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Spacing of buttons for making involute cutters

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iNf20/10/2021 15:04:37
38 forum posts
32 photos

spline cutter

Try this link for the John Stevenson article

iNf20/10/2021 15:11:36
38 forum posts
32 photos

button cutter info

Another of John's articles

Michael Gilligan20/10/2021 15:39:29
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20182 forum posts
1053 photos

Thanks, iNF yes

MichaelG.

.

P.S. __ To fuel further discussion, I will mention that a well-respected horological acquaintance showed me that it is quite unnecessary to make a pair of spaced buttons : one button will [if you have sufficient 'setting' ability] suffice to cut the two sides of the blank.

bernard towers20/10/2021 18:38:06
618 forum posts
109 photos

I used the single button method with a twist , the button was a length of carbide mounted tangentially and 1 side of the blank machined then taken off the mandrel and reversed and the second side machined. This was for Wildings turret clock which works very well.125b7937-ed71-499a-a043-67c0154c87ba.jpeg

Martin Kyte20/10/2021 18:51:57
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2753 forum posts
48 photos
Posted by bernard towers on 20/10/2021 18:38:06:

I used the single button method with a twist , the button was a length of carbide mounted tangentially and 1 side of the blank machined then taken off the mandrel and reversed and the second side machined. This was for Wildings turret clock which works very well.125b7937-ed71-499a-a043-67c0154c87ba.jpeg

Given that you say your method worked , why did you not traverse the crosslide and topslide to turn the second face?

regards Martin

John Haine21/10/2021 07:24:38
4673 forum posts
273 photos

Because you only have to get one feed right.

John Haine21/10/2021 08:51:14
4673 forum posts
273 photos

Actually this raises an interesting point. Since all the gears in a clock famously rotate only one way, it shouldn't be necessary to machine a symmetrical profile on each tooth. The other side could for example just be a buttress to give reasonable tooth strength. Then you need to assemble the gears the right way round to make sure the teeth mesh on their "right" sides.

ega21/10/2021 11:07:29
2539 forum posts
201 photos

I recently acquired a profile lathe tool with a 12mm diameter carbide insert - an instant single button tool, perhaps?

John Haine21/10/2021 11:54:11
4673 forum posts
273 photos

Indeed, but quick calcs using Mike Cox's formulas says that for a 20 tooth 20* PA gear the mod would be 1.7542mm. You can choose 3 of button diameter, PA, teeth or mod, but not all at once alas.

bernard towers21/10/2021 18:11:03
618 forum posts
109 photos

Martin, The reason being that you would need another tangential toolholder of the other hand. Plus the blank is butted up to the collet chuck nut so no room to get to tother side

John P21/10/2021 18:43:23
406 forum posts
257 photos


Button form tools used on the Eureka device can be a problem
to make in the sizes above cutter No 4 the radius is so large
that it would interfere with the body of the device , see here the photo
of 6 off 20 DP 20 pa cutters and tooling to make them .
Only a small part of the circle is needed to form the cutter in the
sizes 3 to 1.

eureka 1.jpg

These illustrations taken from an old book shows how this used
to be done and may be of some interest especially if you have
a shaper ,i don't need to add any more the pages show it all.

John

relieving1.jpg

relieving2.jpg

relieving3.jpg

Howard Lewis23/10/2021 17:37:44
6111 forum posts
14 photos

There was an article in M E dated 2nd September 1994 which dealt with gear cutting and in which there were some a table giving button sizes and spacing, which may be of help.

Howard

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