Logan 1875 rebuild

Finally Photos

Sorry, made a mess, let me try again.DSCF0985.jpgDSCF0986.jpgDSCF0984.jpg
Finally, I figured it out. Please read the description in my last post.
Thanks for everyone's patience! Geoff

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I will see what the arbor I ordered is like when it arrives. Just guessing from the photo on the website it's hardened then ground. Somehow I think they are not selling me the right arbor as this one doesn't have a keyway and the cutter has akey slot. Time will tell unless someone has a gear cutter and arbor they can post a photo of.

You don't need a keyway even though the cutter has one. All horizontal mill cutters have a keyway but Hardinge sold their TM mill with arbors (7/8 and 1) with no keyway in it. Most machinists never installed the key anyway.

Buy a 7/8" arbor and use it. Do not turn down a 1" arbor. You're stacking up imperfections. The arbor seats imperfectly, it will turn imperfectly and the imperfections in the build process will all stack up to make a rather poor gear in the end.

While you can technically cut a gear on a vertical mill with a stub arbor I would highly recommend the rigidity of a horizontal mill. otherwise you need to make many many light passes as the arbor will spring, along with the material spring, and the holding mechanism spring (more imperfections).
 
Geoff
Thanks for the photos. It makes good sense and would save the bull gear except for human error. Thanks again.

Yugami what you are saying about tolerances stacking makes sense to and I will try the arbor like it comes. It doesn't matter if the cutter should turn a bit. I am limited to a vertical mill so I will try that and make light cuts. Thanks for the input! It is appreciated and noted.
 
Your bullwheel has a different catch mechanism than the one on my Logan 10". Your pin is a push pin that enters the face of the drive pulley whereas mine is a little lever that pushes (or pulls on return) the pin into and out of the rim of the drive pulley. My lathe is a 1953 model. The corresponding hole for the pin shows in the rim of the first sheave in the photograph. I'm not sure what a model 1875 is.
During my pondering over how to deal with missing teeth I had an idea to make a ring gear to braze on to the old bullwheel, like a starter ring fits on an automobile flywheel. The scheme is to save machining all the rest of the gear and drilling/reaming/boring operations. The plan was to prepare a mandrel to mount the bullwheel on and then turn the teeth off the gear just down to a diameter a little less than the gear root diameter. Then a ring would be prepared to fit over the turned down gear having the (near to/rough) proper OD of the original bullwheell. The ring would then be sweated with bronze filler rod on to the "reduced diameter" bullwheel and then the unit fitted back on the arbor and turned to the precise OD and the gear teeth cut. The ring could be turned from either cast iron or from steel. Cast iron would be easy to machine (dirty as all get out) but somewhat hard to find unless Dura Bar produces heavy wall pipe or you could find an old. big pipe fitting. Steel tubing would be OK but more difficult to machine. The home made mandrel would serve as both mounting and turning. Someone like Illinois gear of what's left of Boston gear may actually have a stock gear that would save a lot of time if such would be economical, just carefully machine the hub out....
When I had my experience with this $85 to $150 or thereabouts was competitive with my schemes to renew the bullwheel; but $400+ begs for another approach. I bought my wheel before the internet and networking was via phone. Maybe a thorough search will turn up another wheel.
Good Luck, Geoff
 
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Logan Catalog

I looked at the '53 Logan catalog and your model 1875 was made then, a floor model, 10 inch. My model is an 1805, 10 inch with an open cast iron bench leg set up. Your lathe must be a later year with the change in the method of locking in the back gear. My lathe was well used when I got it, a friend of mine pulled it out of an industrial site that was scheduled for demolition, and required a real cleaning up, etc. It has served me well over the last 25 years and I have no real complaints. It is time to renew the cross thread screw on the compound and clean up some other worn bits. Still good American iron, a handy little toolroom lathe.
Geoff
 
