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BillTodd
21-02-2009, 06:35 PM
Why is it so hard to find a 127 tooth gear in a sensible DP or Mod ?:(

The biggest off the shelf I can find is 32 DP which is too small.

Anyone know where I can buy a 20-24dp 1-1.25 MOD gear range?

BillTodd
21-02-2009, 07:24 PM
Ha!

Just found out that Myford ones can be pressed in service on a Hardinge and that RDG has them dirt cheap ATM - happy bunny again

graffian
23-02-2009, 05:13 AM
You can use other gears, I mean less than 127T, to cut metric pitches. There are comibinations that get really close to metric pitches.

BillTodd
23-02-2009, 01:42 PM
You can use other gears, I mean less than 127T, to cut metric pitches. There are comibinations that get really close to metric pitches.

Yes thanks. After several more hours of searching yesterday I found a complete solution here: (with or without the 127 tooth gear)

http://www.practicalmachinist.com/vb/showthread.php?t=116971

But, since I'm having to buy a complete set, I may as well get a 127 tooth.

graffian
23-02-2009, 08:14 PM
If you can use a 127Tand have one thats the best solution. My ratio produced less error than the page you linked to. You never know the error might have made it closer than 127T due to leadscrew wear;-)

Jon Lorton
24-02-2009, 07:41 PM
Be aware that Myford change gears are 14.5 degree pressure angle (PA) whereas the more common PA is 20 degrees. This might cause difficulties meshing with other, different PA, gears. In particular you could experience rough running (with cyclic errors in the thread cut) and rapid wear but may not be a problem so long as speed is kept low. You could also use 63 teeth as a conversion gear without much loss of accuracy. Have you tried HPC Gears of Chesterfield, Derbyshire ?

John S
24-02-2009, 07:47 PM
Hardinge is also 14.5 degree PA.

That information is in the link that Bill posted

John S.

Jon Lorton
24-02-2009, 08:27 PM
Thanks, I didn't know that

BillTodd
24-02-2009, 08:36 PM
Thanks Jon/John

I hope to use all Myford gears for the change wheels (I have no Hardinge gears). I'll have to make a suitable banjo. A chap from the Practical Mechinist forum has very kindly emailed some 3d models of the original banjo. I've just got to work out the sizes of the Myford gears.

John S
24-02-2009, 10:36 PM
If you need any 20 tooth wheels take a look at these.

http://www.metoolsonline.com/product_info.php?cPath=38&products_id=54

Made from steel not cast iron and have a modified tooth form to give a stronger tooth.

John S.