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Changing gears for 1 1/4 TPI and using QC gearbox

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gearhead

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#1
I'm very new to lathes. I need to wind coils with my Atlas 12". It has the QC gearbox, but it is only set up to turn as wide as 4 TPI. I have the manual, and it tells me that I can turn 1 1/4 TPI if I change gears on the banjo. I think, if I'm looking at things right, that I currently have a 40 in the A position and a 48 in the C position. (The 40 actually looks like it's in between the A and B position, so I'm not sure about that.) The manual says I need 64N and a spacer F in the B position and a 20N and 64F in the D position, with a 32 compound gear.

Can I get gears and spacers to do this? And is there anything else I need to know before I start combing eBay for gears? Thanks for the help.
 

Rob

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#2
You can also get new gears from clausing for not much more than used ones on EBay. Amazon also sells Boston gears made from steel that are a direct replacement for the change gears. The Boston Gear PN's are GB20 & GB64
 

gearhead

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#3
Thanks so much, Rob. What terms would I search on to turn those up on eBay? I did not come across anything like that while looking for "atlas lathe gears." Also, what about that spacer that I need? Is that anything special, or is it just a bushing? Actually, even if it's just a bushing I could turn, I still suck at turning pretty badly and might want one that's already done.
 

Rob

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#4
If you do a search for "Boston Gear GB20" a 20T shows up. Amazon also has one that is cheaper than the ones on EBay. I did not see a Boston Gear GB64 on EBay or Amazon. As I mentioned you can still get the gears new from Clausing. You can also get a new bushing from them. When I have checked prices on new gears from Clausing they are just a little more than used on EBay and you will get new ones. If you look at the spacer it has 2 keyways in it.
 

wa5cab

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#5
It was also common to use the 20T gear as a spacer. But gear or spacer, both need to have the double keyways.

Making the bushings takes more than just a lathe as they have double keys on them.

There is a section on coil winding in the MOLO. And a selection chart in Downloads that will show you which version of MOLO is nominally correct for your model number lathe. And another document on the history of the MOLO that will tell you which Editions belong to which versions.
 

gearhead

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It was also common to use the 20T gear as a spacer. But gear or spacer, both need to have the double keyways.

Making the bushings takes more than just a lathe as they have double keys on them.

There is a section on coil winding in the MOLO. And a selection chart in Downloads that will show you which version of MOLO is nominally correct for your model number lathe. And another document on the history of the MOLO that will tell you which Editions belong to which versions.
Yes, I have the MOLO, and am referencing page 133 of the manual which indicates the gears and spacer I outlined above. I've not done this before, and I'm not sure if I'm reading the chart correctly or where exactly the physical positions of those gears are. I guess I'm just trying to get a good understanding of this before I got ordering random parts that might not fit or ordering them and finding out I still don't know what the heck I'm supposed to do with them. Thanks.
 

wa5cab

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#8
First, there are 10 versions (0 to 9) and 33 editions of the MOLO. And they are not all paginated the same. So if giving a printed page number for someone to look something up, you should give the year or Edition (1954 on) or Version (all 1937's). And if 1937V2 through V5, also whether the page number is from part 7 - Threading or not (Part 7 in those versions starts over at Page 1 and then Part 8 jumps back to what it was in V1).

The A,B,C,D positions are variable depending upon what gears you have installed. Where the letters are shown on the drawing of the banjo (AKA change gear bracket) is just the rough location. To load up the banjo, loosen all of the nuts holding the gears on and remove all that aren't going back on in the same letter position. Then lower the banjo. To set up the new combination, you should start with the gear that drives the screw gear or the QCGB. Then the second gear that drives the first. And so on. Put several drops of SAE 20 on each stud as you go. Use a strip of brown Kraft type packing paper or 24# typing paper to properly mesh each gear as you tighten its nut. When finished, swing the banjo up (with paper strip in place) and tighten the clamping lever (and remove and discard the paper strip). Also, I would wear surgical gloves as the gears should be quite greasy. When finished, re-grease the gears before removing the gloves.
 
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