Logan quick change gear boxes, School me please.

[Jon In Tucson]

I recently acquired a Logan 1957 lathe, S/N 64747, that has had the QCGB gutted and a direct drive DC gear motor used in place. In an effort to bring it back to a place where I can use for threading operations I have been in the search for gearboxes and the drive train to power it. I bought a complete gearbox from a Logan 816 as well as the banjo bracket. I also have the reverse drive assembly in route but haven't received it yet. There are still some other parts to fill in the gaps to complete the project that I have yet to lay my hands on. My quandary is: There are some differences in the two gearbox castings, size wise as well as diameters for shafts, some are bushed, some are not.

1. My 1957 gearbox is a LA-1201 casting, the 816 is not.
2. When I lay out all the gear train for the lead screw speeds I have a .5 inch gap in the 1957 that I don't in the 816.

The selector levers will fit and the shaft lines up as it should. Edit:Upon further investigation I'm not so sure...

Bottom line, Am I going to get this to work or did I buy the wrong gear box? Thanks for your help in advance and God bless.
Jon In Tucson

 

[gjmontll]

Hi Jon,

You didn't say which model Logan you have, but looking in my Logan 820 Parts List, I see the QCGB with two different variants. My 1944 model 820 is pre-S/N 46561, and its casting is a LA-475. Post S/N 46561, the casting is an LA-1241. I don't know what the differences them might be.

But perhaps my thread in this forum may help you. See "Greg's Logan 820 Restoration", in particular, the postings dated in September thru November 2013 as I struggled through teardown, repair/replacement/renewal, and reassembly of the gearbox. There are a bunch of photos that might help in your issue.

My lathe is about a week away from reassembly, and the QCGB is quietly sleeping on the carpet in my study. Let me know if I can take some measurements or additional photos that might help you.

Greg

 

[Jon In Tucson]

Hi Jon,

You didn't say which model Logan you have, but looking in my Logan 820 Parts List, I see the QCGB with two different variants. My 1944 model 820 is pre-S/N 46561, and its casting is a LA-475. Post S/N 46561, the casting is an LA-1241. I don't know what the differences them might be.

But perhaps my thread in this forum may help you. See "Greg's Logan 820 Restoration", in particular, the postings dated in September thru November 2013 as I struggled through teardown, repair/replacement/renewal, and reassembly of the gearbox. There are a bunch of photos that might help in your issue.

My lathe is about a week away from reassembly, and the QCGB is quietly sleeping on the carpet in my study. Let me know if I can take some measurements or additional photos that might help you.

Greg

Thanks for the reply Greg. My Logan is a model 1957, S/N 64747, I know that it was produced after April of 1953 as it has a V belt drive rather than the flat belt. It appears that all of the shafts and gears will fit into my casting, LA-1201, However some are bushed on the donor box and not on mine. I will add some photos to clear up my questions. Just to let you all know, I was told that a clean work bench was an indicator of a deranged mind. So just saying...

The 816 gearbox is taller than mine, but not as long as my gearbox. My gearbox is longer, uses 2 drift pins rather than the one on the 816. Both use 48/24 stud gear and the threading charts are the same. The bolt spacing is not the same either. I want to make my casting work with the "innards" of the 816, or have I bit off more than I can chew. God bless.
Jon In Tucson

 

[Tool-in-the-Box]

I didn't read threw it all but this might help:


http://lathe.com/ll-group-archive/adapting_a_qc_gearbox.html

 

[Jon In Tucson]

I didn't read threw it all but this might help:


http://lathe.com/ll-group-archive/adapting_a_qc_gearbox.html

That may be my problem.:banghead: I have no idea of the S/N of the donor gear box. My lathe defiantly is of the "new style" gear box. The 816 is a 10" lathe, and my 1957 is an 11" lathe, however, will it be possible to utilize the parts in my newer style gearbox? Does anyone have pictures of the later gearbox so I can see any differences? God bless.
Jon In Tucson

 

[gjmontll]

Jon

Okay on the Model 1957, I am not familiar with that one and I thought that was the year. I now see that it is an 11" and apparently a somewhat different gearbox than on my 10". BTW, my QCGB does have two pins. About that extra half inch width, here are a few photos of mine after finishing the overhaul. In the first shot, notice how the wider gear is inserted - I think you have yours in backwards. You say the gears all shift okay, so maybe you just need to make a 1/2" spacer.

