I've decided on an X1, here is an idea - opinions please

[chola]

I've now made the decision to buy an X1 machine (part thanks to Mike from a previous thread).

I am going ot cnc it, but here is a theory that I have not seen yet (maybe because it's not feasable), but please feel free to englighten me.

Stepper motors on x and y axis (as usual), however, for the Z axis, why could the stepper motor not be fitted to the fine adjustment wheel on the front of the machine, and a standard dc motor with limit switch / relay setup be used on the z axis.

pretty much all my work will fall under the 30mm travel provided by the fine adjustment mechanism, so the theory would go something like this....

To machine a part that has a total height 20mm from the table, could the dc motor on the z axis leadscrew be used (triggered by an m code output), something like a car wiper motor (these have huge torque so no need for counter weights etc), to take the head down to say...5mm above the job, using an adjustable limit switch to deactivate the relay from the above mentioned m code, the the fine adjustment wheel is controlled by the stepper motor as per normal from the z command.

I know the normal method is to 'stepper motor' the z axis leadscrew, but as I will not need the full length of travel for 90% of my jobs, how does the theory above sound?

Opinions greatly appreciated.

Thanks.

Colin

[Pres]

Yes, it seems ok if it has enough travel for you.

It seems the main problem would be getting the freeplay (backlash) out of that mechanism.

How/where would you mount the stepper motor and have it "out of the way"?

Pres

[chola]

Hi Pres,

I had a little play with the x1 in a shop yesterday, and noted in particular how little backlash there actually was in the fine adjustment mech, hence the reason I though of using it, and just a 'coarse' dc motor for the major movement on the z axis.

I would probably mount the stepper motor on an alloy bracket out the front, no where really to put it so it's out of the way, I guess the good thing with CNC'ing it though is it wouldn't bother me as much being out the front compared to machining manually where I would probably hit my head more often than not!

For the parts I will use the cnc capabilities for, it has enough travel, on the odd occasion I need more, then I will use it manually (famous last words eh).

I wonder if there is a way to increase the fine adjustment travel though? Even another 5 to 10mm maybe??? Something to consider when I get the machine.

[Pres]

Hi Chola,

The handwheel/quill seems to be preloaded with spring pressure sufficient
to keep the backlash out (that is, if you don't go too fast).
On mine, using the big quill lever on the righthand side, it has over 1mm of backlash.

You might want to consider making up a plate to mount the motor on and just drive the hand wheel with a pulley/belt system.
The motor could then be mounted on the backside of the plate -so it is out of the way.
Then only a small belt & pulleys would be protruding out in front.

If nothing else, it sure saves yanking the whole head up/down just to drill a hole.

However, when milling it would be better to have the quill clamped to the head (i.e. only have 2 axis, x-y, milling).

There are lots of combinations can work better. Just depends on the type of work you do with it.

For example; mine is setup for maximum travel and accuracy with a minimum of speed.

Good luck,
Pres

[chola]

HI Pres,

I think you rplate idea for the fine adjutment motor will be the go, like you say, then can have a small belt drive (or even a gear or 2).

My main goal with the machine is similar to yours, speed not of such a great concern as my parts are small, but accuracy is high priority.

Like you say, there are obviously a number of ways this sort of stuff can be achieved, so to a certain extent I will have to wait until I get the machine to see what is feasible for my circumstances.

What sort of parts do you make on yours?

COlin

[MIKE JEFFERS]

google "compucutters" - x1 project for some ideas further to this
i just steppered the z axis and after fitting a counter balance it works a treat
gives full travel and allows you to fiddle the z height on the fly.