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SB 10L Single Tumbler Gearbox - Parts Quest...

opsoff1

Plastic
Joined
May 23, 2012
Location
MA
Looking for two parts for my 10L Single Tumbler QCGB - been scouring all the usual places but with no luck.
I need the gear that goes in the tumbler arm - I believe it is called the Idler Gear P/N PT605R1 and potentially the Main Drive Pinion P/N AS420R1.
Any viable sources?...

TIA
 
Try Boston Gear. Your chances of finding a NOS, or even a used one in good shape of something that old is pretty slim. You'll probably even have to modify any new gear you get. Make sure that you get cast iron gears.
 
Would I specify OD / thickness / # of teeth / hole dia?
Thank you...on the trail!
 
Those are the highest wear parts in the single tumbler gearbox. It's unlikely that you'll find them just floating around by themselves. Your best chance is buying a full gearbox from a partout, even then it's 50/50 whether these parts are shot already. Or make new ones for yourself.

I believe that if you can get the correct diametrical pitch and tooth count in your desired material, you can modify the gears to fit your needs.
And pressure angle.
 
Is that the same as Diametral Pitch?
Looking at the offerings from Boston Gear - they don't mention anything about Pressure Angle.
 
Dammit. Hit some key and deleted several paragraphs. Try again...

Think of DP the same as pitch on a thread. A screw thread has a certain number of threads per length of the screw. DP is the number of teeth per diameter of the gear. A larger DP just like a larger thread pitch allows more teeth per diameter much like more threads per inch.

Pressure angle is just the angle of contact between teeth on meshed gears. See:

 
Looking for two parts for my 10L Single Tumbler QCGB - been scouring all the usual places but with no luck.
I need the gear that goes in the tumbler arm - I believe it is called the Idler Gear P/N PT605R1 and potentially the Main Drive Pinion P/N AS420R1.
Any viable sources?...

TIA
I have the main drive pinion for sale. N.O.S….I don't have the tumbler gear.
 
Try Boston Gear. Your chances of finding a NOS, or even a used one in good shape of something that old is pretty slim. You'll probably even have to modify any new gear you get. Make sure that you get cast iron gears.
I made inquiries to several gear mfr’s to include Boston Gear. All declined to make it. Boston Gear responded:

“The gear you describe calculates to be an odd 14 Diametral Pitch. Unfortunately, Boston Gear does not offer this size gear as part of our standard line of open gearing and it would not be feasible to produce the gear on a special order basis.”

I did find a NOS Main Drive Pinion (thanks to SBLatheman) and scored what appears to be decent condition single tumbler QCGB on EB for $200.
Interesting difference is that the Idler gear on the just purchased gear box is attached to the side of the tumbler with a large thin profile bolt. My current one has the Idler gear installed inside basically a large slot.
Is this the difference between the pressed on and the needle bearing versions?
 
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Interesting difference is that the Idler gear on the just purchased gear box is attached to the side of the tumbler with a large thin profile bolt. My current one has the Idler gear installed inside basically a large slot.
Is this the difference between the pressed on and the needle bearing versions?
The original single tumbler is a shaft held on one side, and that shaft spins inside tumbler arm. I repaired one here:

The type where the shaft for gear is held by two sides of tumbler arm is a newer update, and a better design. I'd be inclined to use that if I had both options on hand. It was an updated replacement part.
 
Texas - impressive repair. I'm intimidated!
It's interesting - the QCGB I just got (talk about lucky - on eB & turns out the guy was 12 miles from my house/ easy pick up) is an older model - QCG-100 with the single support for the idler gear. There is very little wear on any of the gears and main pinion shaft. The shafts ride in (on the L side) what appear to be steel bearings, not bronze. The whole thing is very dirty but also very well lubed. It also appears to be undisturbed - original paint/brass data plate etc. None of the screws have any munged up slots etc.
My current gearbox is a QCG-101 and uses the double support with the Torrington needle bearing. The idler gear is worn to a degree where the teeth are pointed and there are distinct wear grooves in the main pinion shaft. Both bronze bearings were seriously worn which prompted me to make new ones and turn down the shaft journals to clean them up. It really appears to be a visual lesson in the necessity of timely and proper lubrication. All the other gears seem to be in great shape.
I may just clean up, replace the felts and repaint the older QCG100 box and keep it as a spare. I was able to find a newer needle bearing type tumbler arm and idler gear that appears to be in great shape. That coupled with NOS main pinion I got from SBLatheman may prove to be the right combo to getting my gearbox back up to snuff.
One thing is for certain - I am learning a LOT about these machines - and its really satisfying.
Hugely appreciative to all those folks on this forum that have offered advice and comment.
 








 
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