Gallery, Projects and General > Oooops!

This is getting infectious - stuck chuck

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Pete W.:
Hi there, all,

I thought the DIN taper (for drill chucks etc.) was a short section of a Morse taper? 

BaronJ:

--- Quote from: vtsteam on June 29, 2014, 08:41:43 AM ---Well Andrew and Pekka, you guys have me thinking about improving it instead of just living with it.

Maybe I'll just wipe some blue on and see what's happening. If the fit looks good, it's a basic design problem and about the only thing that will help would be Loctite. 

If the fit isn't good it's a manufacturing defect, and then material ought to come off.

But at least I'll find out which it is.

(I do notice that electric hand drills with Jacobs chucks sold here have retaining screws. Why a drill press with a vertical shaft wouldn't need that is a mystery! The weight of the chuck is always applying loosening pressure, the chuck is heavier, and the power is much greater.)

Dollars to donuts,  I won't be able to get it off to blue it!  :lol:

--- End quote ---

Many years ago I bought a "Meddings" pillar drill.  It came, new, without any chuck.  At that time it was an extra.  Anyway I also bought a 5/8" (16 mm) chuck.  I don't recall what brand, other than it was somewhat cheaper than a Jacobs, but there was no way it would stick onto the taper.  After a few usages it would loosen.  Even after I smacked it on with a brass hammer, it still fell off.  I complained to the supplier who swapped it for a Jacobs one.  After that one was fitted it never loosened, that one never came off.

At that time I would never have known to blue the shaft and see how good a fit it was.  An old timer suggested that there was probably a burr on the inside of the taper near or at the bottom stopping the mandrel from seating properly.

 

awemawson:
Taper fitted drill chucks are particularly susceptible to any side pressure, which quickly loosens the taper. This is why you should never hold an end mill in a taper mounted chuck. I think loctite is a perfectly acceptable cure on a drill press where micron accuracy isn't demanded.

PeterE:
Interesting reading here. I have had some issues with my pillar drills chuck as well, but that was when I "overloaded" it using a dia 20 mm countersink in a 13 mm chuck  :bugeye:

What comes to my mind is a question; Can it be so that the mandrel taper bit is just so long that it bottoms in the chuck and just manages to stick. If so it would be very easy to come off. If a small length, say 0.5 mm is taken off the mandrels end it may go in that final bit to stick properly? Just i guess I'm afraid but perhaps worth checking if just to make sure there is no bad fit.

BR

/Peter

Jonny:
Peter whith the 20mm countersink what that's actually doing is pretty much as Awemason said. Its chaffing and in doing so exerting both vertical and lateral pressure loosening from the taper.
I do things like that daily but with drawbar in to MT, never a problem except when don't tighten up more than finger tight.

I often mill with Jacobs chuck on MT taper mainly due to being idle and never ever a problem.
Current mil was a right swine at first for locking up breaking many a draw bar for years. Easy enough to make, just slacken off around 1/2 a rev then follow through as giving it some. Don't just pat it and lock the quill. I leave a 1lb hammer by the side and usually change as many as 40 times a day and shown how easy to a couple on here.

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