| Gallery, Projects and General > Project Logs |
| Retracting toolholder to fit QCTP |
| << < (4/6) > >> |
| andyf:
For screwcutting, a chap on a Yahoo group has made a swinging toolholder for his QCTP along the lines shown in the sketch below. Toolholder A is supported by the ledge on B, and by the adjacent vertical face of B, during the cut. When the saddle is run back ready for the next cut, the work rubs on the tool-tip, raising it to keep it out of harm's way. The motor (rather than the tumbler gear) must be reversed, so that the work runs backwards as the saddle is run back. It does suffer from two pretty major limitations. First, it will only work for RH threads; on an LH thread, there would be no side support for part A. Secondly, it won't work for internal threads, and I suppose that those are where most help is needed because one is flying blind on instruments only. I'm mentioning it for just for interest, rather than as an altenative to a proper retracting toolholder. Andy |
| Darren:
These do look nice though |
| bogstandard:
Darren, Even though I have decided it is not time cost effective to make one, that one you have shown really saddened me. With a slight design change that could have gone from being a mediocre outside threading one, to an all singing all dancing one for both internal and external threading. That's what comes of following other peoples designs religiously. It is OK for what the original designer needed, but not for others who follow along afterwards. As far as I am concerned, it is only half finished. John |
| John Stevenson:
One drawback I can see with the one in Darrens pic is that bloody lever would be very close to the chuck when working on short lengths of parts with large top hat diameters. Not my idea at all but fitted to my CVA which in turn was robbed from the Monarch 10 EE [ sighs of reverence here .. Aaahhhh ] is that the hand wheel dial has the stop built in. This is the hand wheel removed and reversed, the dog on the right is part of the dial, the other two are just floating dogs. What happens is that you position the cross slide close to the work and screw the small side screw in then wind in. Then what happens is the outer dog catches on the screw, then the inner and then the fixed one which gives you nearly 3 complete turns before it all comes up tight. You then use the top slide set over at 1/2 the angle to position the tool. At the end of the thread you wind out, no need to look, go back to start of thread, either manually or under power, and then wind in all the way, then apply new cut with the top slide. This means the operation is machine controlled and not reliant on a special tool holder. Depending on machine build up it may be easy or hard to implement. John S. |
| sbwhart:
We use to have Holbrook lathes that had a quick reatract handle on the cross slide, at the end of the cut you just pulled the handle up, go back to the start push the handle down, put your next cut on etc etc don't know if it worked for internal cutting though. Stew |
| Navigation |
| Message Index |
| Next page |
| Previous page |