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Newbie needs help with Logan 200 spindle runout

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SuperTroye

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#1
Hi All,
I bought a Logan 200 last year and finally getting around to getting it set up as life has caught up. I'm having a problem with spindle runout and I don't know how to fix it. I measure 0.001" runout on the outside of the spindle but 0.015" runout on the chuck..

The previous owner mentioned he changed a bearing, but I don't know if it was the front or back bearing. Perhaps there could have been an issue when he reassembled it? He included an extra and can post the brand if necessary. I will probably remove the spindle next and inspect all surfaces to see what the problem is.

Any advice would be appreciated. I'm hoping the lathe is not totally shot.

Here is a video showing a dial indicator on various chucks and in various places.

 
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Kernbigo

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#2
check the register of the chuck it looks like that may be your problem and needs to be re cut
 

markba633csi

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#3
It's possible that the lathe has been crashed so hard the spindle threads have been "pulled" but I have never seen that. The spindle seems to indicate correctly so the only thing left is the threads. Or...
All of the tooling you have is damaged or wrong somehow, but I am tending toward something wrong with the spindle threads.
Hopefully a Logan expert will shed more light on this
Mark
 

markba633csi

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#4
Ah I see your problem now- none of your tooling is seating fully on the spindle- is that the correct spindle or has it been replaced?
Your chucks and faceplate should screw all the way up to the shoulder on the spindle- you should take some measurements. Don't try to modify the spindle yet! Measure first- check with Scott Logan for the correct dimensions if needed
Mark
ps It looks almost like the shoulder has been cut back too far, I'm not versed well enough with Logans to ascertain that
 
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SuperTroye

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#5
It's possible that the lathe has been crashed so hard the spindle threads have been "pulled" but I have never seen that. The spindle seems to indicate correctly so the only thing left is the threads. Or...
All of the tooling you have is damaged or wrong somehow, but I am tending toward something wrong with the spindle threads.
Hopefully a Logan expert will shed more light on this
Mark
Thanks for your help. It's possible about a crash but I don't see any other damage. I tested with another chuck I have (that didn't come with the lathe) and the same result. So, I don't think it's the tooling.
 

SuperTroye

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Ah I see your problem now- none of your tooling is seating fully on the spindle- is that the correct spindle or has it been replaced?
Your chucks and faceplate should screw all the way up to the shoulder on the spindle- you should take some measurements. Don't try to modify the spindle yet! Measure first- check with Scott Logan for the correct dimensions
Mark
Ok thanks... I just spin them until I can't spin anymore. so they are tight. It's the correct spindle for the Logan 200 = 1 1/2" x 8TPI. What other measurements should I take?
 

markba633csi

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#7
You'll need to determine what the correct register (unthreaded portion) diameter of the spindle is supposed to be and the profile of the shoulder from where the threads stop- what is the correct distance there. You may have to make a spacer if the spindle has been "modified" by an "unauthorized person"
M
 
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markba633csi

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#8
I think Terrywerm has a 200, maybe he could measure his for you, I believe quite a few members have them
 
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Rooster

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#9
The back of the chuck or face plate should seat against the back of the spindle. Perhaps the previous owner turned down the register too much trying to correct run-out. May-be try getting a spacer to fit between the chuck and spindle register, the threads are just for holding the chuck on.
 

T. J.

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#10
Mark and Kernbigo have identified your problem. Pre-finished chuck back plates with 1-1/2"-8 threads will need to have the threads relieved and the shoulder square up to seat against the shoulder on the lathe spindle. I can post some pics of mine this afternoon that may help you.
 

Richard King 2

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#11
Did you align you machine bed with a level first? The machine is not new, so you can't expect perfect. Oh buy yourself a .0005" indicator. Take off the chuck and back plate and run the spindle at high speed for about 30 min. shut it off and lay your hand on the spindle housing and see if it is almost to hot to touch 140 F to 150F. Then mount the mag base on the spindle headstock and put the indicator on the top of spindle and slide a 2 x 4 or 2 x 6 under the spindle and slightly pry up on the spindle say put 20 pounds pressure up. the indicator should not have any movement or less then a tenth (.0001") Then put the mag base on the face of the spindle and check lateral movement. Again you should not have more then a tenth. Look on page 75 - 77 and see what I mean. https://cdn0.grizzly.com/manuals/g4003g_m.pdf. If that checks bad then tighten up the spindle spanner nut a 1/16" or 1/8 turn.
I know the manual is not your machine, but they have good manuals and a lathe is a lathe.

