For some combinations of sizes like MT2-JT6, a pretty common tailstock combination, there isn't enough shoulder for the wedge to get hold of. The Jacobs recommended method is then to drill a hole through the (un-hardened) centre of the chuck and punch the arbor out with a drift.
Richard
I had a look at the wedges in the Arc Euro catalogue and the reason I'd not noticed them before is that, to me, the shape appears to be all wrong.....
I expected them to be just the same as a normal wedge, maybe a bit squarer and wider and with a slot in the centre - but with a much shallower angle - Very thin at the front end and maybe 10mm thick at the back.
The Arc Euro weges look more like the business end of a wood chisel (now there's a thought....)
I haven't found an illustration of the Jacobs ones yet.
Temporarily, I'm thinking of milling a couple of wedges from ally or brass and 'skinning' the sliding surfaces with some 20 thou or so Feeler strip.
Thanks again for all your assistance.....
Barry
PS - hadn't thought about drilling through the chuck - sounds a bit drastic but it would certainly work.
I've drilled a hole and tapped it for a whitworth thread to push the taper out. Tighten the bolt reasonably tight then hit the head wiv hammer and the taper jumps out so be ready to catch it.
Bob
That's a good one....if you're gonna drill a hole anyway, it makes sense to tap it for future ease of release.
Thanks Barry
Tried that dilling out trick today, but it was a definite no, no.
It's not a Jacobs Chuk but one of those expensive German keyless chucks (makers name escapes me at the moment).
It just laughed at a HSS drill, couldn't even get through it with one of my precious diagrit hard cut drills, that went in about 6mm and started smokin'.
It's gonna have to remain as is until I can knock up a coupla wedges.............
Cheers Barry
I've not had a problem with machine tapers (yet) but I've dismantled more suspension taper joints than I can remember. The accepted way is not to drive the pin out but to hit the side of the female taper, preferably with a blow on each side or a blow on one side and a block on the other. That works 99% of the time. The last 1% needs a bit of heat. A kettle of boilibg water poured slowly over the joint is enough. The only time I've ever failed to get one apart was the first time. That's when I tried belting all sh*t out of the pin and it never moved.
If you're looking for taper wedges, google Ball Joint Seperators. Try these
John
Barry,
I bought a lathe with the drill chuck with no tang stuck in the tail stock, I took the tailstock barrel and put it in the freezer for a few days, I then stuck it in the vice and quickly heated the barrel and couple of sharp taps and the chuck came free.
Martin P
You were probably lucky. The drilling method usually ruins keyless chucks (certainly Albrecht pattern ones) as there is a critical part of the mechanism at the back of the chuck. It does work on keyed chucks and in the workshop practice book by Tubal Cain on drills he recommends doing it to new chucks before fitting on the arbor. M6 was the recommended size for chuck up to 3/8" and I can confirm that I did this successfully with a Jacobs 32 last weekedn.
Arc Euro only seemed to sell JT2 wedges when I bought a set. I needed JT33 and JT6, B12 and B16 too so I opted for the drill method!
Alan
I've got the offending chuck in the freezer, where it has been for a couple of days.......
If I get the chance I'm gonna try the 'hot water on cold metal' approach.
I know that that the dam' thing will come out as it originally came with an R8 adapter - I changed to M3 myself - I just hope I wasn't tempted to put a smear of Loctite on the jacobs taper before I popped it in...........
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.