Re: [CAD_CAM_EDM_DRO] Beginners screws ( was ACME ( was Re: leadscrew,

Ross,
getting back to the issue of precision.
I have 400 steps per rev stepper.
Looks like for 2" diameter drive pulley I should have 0.0157" per step.
Can I increase the resolution by using half-step - microstep option?
Does it mean that for half- step I will get 0.00785 resolution, and for
mocrostepping
even less?
Regards, Alex

----- Original Message -----
From: Ross <rrcarl@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, May 16, 2003 10:47 PM
Subject: [CAD_CAM_EDM_DRO] Beginners screws ( was ACME ( was Re: leadscrew,


> > Just want to report , that I was at Home Depot and carefully inspected
> > caster wheels.
> > They seem to be perfectly round to me!
> > Designated them as important component of the future guideway.
>
>
> You should put a dial indicator on them as they rotate. 10 thou is not
easy to see by eye, but if you do things like vee routing text, that error
will show up in your finished part. Roller blade wheel bearings should be
available at a local sporting goods store. If I were looking for locally
available solution, that's the way I'd go. I think you'll find the bearing
to be cheaper than casters also.
>
> I learned all this stuff the hard way. My table started out as a simple 2
axis plasma cutting table. After I got the table, rails and carriages
built, I decided to add a Z axis to retract and lower the torch. After the
Z axis, I realized that I could do some pretty cool 3D carving. It was then
that I figured out that the angle iron rails did not offer much linear
consisency. I made a jig to grind the angle rails and got them to within
.002 which has been working fine for woodworking.
>
> My point is that your choice of rollers will effect your Z axis accuracy.
If all ytou want to do flame or plasma cut, then that is not a big deal, but
if your want to carve photographs and make signs, Z axis precision is pretty
important. Imagine cutting a photograph .020 deep and for every revolution
of an X axis roller, the carriage floats up and down .010 because a roller
is out of round.
>
> Ross
>
>
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