Sound Bend 9" lathe, MT-3 to ER-40?

[rkcarguy]

I'm looking at some of the MT-3 to ER-40 collet adapters for the spindle of my SB9 as a solution to fit 1" collets, anyone tried this?
I need to work with axles which I will be turning to a 1" diameter with a shoulder, then flipping them around and putting that 1" diameter into a collet and a live center in the opposite end. I understand that 1" does not pass through the SB9's spindle that is ok.
It seems the typical collet system that is available to fit these lathes only goes up to 3/4" so I can't pursue one of those.

[whateg0]

Ebay has a bunch of them. I use ER-25 collets in straight shank holders that I hold in a 4-jaw. I can put that holder in a vise, also, though I use collet blocks when I can. Depending on the quality of collets you use, you may get better runout that way than depending on the spindle, adapter, and collets to all be true.

Dave

[rkcarguy]

Ebay has a bunch of them. I use ER-25 collets in straight shank holders that I hold in a 4-jaw. I can put that holder in a vise, also, though I use collet blocks when I can. Depending on the quality of collets you use, you may get better runout that way than depending on the spindle, adapter, and collets to all be true.

Dave

This is true. I'm trying to get away from having to true everything up in the 4-jaw between operations though. That's how I'm working now, with a 1" hub I chucked up and dialed-in in the 4-jaw. I'd like to 3-jaw the rough 1-1/2" bar, turn one end, then insert the collet setup and turn the other end so things are nice and concentric. I guess I could scrap the idea and just continue to use the hub I've got instead of collets.

[whateg0]

My main reason for using collets is for speed, not accuracy. If I spent big $$$ on collets that had less runout, I might trust them more, but as it is, I'm not spending that kind of $$$ and I don't trust the ones I have now.

Dave

[SteveM]

This won't help with your 1" axles as the large end of MT3 is 0.938", but:

You can get an ER collet chuck on a plate you can mount to a backplate and thread on like a 3-jaw. The advantage is that you can pass stock thru the headstock, which you can't with a collet chuck that uses a taper.

The collet chuck on a taper has the advantage that you just buy it and stick it in.

Note that while you can't pass the 1" axle into the spindle, once you have started machining it, that part will be able to go into the spindle.

Steve

[Inspector]

One source for a chuck Steve mentioned. You still need to find/make the backing plate.

https://littlemachineshop.com/products/ ... &category=

Pete

[SteveM]

One source for a chuck Steve mentioned. You still need to find/make the backing plate.

https://littlemachineshop.com/products/ ... &category=

Pete

You can find the backplate at LMS as well:
https://littlemachineshop.com/products/ ... &category=
https://littlemachineshop.com/products/ ... &category=

The first one has three holes already drilled, the second one is undrilled.

Check with LMS is the drilled one is the right one.

Steve

[rkcarguy]

This is going to be a little complicated, because I'm looking to turn 1-1/2" hot roll(which isn't round worth a darn) down to 1" on each end and the axles are about 18" long. I'm not too worried about the center portion being balanced or running true, but just need the ends true to each other.
I'm probably going to have to turn my drill press vice on it's side and center drill the ends of the axles in that because it's way too big to go through the spindle and it would stick out of the chuck way too far to risk center drilling in the lathe.
Then the axles either need to go between centers or into a collet/hub on the chuck end so things are concentric within ~.001".

[whateg0]

Make a ring with set screws in it to run in a steady rest. Then chuck the other end and drill your centers. Actually, I think I watched a video of somebody else who did that recently.

Dave

[whateg0]

deleted quote that was supposed to an edit.

[Harold_V]

it would stick out of the chuck way too far to risk center drilling in the lathe.

Not true. Because the pressure of the cut is along the centerline of the material, it has little reason to deflect. If your chuck will hold the material well enough to support it without sagging, you will enjoy success using your lathe, using a moderately slow speed until the center drill has started. Give it ample time to seek center before beginning to drill. It also offers the opportunity to assure the center drill is in the center of the part, as you should be able to tap the piece lightly to get it to run true. You'll discover that once the hole has started, the material will gladly stay on center as you continue to drill to depth. At that point, you can even increase spindle speed if desired.

H

[rkcarguy]

it would stick out of the chuck way too far to risk center drilling in the lathe.

Not true. Because the pressure of the cut is along the centerline of the material, it has little reason to deflect. If your chuck will hold the material well enough to support it without sagging, you will enjoy success using your lathe, using a moderately slow speed until the center drill has started. Give it ample time to seek center before beginning to drill. It also offers the opportunity to assure the center drill is in the center of the part, as you should be able to tap the piece lightly to get it to run true. You'll discover that once the hole has started, the material will gladly stay on center as you continue to drill to depth. At that point, you can even increase spindle speed if desired.

H

Thanks Harold, I'll carefully give that a try when the time comes. We were always taught the old 3x the diameter or less sticking out from the chuck rule in school, but for center drilling only I guess that can be pushed.