Parts needed for a brown machine co lathe

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Lom
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Parts needed for a brown machine co lathe

Post by Lom » Thu Jun 17, 2021 10:59 pm

Trying to find back gear parts for this lathe I think it’s a model P. This would be the gear on the spindle closes to the chuck for the back gear reduction. I think some call it the bull gear. Not sure if other manufacturers are compatible or not. I have some teeth missing not sure if it’s better to repair or replace.

Any help would be great.

pete
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Re: Parts needed for a brown machine co lathe

Post by pete » Fri Jun 25, 2021 11:25 pm

Due to the damage I'll assume your lathe has a threaded spindle nose? That damage is almost always caused by engaging the back gears to lock up the spindle so the chuck can be changed. Oddly it seems to be a little known trick by most. You'll see a plain non threaded register just behind the spindles male thread. That's what locates the chuck so it's always concentric and axially aligned to the spindle C/L each time it's installed and that's what the chuck or back plate recess seats against. Find a piece of thin cardboard about as thick as the cardboard the old shoe boxes were made from. Cut out a cardboard washer slightly smaller in diameter that that chuck registers face diameter with a hole in it just slightly larger than the spindle threads. Use that always between the chucks back plate and that spindle register. It works like a semi compressible washer and helps prevent the solid metal to metal contact that makes releasing the chuck so tough. If you live in a high humidity area then soaking that cardboard washer in some light machine oil for a few minutes will prevent it from absorbing that humidity and causing rust which you very much don't want. Paper and cardboard products are remarkably consistent in there thickness today so it won't affect your axial run out of the chuck. It's an old machinist trick for threaded spindles that few seem to know about today. And it makes it a whole lot easier to get the chuck released.

Your lathe seems to be fairly uncommon, and any parts will be even more so. It really depends on what other machine tools you have access to and how much machining knowledge and experience you have. Brazing in a piece of probably cast iron to match the original material and then machining new teeth recesses to match the old if you can identify exactly what you have could be done. Even a solid brazing fill well above the teeth that are there and then machining in new gear teeth can work.Without a decent mill, a dividing head (best) or even a rotary table (workable) and the skill to hand grind your own single tooth fly cutter to match the correct tooth profile shape, it's going to be almost impossible. Somebody very highly skilled using hand files could probably do it well enough to have a completely workable gear. But there's now very few who could and not a hope I could. They also make multi tooth gear cutters that again would require that mill and extra tooling. But before buying one you'd need to very positively identify exactly what tooth pitch and angle you have on the other gears. The lathe is old enough it's not unlikely it uses the older 14.5 degree tooth profile instead of the more modern 20 degree pressure angle. Depending on what you have it's not impossible that the correct multi tooth gear cutter is no longer available since there's far less demand today for those 14.5 angle cutting tools. And if you can find any shop willing to do the work it's not going to be cheap at all. I'd guess at least $300 or more. I know how it could be done and would certainly give it a try on my own equipment, but I know enough to know I just don't have enough experience with a repair like this to where I'd be willing to try it on anything I don't own. Machining a whole new bull gear isn't impossible either. But a failure with rare irreplaceable parts is not something I'd be willing to risk at all. I'm sure there's members here who have done this type of work many times before, just maybe one of them might be willing to help, but I also wouldn't expect it for free.

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Bill Shields
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Re: Parts needed for a brown machine co lathe

Post by Bill Shields » Sat Jun 26, 2021 2:31 pm

figure out what the gear is and if there may be something available as a generic spur gear available.

If you can machine the old teeth off and loctite on a ring gear made from a hollowed out spur gear...you have a possible solution.

It the tooth form us not available...well then you can replace both sides of the back gear...the damaged gear and its mate. All you care about is the center to center distance..the gears do not have to match anything on the lathe.
Too many things going on to bother listing them.

Lom
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Re: Parts needed for a brown machine co lathe

Post by Lom » Sat Jun 26, 2021 10:26 pm

Guys thanks for the replies,I am a newbie to using a lathe I can use a torch and mig and stick weld but I am far from a machinist. The lathe is more of a Hobby and if I see use for taking care of some repairs or fabrication for myself it will come in handy.not sure I will need the back gear but I hate seeing in that condition. I’ll have to go to one of our local machine shops to see if they have any interest in repairing it and what the cost will be. Now I will have to figure how to take it off.

