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Logan model 200 shifter rack and back gear engagement/adjustment

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medida

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#1
Hope folks can help me here

Got an old logan model 200 that I have taken apart, cleaned/regreased the bearings, painted the unit, etc. Some teeth were missing on one of the reverse gears and on the mitre gear in the apron (have found replacement parts for these)

Without the back gear engaged, the unit runs very well (did not do that prior to the refurbishment)

However, I am having problems with the back gear alignment to the shifter rack

I have followed these instructions
http://lathe.com/ll-group-archive/logan_lathe_back_gears.html

the issue that I have is when I roll the eccentric around to engage the back gear....I roll it as far as I can (it then becomes an interference at the gears and no backlash). When I put in the shifter rack, as it advances into the headstock it starts to move the eccentric, so backlash starts increasing. By the time I get to the latch position, the back gear is mostly not engaged.

The only way I can see around this is if the eccentric shaft can never achieve an interference between the two gears. It's like I need to rotate the eccentric shaft/gear another 20 degrees or so....but am not able to ....because I achieve a zero backlash and interference

I have had the unit all apart and the spindle out....but do not see any errors in how I have put it back together (and it does run very well with no backgear engaged)

any thoughts?
 

stevecmo

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#2
I think you need to read the page you referenced again. :whistle:

When you push the shifter rack IN it disengages the back gear. The spring loaded lever should position the gears correctly when the rack is pulled out. You may need to adjust the collar on the end of the shaft a little.

Hope that helps.

Steve
 

medida

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#3
Yes, I know when the shifter rack is pushed in the back gears are not engaged

The issue that I have is I need to rotate the eccentric gear another couple of teeth more but am not able to do this, as the back gears are now at an interference interface (that is, I have completely removed the shifter rack out of the headstock)

With the shifter rack out, I have rotated the eccentric gear as far as I can. When I insert the shifter rack, as soon as the shifter rack teeth start to engage, it starts to disengage the back gears. By the time I am at the latch position, the back gears are almost disengaged. When the shifter rack is fully inserted, the back gears are disengaged.

I cannot rotated the position of the eccentric gear relative to the shifter rack any more, so that the backlash is correct when the shifter latch is in place
 

stevecmo

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#4
I guess what you're saying is that the teeth in the rack are engaging the teeth in the gear too soon? I think that would be the only thing that would cause what you're describing. If that's the case I'm not sure what to tell you. The distance between the teeth and the latch on the shifter rack is a fixed, calculated dimension per the design from the factory. Maybe someone reworked the shifter rack?????

Sorry I can't be of more help.

Steve
 
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Mister Ed

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#5
Been a long time since I have messed with this, but, I think you are saying with the rack plunger pulled out ... the gears are not engaging.

I think you need to try and shift the engagement back to the second (or even third) tooth on the rack. Push the rack in a little before lifting the eccentric shaft completely. This is what Scott is talking about in point 6 of the link you posted. You will only push in the rack a tooth width at a time.

Like I said its been a long time ... but I think this will work.
 

medida

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#6
Let me try and say this differently

The shifter rack is out of the headstock. I rotated the shifter gear until the two back gears (28 Tooth and 70 Tooth) are completely engaged with zero backlash. I cannot rotate the shifter gear any more

I then start to insert the shifter rack. As soon as the first shifter rack tooth engages the shifter gear teeth, it starts to rotate the eccentric and it backlash starts to increase. THe shifter rack has not yet protruded out from the back side, so I do not have any shaft exposed to lock a collar on. By the time the shifter tab hits the headstock, the back gears are almost totally disengaged

So I do not understand how I can change the position of the shifter gear to the shifter rack to get the necessary backlash. The only way I can see to do this is to take the eccentric out and install the shifter gear....then put the eccentric back in. This just does not seem right that this is how it works. I would expect that you should be able to adjust the backlash without having to take stuff apart
 

