# Spindle Crank, (for Threading)



## Deanofid (Jan 9, 2010)

Hi all;

Needing to do some metric threads on the Atlas soon, and it doesn't have a reversable motor, so 
I need a way to "rewind" after each threading pass without disengaging the halfnut. 

The folks here who do metric threading on their imperial lathes, (or vise-versa) know what I mean, 
but for the guys 'n gals who aren't doing this sort of thing, here's a quick explanation;
Normally, when you thread "inch" threads on a lathe with "inch" leadscrews, you just make a 
threading pass, disengage the half nut (back out the cross slide) and crank the carriage back to 
your starting point. Then the threading dial will tell you when to re-engage the half nut to pick up 
the thread at the proper point for another cut.

If you cut metric threads on an inch machine, the thread dial won't do you any good because it's 
geared to the lead screw, which has a thread pitch made in fractions of an inch. The two just don't 
get along. If you try to use the threading dial, the machine will just cut threads all over the place on 
your stock, overlapping them, and generally making a mess. You have to leave the halfnut engaged 
throughout the entire cutting process. If your lathe motor will reverse, you can just do that to get 
back to home base, since it will run the leadscrew through the halfnut backwards at the same time.

Anyway, no reversing motor here, so I'll make a crank that will turn the spindle and all the related 
gearing, etc., forward or backward by hand. It will work for the occasional metric threads that I cut. 









I started with a 1/2" piece of aluminum. The spindle bore on my Atlas is just over 1/2", and this fits 
close enough to do what I intend to do. 
First step is to drill it all the way through. I want it to pass a 1/4" threaded rod, so it's drilled 9/32". 
Had to go at it from both sides, so I peck drilled it to help it stay on center. It did an acceptable job, 
and I couldn't see where the two holes met up.










It needs a taper inside one end for an expander plug. I want the plug to be long enough to bear 
on the taper for a little way. Looking through some stuff to get a picture in my mind of how steep 
to make the taper, I came across this Uni-Bit. Perfect shape. It made a nice starting point for the 
taper, too. I ran it in until it was just a bit shy of the full diameter of the work piece.










It made a nice start. 
To set up a boring bar to cut the ridges out of this hole, I put a regular tool bit in the compound slide, 
put a straight edge along the side of the Uni-Bit, and ran the compound back and forth, watching the 
tool bit tip as it ran along the straight edge. In a minute or two, I had the compound matched to the 
taper on the Uni-Bit, and was ready to get to business. 










Then it was just a matter of taking out all the ridges left by the Uni-Bit, and finishing up the taper.

You can see that the work piece is sticking a long way out of the chuck. It's too big to go through 
the headstock on the Taig lathe I'm using for this job. Usually, two to three diameters of the work 
piece is about all you want sticking out of the chuck. Sometimes you can't follow the "rules".

This job could have been done on the Atlas, and then I could have been working closer to the chuck. 
I have my reasons for doing it on the Taig, but it's nothing to do with the Atlas not being able to do it.
It was a preference of the day.










Now, without changing the compound setting, I cut a tapered plug from CRS that will go into the 
taper just cut in the aluminum piece. This will assure the tapers will match. 

At this point the piece has already been drilled and tapped down the center. That has to be done 
before the taper plug is parted off. 










When the taper plug is done, off with it's head!

If you look at the end of the plug, it appears that the tapped hole is off center. It isn't. It's just 
the way the first thread of the hole sticks up that makes it look that way. It should have been 
counter sunk a touch before tapping. I forgot.










Now back to the aluminum rod that had the taper bored in it's middle. This piece will work similar 
to an expanding mandrel, so it needs some slots cut. You can see what's been done here.










After the first two slots are done, the piece is rotated 90 deg and the exercise is repeated. Using 
a square helps to get things right way up. 










Now it's looking kind of like a collet that works inside out.










The taper plug goes in like so, and will be drawn into the rod with a threaded rod and nut. This will 
expand the rod, locking it inside the spindle bore.










It needs some kind of offset to crank it. Just a piece of aluminum flat. 
The smaller hole will be to lock it to the solid end of the expanding rod. Half of that small hole 
is a clearance size for a #10 screw, the other half being tapped for same. The bigger hole just 
being drilled is to fit over the rod.










Then an 1/8" slot is milled to allow the lock screw to squeeze the piece onto the expanding rod, 
(on the unslotted end). The other end gets a hole to mount a wooden handle.

That's just about it for the bits and pieces. I found an old file handle to use for cranking it, but will 
change that out as soon as I find something I like.










Here's the completed item.










It goes into the spindle, like so. When the nut on the end of the expanding rod is tightened down, 
it draws the taper plug into the rod, expanding the slotted end. It locks up very tight in the spindle. 
To release it, the nut on the end is loosened, and a light tap on it pushes the taper plug out enough 
to free the expanding rod in the spindle. 










It's long enough that it can be used with the gear cover closed.

