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Repair/Restore Logan 820 lathe

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vincent52100

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#1
Finally got my lathe into the basement. I’ve started cleaning and reassembling it. I have found the problems with the gearbox. When I got it both gears on one lever were missing. I think someone crashed it. There are two bad gears in the gearbox. Can someone tell me how to remove the lead screw from the gearbox. I’ve removed the set screw from the collar but don’t want to break something trying to separate it. The S/N is 33206
 

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wa5cab

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#2
I could be off in left field with this suggestion as I've never run a Logan. But on an Atlas, you move the carriage up or down the bed until the half nuts are approximately in the center of the lead screw, close the half nuts, and either remove the right lead screw bearing or at least remove the bolts holding it to the side of the bed. Then you use the carriage feed handwheel to walk the lead screw out of the GB. If it takes more force than you feel safe in applying to the handwheel, rig up something to pull on the right end of the lead screw while turning the handwheel. This should walk the lead screw out of the GB. Then open the half nuts and extract the lead screw.
 

Chuck K

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#3
You need to remove the nut on the end of the lead screw, remove the gear and key, and it will pull out. It's a lot easier if you remove the gb and screw as an assembly and seperate them on the bench.
 

vincent52100

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#4
Thanks! I have the assembly on the bench. I’ll get them apart and see how much damage is done. I can see four gears are bad or missing. Hopefully that’s all.
 

vincent52100

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#5
Started work on my gearbox this evening. It looks like I will need five gears. I’ve taken some pictures of the bad gears.
I’m not sure if I have the numbers right but I tried to make a list of the gear numbers.

Gears on lever
LP1014 (LP1300) 40T
LP1016 (LP1131) 22T
Gear Box
LP1002 (LP1137) 32/16T

The serial number is 33206 (Model year 1945?)

I’m hoping that I will be able to find the parts used. The rest of the gears look pretty good. I haven’t cleaned them yet but I don’t see any nicks etc. The same is true of all the other gears.
Does it look like I’ve got the right numbers?
I’ve also put in some pics of the other gears.
Thanks for the help.
 

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Holescreek

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#6
Logan was able to sell a nice lathe for a low price because the majority of the non-cast iron parts were available off the shelf from other suppliers. The gears came from Boston gear. Once you get the dimensions of your gears (DP, ID and width) find the matching Boston Gear part number then search for them Amazon and MROsupply. You will likely find brand new gears for the price of used.
 

vincent52100

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#7
Thanks! I’ll keep my fingers crossed that I can find them.
 

vincent52100

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#8
I’ve noticed that on the Logan site that it looks like there’s two different part numbers. For example part # LP1014 (40 tooth gear) also cross references to LP1300. Is there any difference between them? Thanks!
 

vincent52100

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#9

CluelessNewB

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#10
There are two different quick change gear boxes used on the 820. The LA-24-1 gear box was used on serial numbers 46561 and below (which is what I believe you have). The LA-1240 was used on serial numbers after 46561.

LP-1130 (old LA-497) is a 40 tooth gear with an OD of 2.625" Width 0.495" and Bore of 0.438" (with bushing) used on LA-24-1 Gear Box
LP-1014 (old LA-1213) is a 40 tooth gear with an OD of 2.1" Width 0.370" and Bore of 0.375" (with bushing) used on LA-1240 Gear Box

LP-1300 (old LA-470) is a shaft for the gear stack on the LA-24-1 gear box

I'm not 100% sure which 32/16 gear you need but for the LA-24-1 gear box I believe it is either one of these:

LP-1137 (old LA-500-A) 32/16 teeth OD 2.13/1.13 Width 0.592" Bore 0.563
or
LP-1134 (old LA-502-A) 32/16 teeth OD 2.13/1.13 Width 0.530" Bore 0.563 (with bushing)

This information came from a combination of the Logan 800 series manual, Current* Logan Catalog and the Logan Web Site

*Well as current as I have which I got from Logan about 7 years ago.
 
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vincent52100

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#11
Thanks for the information. I guess I’m on the right track. Now, to track them down!
 

vincent52100

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#12
Here are the specs on the 32/16 SB gears on Ebay. Does anyone know, by the specs below, if these gears could be modified to work? Perhaps bored and thickness reduced? Thanks

Large Gear is 32T, 2.121" Dia. X. 373" thick, small gear is 16T, 1.115" Dia. X. 395" thick (both gears are 16DP) The bore (bushed) is 7/16", the overall thickness of the gear set is. 768". You are purchasing ONE DOUBLE GEAR.
 

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vincent52100

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#13
I’ve gotten measurements from my old gear and the one on Ebay.
Measure Existing Gear. New Gear. Difference
32T thickness. .250. .373. .123
32T OD. 2.120 2.121. .001
16T thickness. .270. .395. .125
16T OD. 1.108. 1.115. ..007
Total thickness. .530. .768. .238
Bore. .562. .440. .122

The new gears are 16DP
I’m thinking that the gears can be faced to the right thickness and bored to the proper size. Do you think that these could be made to work?
Thanks for any info.
 