Like the others said remove the face plate and check for burrs. stone any with med grit Indian lapping stone wipe everything off with your hand and screw it back together. If you were a bit more experienced i would say to blue up threads and taper. check the outside face of the and if it's with in .001" put your chuck back on and snug up the bolts but not super tight. Then check the OD of the chuck and tap it with a dead blow hammer and get it spinning on the spindle axis like you do with a 4 jaw chuck. Get that less then .001". Have to be a detective and test and retest before taking something apart. SKF bearing company says that many times one makes things worse then leaving the bearings alone.

If you do remove the spindle we can talk about how and what to do later. Rich
 

SuperTroye

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#12
Ok thanks to everyone who replied. Let me digest the comments and will report back on what I find. Here is another video where I indicate on a 3MT to 2JT drill arbor. I'm trying to figure out where on the spindle is the issue. I hope this helps in diagnosing the problem.

 

Nogoingback

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#13
Ah I see your problem now- none of your tooling is seating fully on the spindle- is that the correct spindle or has it been replaced?
Your chucks and faceplate should screw all the way up to the shoulder on the spindle- you should take some measurements. Don't try to modify the spindle yet! Measure first- check with Scott Logan for the correct dimensions if needed
Mark
ps It looks almost like the shoulder has been cut back too far, I'm not versed well enough with Logans to ascertain that

Mark is correct: your tools aren't seating on the spindle nose properly. This is what it should look like:

DSCF7310.jpg

Here's a pic of a Model 200 spindle. The total length is about 1 inch and the unthreaded portion is around 1/4".

DSCF7309.jpg

If you can post a pic of your spindle it would help, but it looks as though your tooling is bottoming on the threads rather than bearing
against the shoulder on the spindle.
 

markba633csi

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#14
It's quite possible that none of your tooling was ever properly fitted to the spindle nose in terms of cutting away (relieving) the internal threads to allow full engagement up to the shoulder in which case you simply need to do that and you'll be off and running. But it would be good to know if your spindle shoulder has been cut back enough to make it non-standard.
Mark
 

markba633csi

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#15
I can't explain why your faceplate does not fit properly if it is indeed a Logan original part. It may not be.
Mark
 

Nogoingback

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#16
And this is what the back side of the chuck should look like. Notice how it's relieved to allow for the unthreaded portion of the spindle.
If your chucks aren't like this, there's your problem.

DSCF7312.jpg
 

markba633csi

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#17
If you need some guidance doing the thread relief let us know- you'll need a boring bar and you'll need to machine a temporary spacer
Mark
 

Nogoingback

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#18
I can't explain why your faceplate does not fit properly if it is indeed a Logan original part. It may not be.
Mark

Could be tooling from another lathe: a number of lathes came with that thread. They also could be backplates that were partially machined
and needed finishing, which was never done properly.
 

markba633csi

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#19
That's what I'm thinking too
 

Richard King 2

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#20
I found this for you. Page 4 of the instruction manual says it has 3 rows of sealed bearings. If you do take it apart check the spindle by setting it on precision V blocks and indicate it to be sure it's not bent. Also when your ready to install new bearings we can talk about Instaalling them so the TIR run out is at the low side. Near the bottom of the first PDF shows the spindle assembly in 2 pictures. If you can You could donate something to them as it's an .org.

http://www.vintagemachinery.org/pubs/2093/3353.pdf
http://vintagemachinery.org/pubs/2093/3377.pdf
 

SuperTroye

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#21
Ok yes after reading all the posts I think the tooling is from another lathe. I see what everyone means now. I attached 2 pics of the spindle.

