# Logan 1875 rebuild



## Kevinb71

I am the proud new owner of an old Logan 10 model 1875). I am in the process of tearing it down as it had a few more problems than i knew of at first. I knew on purchase that the bull gear was broken. I have attached pictures here. I am going to try to repair this gear myself. I have done alot of reading and will do more before i start on the gear. I have ordered off of Ebay a #2 (55-135 tooth) 14 DP gear cutter for $20. I thought i was really smart until i realized that this is a 7/8" hole gear cutter. I have not been able to find a 7/8" arbor( i hope that is the correct term for the shaft to drive this cutter). I have been told (by the vendor Victor machinery ) that 7/8" is old technology and arbors for this aren't made any more, only 1". Now if i had a lathe Icould turn the 1" down to 7/8" BUT. Any good ideas on how to reduce the dia of a 1" R8 Stub Milling machine arbor to 7/8" using my mill? Please keep in mind that I am a self confessed brand newbie to this. I know only what I have read. I have a 16" Mill/Drill , but I haven't used it much. If i can accomplish the shaft reduction, then the plan is to set up an angle plate on the mill and using a hub that I have locate and bolt the bull gear to it. I will then bolt the gear from the back gear to mesh with the bull gear and lock the back gear in place so it can't turn once i am set right for the cutter. After I cut the first repair I would then slide the bull gear out and turn one tooth and then cut the next. If this makes sense let me know or tell me what obvious glaring error I am making here. I do not have a dividing head at this point and don't want to buy one for this. Although I would rather spend the $410 on a dividing head and repair my gear than just buying a new bull gear with that money. At least I would have the dividing head for future projects. 
The change gear box was also crashed, but if I can get the bull gear fixed then I can adapt some stock gears from browning/boston to replace the bad gears I have. I have ordered new bushings so hopefully it won't crash/trash again without my help! A total of 8 teeth on the bull gear are MIA. Any advice or comments would be appreciated. Thanks


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## Tony Wells

This would be a good case to use the mill as a lathe. Put the arbor in the mill spindle as normal. Clamp a turning tool in a machine vise in such a way to present a cutting edge to the arbor. Use the power feed if you have it, and skim the arbor carefully to size. It may pretty hard, so try it fairly slow rpm at first. Most arbors have a small relief groove near or at the shoulder, because not all cutters have an edge break on the ID. You may have to grind a separate tool for this, similar to a groove tool, but very narrow. These tools should be carbide.

Turning it in place guarantees that it will run true in the mill. Better than using the lathe imo.


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## Kevinb71

See I Knew i was a newbie! Great answer. Any options if it's too hard of a shaft? That was another concern I had. Thanks!


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## Tony Wells

That would present a bit of difficulty. Unless you are ready to learn hard-turning with ceramics, I'd look for another approach. There's no guarantee the arbor is that hard. When you get it, see if a good file will scratch it. If so, carbide will cut it. If not, it was ground after heat treatment and should be ground to size. Probably could borrow an arbor, or maybe a kind soul would let you use their lathe to make one that could be used in a collet.


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## Kevinb71

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.


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## CharlieW

I made gears for a Monkey Wards logan QC gearbox last year.  I had the same arbor issue.  I just made an arbor that mounted in my R-8 3/4" collet.  I drilled and tapped the end of the arbor so I could retain the cutter with a bolt and collar.

As far as making the gear, I would probably suggest buying a used one on ebay.  You will likely be ahead going that way.  I would recoment you spend the time on lathe turning projects and less on the lathe restoration project.

Charlie W.


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## 110octane

*Logan Bull Gear*

I obtained my Logan 10" about 25 years ago.  The machine has what I consider a design flaw in that the slider rod that changes the head drive from back gear to straight drive has a very small leaf style spring that can (after much use/old age) allow the shaft to vibrate and engage the back gear at inappropriate times resulting in teeth (generally on the bull whee) being shred.  I fabricated a longer selector rod and fitted a steel block to the headstock of the lathe with a hole and pin arrangement so as to securely retain the rod unless the pin is lifted.  This takes about 10 seconds longer to change the gear drive but positively assures that the teeth will be protected.  I purchased a new bull wheel from the Logan Actuator Company for about $80 in about 1989.  Logan Actuator still handles parts so far as I know.
Plaza Machinery in Bethel, VT is another source of used components.  I am not associated with either company.  As to turning your adapter in the mill it certainly can be done but I would be concerned that getting accuracy beyond a few thou would be difficult without a very ridged tool set up and super extra patience.  Maintaining the accuracy required for producing a spur gear with the standard mill drill using a rotary arbor will also be a challenge.  If obtaining a bull gear at an affordable price turns difficult maybe you would consider rigging some pins into the damaged wheel and filing them into tooth profile.  This IS crude, but will get your lathe operating so you can machine down arbors, gear blanks and other temporary jobs. A lot of the fun of this "hobby" is figuring out different ways to accomplish the same ends.
Best of Luck, Geoff


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## Kevinb71

110Octane
Yes Logan still handles the bull gear. $410 I am going to try my hand at repair and then get on to lathe projects. Could you send a photo of your "back gear lock"? At least the external view of it. Thanks.


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## 110octane

Kevinb71 said:


> 110Octane
> Yes Logan still handles the bull gear. $410 I am going to try my hand at repair and then get on to lathe projects. Could you send a photo of your "back gear lock"? At least the external view of it. Thanks.


