Logan 1875 rebuild

Kevinb71

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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

2012-03-13_14-18-22_643.jpg2012-03-13_14-18-34_285.jpg2012-03-13_14-18-00_178.jpg

2012-03-13_14-18-22_643.jpg 2012-03-13_14-18-34_285.jpg 2012-03-13_14-18-00_178.jpg
 
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.
 
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!
 
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.
 
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.
 
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.
 
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
 
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.
 
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
 
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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