Threading intimidation.

Jake M said:
There's nothing wrong with that approach, and you're right, it's often much more efficient to use a tap and/or die. On the other hand, as you say, it could be cumbersome at best to own "every" tap and die... And sometimes you just need that teeny tiny little bet of accuracy that comes from making the threads on the same spindle, and the same setup as the rest of the part. That's not an every day thing of course, but somehow I find that cutting threads, watching them come to be, is very satisfying...

Quick tossout, changing gears is a thing that must be done on a C model. But I can assure you, after the first couple of times, you know which gear(s) are getting swapped, you know where they're going when you shift them into mesh, it gets much better. You still have to do it, but the pain factor drops tremendously.



I think Jim is right, you wanna recheck the gear teeth. I'll bet that is an 80 tooth gear that you have.



Here's how you know- Yeah, you could get an answer, but working through this in your head for a minute will sort out every gear train you see in your life...

In a PLAIN gear train, only the drive and driven gear matter. (The input and the output). Each and every idler in between has it's own gear ratio, but because they are driven on one side, and drive on the other side, they cancel out as one to one in the math, so they can be ignored. Any tooth count for an IDLER will be fine.
You have a "fancier" gear train though. The stud gear, that's a "compound gear", because it "inputs" a different number of teeth than it "outputs". So the "driven" number does not match the drive number, so those must be correct. Yes, they're separate gears, but they're keyed together, and act as one. That WILL change the ratios, and therefore the tooth count on BOTH gear teeth of the compound gear will matter.
In this case, the spindle gear is a given, anything between the stud gear and the spindle (reversing gears) are idlers, and could have any tooth count. The stud gear (both gears) need the correct count. The 80 tooth gear is as large as it is for space and fitment. Any tooth count would work. And the last gear, the screw gear, that one needs an accurate count.

So in the context and constraints of this, the 80 tooth gear would not matter if it was 81 teeth, or 29 teeth, or 256 teeth, as long as the banjo has the physical space to make it all mesh together.


And aside from all of that...

You'll hear that you can thread with the compound, and you'll hear that you can plunge straight in... Both are right, but on a 9 inch south bend, you'll find limits... I strongly recommend using the compound to feed in. You also will hear to set it at 30 degrees 29 degrees, 29.5 degrees... They're all correct, and here's the trick- 30 degrees is the magic number, but you MUST be at or under. Under by a little won't bother anything. Over by ANY amount will bugger stuff up. The answer is "as close as you can get to 30 degrees WITHOUT risk of going over. 30 degrees. You'll want to leave a bigger window until you can sort out the accuracy of the scale on your compound.
And the catch with some lathes. Your lathe is (I believe, mine is) labeled "opposite" of lathes that are most common today. The difference is whether zero degrees is parallel to the spindle axis, or parallel to the cross slide axis. So when you hear 30, you're going to looking for 60 degrees on the compound. (That's thirty degrees away from 90, not 30 degrees away from zero as many lathes are). So you would dial in 60 degrees, 60.5 degrees, 61degrees.

And the Joe Pie way, threading upside down- A very nice method, but there are couple of issues with that in this specific case. First, the carriage is not all that heavy, and the front side is not "tied down" all that tight. You'll be into some chatter and carrying on before you know it. And second, it's got a threaded chuck. Turning in reverse needs to be very much respected, as all the cutting force (and the hammering from chatter and other carrying on IF that occurs) are all working to unscrew the chuck. You wanna be on a REAL HIGH confidence level before you consider that. Once that starts to happen, you WON'T have a chance to stop it.
I highly recommend the "conventional" way, with the tool bit right side up on this particular lathe.
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Good info and thanks for the bit about the compound angles
 
GT-6 Racer said:
If you are concerned about threading towards the chuck, check out Joe Pie’s video on threading with the tool upside running lathe in reverse. Works great especially threading to a tight shoulder.

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Thanks for the thought. I watched this video a while back and it’s brilliant. However my chuck is threaded on and if I screw something up in my end I don’t want that hunk of steel flying off.
 