CNCMAN

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#7
It can be a pain to adjust. :angry: I just did this on my 1922 following Scott Logans instructions.
I ended up cutting a 1/4" dowel about 6 or 8 inches long and using it as a gentle pry bar wedging the bk gear in place after I rolled the the shaft to a point in its arc upward.
then push the selector rod back in to roll the gear into place. I know I'm clear as mud but it works just like the Logan instructions say, just keep trying at different positions of the bk gear arc and it will work. I completely agree it can be very vexing but my lathe sure is quiet now in back gear. I do love my Logan.:))

Kevin
 

TomKro

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#8
You may also want to consider slotting one end of the eccentric shaft, per "Redlinemans Logan 200 Rescue".
That might make the adjustments go a little easier.
 

ddushane

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#9
I'm tickled to see this thread, I've been wanting to ask about this but really haven't had time to mess with it yet. I have a 1920-1, my back gears only engage when I push the shifter all the way in, but nothing if its out a little. I'll go back & read the link yall listed & try to figure it out.

Dwayne
 

Redlineman

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#10
Ummm...

People do realize that the back gears are engaged by pulling and locking the shifter rack OUT, eh? You didn't know that... really?
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Don't worry. I had to clue into that myself. My lathe didn't even HAVE a shifter when I started on it, so I had to figure that one out for myself... in time.
 

ddushane

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#11
Sorry for my ignorance but I had no clue, I'm relatively new to lathes, and had never heard about back gears until I started cleaning up & refurbishing my Logan lathe that was given to me. I'm learning but yes some of us are still in the dark on some issues.

Dwayne
 

Redlineman

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#12
No Worries, Dwayne;

Like I said, I found that light switch. Darkness and light are in equal measure. The overlap between members helps us all get through!
 

RandyM

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#13

ddushane

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#14
I don't get in here and just really spend time looking at old post, I look at the new threads but rarely old ones, this one snuck up on me & I'm glad it did, I'm looking forward to getting my Logan working right as far as the back gears. Everything else seems to be in good working order.
 

epanzella

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#15
There should be a little spring loaded latch cut into the backgear engagement rod that pops out to hold the rod in the "engaged" (fully out) position. It looks a little like a woodruff key. These latches have a habit of disappearing over the years and if you got your lathe with it already gone it could be hard to figure out how back gear engagement works.
 

Redlineman

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#16
Absolutely;

You rarely see a fully functioning lock key on the shifter rack. Without a manual, you might not even know about it at all, and simply be left to wonder what that slot in the handle was for? ... if you even saw it!

I did a LOT of fiddling with my shifter to get it right. I had my headstock together and apart, mostly because I could not wait to see how it all fit even though I didn't have everything that went in there ready. A few times back and forth made it easier to figure out in the end, and to get it spot on. Setting the rack with the headstock on the bench was pretty easy, but doing it bolted to the bed would be near impossible if it were not for the slot mod in the end of the back gear shaft. If you have it apart, do the mod without fail. If you are having adjustment problems, it is arguably worth the trouble to go in just for that purpose alone.

My back gears make very little more noise when working than when not engaged.
 

daveog

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#17
I'm sorry to resurrect an old thread, but I am in the process of trying to adjust the shifter on my Logan right now. I cut the slot in the end of the eccentric shaft like Redlineman recommended. My problem is that I'm not sure how to get it adjusted. If I rotate the eccentric shaft all the way to the back position and insert the rack it still seems to not quite catch the teeth correctly. When the shaft is locked out the gears aren't quite enough in position to engage. I have to pull it almost all the way out to get it where it needs to be and then there is no shaft left to attach the collar to. I hear everyone that I need to adjust it so that I get an extra tooth or two on the gear so it locks, but I can't figure out how to do that. When I insert the rack, it just engages where it is and I can't get it past the gear on the eccentric because it immediately engages it. What am I missing?

Thanks in advance.
 

Briney Eye

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#18
I'm sorry to resurrect an old thread, but I am in the process of trying to adjust the shifter on my Logan right now. I cut the slot in the end of the eccentric shaft like Redlineman recommended. My problem is that I'm not sure how to get it adjusted. If I rotate the eccentric shaft all the way to the back position and insert the rack it still seems to not quite catch the teeth correctly. When the shaft is locked out the gears aren't quite enough in position to engage. I have to pull it almost all the way out to get it where it needs to be and then there is no shaft left to attach the collar to. I hear everyone that I need to adjust it so that I get an extra tooth or two on the gear so it locks, but I can't figure out how to do that. When I insert the rack, it just engages where it is and I can't get it past the gear on the eccentric because it immediately engages it. What am I missing?