Nogoingback

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#14
Here are a couple of Tubalcain vids on repairing a Logan gearbox. In one of them, he describes specifying gears.


 

vincent52100

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#15
Thanks for the information. I’ve looked at both videos but I guess I’m not smart enough to understand everything I need to know. I tried using the formula in the video and am getting weird numbers.
I noticed that my list of measurements posted above ran together after I posted it so I’ll try to re-do it by adding some dashes to keep everything separated.

List of gear measurements
Item——————Existing Gear—————New Gear—————Difference
Thickness———32T, .250———————32T, .373—————-.123
O.D. 32T———2.120—————————2.121———————.001
Thickness———16T, .270——————-1.115———————-.125
O.D. 16T———-1.108————————-1.115———————..007
Total Thickness.-.530————————-.768————————.238

It says the DP for the new gear is 16

I’m not sure of the existing DP. I can’t make it work out for sure.
Can the thickness and bore be machined to make the new gears work? It would br great if I could make them work. The new gears are pictured.
If anyone knows if I can make these work please let me know.
Thanks
Ken
 

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wa5cab

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#16
Vincent (and anyone else)

I can't help any with your gear questions but I can explain why your first table had all of the numbers moved. The word processor software behind the scenes is apparently programmed to delete what it considers as excess spaces. I think that following a period, it allows two spaces but in all other cases it only allows one space. So you did the right thing by using a printing character to substitute for the spaces.
 

vincent52100

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#17
Thanks. I’ll remember that.
 

CluelessNewB

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#18
According to the Logan Catalog I have, the LA-24-1 Gear Box used 16 DP gears. Personally I think you could make that gear work.

(The later LA-1240 used 20 DP gears in the gearbox)

From the Logan Actuator Parts Catalog:

Logan_LA24a.png
 
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vincent52100

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#19
Thanks very much!
 

vincent52100

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#20
Thanks! I ordered the gears. Should have them in about a week.
 

vincent52100

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#21
Now I’m starting to clean up the gears etc. under the left side cover. Someone believed in lubrication. There was so much grease packed in there that you could hardly see the gears. The picture is after I used a roll of paper towels to remove the grease. Disassembled and cleaned everything. Too much is better than too little!
 

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RandyM

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#22
Vincent, you are having way too much fun. :encourage:
 

vincent52100

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#23
Yes, I know! I’m really enjoying it. A couple of years ago due to health issues, we had to move from a 3 story house to a single level. Circumstances being what they were I had to sell my Logan 200. I was just starting to learn a little but I’m happy to say I’m back in the game! After the lathe is done I’m going to start looking for a mill. I’m really getting into this!
 

Chuck K

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#24
Gotta have a mill so you can make stuff for the lathe....or is it the other way around. Either way, both are a must. And then.....
 

vincent52100

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#25
:) Absolutely true! I’ve got a long list of tools I want.
 

vincent52100

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#26
Still working on cleaning the 820. Also got the motor mounted. Replaced the 3 carriage bolts (5/16) with four 3/8 bolts. I’m pretty sure that it is not the original and it also has a single step pulley instead of a 2 step. I will replace that when I can. I was able to find what size I needed from another post here. I’ve found a lot of information looking on this site. I’ve started cleaning the apron assembly. There was no oil in but there is no roughness or play that I can find. To me the gears look really good, just need cleaning. I’ve attached pictures of the gears. Does it look like they are ok?
Thanks a lot!
 

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Chuck K

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#27
The worm gear looks good. Does it have side to side play in it? It's pretty rare to find one of these machines with anything more than a little bit of sludge in the bottom of the apron. A bead of silicone on the bottom third of the apron halves when reassembling will keep the oil where it belongs.
 

vincent52100

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#28
Thanks for the info. I will do that. I can’t detect any side play in the worm. I’ve tried to look closely at all of the gears and the only problem I’ve found was the damaged gears in he QCGB.
 

gjmontll

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#29
Vincent, your mention of "side play" caught my eye. How are all the shafts and bushings?

Five years ago I overhauled/restored my 1944-vintage Logan 820. Although completely operational, its maintenance had clearly been neglected. All the gears were fine. But the carriage and QCGB had bad wear on bushings and shafts. In particular, the front shaft in the gearbox (the one the two gear selector arms slide back and forth) was badly worn. Most of the bushings were worn enough that I replaced them all and I made new shafts.

This was my "Welcome to retirement project", it kept me busy for over a year. I don't remember how many times I had the gearbox out and completely disassembled. I took it apart to assess it, take measurements and make sketches of the shafts, then reassembled and installed it so I could use it to make new shafts. Then again tear down to install my homemade parts and new bushings, and once again reassemble.

That QCGB slider shaft was so worn, I decided to improve on the original and add bushings on the gear selector arms where factory design had been steel-on-steel (cast iron?). That was a long risky operation. If interested in details, look back to my long series of posts, "Greg's Logan 820 Restoration".

Greg
 

vincent52100

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#30
Thanks very much. Going right now to check yours out.
 
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