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Help! 14x40 G0554 owners, gear question

Seanp88

Plastic
Joined
Mar 8, 2021
Good afternoon guys and gals.

So my question pertains to a G0554 lathe I purchased which has been crashed but it has only damaged the apron pinion shaft that rides on the rack gear. I am missing the shaft in its entirety so I will be making it, if and only if I can determine the proper splines on the pinion shaft! For the life of me I cant seem to come up with a proper number of teeth. The shaft with the handwheel on it has a 13t gear which then drives a 50t gear connected on the same shaft as the pinion gear which drives the M2 (2 module) rack. The divisions on my hand wheel have .005" per division, and a total of .58" per rotation. The metric readings show 14.6mm per rotation. The problem I have is that I'm coming up with like 9.5 teeth which is unreasonable, espe ially considering there would be a hell of alot of undercut. Usually ive been seeing like 13 or 14 teeth min on any diagram of a lathe pinion. Is there anyone here that can explain where my math is wrong? Or why Grizzlys numbers are wrong? If anyone could count the gear teeth on their pinion gear that would be extremely beneficial and I'd truly appreciate it!

The rack gear TPI ive come up with is 4.0416.. I measured a whole 12 inches and got 48.5. So 48.5/12 = 4.0416. Which means for the saddle to travel .58" id need to move
2.344 teeth on the rack gear. If one rotation of the handwheel rotates a 13t gear driving a 50t gear, that is .26 rotations of the driven shaft for every 1 rotation of the handwheel (13/50 = .26). I'm then solving for "P" number of pinion teeth. P x .26 = 2.344. Which is P = 2.344/.26. P = 9.01. Is this logical? Thanks in advance!

Regards,

Sean
 

Seanp88

Plastic
Joined
Mar 8, 2021
Bob, I searched online and it's saying the part is no longer available, along with 99% of all the other parts. This machine really isn't that old either.


g0554apronproblem.jpg

Regards,

Sean
 

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David_M

Hot Rolled
Joined
Sep 30, 2014
Location
Midway, GA, USA
Based on your measurement of the rack being 2 module, a 9 tooth pinion would move the carriage 0.5788" or 14.703mm after turning the pinion shaft .26 of a full rotation.

(pi * 2 * 9 * 13) / 50

171767953.png
 

Seanp88

Plastic
Joined
Mar 8, 2021
Based on your measurement of the rack being 2 module, a 9 tooth pinion would move the carriage 0.5788" or 14.703mm after turning the pinion shaft .26 of a full rotation.

(pi * 2 * 9 * 13) / 50

171767953.png

David that' great, I should have drawn it out on Gearotic, it just baffled me to see such a low tooth count on a pinion driving a carriage. It seems like it would be fairly weak, and I guess I just wanted to confirm with other g0554 owners that the tooth count is in fact 9 on the rack gear pinion.
 

HuFlungDung

Diamond
Joined
Jan 19, 2005
Location
Canada
My Clausing lathe had some sort of dumb gear ratio to the rack which did not work well for a graduated scale on the handwheel. I don't recall if it even had a scale or not, been a long time now since I modified it.

I like a graduated scale such as 1" per rev. By making an eccentric bushing for the pinion, I was able to 'drop' the pinion gear enough to add one more tooth, and then I achieved my goal and made up a graduated collar at 1" per rev.
 

Seanp88

Plastic
Joined
Mar 8, 2021
My Clausing lathe had some sort of dumb gear ratio to the rack which did not work well for a graduated scale on the handwheel. I don't recall if it even had a scale or not, been a long time now since I modified it.

I like a graduated scale such as 1" per rev. By making an eccentric bushing for the pinion, I was able to 'drop' the pinion gear enough to add one more tooth, and then I achieved my goal and made up a graduated collar at 1" per rev.


I honestly thought about modifying this also for either 1 inch or .5 inches per rotation, but the issue would then be remaking them feed rate chart to match.. Maybe I'm being too picky about it. Oh and Ill try calling grizzly to see if they have that shaft hiding somewhere! That'd be ideal..
 