You mentioned differences in the bushings. According to the Parts Catalog, I had noted that some of the gearbox steel shafts bear against cast iron, without any bushings. Maybe some prior owner bored it out and added bushings? In my restoration, I had to make a new slider shaft and a new gear cluster shaft because of bad wear. To prevent future selector shaft wear, I added bushings onto the selector arms. (And as my thread details, I had all sorts of self-induced problems doing so!).
Hope this helped, good luck to you
Greg

Thanks for the reply Greg. My Logan is a model 1957, S/N 64747, I know that it was produced after April of 1953 as it has a V belt drive rather than the flat belt. It appears that all of the shafts and gears will fit into my casting, LA-1201, However some are bushed on the donor box and not on mine. I will add some photos to clear up my questions. Just to let you all know, I was told that a clean work bench was an indicator of a deranged mind. So just saying...

The 816 gearbox is taller than mine, but not as long as my gearbox. My gearbox is longer, uses 2 drift pins rather than the one on the 816. Both use 48/24 stud gear and the threading charts are the same. The bolt spacing is not the same either. I want to make my casting work with the "innards" of the 816, or have I bit off more than I can chew. God bless.
Jon In Tucson

 

[Jon In Tucson]

Greg,
Thanks for the reply. I had been stripping the gear box down for a transplant and used a 3/8" tee bar to check fit and had the gear with the setscrew stacked wrong. upon further examination my change levers may not swap over either. I concur with your thought as to why some shafts are bushed and some are not. I'm going set back and study this awhile. I may be in the market for another gearbox and put this one up for sale. God bless.
Jon In Tucson

 

[Jon In Tucson]

Greg,
Thanks for the reply. I had been stripping the gear box down for a transplant and used a 3/8" tee bar to check fit and had the gear with the setscrew stacked wrong. upon further examination my change levers may not swap over either. I concur with your thought as to why some shafts are bushed and some are not. I'm going set back and study this awhile. I may be in the market for another gearbox and put this one up for sale. God bless.
Jon In Tucson

After a email to Logan company I find that I have a LB-1240-1 gearbox. However, My parts manual lists a LA-1240-2 gearbox... By the way what does (20 D.P.) and (16 D.P.) mean in reference to the parts manual for gearboxes? I know that I don't know much about this lathe. God bless.
Jon In Tucson

 

[gjmontll]

Jon,
D.P. is "diametral pitch" - the ratio of the number of teeth to the pitch diameter. Gears with the same D.P. will properly mesh together (assuming they have the same pressure angle. For the Logan, I think the P.A. is 14.5 degrees
Greg

After a email to Logan company I find that I have a LB-1240-1 gearbox. However, My parts manual lists a LA-1240-2 gearbox... By the way what does (20 D.P.) and (16 D.P.) mean in reference to the parts manual for gearboxes? I know that I don't know much about this lathe. God bless.
Jon In Tucson

 

[Jon In Tucson]

After a email to Logan company I find that I have a LB-1240-1 gearbox. However, My parts manual lists a LA-1240-2 gearbox... By the way what does (20 D.P.) and (16 D.P.) mean in reference to the parts manual for gearboxes? I know that I don't know much about this lathe. God bless.
Jon In Tucson

I have learned that the difference in the LA-1240-1 and LA-1240-2 gearboxes is: "The only difference in the 1240-1 and -2 assemblies is the nameplate (and this results in using different change gears on the end)."


So, I'm going to be on the lookout for another gearbox, change gears as well as reverse assembly for an 11" lathe. God bless.
Jon In Tucson