Now I can cut a furrin thread to fit the spindle nose on my American milling machine!

Thanks for checking it out. There's a quick video, below.

Dean 


[ame]http://www.youtube.com/watch?v=8ZFKy36pxlw[/ame]


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## black85vette (Jan 9, 2010)

Well done and useful.  I like the expanding arbor part.  May be able to use that technique on other projects.


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## ksouers (Jan 10, 2010)

Very nicely done, Dean. Great write up, too.

Now all you need is Bogs flipper threading tool and you're in like Flynn.


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## ariz (Jan 10, 2010)

very interesting and nicely done Dean

it's a project that I have started time ago and never completed, you have remembered me to finish it


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## Noitoen (Jan 10, 2010)

Don't forget to make some sort of safety device that prevents you from accidentally switch on your lathe.


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## gbritnell (Jan 10, 2010)

Nice handle Dean, before I put in my own switching to get reverse on my Atlas I had to do the same thing, but by hand. It would still be a usable tool for me to thread up against a shoulder. Another project, darn!!
George


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## zeeprogrammer (Jan 10, 2010)

As they say around here...'cool beans!'

Like black85vette said....very useful for other projects.


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## cfellows (Jan 10, 2010)

Very nice. You can also use it to make turnings during a power outage, assuming you have a flashlight so you can see! :big: I actually made and used one of these on my 12 Logan lathe for a number of years. Still have the lathe but don't know where the handle is... wonder where it got to???

Chuck


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## gunboatbay (Jan 10, 2010)

You really did a professional job on that, Dean. I used a 'safety' wheel/handle on mine so it could be folded out of the way when not in use. My system for attaching the wheel in the spindle sure wasn't as professional looking as yours. I utilized the same system that is used to hold a handle-bar gooseneck in place on a bicycle (see attached)


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## hobby (Jan 10, 2010)

Nice work on that.

That gives me an idea for my mini lathe, of how to attach the spindle to some sort of indexing attachment.

Very good write up, too.

I like your method for making internal tapers.


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## Deanofid (Jan 10, 2010)

Hi all;

Thanks for all the comments and kind remarks!

Gunboatguy, that bike gooseneck idea sounds like a perfectly fine idea, to me.

Chuck, I have candles! 



			
				gbritnell  said:
			
		

> Nice handle Dean, before I put in my own switching to get reverse on my Atlas I had to do the same thing, but by hand. It would still be a usable tool for me to thread up against a shoulder. Another project, darn!!
> George



George, I only spent about three hours on it, so, at least it doesn't kill a whole day of shop time. Heck, 
three hours on "Dean" time may be only 1 1/2 hrs on "George" time.
I was hoping to put a reverse switch on the motor for the Atlas, but it has only two wires coming out of 
it going to the cap, so I think it is a single direction unit. It's from a drill press.




			
				Noitoen  said:
			
		

> Don't forget to make some sort of safety device that prevents you from accidentally switch on your lathe.



I have one of those safety devices. It's my brain, which tells me to unplug the lathe before I put the 
handle in the spindle. Same device that keeps me from putting my fingers into a spinning chuck! 
My "self preservation monitor". 

: )

Dean


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## Twmaster (Jan 11, 2010)

Very timely project Dean. This is 'pert dern close to what I was thinking of making for mine. I was just trying to decide how to make the expanding plug end of the crank.

Once again a wonderful project and a terrific treatise on it's creation.


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## Deanofid (Jan 11, 2010)

Thanks Mike.
I think that folding handle on the one Gunboatguy made is pretty nifty. Worth a look when it comes time for you to make yours.

Dean


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## Twmaster (Jan 11, 2010)

Weighing all my options as they say.

TO me I think the folding jobbie would be a problem. It may make it harder for me to remember to remove the thing before attempting to power on.... Nothing wrong with that idea. Just to my goofy brain I have to take certain precautions.


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## bucketboy (Mar 2, 2010)

Why not use a cordless drill fitted with a socket and use that on your expanding arbor :-\

Bb


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## John Rudd (Mar 2, 2010)

Noitoen  said:
			
		

> Don't forget to make some sort of safety device that prevents you from accidentally switch on your lathe.



I must re-iterate the need for extreme vigilance when using a manual crank for threading...

Last night I needed to thread a piece of bar with an M6 thread, out came the hand crank that fits into the spindle of my Chester 9*20, it only needs a nip up with a 13mm A/F spanner and thats it sorted. Thread cut on the bar and I'm ready to clean up....

So power back on the lathe by resetting the Emergency Stop switch and away we go....( I should add that there are two further manual steps required to bring the machine to speed..)
There was a lot of noise and a tin of WD40 fell to the floor before I realised what was happening!!!

I some how managed to catch my left hand on the rotating crank, fortunately I was wearing some thin gloves else the damage may have been worse...

I hit the EM Stop before the machine had managed to build up too much speed......

In my haste to complete the job I forgot to remove the crank from the spindle much to my own suffering!!!