I bought a SB 10k with QCGB that I can set up to do the relief cuts [I'm trying to sell the Logan and set up the SB :)]. Maybe I should just buy a proper 3 jaw chuck on eBay made for Logan and call it a day.
 

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middle.road

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#22
Check the bearing replacement that the PO performed. Logans are stout, and the spindles have proper bearings in them, but as with everything else with machine tools it has to be done properly.
I grabbed an extra 3-jaw off of EBay several years ago, cleaned it and slapped it on and had only .0015 runout.
They do have to register properly as noted above.
 

T. J.

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#23
You need to perform the cuts on whatever lathe you're going to use the chuck on. Even though the Logan and the South Bend both have 1-1/2" - 8 threads, the spindle noses are different.

Take the back plate off of the chuck. Thread it on the spindle backwards with a spacer between the face and the spindle shoulder. Cut the thread relief with a boring bar, then face off the shoulder of the back plate so it is square. Then, turn the back plate around and thread it onto the spindle in its normal orientation. Ensure that it is seating against the spindle shoulder. Then take a light facing cut on it so that it is running true to the spindle axis. You may also need to recut the register to match your chuck. Now mount the chuck back on it and test the runout.

Edit: Even if you buy a new chuck for the Logan, the above procedure will still need to be done with the new back plate.
 

Silverbullet

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#24
Any thought the spindle isn't installed correctly . And isn't seated in the bearings , or its been abused.
 

SuperTroye

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#25
You need to perform the cuts on whatever lathe you're going to use the chuck on. Even though the Logan and the South Bend both have 1-1/2" - 8 threads, the spindle noses are different.

Take the back plate off of the chuck. Thread it on the spindle backwards with a spacer between the face and the spindle shoulder. Cut the thread relief with a boring bar, then face off the shoulder of the back plate so it is square. Then, turn the back plate around and thread it onto the spindle in its normal orientation. Ensure that it is seating against the spindle shoulder. Then take a light facing cut on it so that it is running true to the spindle axis. You may also need to recut the register to match your chuck. Now mount the chuck back on it and test the runout.

Edit: Even if you buy a new chuck for the Logan, the above procedure will still need to be done with the new back plate.
Roger that, thank you for taking the time to explain it. I will need to tool up (get a boring bar, etc) for this. I look forward to it. Thanks to all who have helped along the way!
 

T. J.

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#26
I hope we're all on the same page, but just to clarify, I believe there are two separate issues here:
  1. The spindle runout.
  2. The improperly fitted chuck(s).
I've limited my comments to the chuck issue, as I've not disassembled my spindle and have no experience to add to the conversation.

Carry on:)
 

SuperTroye

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#27
Any thought the spindle isn't installed correctly . And isn't seated in the bearings , or its been abused.
That was my first thought... so I bought the dial indicator to start checking. The first video shows about 0.001 runout measured on the spindle itself. Visual inspection shows it to be ok and free of catastrophic crashes.
 

T. J.

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#28
Oh, and if you determine that the spindle issue needs to be addressed, do that before fixing the chuck!
 

mikey

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#29
I agree with Richard - you need to determine how accurate the spindle is. I'm sure the guys are right and the excessive runout of your chucks have to do with how they fit on the register but that is a separate issue. You first need to know how accurate the spindle is. I would suggest you begin with using a 0.0005" dial test indicator, not a drop indicator, and measure for concentricity in the taper at several points to make sure the readings are consistent. If the spindle is accurate then check play in the spindle bearings as Richard suggested; if there is a lot of play then the spindle bearings may need adjustment or possibly replacement. If there is no significant play then your spindle is okay and you can focus on the fit of your chucks on the register.

Nailing down the source of runout is a process of elimination and you need to diagnose it before taking corrective measures.
 

SuperTroye

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#30
I hope we're all on the same page, but just to clarify, I believe there are two separate issues here:
  1. The spindle runout.
  2. The improperly fitted chuck(s).
I've limited my comments to the chuck issue, as I've not disassembled my spindle and have no experience to add to the conversation.

Carry on:)
Indeed... I will take care of #2 first, then go after #1. In your opinion how bad is the spindle runout? Is there another measurement you want me to take?
 
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