How to "unstick" this chuck from the mill spindle?

[rlb]

Hello all,

 

Today I had the opportunity to buy a used Sherline lathe and mill, so I did.

 

I have no prior experience with them so I am reading the online manual from the Sherline website, and trying to familiarize myself with the basic nomenclature and basic operation of these machines.  From what I have learned so far, they are somewhat older machines, (probably pre 1999) but still model 4000 for the lathe, and 5000 for the mill.

 

I have one roadblock immediately.  The jacobs chuck is stuck in the mill spindle--

 

  

 

Am I right that this should be just a friction fit?   What is the best way to loosen/remove this?   I ask this knowing that some may be thinking "if he can't do this, these machines are wasted on him".

 

Any advice is appreciated.

 

Ron

Edited January 30 by rlb

[BANYAN]

Hi Ron, I have a Sherline mill also.  That chuck usually comes with a draw bar (threaded on one end and a bolt type head) that you put in from the top of the spindle assembly.  I partially engage the thread of the draw bar into the chuck bore, give it a tap or two with a small rubber mallet (small hammer will work also) which usually disengages the tapered (morse) chuck head.  If you don't have the draw bar, putting a metal rod of suitable OD down into the spindle bore and tapping that should also work, BUT put a rag or something under the chuck so that if it dislodges completely, it will fall onto a padded surface and not damage the cross-table or the chuck etc.  The rod could be one of the many different bars/rods provided by Sherline, but should be a smaller OD than the bore, but bigger than the internally threaded bore in the top of the chuck (so that you don't drive the bar into this and damage the thread).

 

I hope that resolves the issue for you.

 

cheers

 

Pat

Edited January 30 by BANYAN

[AON]

I do not have this machine but, having said that, there should always be an access hole on the far side to knock it out with a rod if/when it sticks.

If you cannot see it, there must be a cover over it. It should be a tapered hole.

Can you remove a cover?

Put a towel or something below to catch it as it drops out.

Good luck

Edited January 30 by AON

[rlb]

Thanks Pat and Alan.

 

I was able to find a draw bar in the box of accessories, and thread it into the top of the chuck through the spindle assembly. 

 

 

 I gave it a few taps with a small hammer but it didn't budge.  I'm nervous of hitting it too hard.   But am I on the right track?

 

Ron

 

 

[Dziadeczek]

Don't thread it into the chuck all the way! Just loosely place it there and tap it.

[Jaager]

Would cold cause the components to contract?

I have a vague memory of an aerosol something that acted like liquid Nitrogen.

[Roger Pellett]

When you buy something from Sherline that fits into a Morse Taper it usually comes with a steel pin to tap it out of the tapered socket.  The threaded bolt is to be used for drawing it into the taper, not driving it out.  A piece of steel round stock larger than the hole in the tapered tail of the chuck with the two ends machined or filed square is the correct tool to use.  I believe that the pin supplied with my Jacobs Chuck is 1/2in dia.  A good hard smack should dislodge it.  Keep in mind that since it’s tapered, as soon as it starts to move it should drop out.

 

Roger

Edited January 31 by Roger Pellett

[druxey]

Please use a soft-headed hammer for the purpose!

[thibaultron]

I would stick a wood block between the head and table, and run the head down to lock the block in place, also. If it is really stuck, you might damage the ways (the piece the head slides on), or the head if you have to hit it hard. These are small machines.

[mnl]

Please do not use any hammer on the top of your spindle. The bearings will not like it.

 

You will notice there is a small gap between the top of the chuck and the spindle. They make wedges specifically to separate Jacobs tapers.

 

http://www.jacobschuck.com/Wedge-Set/52.html

[mnl]

See brinelling bearings for what happens if you use a hammer.

Edited January 31 by mnl

[Bob Cleek]

45 minutes ago, mnl said:

Please do not use any hammer on the top of your spindle. The bearings will not like it.

 

You will notice there is a small gap between the top of the chuck and the spindle. They make wedges specifically to separate Jacobs tapers.

 

http://www.jacobschuck.com/Wedge-Set/52.html

Exactamente! And I believe that the threads on the spindle above the Jacobs chuck accommodate a threaded collet holder for your milling bits. A Morse or Jacobs taper arbor would likely not hold the tapered arbor when side-loaded by milling forces and the arbor and chuck would fall out of the spindle at speed, which might not be pretty. The Jacobs chuck is for vertical drilling, not milling processes.

 

You will have to purchase wedges to match the size of your Jacobs chuck. 

[rlb]

Thanks everyone for your advice.   

 

Sherline does sell a "knockout bar" as described by Roger Pellet, so perhaps they expect light tapping (with a soft hammer) would not be harmful?   I do take mnl's caution seriously though, and I have also looked into the Jacobs chuck wedge sets.  With shipping and tax one of those would be around $30, not the end of the world, but it would be easy enough to make a similar "U" shaped hardwood wedge that I think I will try first. 

[AON]

If they are ball bearings they are not designed for a side force. As the spindle is vertical I'd suspect they are tapered roller bearings that will take side loading by design so light taps with a soft hammer/mallet should dislodge it.

If not tapered roller bearings then the machine is a poor design mechanically speaking.

 

If you use the long threaded bolt you might damage the threads. The rod should be a larger diameter so as not to engage or contact the threads at all.

[AON]

Some machines are designed that if you retract it completely it will self dislodge. That is how the spindle on most lathes work.

[Roger Pellett]

I have a brass hammer that I use to dislodge the cluck from my Sherline Lathe, but I have never had to repeatedly pound the bar. And the knockout bar is just a piece of steel. If the end gets peened, file it off.

 

Normally when you dislodge the chuck you are not transmitting the full impact of the hammer to the headstock bearings. The knockout bar rests only on the end of the tapered shank holding the chuck. As soon as the chuck begins to move there is no load on the bearings at all.  You are not pounding on the spindle itself.

 

The tailstock on the Sherline lathe is fitted with a #0 Morse Taper.  Tools in the tailstock are removed as Alan O’Neil writes; by retracting it completely.  This is not true of the headstock.  Sherline uses drawbolts to snug the Jacobs Chuck and milling tools into the threaded socket. It is necessary to use the knockout bar to dislodge them.  Other Sherline chucks and tools are thread onto the headstock spindle.

 

Give it a good hard smack.  It should pop loose.

 

Roger

[Dziadeczek]

 

[rlb]

Thanks for the video, Dziadeczek.   He looks like he is tapping harder and with a bigger hammer than I did, so I will probably try this again.   The mill sat unused for many years, which might make the chuck harder to dislodge.  I did try with a wooden wedge, but the wedge broke apart.

 

Ron

Edited January 31 by rlb

[AON]

Excellent  video! Answers all the questions.

[rlb]

Got it!!   After a few more vigorous taps (still with a very small hammer) it came loose--

 

 

Thanks everyone for your help--this case is now closed.

Ron

[Roger Pellett]

Correction of my post from this AM.  The knockout bar furnished by Sherline for removing tools from the #1 Morse taper headstock is 5/16” diameter, not 1/2”.

[druxey]

And now, a really good clean up, I think.

[CPDDET]

I use a piece of brass round stock . Same diameter as the sherline knockout bar which didn't come with my sherline mill. I've always been fearful of ruining threads using the bolt method.