Thanks in advance.
I had the spindle out of my old 200 to lube the main bearing and replace the tail bearing, but I didn't pull the backgear assembly (because it was working fine). So I don't actually have any informed advice to offer.

That said, I'll dive right in anyway :). The way I read your description it sounds like you might not be rotating the eccentric shaft to get the gears in full mesh with the spindle gears before you insert the rack. Or you haven't pulled the pin on the bull gear to disengage it from the cone pulley, keeping the gears from fully meshing. You might have to jiggle the spindle to get them to mesh.

When I visualize it, if the eccentric is rotated toward you to fully mesh the back gears, the first tooth on the rack couldn't move past the shifter gear on the eccentric. So the eccentric needs to be rotated back just enough allow the rack to slide in past that first (or second) tooth, then rotated back toward you to mesh the rack, shifter and back gears simultaneously. Then put the collar back on.

The real difficulty looks to be in getting hold of the eccentric shaft assembly without pulling the headstock, but you've done the slot modification, so you're golden.

Somebody needs to do a YouTube video on this. It won't be me any time soon, so here's your chance.

All the best!
 

daveog

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#19
Hey Briney,

Thanks for the advice. I got it working tonight and your advice helped a lot. I was trying to do it off the bed without the spindle installed and eyeballing where I felt the gears needed to be to engage...dumb, right? So I put it all back together and used the slot to rotate the eccentric until the back gears were fully engaged, which turned out to be off of where my eyeball point was, go figure! Once I did that and got the rack in, everything lined up and works great!

My next step is to get the belt back on the motor and adjust the variable speed belt to get it running again. I'm not looking forward to any of that, especially the variable drive system. After I get it all powered back up and running, my next step is to remove the static converter and install my VFD. It's gonna be a long road, but hopefully worth it.

I bought the machine from a guy who was just making bushings with it and really didn't know what he was doing. The lantern tool post he was using was missing parts and not even close to the center of the work. The cross slide and compound were so poorly adjusted they could be pushed back and forth by hand. Before I bought it I just did a simple cut on a scrap piece he had about six inches long and somehow the machine managed to hold very tight tolerance on that despite the poorly adjusted parts. So I decided to completely tear it down, clean it up, and put it back together. I'm glad I did, I found a gear in the quick change box with broken teeth, so I replaced it. Keeping my fingers crossed that it still cuts straight when I'm done with it!

Thanks again all!
Dave
 

Briney Eye

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#20
Hey Briney,

Thanks for the advice. I got it working tonight and your advice helped a lot...
Excellent! So you have a 200 that's been retrofitted with a gear box, but still has the original, no clutch apron? If so, be very, very mindful when you're power feeding and near the end of travel. With no clutch, if you hit the end of travel catastrophic damage will ensue. Don't ask how I know. Be mindful even if you have a clutch, because it can probably still pop gear teeth.

I'm trying to finish up an electronic lead screw on my 200, and hoping that the stepper motor torque limit will provide some protection, but I don't think I will have the nerve to test it. I haven't been able to stall it yet, so it might still have enough torque to break something.

Have fun! Glad I was able to help a little.
 

daveog

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#21
No, I'm not sure what model it is exactly. It is a later model, probably early 80's. It's a Powermatic by Houdaille with the variable speed drive control. The apron has a clutch. From what I can tell, the headstock hasn't changed much in the Logan machines, so all the information about the back gear applies directly.

Sounds like an interesting project you are working on. I don't blame you for not wanting to test it...better to take care and never know the answer to that question.

Thanks again!
Dave
 

Briney Eye

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#22
Well, you should put up a picture or two of your machine for our edification.
 

daveog

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#23
It is in pieces still and I didn't take any prior to the teardown. I'll take some of it in it's current state thought and put them up. It is very similar to this image I found on Google:

 

Briney Eye

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#24
Ought to be a very capable machine. I'm sure you'll have it looking like a new one.
 
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