Wow!  Inflation, I never would have guessed that increase; maybe 2X.  I will get a shot for you.  The external view will be all that you need to see the theory.  It is a very simple modification.
Geoff


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## 110octane

I am going to attempt to post three photos of the modification.  The locking pin is shown disengaged for clarity.  The block itself is 1-3/8 X 2 X 3/4 inches.
I used the existing Logan change shaft and machined an extension to it to avoid having to cut a rack.  It was about 25 years ago and I do not recall exactly how but it would involve threading one end and drilling and tapping the other to make a seamless connection.  Use fine threads and red Loctite.  I drilled the indexing hole and the block at the same time. There is an "almost" flat area on the headstock at the change shaft hole and I believe those are No. 6 socket head cap screws.  Use the shaft as a locating pin and using a transfer punch locate the first hole to drill and tap using the steel block for a guide.  I always use the tap drill size for the guide and then drill out the hole for clearance after the holes in the thing I am screwing to is drilled and tapped.  I feel one should always finish one hole and install the first screw or bolt before drilling and tapping the others; things have a tendency to move about.  I have learned this the hard way. Yeah!
The "cone" pulleys on my Logan are grooved for mini-V belts.  I did this on another lathe in a "friendly" machine shop that belonged to a friend of mine.  The lathe pulls like a tractor.
Happy turning, Geoff


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## 110octane

*Finally Photos*

Sorry, made a mess, let me try again.
	

		
			
		

		
	





Finally, I figured it out.  Please read the description in my last post.
Thanks for everyone's patience!  Geoff


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## yugami

Kevinb71 said:


> 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).


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## Kevinb71

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.


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## 110octane

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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## 110octane

*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


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## Kevinb71

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.


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## 110octane

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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## Kevinb71

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.


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## 110octane

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


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## BRIAN

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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## 110octane

Hey Brian, Thanks.  This was one of the options that was discussed.  It is certainly a good method.  There may actually be just enough material on the bull wheel to allow for machining a step, or shoulder, to make locating the red hot ring correctly in the axial sense. The downside is having to get the tolerance for the interference spot on and the fact that all the teeth have to be cut from scratch.  The ring material would be good in cast iron because cutting the teeth would be very smooth. Cast iron could be difficult or expensive to find although I think Durabar has a line of very thick wall tubing.  They will sell directly if you approach them in the correct manner (and you're lucky-I happened to call on the day a big customer changed requirements and they were left with some surplus bars that I could use) and be prepared to pay a minimum.  They might refer you to one of their distributors who will cut to size, you never know until you try.  Cast iron is really messy-no wonder the 19th Century was.....

Cutting the teeth from steel would be more problematic depending on the grade of material and the machinery available.  I think it's just a matter of weighing the options and matching available skills and machinery to the job.  This is the kind of stuff that keeps things interesting.
Regards, Geoff Morgan


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## BRIAN

Hi Kevin
 It may be worth thinking of useing a good quality Aluminum for the ring ,Quite strong enough for this job I think, easy to work, and shrink fit. I have used alloy for change gears with great results.

Another method of fitting could be locktite you will have a large contact area thats good for locktite. 

Brian.


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## Kevinb71

All I can say is WOW! The help on this site is amazing! At the risk of offending anyone I have already begun the process of pinning the two one tooth breaks and will pin the two tooth break as well. The four tooth break at the present time I am working on machining a piece of cast (as the original gear is) to dovetail in and then braze. I really want to try this my self for the education of it. I will try to take photos and post my progress. It may be slow as along with work it is presently lambing season and that occupies much "spare" time. Thanks to all of you who have offered thoughts, ideas and help. I may have to ask more questions after I goof this repair up.:biggrin: I have throughly enjoyed this site and hope to be able to contribute back in the future.


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## joebiplane

*Re: Logan Bull Gear*



110octane said:


> I obtained my Logan 10" about 25 years ago.  The machine has what I consider a design flaw in that the slider rod that changes the head drive from back gear to straight drive has a very small leaf style spring that can (after much use/old age) allow the shaft to vibrate and engage the back gear at inappropriate times resulting in teeth (generally on the bull whee) being shred.  the same ends.
> Best of Luck, Geoff



Geoff.
I recently had a Logan lathe that had the back gear engaged when the " sliding Rod "  was pushed in as you describe above....  THIS IS BACKWARDS !!!!!   The back gear should only engage when the Rod is OUT...
It appears that the ecentric  can be installet owo work either way... BUT YOU HAVE SEEN THE PROBLEM OF HVING IT BACKWARDS !
Joe


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## 110octane

*Re: Logan Bull Gear*



joebiplane said:


> Geoff.
> I recently had a Logan lathe that had the back gear engaged when the " sliding Rod "  was pushed in as you describe above....  THIS IS BACKWARDS !!!!!   The back gear should only engage when the Rod is OUT...
> It appears that the ecentric  can be installet owo work either way... BUT YOU HAVE SEEN THE PROBLEM OF HVING IT BACKWARDS !
> Joe


I did not realize that the rod could be installed in both operational modes, it never occurred to me that the eccentric could be rotated to accommodate the opposite operation.  It did not matter in my case because the damage to the bull gear was already done when I acquired the lathe.  About two teeth here and another single tooth here and maybe another single tooth there.  I "pegged" the teeth in to start with and then about two years later (prior to internet) I learned that Logan was still supplying parts and I purchased a bull wheel.  Luckily the back or layshaft was not damaged.  I then made a block that attaches to the headstock that utilizes a locating pin.  Now it would take a blow from a big hammer to force the bull gear into back gear without deliberately pulling the pin.  I could still relocate the eccentric without further modification, but things are fine for the time being.  I like the Logan.  My only complaint is the same with most of the 10" lathes that I have used (Yes, including the Southbend 10H) is the cross slide screw and nut are on the light side and wander a little.  These screws require a lot of attention and inhibit threading to a certain extent.  One has to be diligent to keep the play to a minimum and replace the screw and nut frequently.  I think the next time I will make an adjusting screw nut so has to compensate for wear.
Thanks, Geoff


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