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View Full Version : Fuel for the register debate......



Oso
02-27-2003, 01:48 AM
maybe.

I remembered something, and went to look at the Sherline products to see. Can't be sure from the pics.

BUT

It looks like the Sherline lathes MAY be made with no register at all, it LOOKS from the pics as if the threads are larger than the area behind them. Looks like that may be undercut.

Anyone have a Sherline and can confirm or deny?

One thing, those little buggers are accurate enough. I have seen the sort of stuff turned out on them, and they must be good machines.

So if they have no register, that would certainly be an argument against the need for it.......

SGW
02-27-2003, 08:22 AM
For what it's worth, my South Bend 10K doesn't have a register. The diameter back of the threads is no larger than the thread diameter.

nheng
02-27-2003, 09:31 AM
The spindle diameter is 0.990 and the undercut behind the threads is 0.666. It was a little disappointing the first time I had to remove a chuck which was a bit too tight. One of the tightening bars was not inserted far enough into one of the two spindle "spanner" holes and the hole entrance mushroomed out without extreme pressure on my part.

I haven't done any other hardness tests since then.

Oso
02-27-2003, 01:50 PM
0.990 on what?
The Sherline has a 3/4-16 spindle nose, so you must be referring to another unit.

nheng
02-27-2003, 04:32 PM
Oso:
You are correct, the thread is 3/4-16. The diameter of the undercut is 0.666 and the shoulder is 0.990. "Spindle diameter" was as clear as mud. The 0.990 shoulder has 2 holes (may be a single thru hole ??) in it for one of the bars used to tighten threaded attachments.

SGW:
I may be confused but isn't what you're describing considered the register? If it were any smaller, it couldn't be but right at or greater than the thread diameter, it could be.

I put a stock Bison 1-1/2x8 threaded back 3-jaw chuck on a Maximat 7 recently. Had less than 0.0005" between the register and the chuck . TIR is around 0.0005 on 1" bar stock. My Sherline probably has around 0.003 or more as I can watch 3/8" rod wobble around. It's pretty much in new condition. Of course, if you cut all your ODs while the work is in the chuck, you have pretty close to zero TIR.
Den

[This message has been edited by nheng (edited 02-27-2003).]

Oso
02-27-2003, 05:42 PM
That 0.003 is fairly normal for a 3jaw, maybe the little Sherline chucks are not the same quality as Buck, etc!?

Anyhow, with something like 0.05 (50 thous)clearance all around the "register" if it hits the standard 3jaw runout, that sounds like the "register" might not be too important.

darryl
02-28-2003, 05:55 AM
Just checked the difference between the register and the chuck on the 8x18, there's about 3 thou of atmosphere in there. The register surface looks like it was just freshly machined. I can mount and remount the chuck, and the runout is small, but measurable and repeatable. If I machine an arbor, remove and remount the chuck, it runs true every time. My shopmade adapters, which I finish machined on the spindle, always run true. All this, and no contact with the register visible, ie. no scratch marks, dulling, hazing, scuffing at all on the register. IMHO the register has two functions, one, it keeps the threads attached to the spindle, so your chucks don't fall off, and two, it will always be shiny, so if you need a reminder of what a good surface finish looks like, you can look at it.

crypto
02-28-2003, 06:10 AM
Darryl,

Dagnab it ! This old grump says it's about time one of you young whippersnappers came up with the right answer!

OF COURSE, durn it! It keeps the blasted threads on the spindle.

Now let's get down to important stuff like, good lookin' wimmen past 70.

Register, registers?----who gives a hoot.

Oscar

nheng
02-28-2003, 11:41 AM
Oscar: Why limit the range to > 70 ?

All: If the register is a precise fit to the chuck and the chuck bottoms out on the spindle shoulder, you should be able to achieve all accuracy that the chuck can deliver. I suppose a perfectly fitted thread could do the same thing and this was mentioned in an old register topic but IMHO, the register and shoulder really pull it all together in the same way a short taper mount does.

Den

lynnl
02-28-2003, 11:54 AM
nheng, haven't you heard the expression "..robbing the cradle?" Oscar does NOT want to be known as a cradle robber! http://bbs.homeshopmachinist.net//smile.gif

My old 13" LeBlond has at least a 3/32" gap between register and backplate on a 8" Pratt Burnerd 3-jaw (probably good to about 3 thou TIR); and probably close to 1/4" on the 4-jaw backplate. I think Darryl's hit on the main purpose of the register. (...and Oscar's hitting on the important stuff.) http://bbs.homeshopmachinist.net//smile.gif

[This message has been edited by lynnl (edited 02-28-2003).]

JoelK
03-01-2003, 10:25 PM
I bought a ER40 collet chuck with a full set of collets at an MSC tent sale. I have no idea what the chuck taper fits. I just wanted the collets and nut. I turned up a chuck for my threaded lathe spindle to use the nut and collets. This was before I read anything about the spindle register supposedly aligning the chuck. I thought it was just clearance space for the threads. I probably have at least a .030 difference between the register OD and chuck ID and I'm sure my threads are anything but perfect. Using the same test bar, I have repeatedly measured .0015 runout at 6" out after removing and installing the chuck. The only thing that can be registering it is the threads and spindle face. I think Darryl has it right.

crypto
03-02-2003, 12:53 AM
Friends,

There is a very practical reason for narrowing choices to "over 70".

There is so very little competition in that phase of the game.

Ladies of that often lonely age are generally so very grateful to have their charms appreciated and in gentle manner addressed.

Watched a biographical TV sketch of John Huston the movie producer. He commented on "the often overlooked pleasures of old, soft, sweet flesh". A wise man indeed.

Oscar

darryl
03-02-2003, 04:20 AM
Somehow, limiting the choice to the over 70's group of women doesn't register with me. I'm not going to think about that anymore. So, here's more fuel for the fire. What happens if the hole in the chuck plate is a precision fit over the register? Besides there being the possibility that the chuck may never be able to fully seat against the shoulder without having to flex the threaded portion of the spindle, (this not being especially good, itself being a source of wobble) when the spindle heats up from extended running, the register will expand, the mass of the chuck will keep it's temperature lower, and the chuck is seized until things cool down. (or the chuck's temperature raises to match the spindle) This will give you time to register some new ideas about the register.