I had found a bull gear from a gentleman on Ebay. It had the right part
number(I thought) LA-654. When I got it, it had the lever style you
mention. Turns out that I need an LA-654-2. Have to pay attention to the
-2. I was fortunate and he let me return the gear even though he had
done nothing wrong on his end. He was very good to deal with. He sells
parts on Ebay by the name of Trikerdad.
The problem with a "stock" gear seems to be that this is a 14dp gear.
14dp seems to have fallen out of favor as a gear pitch. Nobody (that
I've found) makes 14dp anymore.
At this point I am still hopeful that I can come up with what I need to
repair this gear. I think that I will get it done, but it's going to
challenge my machining ability, which is why we do this as a hobby
right? Thanks for your thoughts on my problem. It is appreciated.

Also you login of 110octane. Would that imply some former or current
racing hobbies as well? I have some older Mopars and occasionally race
them 1/4 mile.


 
Sorry, Kevin, I have not been on the site for a while and then there have been some technical problems with the site (hackers?). Regardless, you are correct that 14 DP is the tooth profile. I had forgotten that. At least it proves that the pressure angle is 14 1/2 degrees since 20 degrees was not used on earlier gears. I think that I would try pinning and brazing replacement teeth onto your gear and machining the finish profile. DP gear cutters are becoming scarce and expensive, too. It must be that CNC equipment can profile gear teeth with a different cutter geometry. Would some up to date machinist please comment on that.
The Logan was a good little lathe because the headstock ran sealed ball bearings, at least on the models we have. Good luck with your machine. As to my handle it is the current (soon to change) rating for reciprocating engine aviation gasoline. I do own some junk cars but nothing that would hold up on the race track.
Geoff
 
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Ah an airplane man. I took some classes 4-5 years ago. Solo'd then couldn't afford anymore. Three weeks later the plane I solo'd in crashed in OK due to an engine failure. It was a case of less than stellar maintenance.
Back to the gear. I found the right gear cutter on Ebay for $20. It cost me $35 for an arbor to run it, but at least I can use that for other things as well. I am going to pin and bronze the single tooth sections and put in a piece of cast for the four tooth section. I guess i am just too bull headed to buy a new gear! Probably have more in all the tools to fix this one than the gear would have cost, but buying one wouldn't teach me much and I'd have no toold to show when I'm done. In the long run I think this will be the best way.
 
Yup, it's too expensive for all but the Gulf Stream corporate big wigs, these days. Haven't lifted any gear in many years. I have a few friends who still fly and that's about it. (My wife would say-He just likes to talk).
As to your purchase of the tooling, I have done the same thing more than once or thrice and in most all of the cases, I came out when I used the tooling and the rigging the second and third time (and in a case or two, even more times). I usually learned something in the process which unfortunately once or twice was that maybe I had have been better off...
I seems that most CNC machining of gears involves hobs or high speed single point profile cutters. Perhaps an up to date machinist would comment on this, I would welcome that. There is a guy down near Tampa, FL that makes replacement gears for Atlas/Clausing on CNC. I don't know what type of machine or tooling he uses, but he has the components programmed and just sets up the blank, zeros the tooling, and turns the machine loose. I'm not sure if he makes any other replacement gears for different lathes. Atlas/Clausing/Craftsman used die cast and "Zamak" (crapalloy) powder metal gears and levers, etc.
Your Model 1875 must be one of the later production machines considering that the back gear engagement is different from the one I have; I have not seen a Logan like yours. I think most South Bend lathes in our size machine used a set up similar to your Logan.
I think that your approach is solid. You may want to slow cool the gear after brazing in lime to prevent distortion. There have been, from time to time, some decent prices on gear cutters on ebay. I think you did fine considering that new DP cutters are running from about $50 and way on up in price. Good luck, Geoff
 
Hi kevin71,
Just a point to note, auto ring gears are a shrink fit, just heat them up and drop them over the fly wheel, usualy spin the ring around to ensure a good seat, then let it cool slowly. I think this approach may be better than bronze welding. and less work.
Just a thought Best of luck with your project Brian.
 
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