Handwheel Driven Leadscrew

I have a Quantum 210 x 400 mm Metric Lathe with a 2.0 mm leadscrew. This lathe is very similar than the Warco 180 lathe.

I recently visited the Warco 180 lathe web page and asked the owner a question or two. One of the questions was about backlash in the Handwheel that moves the saddle left and right. I found the answers on the page of the gadget builder as his lathe is similar as well.

Andy pointed out that I will have better results if I put a handwheel on the leadscrew. I have studied the mod on this page and I wholeheartedly agree that it will be a very good mod / improvement.

My leadscrew ends exactly flush with the end of the lathe bed and my leadscrew is of right hand thread. If I add the handwheel onto the leadscrew directly, it will have to be turned anti clockwise to move the saddle left, and not clockwise as all the other handwheels. I am thinking of adding a small gear onto the leadscrew onto a small axle that I will epoxy into the leadscrew. Onto that gear will run anothe gear that will turn the laedscrew in the opposite direction if I turn the handwheel clockwise, causing the saddle to move left (towards the spindle). This way will cause the handweel's centre to be not on the leadscrew's centre but about 20 mm towards the rear. I can mount it in a movable part that can slide away to disengage when I do screwcutting or anything where I don'st want this handwheel to turn.

Is there perhaps somewhere a mod of similar design? The mod that I have seen on mike's mod page is where the owner has extended his bed a few inches and added a longer leadscrew. The new handwheel have space left on this extended bed to be mounted and can move to disengage. I do not have this space, however I may be able to fix a type of an angle plate to do this mod, mut it will extended more to the right as the first mentioned idea and will still be working the othe way around.

I will appreciate any suggestions or references to other existing mods.

I would be wary of adding an idler gear to the handwheel as the backlash in the gears will be counter productive to what you are trying to achieve. Also have you measured how much backlash there is in the half nuts before you start.

Also having previously had an Emco for 20years that had a handwheel on the end of the leadscrew I seldom used it and hardly ever for turning.

J

I never found the reversed motion of a directly fitted lead-screw hand wheel any great problem. One tends to adapt quite easily. I'd agree with Jason that such handles are rarely used for turning. Once I got a graduated ring fitted mine was mostly used to help set up rods on a 6 position turret type bed stop. Very handy when a job had steps of various diameters. In my view a multi-position bedstop is an essential accessory.

A calibrated leadscrew handle is, of course, pretty much essential if you wish to get much use out of a vertical milling attachment.

Clive

There is now backlash on the halfnut but on the saddle wheel that is connected to the rack, the play is noticeable, about 10 degrees of a turn of the wheel and relates to about 0.1 mm.

That's very good.

Saddle handwheels were never designed to be backlash free, I can't recall one lathe, even high end lathes that have any method of adjustment.

If you need to work both ways you just go further to take the backlash out and return.

The Peatol\Taig has it's handwheel in an eccentric bush so you can set the engagement between the pinion and the rack. Works rather well once you get it set up properly.
Whether it would work scaled up to a 'real' lathe is another matter though...I'd guess not but I'm often wrong

My Myford ML10 has the handle on the leadscrew, use it all the time, no problems.

I fitted the leadscrew mod to my mini lathe - I added a short spigot to the end and fitted a 'spare' saddle/tailstock handwheel.

It works much better than the saddle handwheel, and I use it when I want to remove bulk material by facing, only using the topslide tobring the durfae dead to size. I graduated it with 64 divisions so each one is 1/1024 of an inch.

With a metric leadscrew I could have used 80 divisions* and had each division as 1/1016 of an inch.

Neil

*I'm assuming a mini lathe leadscrew is 2mm pitch. Can someone confirm if it is 2mm or 1,5mm?

Edited By Stub Mandrel on 27/12/2012 21:26:05

Metric Sieg and Real Bull "7x" minilathes have 1.5mm pitch leadscrews, Neil. That's fairly close to your imperial version's 16tpi. I guss yours is a Sieg, or you wouln't have needed that spigot. On a Real Bull, there's already a threaded extension for an endfloat adjusting nut, which can be used as part of the handwheel arrangements.

Andy

Thanks Andy, that would mean 60 divisions then.

Neil