I might add, I usually remove the spindle drive belt to prevent me doing such stupid things, but this time I thought it was only a 2 min job to thread the bar.......

I'd have posted pictures of the injury to my left hand but thought it may have caused some distress, I leave it to your own imagination 

Be warned gents, these things can bite real hard if you get it wrong..I've learned a lesson which could have cost me my fingers or worse..

I cant stress how conscious we need to be when operating machinery..

Please, Be Safe..... 

John ( aka Fingers...  )


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## Blogwitch (Mar 2, 2010)

That is so true John. These machines have no feelings and will be quite happy to turn you into mincemeat instead of doing their proper job.
Even the smallest item in your shop has the ability to make your eyes water or even worse. That is why I hadn't done any machining for so long, I didn't consider it safe to even go in the shop because of the mind numbing medications I was on, I was bound to have an accident sooner or later.

The old Hill Street Blues saying comes to mind, 'Let's be careful out there'.

Dean,

Very nice job.

While you are in the mood, consider fitting say a 3" or 4" round handle to the end of your leadscrew.

When you get to the larger pitches of threads, you might find it almost impossible to turn your handle because of the gear ratios being fed to the leadscrew and saddle. What you do then is use the leadscrew handle to do the same job, as the ratios work in reverse and you will find it gets easier the larger pitches you have to make.

You will find this mod is standard on some production machines.


Blogs


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## John Rudd (Mar 2, 2010)

Blogwitch  said:
			
		

> That is so true John. These machines have no feelings and will be quite happy to turn you into mincemeat instead of doing their proper job.
> Even the smallest item in your shop has the ability to make your eyes water or even worse. That is why I hadn't done any machining for so long, I didn't consider it safe to even go in the shop because of the mind numbing medications I was on, I was bound to have an accident sooner or later.
> 
> The old Hill Street Blues saying comes to mind, 'Let's be careful out there'.
> Blogs



John,

I too have been on serious medication of late ( Tramadol..)

I would never ever advocate using machinery while under the influence of drugs or alcohol...It just doesnt bear thinking about...
Yet people will drive cars...


Hope you are feeling better


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## mklotz (Mar 2, 2010)

Put a key-operated electrical switch in series with your lathe power supply. Weld a short length of chain to the key. Weld other end of chain to your spindle crank.

Ensure that the chain is short enough that, with the crank in the spindle, the key can't be inserted in the switch.

Same principle that a lot of folks use on their drillpress. The chuck key must be inserted into a tube where it operates a microswitch in series with the power to the DP. No more chuck keys flung across the room.


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## Deanofid (Mar 2, 2010)

John Rudd  said:
			
		

> I must re-iterate the need for extreme vigilance when using a manual crank for threading...



You can't be too safe. There is no way to get around the need to think, think, think. 
I unplug the lathe before I put the crank in the spindle.




> fortunately I was wearing some thin gloves...
> 
> John ( aka Fingers...  )



Really, what makes you fortunate is your machine did not grab your gloves. A definite no-no in a situation that involves rotating machinery.  No gloves, no rings, no wrist watch. People loose parts because of those things.


Dean


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## RonGinger (Mar 2, 2010)

I also made a crank like that for my 11" Rockwell lathe, but I use it mostly for spring winding. I feed the spring wire through two strips of wood clamped in position as if they were a lathe tool. That lets me set the tension on the wire, then I crank the spring by hand.

Instead of a permanent handle I made the end of my arbor with a square shank to fit the knee crank on my Clausing mill. I made the collett end exactly like Dean


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## zeeprogrammer (Mar 2, 2010)

Just a couple of thoughts...
(and also related to Matt's question about limit switches)...

I'm a software engineer...I don't trust software and I don't trust the hardware it runs on. Too often I've been sitting in the lab and have seen a piece of equipment suddenly take off. Maybe it's static electricity, maybe it's a software bug, maybe it's a failed piece of hardware, maybe it's a cosmic ray that flips a bit...but...

I believe in Murphy. Done.

I kick myself every time I grab the spindle to change a bit, or to loosen/tighten a chuck, and I haven't shut off the emergency switch. And even then, I ask myself..."Can it still turn on? Should I unplug it?".

Remember...many of those little nicks on your hands are "Wow...that was close!"


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## 1hand (Mar 2, 2010)

Zee I seen your post, and noted. thanks.

little nicks..........I shouldn't need reminding, but I do.  thanks.

Matt


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## SAM in LA (Mar 3, 2010)

Yesterday I was doing a counterbore using the mill on my 3 in 1.

When milling, I lock the carriage by engaging the gears between it and the lathe spindle.

I reached over to turn on the mill, without looking, and accidentally turned on the lathe.

 :hDe:

Lucky for me, the lathes speed was very low and I was able to turn it off before my endmill broke.

It is so easy to become careless.

 :wall:

I need to be more cautious and pay attention to what I am doing.

 *club*

SAM


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