Hand Crank for Threading in a Lathe

[rsterne]

This is the setup I use for accurate and square threading, using my lathe.... It can be used with a tap (as shown), or for single point threading.... My thanks to Lloyd Sikes for the idea, I don't know how I would live without it....



There is a lot to see in that photo.... On the left is a hand crank, inserted into the hole in the spindle, and secured with a split/tapered nut the same way the seat post on a bicycle works.... You slide it in from the left, and reach inside the spindle with a socket wrench to tighten it in place.... This allows you to turn the chuck by hand, with good leverage.... The tap is in the chuck.... The part is clamped in the milling attachment.... It sits against an end stop (against this end of it), back against the vertical part of the milling vice, and clamped down, so that it can be removed and replaced at will and will always go back in the same place, allowing multiple parts to be made without altering the vertical or crossfeed settings, they are locked in place once the correct location for drilling and tapping the hole is determined.... The carriage moves left and right, to drill the holes, and you can see a dial indicator on the ways that tells me how far in I have drilled or tapped.... When tapping, I run the part up against the tap, zero the dial gauge, push the carriage to the left by hand to load the part against the tap, and start cranking the chuck by hand.... Once it gets a good bite, the carriage just follows left and right as the tap screws in and out of the part, and the dial indicator tells me how far in the tap has advanced....

For single point threading, you can engage the half-nut when you begin, make one cut, even up to a shoulder, leave the half-nut engaged, back out the tool, turn the crank backwards past the beginning of the thread, advance the tool deeper for the next cut, and crank in again.... There is no reason to disengage the half-nut until you have completed all passes and the thread is at full depth.... You don't end up with a clearance groove at the bottom of the threads, although if you want one you can turn it ahead of time.... One neat trick is to turn that groove to the depth of the minor diameter of the thread (major for inside threading) and when the point of the tool touches it, you know you are at the correct depth.... Thanks, Lloyd for making threading in the lathe MUCH easier and safer.... BTW, it's a good idea to unplug the power so you can't accidently turn on the lathe and end up with the hand crank flailing around.... 

Bob

[Pellethuntr]

That's pretty cool Bob I may need to make one myself!

Just out of curiousity what is the spindle bore on your Atlas?

[rsterne]

MT3= just over 3/4"....

Bob

[Pellethuntr]

MT3= just over 3/4"....

Bob

What model is it Bob?

It looks very similar to my friends, I can't recall what his is from the top of my head but I will have to ask.

Yours is in fantastic shape btw!

[rsterne]

12" x 36", with a quick-change gearbox.... no idea of the Model number.... Milling adapter is also an Atlas part, and I have a steady rest as well.... plus a 4-jaw chuck.... 3/8" and 1/2" end mill holders for the MT3 headstock and MT2 tailstock.... Oh, and I also have a set of 5C collets 1/4" to 1" (1/16" increments) and a square and hex holder for them and have modded the milling vice to hold them.... great for orienting parts for multiple angle drilling and tapping operations.... and a quick-change tool post....

Bob

[Pellethuntr]

Here is a pic of my South Bend Heavy 10 from when I went to pick it up: (Guess I should take some current photos of it all hooked up)



The only things I don't have and need to still get for this machine are a collet set and steady rest.

Do you have a mill as well or do you do all of your milling with that attachment?

[rsterne]

No mill, I do all my milling with the Atlas milling attachment shown in that photo....

Bob

[Pellethuntr]

I made a quick version today and it turned out pretty well:



I need to get a bigger bolt to go from the spindle to the handle as this one is too flexible, I also need to weld a few things for added strength.

It does work and I can't wait to use it thanks for the idea Bob!

(P.S. ignore the messy shop I have been busy and it has gotten out of control lately)

[MultimediaMan]

Very cool idea, Bob (With props to Lloyd): Doing this one soon!