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dp
10-22-2006, 01:26 AM
One of the misguided activities of my youth was motorcycle racing - it resulted in my breaking my back a couple times and some other inflexible components essential for upright activities. As a result I can't stand over my lathe or mill as long as I'd like. So I've decided to look into some way to make stuff without standing over and turning the wheels. I'd like to motorize (different from CNC) some stuff - in particular, I'd like to motorize the lead screw of my Grizzly 3 in 1 lathe as a starter. And while I know this is common place and takes you right to CNC very quickly, I don't know what there is out there for motorizing machines without going full bore into CNC. I don't have a political problem with CNC, but I work with computers all the damn day long and don't want to work with them on my own time.

So the question is - what stepper motor sources are there out there that have the cajones to drive a lead screw? I've worked extensively in robotics and rate feedback systems and know and understand much of the science of that stuff but that was for some pretty large tonnage robots - oil tankers, mostly, so I am not at all familiar with things that are already appropriately scaled and readily available for the hobbyist machinist and the typical bench top lathe or mill. Anyone have links/sources for this stuff?

Michael Moore
10-22-2006, 02:12 AM
FWIW, many CNC controls will accept input from manual pulse generators, so you can still twirl the dials (though on mine it is only one axis at a time) if you want. A nice feature on mine and probably others is that you can set the sensitivity range. I can have one click be .0001, .001 or .010. I don't think I was ever able to move the manual machines a ten thou'.

cheers,
Michael

John Stevenson
10-22-2006, 03:15 AM
DP, the last two issues of MEW have had an article running in them about using a stepper to drive the X axis on a Wabeco mill.
Simple drive setup with just two pulleys.The electronics consist of a power supply, a driver, a box to hold it with switches and a small board with about 10 components and a 555 timer chip.

This basically duplicates the electronic power feeds like the align that fit the bridgy but with a bit of ingenuity can be made to drive anything.

.

Mcgyver
10-22-2006, 09:00 AM
not sure what you are trying to end up with - are you motorizing an axis like a power feed or trying to control exactly how far an axis moves? if its the later, how do you plan on controlling it, with a keypad entering rate, ramp, depth etc? Even if you make the colossal effort to diy still sounds a lot like a computer. if its the former, power feed has little to do with cnc, no need for steppers just a motor and controller. Evan has some good material here somewhere on a dc motor speed controller used to drive the leadscrew on his lathe.

dp
10-22-2006, 11:00 AM
not sure what you are trying to end up with - are you motorizing an axis like a power feed or trying to control exactly how far an axis moves? if its the later, how do you plan on controlling it, with a keypad entering rate, ramp, depth etc? Even if you make the colossal effort to diy still sounds a lot like a computer. if its the former, power feed has little to do with cnc, no need for steppers just a motor and controller. Evan has some good material here somewhere on a dc motor speed controller used to drive the leadscrew on his lathe.

I'm going to try to use a simple toggle switch for directional control, and a dial for speed control, all in a hand-held box. I'd thought of using linear controls such as in RC airplanes and that's simple to do to. It simply becomes a remote control for the carriage hand wheel. If it works I'll consider repeating it for the cross slide. If all that fails I'll consider having my lumbar fused - should probably have done it 20 years ago. After a couple hours in the shop I can barely get up the stairs. I need to find a way to do this while sitting on a stool and turning the hand wheels from a stool just doesn't work well.

Timleech
10-22-2006, 11:22 AM
Just a thought, there are/were one or two european precision lathes designed to be used from a sitting position, I don't know what your chances are of finding one but you never know. It might be worth your doing a search on the Schaublin etc forum on the PM site. I don't know what you would search for, though ;)

Tim

dp
10-22-2006, 11:34 AM
Just a thought, there are/were one or two european precision lathes designed to be used from a sitting position, I don't know what your chances are of finding one but you never know. It might be worth your doing a search on the Schaublin etc forum on the PM site. I don't know what you would search for, though ;)

Tim

I'd start by googling the role of machinery in failed marriages :)

alanganes
10-22-2006, 01:45 PM
I know this is not an answer to the question you were asking but...

A woman at a place I once worked had some sort of lower back surgery. She used some type of ergonomic workstation support that allowed her to sort of stand while lightening the weight on her back. It was an odd looking thing that she ordered from one of those places that make specialized industrial workstations. A bit hard to describe, it was sort of like sitting backwards in a tall stool or chair and leaning forward so that your chest rests on what would normally be the back of the chair. You are mostly standing, but able to lean forward on a support. Of course the sizes and angles were not the same a regular chair. It was on wheels, and she would scoot around her work area, going about her business, without screwing up her back again. It looked a bit strange, but was actually very comfortable even if your back was not bad.

As I understand, they are designed for people who do certain types of assembly work that would normally require one to be standing up, but leaning forward all of the time, causing lower back stress problems. I'm not sure what it is called or where to get one, but may be worth some quality time with Google to see if such a thing would be of any help.

Back problems are bad stuff.

AL A.

BobWarfield
10-22-2006, 02:16 PM
There is a Yahoo Group that concerns itself with electronic leadscrew drives:

http://tech.groups.yahoo.com/group/e-leadscrew/

An article will be appearing in the November issue of the magazine "Circuit Cellar" describing their results.

I started out on this path, and it is pretty easy to design a simple circuit to generate pulses at a rate consistent with a rheostat with switches to control direction and throw it into neutral. In other words, to create a power drive. It's considerably more trouble to synchronize for threading, so in my mind this makes a better technology for cross feed.

In the end, I concluded that you do 90% of the work needed to just CNC the lathe in the first place. After looking at the "conversational CNC" options in Mach 3, it seemed clear you wouldn't even need to be a g-code programmer to derive benefit.

Here is the list of wizards for the lathe in Mach 3:

http://www.thewarfields.com/img/Toys/MachineTools/CNCCookbook/Mach3TurnWizards.jpg

Pretty comprehensive bunch of operations, no? Some would take a fair amount of doing manually.

And here is what the taper wizard looks like:

http://www.thewarfields.com/img/Toys/MachineTools/CNCCookbook/Mach3TaperWizard.jpg

Pretty darned easy, isn't it? Some angles, your starting and ending locations along the length of the part, feed rates, yada, yada. You are looking at the lathe taper attachment of the digital age. No programming required, but some computer familiarity is definitely a must.

Best,

BW