Involute gear cutter type for carriage travese gear please

[Dranreb]

Hi folks, I've had limited success broaching these two gears, it was an interesting exercise but I think the time has come to make a proper job of it!

I'm thinking someone here must have made some, so to save me a lot of head ache work, does anyone know what type/size of involute gear cutters I need to order to cut the two apron traverse gears please?

old gears



new broached gear



Bernard

 

[benmychree]

You could probably take it to a bearing house that may have gear gages to determine the pitch and pressure angle, otherwise consult a machinist's handbook and count the number of teeth and pitch diameter, from that you can determine the diametral pitch and all the dimensions should fall into place; without knowing where it was built, one cannot assume it to be diametral pitch, it may be metric (module), depending where it was built. By the looks of it, I'd say it looks to be
14 1/2 deg pressure angle, not 20 degree, but without straight on pictures, that is a guess.

 

[pdentrem]

Do I assume that this is off one of the Atlas lathes? If so, not module, just standard. Download Boston Gears chart

http://www.altraliterature.com/pdfs/Spur Gears 17-62.pdf

or use Machinery's Handbook gear charts to identify the gear.
Pierre

 

[Dranreb]

Thanks Pierre, I've been looking for something like that for ages!

Sorry, I should have mentioned it's for an Atlas..

Bernard

 

[docn8as]

number of teeth +2 /O.D.= P. For just a couple gears , grind the tool bit from a lathe bit to fit a good section of the broken gear & save yourself abt $75+ dollars .. IT WORKS WELL
best wishes
doc

#8 cutter - 12-13 T of
#7 for 14-16
#6 for 17-21
#5 for 22-25
$4 for26-34
#3 35 54
#2 55- forgotten
#1 rack

 

[rgray]

number of teeth +2 /O.D.= P fo rjust a couple gears , grind the tool bit form a lathe bit to fit a good section of the broken gear &save yourself abt $75+ dolLARS .. IT WORKS WELL
best wishes
doc

#8 cutter - 12-13 T of
#7 for 14-16
#6 for 17-21
#5 for 22-25
$4 for26-34
#3 35 54
#2 55- forgotten
#1 rack

#2 55-134
#1 135-rack

My info says #6 17-20
#5 21-25

 

[docn8as]

yes ...i havent checked a text ,but pretty sure your numbers are correct & mine are in error.....chalk it up to an 82 yr old memory ...
FWIW..... for those may be obsessing abt cutting gears "by the book",.......particularly with adjustable meshing , things are not so critical ......i have been using a 24 tooth stud gear on my 1895 Reed 14 in lathe that i cut w/ a # 6 cutter which was what i had on hand .....no problem in 12 years now.........when i cut the gear for my Barnes 4 1/2 thread dial that i made , i calculated i needed near a 32 pitch gear ( EXACT pitch not necessary & near impossible to cut in home shop.....,it just needs to roll in mesh .slack being taken up ..even xact FORM not necessary ) .....i happened to have a 30 pitch cutter , & cut a slightly smaller gear blank than "spec" ,.... the larger spaces & thinner teeth allowed a nice easy rolling action....have not cut any thrds on it yet , but test cuts have been just fine ...no cross threading on successive cuts ....
i have seen a statement in a "Brit " book that due to cost , many just cut all change gears w/ a mid size cutter & ran them in w/ abrasive .....kinda xtreme & unnecessary since lathe bits carefully ground to fit a gear used as a gauge , work quite well ..i used one of these on my monarch A thread dial that i made .( used the 12 pitch lead screw gear as a gauge , ...4 Pitch lead screw)......
best wishes
doc

 

[iron man]

I dont know but the gear you made looks pretty good it is such a slow turning gear I dont think you would have much problem with the one you made if I had that gear laying around in my shop I would use it, I need to cut one for mine as well I just have not got around to it. Ray

 

[jererp]

An easy way to check the pressure angle of a gear is to roll it in some modeling clay. That will generate a tooth form with straight sides. Then just measure the angle of the tooth formed in the clay.

 

[rgray]

yes ...i havent checked a text ,but pretty sure your numbers are correct & mine are in error.....chalk it up to an 82 yr old memory ...best wishes
doc

Pretty amazing to have all that in memory. I have a cheat sheet on my desk is the only reason I had the info. I buy a cutter or two on ebay when I find a good price and my cheat sheet is how I keep track of what I have so I don't by duplicats.