Put Hot Chuck on Cold Arbor & it Still Fell Off

[SteveHGraham]

Here's something weird.

I got a new Albrecht 1/2" chuck during one of Enco's mega sales. I mated it to an arbor with a straight shaft. I heated the chuck and cooled the shaft, and I joined them together.

Someone told me they were going to be together for eternity, because the method I used was over the top.

Yesterday I was drilling in pine with a 13/16" S&D bit, and the chuck fell off the arbor. Just fell off. It wasn't under a lot of stress. It was shaking somewhat because the wood was trying to grab it.

No idea what happened, but now I have to put the chuck back on the arbor.

[Rich_Carlstedt]

Steve, I suspect the arbor is a Chinese Or India origin tool
Try bluing the two and fitting at normal temps.

A thermal fit would make it a killer normally
Even though you were using a SD drill,the wood should not have had the torque to break the bond.
Make sure the hole depth did not stop the taper from sinking deeper ?
( If so, remove stock on the end of the arbor )
Rich

[SteveHGraham]

Thanks, Rich. I will get on it. I'm wondering if the peculiar vibration the wood caused had something to do with it.

[WJH]

Blue it, see if the tapers are mating

[reggie_obe]

How cold was the arbor? How did you prevent condensate on the arbor from interfering with the fit. How did you heat the chuck and to what temp?

[mcostello]

If the vibration from wood removes the chuck, You better not use the machine on metal.

[spro]

The tips are great but the question puzzles me.

[david5605]

Stupid question? Did the taper on the chuck match the arbor taper? I've hammered matching tapers together with a rubber mallet with both parts at room temperature and they don't fall apart. Even with side loading.

Leave the shaft in the freezer overnight and heat up the chuck in the wife's stove a few hours at (maybe) 300 F. Put your welding gloves on, grab the two parts and slap them together.

You get one try, 15 seconds long.

You can even use dry ice if you can find it.

[tornitore45]

Bluing will tell if there is an obvious ding or something. Assuming the surfaces are OK. Is a good idea to clean both parts with acetone to make sure no trace of oil exist.
On a good fit moderate shaking in wood should not be a problem but the fact remains that radial forces can dislodge the taper, that is why all types of taper use drawbars. Was the wood clamped or held by hand, pine with its soft and hard veins is notorious for dictating where the drill goes unless constrained, and even then is still wants to wobble the bit.
I do not think heating/cooling is necessary, just tap like you do to firm a hammer head.

[dgoddard]

Assuming the problem may be an imperfect match and assuming that the following will provide adequate accuracy, you might consider cleaning the parts with a degreasing solvent and then something like acetone (which takes off a lot of stuff but is not the best on oil/grease. Then apply some press fit Loctite or equivalent of the high strength variety and assemble with a rap from a mallet of some sort. However, should you later care to disassemble this you may have to raise the temperature to around 350 F and then apply normal forces required for separation. the loctite should accommodate small imprecision in the tapers and greatly resist any radial forces. If the chuck temperature even approaches the loosening temperature for the Loctite you have a strange situation or something is wrong.

[Harold_V]

The use of a hammer when installing an arbor isn't required (nor desirable). Simply place the arbor in the chuck, then, grasping the arbor, give it a sharp rap on the end, on a piece of aluminum which is placed on an anvil, or even the table of a milling machine. The use of a piece of aluminum prevents any damage to the critical surfaces. The weight of the chuck is more than ample to create a proper seat, even without temperature differential. It is critical that the mating surfaces have no traces of lubrication.

Harold

[dgoddard]

Different words/method ..... Same concept (I think)

give it a sharp rap on the end, on a piece of aluminum which is placed on an anvil

vs

.... assemble with a rap from a mallet of some sort.....

By which I mean when I say "mallet", wood, rawhide, polymer, dead blow polymer, brass or the like.

I have an old rawhide mallet from 40 to 50 years ago, It is sort of light so it has to be swung fast. or I might use my dead blow with a gentler swing or if using the brass I only use a tap. For such work I will often hold the item in one hand when I strike it and depend on its own mass to provide enough inertia. I suspect the anvil buffered by aluminum imposes much higher forces. I like that idea when high force is required.

My most frequent use of my rawhide mallet is at the lathe when changing chucks. After releasing all three locks on the chuck, the chuck is still stuck on the taper and I place one hand under the chuck and swat the top side with the rawhide mallet. The chuck comes free but is still supported on the pins and is cradled in my hand. Also since my back is not all that great, when tightening the chuck on a work piece, I will insert the chuck key in the lathe chuck and then swat the end chuck key T-handle with the lightweight rawhide mallet rather than try to muscle the key tight or loose. Much easier on the back ! A light mallet like that has its uses.