Thanks again.

pete
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Re: Parts needed for a brown machine co lathe

Post by pete » Sun Jun 27, 2021 12:30 pm

I've never seen one where the only way to get the back gear off wasn't to pull the spindle. Possibly your spindle bearing caps (assuming sleeve bearings) will only go back in the same orientation as they came off. But I'd number and add an arrow for each cap and which way they face with a felt pen, if it's the front (lathe chuck end) or rear, and make notes if there's any bolts of different lengths for where they go so everything does go back in the correct positions. Yes that back gear assembly is 100% necessary and it's used to drop your spindle rpm by it's gear ratio. That's also a torque multiplier when turning larger diameter work. Don't rush this job, take your time and pretend your doing brain surgery, think things through and don't force ANYTHING. And like brain surgery cleanliness is not optional, everything should be spotless during reassembly including your hands. If it does have sleeve bearings inspect all 4 bearing surfaces of the bearing halves and the spindle journals for score marks. Hopefully you won't find any. If it really does have sleeve bearings it also could be very likely they may need adjustment, let us know what you find for bearing type. They could be silver colored which will be a babbit bearing, or yellow which is bronze. There may be oil wicks, oil grooves in the bearings and oil ports to direct the oil. All of that will need a good cleaning and probing to be sure nothing is plugged with contamination.

Sleeve bearings are mostly considered inferior by many today. There really not if there in good condition and properly adjusted. With an old school drip type oiling system like that lathe there one deficit is there rpm limited. Today they use a temperature controlled pumped pressure systems, but the worlds most accurate cnc lathes today still use sleeve bearings because of there rigidity and accuracy. Given the rough time period when that lathe was designed it's only guesses on which bearing type it might have. It's also not impossible it has proper roller bearings. If so there extremely delicate and require the correct spindle disassembly so the bearings don't see any shock loads or pressure being put on the incorrect parts of the bearings as there pressed off or on.

Mr Ron
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Re: Parts needed for a brown machine co lathe

Post by Mr Ron » Sun Jun 27, 2021 2:09 pm

Reply to Pete: Thank you for the tip on the cardboard washer. MY Sheldon has a threaded spindle and I find it difficult at times to remove the chuck for fear of damaging the bull gear. This is probably the most valuable piece of information I have gotten from this forum. I hope everyone with a threaded spindle reads this.
Mr.Ron from South Mississippi

Lom
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Re: Parts needed for a brown machine co lathe

Post by Lom » Sun Jun 27, 2021 4:54 pm

Thanks Pete
I got it apart the lathe says it has Timkin bearing, the bearings and races seemed to be in good shape. The hardest part to get off was the gear on the left end of the spindle. The spindle had to be removed the get the bull ring off. I will take some pic and post. Now I need to find someone that can fix it. Wasn’t to complicated gear on left end then a thread retainer ring with a set screw. Spacer between bearing housing and left back gear on spindle, then the three step pulleys. Then finally the bull ring with the broken teeth, just had to get the woodruff key to nose down and it allowed the spindle to pull of the gear and out the right side.

Lom
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Re: Parts needed for a brown machine co lathe

Post by Lom » Sun Jun 27, 2021 7:15 pm

08187D1C-4D21-4C7B-A445-0BBB9AECA572.jpeg
2E87ABCF-A221-46D4-8BDC-0EAA5ED44269.jpeg
A65245D6-CD0B-421E-B077-5B19E5E3AB10.jpeg
This is what I am dealing with, you can see the gear with broken teeth.

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Bill Shields
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Re: Parts needed for a brown machine co lathe

Post by Bill Shields » Sun Jun 27, 2021 9:24 pm

Think you will find it easier and more economical to just replace the gear...rather than fix it
Too many things going on to bother listing them.

Patio
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Re: Parts needed for a brown machine co lathe

Post by Patio » Sun Jun 27, 2021 9:35 pm

If push comes to shove, you could braze the entire area in and use a hack saw and a file to recreate the tooth forms. Just a thought.
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