Using a spindle crank to thread on a lathe ?

[Alcap]

On my bench lathe ( similar to a Smitty 1220 but made without the mill head ) there are change gears to do metric threads . There are no threading dial so the the feed knob can’t be disengaged . How practical would it be , on small lengths anyway to make a spindle crank and do it all by hand ? I’ve never tried any threading on this lathe yet . Thanks Al

 

[T Bredehoft]

I don't see why you couldn't do it, just take very fine cuts. and remember where you are at all times.

Edit: correct typo.

 

[C-Bag]

I made a spindle crank for doing single point threading by hand. The slowest rpm my 9x20 is 120 so I didn’t feel comfortable with that. I use the spindle crank a LOT for reaming, with taps and dies etc. one of my best shop made tools.

 

[compact8]

The size and features of your lathe should be similar to my EMCO Compact 8 with which I have cut fine threads on aluminium tubes. Turning the chuck directly with hands worked quite well in my case so I doubt if I will ever make a spindle crank. If I need to cut deeper threads I think I will use power drive but the lathe will be set up so that the tool will move away from the chuck when cutting.

I also don't have threading dial but I have no problem to put the tool back to the original position when re-engaging the feed lever because with the lever engaged and the feed screw stationary, the carriage hence the tool can only take up positions in steps and there is only one position that the tool will line up with the thread perfectly at the starting point of the threads. I therefore don't see the dial to be necessary.

 

[jwmay]

Seems to work pretty well for this guy.

 

[Bi11Hudson]

A while back (~20 yrs?) a 9X19 group on Yahoo got into devising a hand crank system. I personally built a reduction gear for my spindle, for many purposes but it also worked with threading. So I didn't get into the manual threading. But my reduction gear, when I published it, had several points for attachment of a threading handle if it was desired. I seriously doubt, after all this time, that the Yahoo group is intact, certainly not the same people anyway.

If there is serious interest on the subject, I still have the text, I think, for the reduction gear mechanism. Built from junk used automitive parts, it reduced the spindle speed to roughly a third, ca. 40 RPM. The text is closer to a small book, 40 odd pages. I tend toward the verbose when I get going. But as the originator, I would be quite happy to "donate" it to the archives. It actually is in the archives of several web sites of the times. I don't remember the names, but the article is already published in several places.

.

 

[silence dogood]

It is very possible to make threads without power and using a handcrank. After all, one can make keyways or even gears by just using the carriage manually. Of course, unplug the lathe, and even maybe even take the drive belt off for less force in turning the crank. Put a mark or dot with a sharpie pen on one of the teeth on the lead screw gear. It will then indicate where you are just like a threading dial. Before you make that next cut, you just make sure that one gear tooth is at the same starting place. The nice thing about this is that you have complete control when to stop (Unless you use Joe Pie's method, but that is another story).

 

[Alcap]

Thanks for all the encouragement ! Now a new project !

 

[savarin]

I use a handle to cut many threads on my 9x20, its not difficult.
The largest I cut by hand was an M39x4 thread for a new backing plate for a new 4 jaw chuck.
Take it easy and you should have no problems

 

[tonydi]

Admittedly I haven't done many single-point threading jobs but a spindle crank is something I made early on for my little HF lathe. I just couldn't get the hang of using the threading dial. But if I recall correctly, I didn't even have to back off the carriage when I got to the end of each thread pass. I just reverse cranked the spindle back to the beginning and dialed in more carriage for the next pass. Seems that the few I made came out just fine. Luck or is that an acceptable procedure?