20/40 DP gear hob

20/40 DP gear hob

This topic has 6 replies, 4 voices, and was last updated 27 December 2011 at 12:19 by John Stevenson 1.

Viewing 7 posts - 1 through 7 (of 7 total)

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24 December 2011 at 04:53 #80354
GoCreate
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@gocreate
Hi

I was looking at gear hobs on ebay.

This one is described as 20/40 DP,

I know what 20 DP is and what 40DP is.

How can it be both 20/40 DP? Can anyone explain this description?

Cheers

Nigel
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24 December 2011 at 04:53 #5806
GoCreate
Participant
@gocreate
What is 20/40 DP?
24 December 2011 at 06:05 #80355
GoCreate
Participant
@gocreate
Spoke to soon

I found the answer here

It’s not an involute gear hob but it is an involute spline hob. The spline is 20DP but has a shallow depth equivalent to 40DP.

So no good for cutting gears I presume.

Nigel.
24 December 2011 at 17:32 #80427
John Stevenson 1
Participant
@johnstevenson1
No, as you say they are for splines.

I have bought quite a few hobs off this guy, don’t be put off by the life left in the pics, he tends to use the same picture and all the ones I have had have had far more life in them.

He does have other hobs but usually metric.

I think ARC still has some imperial hobs left

John S.
27 December 2011 at 08:35 #80567
Richard Parsons
Participant
@richardparsons61721
Does anyone know where to find the ‘wire’ sizes for making involute cutters and hobs?
rdgs

Dick
27 December 2011 at 10:46 #80582
Rufus Roughcut
Participant
@rufusroughcut
Hi Dick
Try Hear

http://books.google.co.uk/books?id=J2p2yBMOyI4C&pg=PA9&lpg=PA9&dq=involute+gear+hob+wire+sizes&source=bl&ots=OFpkKgEnZV&sig=Js6BA9oOQsHf3vfONG3nM8ao9G8&hl=en&sa=X&ei=NqH5TvTQDsPotQbBu5nSDw&sqi=2&ved=0CG4Q6AEwBw#v=onepage&q=involute%20gear%20hob%20wire%20sizes&f=false

which may be of use
27 December 2011 at 12:19 #80589
John Stevenson 1
Participant
@johnstevenson1
Dick,

As far as I know there are no published tables but worked out by the makers of the hobs.

The tables in the linked page above are for gears and not hobs.

Hobs will be different in that they have to take clearance into account.

John S.
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