gear cutting with an old newark

idacal · Apr 15, 2020

I pulled my old gear cutter out of storage to build a new gear for a piece of equipment. it running great for a 100 year old piece of equipment. I'm still struggling with how to find the center of the blank and the center of the cutter easily. I know it can be done with squares, math, and time that's how we are doing it, but its too easy to mess up and Im still not sure if centered. anyway I pre cut to depth with a slotted cutter and am now going to change over to a form cutter. dont know if thats the right way to do it but my last gear sure seamed to hammer its way through very rough on everything. some reason Im suddenly having issues posting pictures here

DeSelle · Apr 16, 2020

We ran a lot of those machines in the past. Very few now. There were times we would run a smaller form cutter before the final one. If that helps you. I am glad to see you’re back to posting about this machine. Let me know if you need any change gears. I may have them.

idacal · Apr 16, 2020

Thank you, this machine came with whole set of change gears. I dont need it often but trying to get someone to build a 1 off coarse tooth gear for these old machines is a little tough especially without a drawing dont blame them. I wouldnt do it. anyway i slit the gear with a 5/32 slotting cutter and the form cutter cut smooth this time, no hammering and shaking. it is a 54 tooth 4 dp gear. I cut this one out of 4140 but what is a good gear steel? is there any special steel that will work harden?and is weldable

jhruska · Apr 17, 2020

Are you using a rim rest?

John

idacal · Apr 17, 2020

it came with it, but this was only a 14" gear so I dint run it. dont know where I should start running it though. I haven't figured out how to set it up

jhruska · Apr 17, 2020

For smooth cuts and longer tool life that 14" gear should be cut using the rim rest and outboard support.
At time of set-up, set the spindle in neutral and rotate the gear blank. The rim rest should clear the full depth of the
gear tooth profile and should not bind against the blank.

JB Bergman · Apr 17, 2020

Nice old machine you have, it looks VERY familiar!!!!
JB

idacal · Apr 17, 2020

yep, thats your old machine, second gear I have cut with it, its a great machine to have around for the repair of old cable tool drilling rigs, which throughout my family there is probably 10 rigs. thank you jhurska I will do that on the next one. seemed like a lot of weight just hanging out there but wasn't vibrating much so I went for it.

DanielG · Apr 17, 2020

On the old cast gears, did they face a portion near the OD for the rim rest to ride against?

sfriedberg · Apr 17, 2020

idacal said:
I cut this one out of 4140 but what is a good gear steel? is there any special steel that will work harden?and is weldable

Most of the time, people explicitly harden gears rather than relying on work hardening. But you might try 304 stainless. Definitely weldable, and part of what makes it less pleasant to machine than 303 is a tendency toward work hardening.

On the other hand, you could be boring and conventional and make it from 8620 then send it out for carburizing, nitriding, or carbonitriding.

Garwood · Apr 17, 2020

If it needs to be hard 8620 then carburize would be my choice. Carburizing is cheap. 4140 hardened would be my second choice. Cost of materials probably the same, but 8620 gets way harder than 4140.

Does this kind of gear cutter automatically advance every tooth or is it all manual?

cyanidekid · Apr 17, 2020

sfriedberg said:
Most of the time, people explicitly harden gears rather than relying on work hardening. But you might try 304 stainless. Definitely weldable, and part of what makes it less pleasant to machine than 303 is a tendency toward work hardening.

On the other hand, you could be boring and conventional and make it from 8620 then send it out for carburizing, nitriding, or carbonitriding.

304 sounds terrible for a gear, galling, can be difficult to machine, tends to be inconsistent in analysis depending on source, oh yea, sounds great! " LAST choice" comes to mind..

idacal · Apr 17, 2020

this one automatically advances to the next tooth to cut, happily runs around in circles until its shut off, I will probably harden and temper this in my potters kiln after all the assembly and welding is done wouldn't be to a spec but I bet it quite happily wears out the other gear which is a 36" gear in 70 years when it wears out again I will not be fixing it. I wouldn't want the price on a chunk of 304 stainless that size. I deal with threaded 304 and that stuff is horrible dont use the right pipe dope galls together and still leaks. just got 400' of 14" stainless 304 pipe out of my yard finally, can't stand working with that stuff.

sfriedberg · Apr 17, 2020

Well, you can be boring and conventional and successful with 8620. I only mentioned 304 because you asked for something not normally chosen for the purpose.

idacal · May 6, 2020

my old drilling rig is almost back together again this gear cutter makes fixing things that otherwise would junk the rig possible. I changed from a bronze bushing to a double set of ball bearings. will see if the bearings last longer than the bushings. I'm tired of destroying bronze bushings in a few hundred hours.
just like to finish out a thread with the results. thanks for all the help
also haven't figured out why my pictures are so small are we limited to how many pictures we can have on the site?

Dan from Oakland · May 6, 2020

Regarding centering the cutter. Our old B&S had a machined shoulder on the cutter slide that could be used with a parallel or straight edge to align the side of the cutter to. There was a graduated dial that provided the ability to unclamp the cutter slide/arbor and shift it a precise amount. So once the side of the cutter was aligned to the surface, you simply shifted the cutter half the cutter width, which centered the cutter on the machine centerline.

Ours was a universal machine that could cut bevel gears so this feature was also needed to offset the cutter a given amount on both sides to thin the heel of the bevel gear teeth.

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