Need tips on single point threading

I works to do it backwards on my 10EE. Put cutting tool on back side, lathe in reverse. Stop machine with 1/2 nut engaged right at shoulder, you can fiddle till its just right. Turn compound in to make cut. Turn lathe on in reverse, it threads from the shoulder out. You need a small narrow groove right at the shoulder to have a spot to advance the compound when the machine is off.

That sounds much more likely to achieve success. Since I planned in the groove, I'm all set.

Thanks,

Wes

A lot of guys in the magazines advocate adding a hand crank to the back side of the headstock spindle, and slowly cranking it towards the end of each pass. They use an expanding rod arrangement to lock a shaft inside the headstock tube, the shaft of course having a crank handle fitted.

GWE

======= For one way to do this click on

Unka' George [George McDuffee] ============ Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.

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Hey Wes,,

If threading fully to a shoulder is absolutely necessary, then sometimes it is possible to add the shoulder later by some means. Depending on the "meat" forming the shoulder, it is possible to do a trepanning cut that allows the thread to actually go BEYOND the shoulder face. Another thought is to undercut the "nut" part so that the face of the nut contacts the shoulder, but there is a half a turn or so turned off the nut, and the shaft thread can stop a half turn "short" of the shoulder.

Good luck. Take care.

Brian Lawson, Bothwell, Ontario.

ps....I realize the drawing was made only for your own purposes, but for the rest of us to view it is nice if all the "text" part is set in the same direction, and it is also standard practice to indicate the threaded part(s) with an arrow and text describing it, rather than just with dimensions eg. 2-1/2 - 14 TPI ----------->

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Grant sez:

"A lot of guys in the magazines advocate adding a hand crank to the back side of the headstock spindle, and slowly cranking it towards the end of each pass. They use an expanding rod arrangement to lock a shaft inside the headstock tube, the shaft of course having a crank handle fitted."

Yep ! Count me amongst them. I made a nice hand crank from a HF tailpipe extender to fit back side of the headstock tube. Also made a 2nd one for the 5-C collet draw tube. They are great for careful threading in either direction as it is almost impossible to make any speed-related mistakes.

Bob (slower is better sometimes) Swinney

extender to fit back side

are great for

speed-related mistakes.

Well the lathe that I have access to won't hand crank worth a chit unless I leave it in neutral from the start. I'm curious about the lathe I'm fixing. Since the motor and varidrive is out, I wonder if threading the whole shaft at home using a crank is an option. I only need to turn .75" at 14 tpi.

I'll look into the feasability in the morning. It isn't like tying up the lathe until I get done is a problem.

Any tips on making an expanding arbor for spindle? Mine is 1 3/8" id.

Wes

extender to fit back side

They are great for

speed-related mistakes.

Some years ago, I improvised an expanding arbor from a Dynabolt (is that the US term? Expanding bolt for concrete). A strip of flat for the crank, & an old wooden handle completed it. Worked fine.

extender to fit back side

They are great for

speed-related mistakes.

If the lathe has a bottom speed of 45rpm, just practice a bit more. You should be able to get better than half a turn repeatability if there aren't any distractions.

good luck

Mark Rand RTFM

Maybe buy a friend a beer to do it then and don't bother to learn, unless you really want to. Randy

Wes, there is a shop-made hand crank near the bottom of my 9x20" lathe page, for an idea that was fairly quick to fabricate.

The center hole was drilled, the angled cut was made, then the hole was filed at the clamping end to allow the drawbolt (allthread) to shift sideways to allow the end piece to pull off-axis. Since the spindle pass-thru hole is under 1" on this small lathe, filing the center hole seemed necessary for using a 3/8" drawbolt.

The handwheel knob is a ball bearing assembly with a short piece of nylon round stock pressed into the bore, drilled and tapped for a 1/4"-20 bolt. I had tried using an aluminum bar with a longer offset for the crank, but it was a bit cumbersome, and the handwheel proved to be very easy to turn while wathching the threading operation.

The handwheel isn't left in the spindle, as it's very badly off-balance. I pull the power cord from the wall outlet and disengage the drive belt when using the hand crank.

For the short offset of the handwheel, and because the lathe is small, the hand threading method doesn't require a lot of effort.

WB ......... metalworking projects

Well, the lathe that works is at work. My friends near by don't have lathes. I'm gonna do it but I figured I'd draw on the wisdom of the group for any ideas to improve my chances.

The whole point of aquiring the lathe was to be able to build stuff. Screws are high on the list. As soon as I get it going, I want to make a new cross feed screw for my bridgeport but that is questions for another time....

Wes

I'm thinking a dab of paint marker on the shaft and additional lighting would help my chances out a lot. I'll practice a bit more and get some muscle memory going. Noticed that the lathe I'm repairing engages the half nuts by pulling up. The one I'm using engages by pulling down. I wonder which way of engaging the nuts is standard?

My co-worker that was showing me a few things floundered when he pulled the wrong way out of habit. In the past he has run some very big machines though he doesn't do machining where we work. We fix em after the operators break them.

Wes

A simple wedge clamp. I've repaired enough bicycles I should have come up with that.

Thanks

Wes

Practice on a straight bar to pull out at the same point. The white mark on the chuck will make it a lot easier to hit the same spot each time. 45 rpm is more than one second per rev. Ive seen really experienced lathe ops. run up to a shoulder at a lot faster rpm than that.

John

I've been able to disengage the half nuts when the tool reaches a

jw

According to Wes :

If you're going to hang a hand crank on it, it *better* be in neutral through the whole task.

And if you expect to be switching between hand cranked and power, take the time to make the hand crank assembly well balanced, or the lathe will be hopping all over the place. Ideally, I would suggest a spring-loaded folding crank so it won't be out there bashing at your hands or anything else which gets close when you have power applied.

Though applying power while you've got a hand crank mounted is still asking for lots of trouble.

It might well be. If the lathe is belt drive, disengage the pin which transfers from the pulley to the bull gear, and leave the back gears disengaged and you should have little trouble hand cranking. (And be sure to back the cutting tool out of the thread before you hand crank it back to the start position. (Though the real need for the hand crank is when you are doing metric threading on an imperial leadscrew, where you have to back up without disengaging the half nuts to avoid losing your thread position.)

If it is a gearhead lathe, however, I'm not sure how to make it totally neutral.

Others have already suggested the expanding grip used for bicycle handlebars. Maybe make three splits instead of two so it is a bit better balanced.

Good Luck, DoN.

Thats another good way to do it, better than the one I suggested. I forgot about that one. Let the dial go around at least a full turn so you can get ready to pull the handle.

John

On the Clausing / Metosas you just put the 1 2 3 gear shift between numbers and the spindle turns very easily, ...lew...