I have a Logan 400 and am puzzled in why this lathe will not stay in backgear. I have read every posting on the internet on this topic and nothing works for me. My lathe engages the backgears when the lever is pulled to the front of the machine but disengage when the lathe is turned on. Upon complete disassembly of the backgear shaft, etc. I find this is the only way to engage the backgears. Some other internet replies to this problem indicate that the lever must be pushed to the rear to engage the backgear. That configuration is not possible after studying the eccentric shaft. My lathe has, of course, the "bull gear plunger" which works fine and disengages smoothly. My lathe does not have a "back gear plunger' as some more recent models might. These are terms from the Logan 1400 instruction manual which was sent to us in 1956 by Logan Engineering Co. as a 'close substitute' to the Logan 400 manual which they no longer had back then. I do not have a Logan 400 manual. Any suggestions on how to engage the backgears so that they stay engaged?
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Logan 400 Lathe, Will not stay in Backgear
- Thread starter rhamm17
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I don't have a Logan lathe, but my South Bend 9C wouldn't stay in back gear. It was
supposed to have a spring loaded screw with a brass shoe that put tension on the eccentric
that kept it from popping out of gear. I made a replacement and it will now stay in gear.
supposed to have a spring loaded screw with a brass shoe that put tension on the eccentric
that kept it from popping out of gear. I made a replacement and it will now stay in gear.
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- Jun 7, 2013
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Some south bend lathes had a split bushing on one end of the shaft; a setscrew is snugged up that pinches the bushing together, binding on the eccentric shaft. My 9" Monarch has the same device.
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I remember using a Logan where the back gear shaft rack had a slot in the bottom of shaft where a spring pushed a stop down . And the stop was worn down where it entered the side of the lathe. And on the lathe the spot where it was meant to stop was also badly worn. And the rack or shaft would not hold. A quick fix was to pull the rack out and use a c clamp on shaft so it could not slip past where it was meant to stop. Look for Logan parts LP1204 and LP1376.
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Logan lathes have FANTASTIC SUPPORT. Ask for Scott Logan, grandson of founder.
http://www.lathe.com/contact_us.htm
http://www.lathe.com/contact_us.htm
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From what I understand the 400 is different than the 10" & 11" models, it doesn't have the pull out knob with latch like the 800 and 200 series. I believe it has a lever connected directly to the "eccentric shaft" rather than the "shifter rack" and pinion used on the 800 & 200 series. I have never touched a 400. I don't know if it may be possible to get the gears "out of sync" like the larger lathes. From the pictures I have found it doesn't appear the 400 has any latch to hold the lever in place. So my not so uneducated guess would be to first try to sync the gears and if that doesn't work maybe fabricate some sort of latch to hold the back gear lever in place.
These are Logan's instructions for the larger machines:
http://lathe.com/ll-group-archive/logan_lathe_back_gears.html
These are Logan's instructions for the larger machines:
http://lathe.com/ll-group-archive/logan_lathe_back_gears.html
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Where I worked, years ago, we had the same lathe and the same problem. The quick fix was to pull out the plunger and measure the space between the headstock and the knob. I cut a piece of copper tubing that slipped over the knob and hung on the shaft. It would stop the plunger from pulling back it. I painted it red and made a wire hook for it right on the lathe. This was quick fix that was still being used when I left and I will bet money it is still being used that way.
Dennis
Dennis
OK, thx for all the replies you people have posted. Finally, after several hours of disassembly and assembly of the backgear shaft, I figured out the problem. There is not a locking mechanism for the backgear assy on this lathe. There may have been on later models of Logan 400. On the right side of the headstock housing, on the back, there is a small set screw pressing against a cast iron "slug" that is presssd against the backgear eccentric shaft. Adjusting the inward pressure on this set screw creates friction and snugs up the eccentric shaft to the point it holds the backgears in the "engaged" mode and does not slip out. Now it is working OK. Nothing in the Logan manual addresses this issue or periodic adjustments required. This set screw must be tightened exactly the proper amount, too loose and the backgears disengage, to tight and they lock tight and bind. Who knows, this may help somebody in the future who has the same problem with this issue. Thx again!
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Might be worth replacing the set screw with something like a screw with a handle, so you can loosen it to move it and tighten it to keep it from moving. Not sure how difficult that area is to reach, but if that is not a problem, why fuss with a fussy setting?
That is an excellent idea. The set screw is 1/4'-20 thread and I will put a short hex head bolt in as a replacement and leave a 7/16" wrench close-by to adjust the tension as required. This should work great and provide a very solid backgear shaft locking mechanism.