I think the Myford wheels are 14.5deg PA. Same with the reasonably priced cutters from RDG all 14.5deg.

Two gears from HPC would be cheaper than two cutters unless they are an odd material or very wide. I did that with the smaller gears on my 2" Fowler just bought stock gears and machined the bore and sides to suit.

Tap die list 20Dp, 20PA

J

Edited By JasonB on 19/07/2013 08:20:47

They will also do custom sizes for not a lot more, I did that, bought a wider gear for 10 or 20% more then cut it in half

1.25 Module is 20.32 DP and a No.4 cutter (26-34) would probably do for both gears, depending on the application. Watch the number designation of module cutters, they seem to start with No. 8 as rack. CTC in Hong Kong do good value module cutters.

HTH

Rod

I am sure Gray will be along soon to explain, but I wouldn't be making those idler gears from steel.

I would thing twice about mixing DP and Module gears as well.

I have built the clutch you are talking about, and used Tufnol for those gears, if you use steel they will be extremely noisy, and if you have a crash they will not break a tooth off, so you will risk damage to your lathe.

Think about using an engineering plastic instead. If you turn the blanks, I can put the teeth on for you.

Phil

Edited By Phil P on 20/07/2013 09:21:54

I'v only cut 3 or 4 gears, they were to match existing gears, and did not require to be perfect, and each time I ground up a tool (by eye) and used it in a flycutter, it takes time, but it worked for me. Ian S C

Can something be done about the photos, when they are transfered from the albums, they grow to about double the width/depth, and this is having an adverse effect on each thread it happens on.

Ian S C

My photo was OK for width when I transferred it and viewed the result before ADDING POST.

I'd follow Ian's advice and make a single-point cutter, either by the Ivan Law method or filing to match an existing gear. This is a hand filed cutter that made the alloy gear below.

Neil

One of the gears I cut was Tufnol, for a water pump, its been in use for the last 15 years or so. I made it sandwiched between two steel washers, these were also gear cut. Ian S C

Phil,

I beg to differ and bearing in mid we are talking units of scale here.

Now if you swap a 25T 20 DP gear for a 25T 1.25 mod gear one for one then the Mod gear will be 1.328" and the Dp will be 1.350", a difference of 21 thou which would be a no no.

However if you use the mod cutter to cut the gear based on an OD of 1.350" and cut to the designated depth for the DP gear of 0.1079 you will need measuring equipment far in advance of anything found in the home shop.

I drew both gears and over laid them, then moved one tooth of the Mod gear to match the OD of the DP gear.

Not probably the best picture but the inner yellow gear is the mod gear, the outer brown gear is the DP and at the greatest distance which is towards the root the difference measures 0.00027"

So basically using the 1.25 mod cutter but using the DP calculations will get a you a gear that is more than serviceable, in fact it would be interesting to measure a genuine gear to see how close to specs they are.

I could do this as i bought all Myfords gear cutters re the sale but unfortunately i don't have any method to measure to this accuracy.

What is important is the fact that the first 4 gears are 20 PA, something that the people selling the red plastic gears on Ebay haven't realised

Edited By John Stevenson on 21/07/2013 12:10:02