Gallery, Projects and General > How do I??

Cutting internal gear teeth

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bogstandard:
This is one thing I have never attempted.

I went in search on the web to see how it is achieved, and it looks like that it is done with a single tooth cutter, like cutting a keyway slot, but going around the internal diameter to produce the number of teeth required (looks to be a good job for a shaping machine).

To all those more experienced than myself, is it a feasible proposition to do this by hand using a dividing head and a hand powered keyway slotter, or is there an easier way?

Bogs

John Stevenson:
About the only way John,
If the gear is big enough inside another way is to get a small gear of the same pitch turn it dished, harden it, hollow grind it and use this as a cutter indexing round one tooth at a time.

Advantages are finding a ready made gear of the right profile may be easier than hand grinding an involute. As you also cut one tooth you also part cut the teeth to the side. As you index round the multiple cuts will generate a nearly perfect involute.

This is the way it's done commercially but the blank and gear rotate in sync each straoke of the ram.

John S.

bogstandard:
No worries on that score John, I had delivered this morning a set of module hobs from Arc Euro.

They managed to get me a full set together, even though it says they are out of stock. :clap:

What nice people to deal with. :thumbup:

So not only will I be able to cut normal spur gears, I should be able to make the cutter as you suggested.

It sounds like a bit of a long job, but what you have told me, instills me with confidence that I will be able to do it. :ddb: :ddb:

Many thanks.


John

John Stevenson:
You will be please with them, they are very good quality.
When they got the samples in they passed me a 20 DP hob for testing as I have a gear hobber, well I love testing other peoples gear  :zap:

So found a nice laser cut blank still with the outer scale on and dross from cutting, dialled in a reasonable high speed and feed and ploughed  thru.

No problems, nice gear good finish and no damage to the hob, might sound rough but someone is going to do the same and moan if it shags all the teeth off.

I'm still using the same cutter to cut all the 20 DP gears I have to produce and so far it hasn't needed retouching.

How are you going to drive these ?

John S.

DeereGuy:
John's do either of you have a link to the hob  you are talking about?

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