Thread: Too much rigidity?

Ah so! I'm just doing it wrong. Again.
Thanks Dave.

You could get a milling MT2 arbour to suit your chuck, it has a thread in the back instead of tang, or if you cut off the tang off, the centre might be soft enough to drill out and put a thread into it.
One thing I would be concerned about after the sleeve is secured properly, is if the chuck is going to stay on it's taper. If it's screw on it will be fine.

Dave

Dave, both my small chucks have tapers. I can use the 4 jaw, but then what? It seems like (and this relates to my original question) I plug one hole so to speak and it just exposes another one. That's what you get for trying to hammer with a screwdriver I guess.

Couldnt you make something like this?(the undercuts are exaggerated) or do you mean you are worried about getting the angles correct?
I'm take some pictures of my holder tomorrow if I get time.
Stuart

Originally Posted by Bryan

Dave, both my small chucks have tapers. I can use the 4 jaw, but then what? It seems like (and this relates to my original question) I plug one hole so to speak and it just exposes another one. That's what you get for trying to hammer with a screwdriver I guess.

I know what you mean.
You may be able to put a small thread into the end of the arbour for a socket head bolt to hold the chuck on. Cordless and reversible drills have that to stop them undoing in reverse.

Dave

Bryan,

If your cross slide has tee slots you could mount a rear tool post. Makes parting off a lot less stressful. The cutter in my post is held in position with a screw fixed top clamping plate and the tapered blade positioned vertically be means of a pair of small set screws. I don't know whether any of this is applicable to the problem that you have with your broken holder but it might suggest another way of rigidly supporting the cutter.

Bob.

Here is another way of dealing with the parting off tool holder issue.

parting off holder

Bob.

Bob, thanks for the suggestions & pics. The rear mount idea is interesting (and beautifully implemented as usual). I don't have T-slots, but I do have some threaded holes I could use. Do you find it gets in the way, or do you just pop it on as needed? I'm not real flush with big lumps of steel for things like that. Might be time for some serious scrounging.

As for quick change, that's a whole other place I'm not ready to go yet. I have my own QC system. It involves each commonly used tool having its own holder and shim stack, held together with a rubber band, ready to grab and pop in the 4-way. I only shim a tool after sharpening. It's quick enough for me, and cheap as chips. The 'holders' are just bits of 3/4 square stock with a 3/8 slot for the tool and a slit for closure.

Bryan,

You are better organized than me. I had my packers, offcuts of zincalume flashing, strips of aluminium and slithers of brass shim, scattered about the bottom of a drawer before I made my first quick change tool post. Unfortunately, I only made one tool holder and had to readjust the height of the thing with each tool change.

The rear tool post does get in the way but it is readily removable. I'm thinking about revising the design to enable it to rotate. G H Thomas featured a rotating and indexing version for a Myford in his "The Model Engineer's Workshop Manual".

The steel I used was cheap 1214. I bought it from Bohler Uddeholm for about 20 dollars. I will dismantle the tool post and take a couple of snapshots to show how the parting off blade is retained.

Bob.

I agree with Bob , the rear tool post is the only way to part off, once you try it you'll never go back , it works well for me and it hardly gets in the way, and it is a real chunky one
Cheers, Richard.

Bryan, Here's my attempt at a parting tool. It was made on the lathe before I got a mill. It will go about 10mm deep in MS, althought I have parted 40mmDia Brass. It just uses carbon steel hacksaw blades.
Stuart

Thanks Richard, good to know. Will seriously consider this option. Think I'll just some sort of parting tool organised first, then look at a rear toolpost later.

Stuart, sorry, thought I'd already replied. Yes, your sketch is what I had in mind too, except for proportion. The blade is 1/8 x 3/4, and my smallest cutter is 1/4. So the angle cuts would be a lot wider than your drawing. In fact there would only be 1/4" left in the middle for support. I'd try it anyway, but I need some larger material. The biggest square stock I have is 25mm. I think I really want a smaller blade.

Stuart, that's a power hacksaw blade, right? How thick you reckon? Have you ground some side clearance? Rake would be 5 deg?

I had my rake at zero or even slightly negative and it still pulled in.

Originally Posted by Dave J

I would say it is either Chinese or Indian tool holder that was mad out of crap metal.
Dave

Maybe not so much that the metal was crap, rather that heat-treatable steel needs to be heat-treated correctly. Hard is good, but too hard means brittle as well. So, a tempering process is also required, which reduces the hardness slightly but imparts toughness.
Mild steel could be used instead. It's not as hard wearing as HT tool steel, but won't smash like glass.
Alas, cheap Asian products still sell on image rather than substance.

Jordan