Stuck spur center

Get a plastic bag of ice and place on the spur center, wait a few minutes, and whack the hell out of the drift rod. Heating the hub would help as well, but be careful not to damage the bearings/paint/etc. This will generally give you .001-.003" more clearance for disassembly.

FWIW,

Greg G.

I have used a small pipe wrench on them. Just needed to break the "seal" and it popped out! You can use a tape wrap around it to eliminate any teeth marks from the wrench. That'll save your ice for better things! *G*

"Leif Thorvaldson" wrote: I have used a small pipe wrench on them. Just needed to break the "seal" (clip) ^^^^^^^^^^^^^ If you have someone to help you, I suggest using Leif's pipewrench approach along with a big hammer on the knockout bar. The combination of torque and impact should get it out easily, and maybe with less wrench marking.

turn something important on it.. the damn thing will decide to fall out on it's own...

Want to cure Aids? Give it a Dewalt part number and nobody will ever get it...

I have Jet Mini and had the same problem once. I couldn't get it out with the drift rod either. My spur center has a hole through the side of it, so what worked for me was popping out the spike in the tip of the spur center (mine is just set in, not attached) and inserting a screwdriver or other appropriately sized metal rod through the hole in the side of the spur center. Lock the headstock with the indexing pin in your case. Now try to twist the spur center out, the screwdriver will give you lots of leverage.

Hope that helps.

Andy

get a 1X8 nut, cut it in half, put it on the threads of the spindle, put a wrench on it so that the wrench holds the nut closed, and unscrew it - it will push the spur out as you unscrew it.

(if you get desparate, I do sell nuts alone, but you ought to be able to find one locally for a few $$)

Puzzling. Another common problem I have so far escaped. Harry, are you seating your work by rapping it into the center with the center mounted to the lathe? I don't think that it's a good practice.

Best, in my experience, is to make cuts on the bandsaw or with a chisel to seat the spurs, second best is to remove the center and use a few mallet taps to split the piece ... I mean seat the spurs in their self-made recesses.

If things haven't moved already, might I suggest you take care of cosmoline ("first time") and / or corrosion first by running some light oil or WD 40 into the area before you try to unseat with a rap, followed by a strap wrench or pipe wrench. Even there, you want a sharp initial attempt, like rapping the end of the handle smartly, not a slow torquing.

Harry,

If Mac's advice fails, try going barefoot at your lathe. ;) NO DON'T.

Turn to Safety, Arch

Fortiter,

At last! I finally got the spur center loose last night after several days effort. Prior to last night I had tried several treatments with penetrating oil (3-in-1 oil and WD40) along with a number of hard whacks on the drift rod with a steel mallet. I had also tried putting tape around the spur center and turning it with vice scripts to unlock it. No luck here either. It appeared that I was going to tear up the outer rim of the spur center before it gave way.

Last night I started with a cooling-heating treatment using a hair dryer to heat the spindle and a bag of ice around the spur center to cool it. After about 10 minutes of this treatment, a hard hit on the drift rod moved the spur center enough that the drift rod could no longer reach the spur center but the spur center was still stuck. At this point I tried the split nut approach. The nut did exert pressure on the spur center but I had a problem with the nut spreading and sliding up over the spur center. After the split nut treatment, I searched and found a long steel rod to use in place of the drift rod and one hard blow knocked the spur center out. I must admit I was beginning to have some doubts if I was ever going to free this sucker up.

Thanks to you guys for all the ideas. They were certainly a great help in solving this problem.

Harry

Good that you got it out, I've never heard of one that was THAT tight... Thermal expansion and contraction is a time honored method of assembling and disassembling machinery parts. And the best part is, no mangled, scored up parts to deal with from trying to force something.

I guess Leif can save his ice for better things, like soaking his battered hands from the pipe wrench... ;-)

Greg G.

Hey! Come on now guys! If I had realized that you were still having problems with the sucker, I had a couple of other aces up my sleeve. First, though! Did you try the pipe wrench? You mentioned visegrips, but they wouldn't be strong enough. All you needed was a an 18 or 24 inch pipe wrench and a ten to twenty foot length (*G*) of galvanized pipe to slip over the handle of the wrench and you could have rotated your shop and perhaps the world. I forgot to mention that I now use an old bicycle inner tube to protect the spur drive collar instead of tape. The rubber really grips it.

Now to the causes and conditions of the matter. What caused such a stubborn issue in the first place? I read on this newsgroup that this type of sticking is due to not keeping the morse taper clean. Since that time, I have had no problem with sticking drive centers. Get a metal gun bore cleaner brush and some solvent and clean that puppy up. Both sides: head stock and tail stock and also the drive centers themselves!

Leif

Just revving you up... ;-)

But seriously, I heat connecting rod bores with a hot plate and cool piston pins with cryo freeze to assemble engines with non-floating piston pins. Works great and is more accurate than using a 20 ton hydraulic press - I get no scoring of the pins or bores. Works for anything that has an interference fit. No force, just finesse.

I also wonder why it was so tight. Once the thing moved at all, it should have just popped out. I wonder if there was extensive rust or corrosion in there. A tapered MT joint should not have been that difficult to remove.

You are right about keeping the Morse tapers clean, however. It not only makes them easier to remove, but makes them less subject to slipping.

FWIW,

Greg G.

Comments for Leif - No, I never did try a pipe wrench. Perhaps that would have been better. Certainly the bicycle inner tube would have offered much more protection that the tape I used.

As to why I had such a bad sticking problem, the spur center came installed in the lathe and had never been removed in 2 years. I used to tap the wood gently onto the spur center with a mallet (I think this is recommended in the Jet manual). Perhaps this was the culprit. In any case, I won't do that anymore. In the future I will keep a nut on the spindle when using the spur center to assist in removal.

Good plan. Might have been some cosmoline in there, too.

Hi Greg

Yes I was wondering about the same thing, unless the straight end on the taper and the hole through the spindle somehow have a interference, which should not be that way, but it is not impossible of course, many times the knock out bars are made out of steel and they will flare the ends off the tapers if hit enough times, and if the size of these are to close they could give you trouble, to prevent the flaring I use a brass bar, it was hollowed and I filled that up with lead, works like a charm. The fitting of parts that have to spin true by heating one part and warming the other is a favorite way for me as well, rather than welding with all the problems of uneven shrinking etc., I machine just under size and cool the one by placing in the freezer for a few Hours and then heat the other part on the stove or in the oven or with a torch whatever is the best way, then have every thing set up and ready and then do it quick and right. Made a couple of #5 mt with flanges that way, just shrunk on and there have been some big and heavy chunks of wood spun on them, never budge.

Have fun and take care Leo Van Der Loo