Gear Cutting

[pgk pgkParticipant @pgkpgk17461]

Excellent, Neil. Did you ever get one the right size ?

[Neil WyattModerator @neilwyatt]

Posted by pgk pgk on 30/12/2016 18:27:37:

Excellent, Neil. Did you ever get one the right size ?

😛

Well I got plenty that weren't… actually one advantage of this approach is you can cut gears over or under size and have (say) 50:40 and 47:45 on the same PCD.

I keep putting off the final gear as it will have to be done on the shaper… with 344 teeth

Neil

[John Stevenson 1Participant @johnstevenson1]

Posted by Michael Gilligan on 30/12/2016 12:11:16:

(a) an Adept No.2 shaper can be purchased for less than the Minnie gear set, or the set of cutters.

MichaelG.

.

Link please ?

[Michael GilliganParticipant @michaelgilligan61133]

.Posted by John Stevenson on 30/12/2016 18:44:44:

Posted by Michael Gilligan on 30/12/2016 12:11:16:

(a) an Adept No.2 shaper can be purchased for less than the Minnie gear set, or the set of cutters.

 

MichaelG.

.

Link please ?

.

Well … as you ask nicely, John:

Strictly speaking, I should have written 'could' not 'can'

… Prices may have escalated in the last three years.

I bought it in November 2013 from an advert on this very forum.

… Perhaps Neil can confirm the current 'going rate'

MichaelG.

.

P.S. a quick check on ebay shows one sold at £99 [which is pretty close]

… on 02 Oct, 2016 19:00:14 BST

Edited By Michael Gilligan on 30/12/2016 19:29:10

[AjohnwParticipant @ajohnw51620]

People can make a hob without a lead angle with just the rack form and do what Jason has shown. Hardened etc silver steel. It wont work too well on low tooth counts. That needs both parts to mover relative to each other.

The button method can be used to get a pretty accurate tooth form and also used to make multi tooth cutters.

I vaguely recollection that it was Tubal Cain who mentioned another way of keeping costs down. Don't buy the entire set of cutters. As the forms get modified and aren't perfect just close using a lower count cutter above it's range should be ok IMHO as that is how I would go about it. Where things start getting daft is at the lower tooth counts so if cutters are being bought do it on the basis of the lowest tooth count you need to make. I think TC mentioned it on the basis of buying a 1/2 set.

If you want to do a Neil I would suspect that a nice hefty acme or these days trapezoidal tap is a better option but with the blank gashed first and the edges thinned down. Not sure by how much but would suspect about 1/3 of the diameter of the tap. Maybe 1/2 tops. The ones that are on my Dore Westbury and dividing head were made like this but sadly the person who sold me the miller wouldn't part with the thing used to do it.

When buying propa cutters metric may well work out cheaper. As Rod has noticed. Plus some metric ones happen to have a circular pitch that works our rather nicely in imperial.

John

–

Edited By Ajohnw on 30/12/2016 19:32:09

[BWParticipant @bw]

Hey pgk,

This is the best explanation I have seen of making a rack type cutter and why it works

**LINK**

Post 8 in this thread gives an interesting variation on the button method

**LINK**

Bill

[pgk pgkParticipant @pgkpgk17461]

Bill, that first link is the one I 'discovered' a few days ago that prompted this thread.. thanks for finding it

pgk

[pgk pgkParticipant @pgkpgk17461]

OK. I've done a lot more reading (head hurts now) and decided that the simplest way forwards is to have a go at making a gear by fly-cutting using the 2-button math and a cone drill (might try making my own cone drill first). the reasoning is that the rack cutter is going to leave steps in the teeth I'd like to avoid and full circle cutters formed with button tools hopefully aren't necessary for the few gears i need and |'d have to make a mess with flood coolant to cut that much hardenable steel.

So advice I need for these 20DP gears starting with a 20T is width and thickness of gauge plate. I was thinking 10mm x 6mm thick as a compromise of robustness. I may mount it on a carrier since more stick-out would give a flatter base to the teeth. Does that sound reasonable?

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