Advice On Removing Bent Arbor From Spindle

[GavinT]

I need some advice, please, on a recent hand-me-down. It's a DAYTONA DF-12 (not Dayton), 12 speed, that I think is a Rexon, it's made in Taiwan. The badge on the DP says JT.3 for the spindle.

I thought I could use #3 Jacobs wedges, but as you can see in this picture, the tapers can't get above the shoulder on the arbor and when tapping the wedge in, it rides down over the shoulder. Similar for when I use both wedges below the shoulder to try and remove the chuck, the top wedge rides up over the shoulder on the arbor.

The arbor is definitely bent! Using a dial indicator, I get runout of 0.008 at the arbor below the shoulder, 0.01 at the top of the chuck sleeve, 0.25 at the bottom of the chuck sleeve, 0.05 at the body near the keyhole, and 0.65 on a bit in the chuck.

There is 0.005 front to back movement when measuring the end of the extended quill, which might be expected, though I do plan on replacing the bearings, if I get that far.

Here's few more pics that hopefully help...

Finally, what is this notch (A) used for on the end of the quill in this picture, below?

Any advice (other than put it on the curb) is greatly appreciated! It has sentimental value and getting it running true again is what I'm after. If it turns out I need a new chuck, too, then it might not be worth fixing

Sincerely
Gavin

 

[RJSakowski]

Are you sure that the JT3 arbor separates from the spindle. Your nameplate states JT3 spindle. If you had an adapter, the spindle should be designated MT2, e.g.

On my similar drill press, the JT3 taper is integral with the spindle. You would want to pull the chuck, in which case, the Jacobs wedges should do it.

It looks like the notch is just the end of the keyway cut on the quill.

 

[Bob Korves]

The spindle ends with a JT3 taper, which is a Jacobs chuck taper. There is no Morse taper in the spindle on that drill press for an adapter. You will need to use spacers between the chuck and the quill to remove the chuck, hopefully without ruining a bearing doing it. Perhaps the spindle will come out with the chuck still on it, if so, you can work on the chuck and spindle off the machine. Depending on the length of the taper that does not now enter the chuck, there might possibly be enough metal left to true up the existing taper. Failing that, find another spindle or try to straighten the bend. Both of those are tall orders, and straightening the spindle could cause immediate or later danger. First get the spindle out if possible, get the chuck off, and see what you really have going on there. The notch in the spindle is an artifact of producing the keyway in the spindle. The circular cutting cutter needed to go that far to finish the keyway.

Edit: The existing taper may be able to be ground to a smaller Jacobs taper. You will need a different chuck then. I suppose the spindle could be ground and a tapered bushing made to bring it back to the correct size and taper, but that may be too fussy to even try. I know I wouldn't...

 

[Bob Korves]

That looks like a decent machine, Taiwan made, looks to be in decent condition other than the spindle. It is definitely worth doing some repairs on it and getting it back in good shape again. It is also an interesting challenge.

 

[GavinT]

Hi Bob & RJ, thanks for the response. I'll go ahead and remove the quill, spindle, etc, along with the chuck and see what's up. I have a buddy with a shop who I can ask for help truing up the spindle. I read that a good whack on a rod in the chuck can bend it back, probably something easier to do with the assembly out of the head. I'll post progress, though that may be few and far between.

There is one part that has been replaced with a botch job... the quill set screw doesn't have a round dog point to fit in the channel on the quill, it's a grub screw that has 2 sides filed down, which of course won't turn in the channel once it touches the quill. Easy to replace (or round off the end of the grub to rotate in the quill channel.) Yes, an interesting challenge!!

Anyone know where I can find a replacement spindle?

 

[RJSakowski]

Pounding a spindle back into alignment is a trial and error process.

Years ago, I had made a jig to straighten bent lawnmower crankshafts. The trick is to undo the bend that you now have. This means supporting the shaft at the proper point; otherwise you will end up with an S curve. My jig used a split block to replace the lower bearing and an adjustable block for the upper bearing. They were mounted on a 9' piece of I beam. A tube was made to fit the lower portion of the crankshaft and a long lever used to apply the bending torque. A slight bend was made and a dial indicator was used to monitor progress. I was able to straighten the crankshaft to .001 -.002" TIR which gave me a serviceable crankshaft.

You should remove the spindle and use a solid bushing, well supported, to try the unbend. I would recommend using a long lever rather than beating it to death (or life). Do not use the bearings for support while attempting this.

Personally, I would favor having the taper reground, as Bob has suggested. In all probability, you are dealing with hardened steel and trying to unbend the shaft will add more stress to the already stressed shaft which could cause a fracture.

 

[GavinT]

Thanks for the recommendation to turn the taper down, #2, right? I don't have the experience to know how much force would be needed to bend it back. I know my limits and that's way out there! Or build a jig to apply the necessary pressure in a specific location. Times like this I miss having my granddad around, he had a great machine shop.

I'll keep y'all posted.

 

[Spike440]

I have a similar machine and it lists a bit more info than your plate does. Hope this helps.
-Spike

 

[RJSakowski]

You may be able to keep the JT3. The effect of regrinding the taper will be to move it upwards and it looks like you have enough clearance to move the taper up slightly. At any rate, I would start there. If you run into a problem, you can cut it to a smaller taper. If you do cut a smaller taper, consider a JT6. It is the next size smaller than the JT3 and drill chucks are available with that taper. It is unlikely that you will find a 1/2" or 5/8" chuck with a JT2 socket.

 

[JimDawson]

IMHO you guys are really overthinking this one. This is type of job is why dead blow hammers were invented. Smack the chuck body on the high side with a dead blow. Check with dial indicator on a drill shank or dowel pin in the chuck. Repeat as necessary. I do this on my mill when needed, and have done it on drill presses. It won't hurt the bearings.