Saving a Logan 825

[Nogoingback]

10" Logans can be like that. You've pretty much covered the possibilities, though it might be possible to find tool holders that position the tool a bit lower. For mine, I decided to make a solid plinth that's about .100" lower than the compound and use 3/8" tools when the compound is required.
I use the plinth most of the time. The other advantage of the plinth is that there's greater rigidity, so less chatter and better DOC's. I also
like working around it: no handle on the compound to bump into just before I make my last pass...
The only option on your list I would avoid is milling the top of the compound. There isn't a huge amount of material there
to begin with and you could cause it to break when tightening the nut.

 

[bhusted]

Thanks for your thoughts. Always appreciated. I've been reading about lots of people removing the compound to increase rigidity on these smaller lathes. I took a break from online meetings and pulled the compound to make some measurements.

The first thing I noticed/remembered is what a pain it is to pull the compound off. With the t-bolts captive and the nuts in the slots on the compound, there is a dance of loosening the nuts back and forth to be able to lift the compound free. By contrast, the compound on my Atlas/Craftsman is removed by simply loosening the 2 bolts and lifting it off of the dovetail plug. I think South Bend did theirs this way too. I guess my thinking here is that if I take the compound off, I'm not putting it back on unless there is a really good reason.

The flange on the bottom of the compound that mounts to the cross slide is 5/16 thick, so removing material here seems like a no go. This would all but eliminate the degree markings on the flange of the compound. My compound is 2.135" tall, so I'd need a replacement that is about 2" tall. What material did you use for your plinth? Are all of the Logan compounds the same style mounting? Is there any variation on the height of the compound between models?

 

[ThinWoodsman]

Check out the XL-sized AXA toolholders. They have a larger slot for the toolbit, and that may lower the bottom of the slot sufficiently for you to use 1/2" tooling. My understanding is that generally, people use 3/8" tooling in the AXA toolposts.

As for fixing what you've got, mill some metal off the base of the toolholder. You can always replace the toolholder if you screw it up too badly to fix.

 

[Nogoingback]

Thanks for your thoughts. Always appreciated. I've been reading about lots of people removing the compound to increase rigidity on these smaller lathes. I took a break from online meetings and pulled the compound to make some measurements.

The first thing I noticed/remembered is what a pain it is to pull the compound off. With the t-bolts captive and the nuts in the slots on the compound, there is a dance of loosening the nuts back and forth to be able to lift the compound free. By contrast, the compound on my Atlas/Craftsman is removed by simply loosening the 2 bolts and lifting it off of the dovetail plug. I think South Bend did theirs this way too. I guess my thinking here is that if I take the compound off, I'm not putting it back on unless there is a really good reason.

The flange on the bottom of the compound that mounts to the cross slide is 5/16 thick, so removing material here seems like a no go. This would all but eliminate the degree markings on the flange of the compound. My compound is 2.135" tall, so I'd need a replacement that is about 2" tall. What material did you use for your plinth? Are all of the Logan compounds the same style mounting? Is there any variation on the height of the compound between models?

Yes, I know what you mean about getting the nuts in/out on the compound. I loosen them as far as they will go and then spin them off with the tip of a small screwdriver while lifting up on the compound.

I can't say if all the 10" Logans have the same compound, but mine measures the same as yours, (Model 200).
I think it's better to make a plinth than machine material off parts of the lathe, though Thinwoodsman's suggestions
are easier. I've found that the plinth was worth the effort however. I made mine from 1144, which is becoming my
favorite go to material. Compared with something like 1018, it's nicer to machine with better surface finish, and a bit stronger if that matters.

 

[wa5cab]

The first 3969 Atlas 10" and a similar number of Craftsman 12" had the same type of captive screws for swiveling the compound. Then Atlas, as you said, changed to the inverted cone or Pintle type compound swivel. It may not be as stiff as the captive bolt type but there are no limits on the angle that the compound swivel can be set to. I've never understood why none of the Atlas competitors ever changed.

Check out the XL-sized AXA toolholders. They have a larger slot for the toolbit, and that may lower the bottom of the slot sufficiently for you to use 1/2" tooling. My understanding is that generally, people use 3/8" tooling in the AXA tool posts.

The primary purpose of the XLA tool holders was or is to allow someone to run 1/2" cutter holders. But those along with the normal 3/8 cutter holders might be another solution to the height problem. And allow you to keep the compound.

 

[mattthemuppet2]

I would just mill the material out of the bottom of the tool holder slot to get things on center. They're not super hard and a carbide end mill should have any problems.

 

[bhusted]

Thanks for the feedback. I appreciate all of the responses. After looking at it again and hearing your thoughts, I've decided I really want to keep the compound in place for now. I'm going to take the route of milling .08 off the bottom of the tool shanks. This way I won't be making any permanant changes to the lathe and can still retain most of the rigidity that the 1/2" shank tools offer. I'll probably pick up a couple of the XL tool holders to try them out too.

 

[bhusted]

I spent a little more time working on the Logan last night. While I've got the lathe setup on my test stand, I want to get everything functional and I have not addressed the back gears. A while back I brazed and cut a new tooth for the large gear, but never assembled the set in the headstock. The eccentric shaft is in good shape, but the bushings the gear shaft rides on are toast. They were oblong and very scarred. I'll also note, that looking at the parts, I'm not the first one to have taken these apart and is on par with other "work" performed by previous owners of the machine.

To remove the old bushings, I had to bore them out. The inside of the shaft has a very poor finish and measures at .927. The closest off the shelf bushing size seems to be 15/16 at .9375, but that would be a very tight fit. I'm wondering if the shaft used to have an ID of 7/8 and the bushings wore so badly that they did a poor job of boring it out to fit larger bushings? I also found it strange that the bushing bores intersected with the woodruff key slots. The eccentric shaft measures .001-.0015 undersized from 3/4. Does anyone know the size the bushings are supposed to be? There also doesn't seem to be a provision for oiling these bushings. I know that the back gear doesn't get used all the time, but it seems there should be some provision for lubrication to prevent the issues I'm seeing.

 

[bhusted]

The backgears have been set aside for a little bit while I wait for replacement oilite bearings to arrive. I'll have to bore the tube to accept the oversized bearings and then I plan to add a ball oiler to the cavity between the 2 bearings. I have an Eagle oiler that has a long enough spout that I think can reach down into the headstock and add some oil when the backgears going to be used.

Another issue has been the gear train to the QCGB. The idle gears that select forward or reverse feed also had worn out bearings. One had .012 and the other had .020 of play. They had also been bored and replaced by someone in the past. Anything over a slow spindle speed would create a loud rattle when feed was engaged. Instead of boring these out as someone did in the past, I opted to install sealed ball bearings. Perhaps a bit controversial, but now they should outlast the rest of the machine. The bearings are R10-2RS.

The next up in the gear train is the 60T gear that links the stud gear to the QCGB. I bought a steel replacement 60T gear for a few bucks on eBay and plan to install some similar ball bearings in it too. The original keyed, threaded bronze bushing is also worn out.

 

[mattthemuppet2]

as long as they work who cares? 2 less things to oil too! I put sealed bearings in both the spindle pulley and the back gear on my Atlas 618, partly to cut down on the amount of oil getting everywhere in the headstock.