mandrel handle

One thought, the collet (of any design) is best made an easy push fit, this means it has to expand very little but also ensures sufficient concentricity if you also use it to mount a changewheel at the back of the lathe.

Neil

mandrel handles are one of those things which seem to be essential equipment for model engineers, but are never seen in industry. I just screwcut under power. Only if lathe had no backgear and so wouldn't go slowly enough would I consider a manual winding handle. If cutting up to a shoulder, turn a short groove for the tool to run out into, or something I've seen suggested but never tried, run the lathe backwards and put the tool upside down (or in a back toolpost), then the tool runs off the end of the job. For internal screwcutting I usually put the tool upside down but run the lathe forwards and cut on the far side. The turnings then fall away from the tool, and you can see the tool a bit better

My WM250 lathe runs at 100 rpm at the lowest speed which is to fast for my slow reactions when screw cutting. So I made a mandrel from a Halfords tyre lever and other bits which lock into the backend of the spindle. It works very well not just for screw cutting but tapping as well. (Yes, I confess to being a bit windy re: tap breakages.) When finished using the mandrel the large knurled knob is unscrewed a turn or two and the threaded rod tapped gently with a lump of lead after which the mandrel slides out freely.

Unlike JasonB I HAVE forgotten on several occasions to remove the mandrel before pressing the GO button but I have a cunning plan to stay safe. Before inserting the mandrel I ALWAYS turn the power of at the wall socket. It is a golden rule and so far it has kept me safe (and momentarily surprised as well when I press GO and nothing happens.)

Since I made the mandrel I discovered that I have an option to reduce the lowest speed on the lathe by backing of a small pot on the speed control board. It’s one of two at the bottom left hand corner in the photo marked MAX and MIN although I have yet to make the adjustment. With the lathe running OK at the mo (touch wood) I am leaving well alone and relying on the mandrel.

Rik

Edited By Rik Shaw on 10/08/2016 17:53:13

Edited By Rik Shaw on 10/08/2016 17:57:47

Hi Rik, I have a very similar lathe, a Warco 240 and that handle you made is just what I need, may start building it tomorrow. I have a small, warco mill, wm14 which has a similar control board, I tweeked the Min pot to the lower the speed to zero so I can turn the speed knob down to nothing rather than keep turning them mains on and off all the time, I did this a year ago when I bought the mill and it has worked fine ever since.

With envy I look at all those beautiful made mandrel handles, when I needed one I hastily put one together. Niko.

Edited By speelwerk on 10/08/2016 19:23:50

Thanks for that information Michael and Howi, I see now how that system works but I must say I have never come across that idea before. I use the split tube and tapered wedge method for my handle but it is good to see other ways of doing it.

I rarely seem to cut threads without the handle as it is so controllable and easy on the nerves. Very much a must have item.

Doug

My mandrel handle is a wheel, an ally drive wheel of an old water pump, about 12" dia. Easier to use than a handle and can be left in place. It was made in a hurry, the split tube is a bit of ally tent pole and was a bit loose so wrapped with aluminium tape to suit. Only part made was the brass taper plug, tapped M6. The spindle bore is pretty rough but so far this has worked well.

mandrel handles are one of those things which seem to be essential equipment for model engineers,

I'm in Duncan's camp. I can turn the chuck by hand, if really needed, for starting a thread with a manual tool. Apart from that I use the lathe motor. My LJ turns at a reputed 36rpm minimum in back gear and a lot less if I reduce the motor feed Hertz. Who could want it any slower than that?

wow that sounds potentially nasty. I have seen (in MEW?) mandrel handles made out of those double-ended ratchet ring spanners, which would simply make a very loud ratcheting noise but go nowhere if the lathe were started. Or one of those one-way needle roller bearing clutches could be built into the centre of the handle.

Not that I need to worry on the mighty Drummond with its dog clutch and knockout bar to stop the tool dead at the appointed spot. I like to do my screwcutting at 250rpm - but that's just showing off that is.

Edited By Hopper on 11/08/2016 14:08:04

I only use a handle when I mill the thread of a musical box worm gear, they can get small with a diameter of 1.8 mm with 0.8 pitch and find it gives you more "feel" with the work. Niko.

So when the great exhaustive survey of model engineers mandrel handles is complete will they actually find any two (or more) of the identical design? Judging by this thread I have my doubts.

Clive

... & here is my attempt

George.