Boring Head Shanks

[JimM]

Hi all

I recently picked up an Elliott boring head, but as usual I didn't bother to look closely enough at the pic on the listing and now that it's arrived what I assumed was a MT3 taper shank is actually a 3/4" straight shank. Was hoping that this would be a simple swap but the shank seems to be well and truely stuck in place.

Anyone have any tips on getting these things apart? I've removed all obvious fixings - basically one cap screw that was accessible after removing the slidey part and I'm assuming that the shank would be threaded at point A but is it possibe that this was pressed in rather than threaded ?

I've got as far as trying to hold the shank in a split piece of wood held in the vice, and with a long bar in the head slot trying to jerk the shank free but the whole lot just spins.

Any other suggestions much appreciated

Cheers

Jim

 

[BillTodd]

That looks like a Int30 or 40 taper fitting that has been turned down to straight. I'm sure you're right about the two parts separating at 'A' .

To me the 'joint' looks too big to be a taper (and most boring bar arbours that I've seen are threaded). If it were mine, I'd grip the arbour in a vice, heat the body nice and hot with a blow lamp (don't melt it ) and try again to unscrew it.

Bill

http://www.rdgtools.co.uk/acatalog/BORING_HEAD_SHANKS.html

 

[winklmj]

Got a Criterion Mod 1.5 head the other day. Has a 1/2" straight shank and I need an MT3 taper as well. I tried chucking it up but the shank just spun in the chuck. Tried it in a small vise with some soft jaws and it still spun. I drilled a 1/2" hole in a bit of aluminum rod then split it lengthwise with a hacksaw to act like a sacrifical collet. That clamped in my puny vise and it STILL spun. Cleaned the shank and "collet" with brake cleaner and grabbed the collet with a pair of vise grips and with a big wrench on the head I was able to break it loose. Luckily it's the square-head model so I had something I could wrench on. Next step would've been the propane torch.

 

[BillTodd]

Next step would've been the propane torch.

Heat usually does less damage than a pipe-wrench, so I always heat first

 

[Lakc]

Pressed or threaded, either way it helps to have heat, and use the Pink Floyd method. (short, sharp, shock) Brass hammer or drift punch are invaluable here. Without some shock or vibration, as you found, the workholding requirements increase exponentially.

 

[JimM]

This thing really is stuck in well !

By putting a couple of pieces of square bar in the cut-outs on the shank, I can now get a good death grip of the shank in my big vice. For a tommy bar I'm using my 3/4" socket wrench breaker bar, the handle end of which fits just about perfect (although the knurling has marked the inside of the head slightly !) However even with my full weight on the end I can't get the head to move, tried thumping the end of the tommy bar with a dead blow mallet, heating with a propane torch, swearing at it and offering my next born child to the god of infeasibly tight threads but to no avail

Before I go any further can I just check that these things do have standard right hand threads ?? It'd be just my luck to spend hours on the thing only to find I'm actually trying to tighten it !

Thanks

Jim

 

[chimpera]

I drilled a whole in mine to stick a bar in. A cobalt bit would work best

 

[Mainer]

I would expect it to have right-hand threads.

 

[djc]

If it's really well stuck, grip the head of the er.. head in a four jaw chuck, centre it up and drill and bore out the shank carefully. If it is not a conventional fitting, you can thread it for the shank someone shows above. If you think about it, absolute concentricity is not actually necessary.

 

[JimM]

Hi guys

Just an update on this, I've given up on trying to separate the shank, it got to the point where I had the shank gripped in the vice a 5' bar in the head and it still refused to budge - I have since seen a similar head on Ebay and it would appear that the shank may be a press fit with a keyway :-[

I've decided I may be better off keeping the straight shank and getting a 3/4" MT3 collet and trying that to hold the head.

Cheers

Jim

 

[Trevor55]

Follow on from old post about elliot boring head, but I've just picked up same head and the bar coming out looks odd do you have any photos of the tooling to fit this head?