darrin1200
Darrin
Sorry for the delay. Not sure if these were standard issue.
It is MT4 taper on the outside, with chamfer on the inside to fit 4C.
Its pulled into the adapter with a drawbar.
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- Thread starter skippyelwell
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It is MT4 taper on the outside, with chamfer on the inside to fit 4C.
Its pulled into the adapter with a drawbar.
TorontoBuilder
Sapientia et Doctrina Stabilitas
my understanding is that there are old lathes that have sleeves for a slew of different collets sizes.
One day I am going to make a sleeve for my chippie to see just how little run out I can get for 5C collets, if I ever need less than I can get with my 5C chuck.
Mine is simply amazing. I've never needed or wanted better.
In some respects, it's even better than a 4 jaw because the distortion is so minimal.
TorontoBuilder
Sapientia et Doctrina Stabilitas
That is why I broke down and got the 5C chuck.
Someday I may get a 6 jaw scroll chuck for those times when I need to hold things bigger than 1-1/8. For now, I make my own collets when I need to do that.
Maybe Christmas 2030.......
Almost all of my smaller lathes take collets directly in the spindle nose; which is the ideal set up. Next is an adapter and drawbar. Ideal in the sense of minimizing error and overhang. That's why there is an MT 4 1/2, it is its the smallest you could make a spindle taper and still fit an adapter for a 5C collet, but as Darrin shows, there are other collect sizes to pick from.
If you don't yet have a chuck, the adapter drawbar route is worth considering instead of a chuck, it will give better performance. Royal used to sell a drawbar via KBC, not sure if they still do, but they were expensive, but so is a good used chuck. A practical reason I didn't go that route on the bigger lathes is not having the room out the left side of the HS need to get a drawbar in and out.
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If they do, I couldn't find it. Royal doesn't seem to make it anymore either.
My Bison 5C chuck is pretty compact and I can't complain. But I've wanted to try a drawbar setup. I have lots of room for drawbars and long stock on the left side of my headstock. There is a storage rack there with an open window through to the spindle from the other side of my shop.
TorontoBuilder
Sapientia et Doctrina Stabilitas
The closest I've seen now is cut to fit 5C drawtube from dunham to make your own
OK, so I have a dumb question.
I would think that any kind of drawbar arrangement has to compress the spindle somewhat to tighten the collet which has to affect the bearings somewhat. I'm suddenly realizing that this has to affect the short term and perhaps long term precision of the spindle.
Is that a reason to avoid using a drawbar system? Or is the effect totally temporary?
darrin1200
Darrin
I don’t think the draw bar would have any effect on the bearings. In mine, the draw bar only contacts the ends of the spindle. It’s tightened hand tight, and I don’t think I can generate enough force to compress the spindle.
The only other acting force is the outward pressure, on the spindle nose, caused by the collet being drawn into the spindle. Once again, I don’t think enough force is used to cause damage. The same sort of force would be created with an MT taper begin pushed into the spindle.
I didn't imagine any damage. Just a loss in precision.
Everything is rubber. All forces - no matter how small - cause distortion in metal no matter how strong. It really isn't if. It's only how much.
To be honest, I don't think it's much, but it is there. Hence my question.
My guess is that any deformation is less than what already happens as the bearings warm up. But it's just a guess. I was hoping someone would actually know.