Beginners screws ( was ACME ( was Re: leadscrew,

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "alex" <telecomt@t...> wrote:

> 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
>

I'm not sure of your distance. are you using a lead screw ? sounds
like one revolution is 400 steps for your 2" OD.

and yes, you will have better resolution if you use a microstep drive.
but you will have better resolution and more power if you change the
gearing to a 2:1 or 10:1 ratio.

Dave

> ----- Original Message -----
> From: Ross <rrcarl@n...>
> 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
> >
> >
> > Addresses:
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