I'm gonna have to take back (part of) what I said earlier. South Bend DID have an 81 tooth gear, but it WAS a compound gear, and it wasn't for a 9C. I found it for a 9 "Junior", and "could" have carried on to other nameplates well before the A, B, C lathes came along. Their 9 inch lathes were an evolution early on, and fell under several names with incremental design changes. If I'm on the right track, that would have been an 81/18 compound gear, and the whole set would have been 16, 18, 24, 30, 32, 40, 44, 46, 48, 52, 56, 60, 64, 72, 80, 92, and the 18/81 compound gear.

We're gonna need pictures. We gotta sort out what lathe you're on, if the change gears match the lathe you're on, and if the threading chart matches... If you're right (and you've double checked now, I'm guessing you're right), and you've got an 81 tooth gear... One of those three items is amiss. And finding that will probably solve a lot of questions, now and in the future.
 
Jake M said:
I'm gonna have to take back (part of) what I said earlier. South Bend DID have an 81 tooth gear, but it WAS a compound gear, and it wasn't for a 9C. I found it for a 9 "Junior", and "could" have carried on to other nameplates well before the A, B, C lathes came along. Their 9 inch lathes were an evolution early on, and fell under several names with incremental design changes. If I'm on the right track, that would have been an 81/18 compound gear, and the whole set would have been 16, 18, 24, 30, 32, 40, 44, 46, 48, 52, 56, 60, 64, 72, 80, 92, and the 18/81 compound gear.

We're gonna need pictures. We gotta sort out what lathe you're on, if the change gears match the lathe you're on, and if the threading chart matches... If you're right (and you've double checked now, I'm guessing you're right), and you've got an 81 tooth gear... One of those three items is amiss. And finding that will probably solve a lot of questions, now and in the future.
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It is a 81 tooth compound gear. Well maybe my lathe is a junior. How does one go about figuring that out?
 
Tb1988 said:
How does one go about figuring that out?
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You can figure that out by just knowing everything, or you can post some pictures. We don't know everything either, but there's lots of us, so somebody'll recognize it...

Can you get pictures up? A picture with a good view of the headstock, from an angle that shows clearly at least one of the headstock bearings, rotate right, and another picture that shows the cross slide/compound, and a picture behind the gear cover that shows the gear train.

If not, I'll (do my best to) figure out how to figure it out with measurements and observations. I had a LOT of stuff saved when I got my lathe, and just went through it for another post, realized how poorly I'd categorized and labeled it... So it's not fast, but I'll go dig back in again if need be. But somebody will probably recognize it. There's enough Junior owners hanging around, they'll probably beat me to it. If that's where the descrepancy lies. We've gotta be sure at this point, or you're gonna get bad advice from well intended folks....
 
Jake M said:
You can figure that out by just knowing everything, or you can post some pictures. We don't know everything either, but there's lots of us, so somebody'll recognize it...

Can you get pictures up? A picture with a good view of the headstock, from an angle that shows clearly at least one of the headstock bearings, rotate right, and another picture that shows the cross slide/compound, and a picture behind the gear cover that shows the gear train.

If not, I'll (do my best to) figure out how to figure it out with measurements and observations. I had a LOT of stuff saved when I got my lathe, and just went through it for another post, realized how poorly I'd categorized and labeled it... So it's not fast, but I'll go dig back in again if need be. But somebody will probably recognize it. There's enough Junior owners hanging around, they'll probably beat me to it. If that's where the descrepancy lies. We've gotta be sure at this point, or you're gonna get bad advice from well intended folks....
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Did the pictures I posted not work?
 
22-YB is a "junior", not a workshop 9". It should be a short bed (3' end to end - they didn't measure between centers on those). I have a 9" junior as well. The standard 9" stuff does NOT fit it. Many parts from a heavy 10 will fit, including the headstock.

Gears are 16 pitch, not the 18 pitch you'd find on the workshop models.

Look for a manual for the juniors. The thread chart will be accurate. You can even find images of just the thread charts, I think.

Sent from my SM-X510 using Tapatalk
 
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