HuFlungDung

Diamond
Joined
Jan 19, 2005
Location
Canada
Feed rate chart! What's that? :D

You figure out where you want to be, ONCE, and then you never refer to the chart again anyways ;)
 

David_M

Hot Rolled
Joined
Sep 30, 2014
Location
Midway, GA, USA
If a concerted effort to buy the pinion and shaft fails, be sure to check the pressure angle of the teeth on the rack. They may have gotten sneaky and made it wider than twenty degrees to reduce pinion undercutting.

Shown below is twenty-five:

171769590.png
 
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Seanp88

Plastic
Joined
Mar 8, 2021
Feed rate chart! What's that? :D

You figure out where you want to be, ONCE, and then you never refer to the chart again anyways ;)

Yea you're right I'd never need it but my OCD with things like that would drive me nuts lol.. But honestly... .58" per rev on the dial is probably going to really make me pull some hair. I guess a DRO is the next fix, then i wont be counting turns.. ;)
 

Seanp88

Plastic
Joined
Mar 8, 2021
If a concerted effort to buy the pinion and shaft fails, be sure to check the pressure angle of the teeth on the rack. They may have gotten sneaky and made it wider than twenty degrees to reduce pinion undercutting.

Shown below is twenty-five:

171769590.png

Good call, I did check the gear and it is 20 degree. I had a piece of m2 rack gear laying around about 10 inches long and it meshes perfectly with it so all is good there. My only other question is that cant they also cheat with the pinion by making it actually larger than 22mm diameter, which is the actual diameter a 9 tooth M2 gear should be. I was actually thinking about trying this out to see how it rides on the rack. I did order a piece of 7/8" 4140 but that is only slightly larger than 22mm. Hopefully the 4140 annealed will be ok for the shaft. At some point I will be able to heat treat it myself because I just got 3 Amaco kilns for dirt cheap.. I just havent got them set up for use as an actual heat treat oven.. Soon hopefully.
 

David_M

Hot Rolled
Joined
Sep 30, 2014
Location
Midway, GA, USA
It's called profile shifting (expanding the pinion (pitch) diameter). I would want an expert to do it using a Gear Hob Machine, though.


It would be worth your time to save the 4140 material and get 8620 instead. Case-hardened 8620 has the properties you want.
 
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Dan from Oakland

Titanium
Joined
Sep 15, 2005
Location
Oakland, CA
David M is probably correct as a 9 tooth pinion would be severely undercut. Your gear is most likely a profile shifted tooth design. Just FYI, these cannot be cut with an involute space cutter. They need to be cut by a process that generates the tooth profile.
 
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Seanp88

Plastic
Joined
Mar 8, 2021
Well guys I managed to find the shaft at work. I dont know how it was overlooked before but I just literally stumbled upon it today. I wasnt thinking of looking at work because I purchased the lathe from my boss but at his house. Anyway, ill get back to you you guys on the profile shift just to clear any questions on that. It is in fact a 9 tooth pinion like we suspected, and i believe I can save the shaft as it is only a minor bend on it. What a relief! Thanks for the help! And thats also good to know about the profile shifted gears and not being able to use an involute cutter. I guess one could always make a custom cutter though to match the profile.
 

Seanp88

Plastic
Joined
Mar 8, 2021
So I believe you are correct on the profile shifting. The diameter is actually 22.7 mm. Do you think this too much to use an involute cutter? .35 mm radial. The shaft is bent every which way ever so slightly so I dont think Id ever get it to turn nicely in the apron bearing (bore) surfaces..
 

HuFlungDung

Diamond
Joined
Jan 19, 2005
Location
Canada
I'd just make one and try it with the cutter you have. If you make a flycutter to match a good profile (not worn), so much the better. These gears operate well past the moment when they are 25% worn out, so you don't need perfection, IMO. They end up all gritty and gnarled from chips embedding in them.
 

Seanp88

Plastic
Joined
Mar 8, 2021
I'd just make one and try it with the cutter you have. If you make a flycutter to match a good profile (not worn), so much the better. These gears operate well past the moment when they are 25% worn out, so you don't need perfection, IMO. They end up all gritty and gnarled from chips embedding in them.

Thanks for the advice, I'll post some pictures when finished and let you know how it works.
 








 
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