gears, and the method works well. At a push it could be done with just a lathe, if you have a vertical slide to do the small bit of basic milling required to form the teeth...or cut the slots with a saw and file, before hardening.

How a rack cutter can produce gear teeth

A good approximation of the involute tooth form can be made with several passes of a rack cutter - a simple hobbing cutter

www.helicron.net

Unlike a 'proper' hob, this one is not a spiral, thread-like form - you need a set of 5 or so rings turned on a bar, each with a profile like the rack form (straight sided teeth) of the gear you want to make. You then interrupt the rings with flutes like on a tap, to form the cutter teeth.

 

[AndrewW]

I’m going to be building a Farm Boy engine and I’m wondering if anyone would have a couple of gear cutters they would be willing to sell, I hate to spend a lot of money on new ones just to use them one time. What I need are a
48 pitch 14 1/2 pa number 2 cutter and a
48 pitch 14 1/2 pa number 3 cutter
Thanks Jon

Kripto beat me to it! Take the easy option and buy a couple of Mod 0.5 gear cutters. You just need to modify the distance between centres, as in my video.