Note sure what type of z axis you have one microstep is typically a lot less than 0.04mm. With just x16 microstepping and a typical 200 step motor you get 3200 microsteps. It is preferable to step in multiples of whole steps to get better accuracy but even then 200 x 0.04 would imply a lead screw with an 8mm pitch, which is extreme. On Mon, 19 Jun 2023 at 09:22, Roger Whiteley via Discuss < discuss@lists.openscad.org> wrote: > > > > ---------- Forwarded message ---------- > From: Roger Whiteley <roger.whiteley@me.com> > To: discuss@lists.openscad.org > Cc: > Bcc: > Date: Mon, 19 Jun 2023 09:21:29 +0100 > Subject: [OpenSCAD] Re: Nut needed for nutless pot > One thing you could do to help the self tapping process is to make the > hole tapered to help with a ‘lead in’. > > If you try printing a small pitch thread, make your layer height 0.04mm > (one micro step) or multiples of 0.04, setting the layer height to > arbitrary values other than a multiple of 0.04 asks the Z stepper to do > things it cannot do - rotate to angles that it’s not designed to do. > > Roger. Sent from my iPhone 6 > > > ---------- Forwarded message ---------- > From: Roger Whiteley via Discuss <discuss@lists.openscad.org> > To: discuss@lists.openscad.org > Cc: Roger Whiteley <roger.whiteley@me.com> > Bcc: > Date: Mon, 19 Jun 2023 09:21:29 +0100 > Subject: [OpenSCAD] Re: Nut needed for nutless pot > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

Roger. 

On Mon, Jun 19, 2023 at 09:38:02AM +0100, nop head wrote: > Note sure what type of z axis you have one microstep is typically a lot > less than 0.04mm. With just x16 microstepping and a typical 200 step motor > you get 3200 microsteps. > > It is preferable to step in multiples of whole steps to get better accuracy > but even then 200 x 0.04 would imply a lead screw with an 8mm pitch, which > is extreme. Right. You need to figure out the pitch of /your/ Z-screw and then do the math for say 400 half-steps. The positioning on microsteps is not 100% accurate. Along a cycle (4 fullsteps) the rotor might lead or lag a bit compared to the line between the two endpoints. If your pich is say 4mm, you can calculate an "accurate layer height" of 4mm/revolution / 400 steps per revolution = 0.01mm. Roger. > On Mon, 19 Jun 2023 at 09:22, Roger Whiteley via Discuss < > discuss@lists.openscad.org> wrote: > > > > > > > > > ---------- Forwarded message ---------- > > From: Roger Whiteley <roger.whiteley@me.com> > > To: discuss@lists.openscad.org > > Cc: > > Bcc: > > Date: Mon, 19 Jun 2023 09:21:29 +0100 > > Subject: [OpenSCAD] Re: Nut needed for nutless pot > > One thing you could do to help the self tapping process is to make the > > hole tapered to help with a ‘lead in’. > > > > If you try printing a small pitch thread, make your layer height 0.04mm > > (one micro step) or multiples of 0.04, setting the layer height to > > arbitrary values other than a multiple of 0.04 asks the Z stepper to do > > things it cannot do - rotate to angles that it’s not designed to do. > > > > Roger. Sent from my iPhone 6 > > > > > > ---------- Forwarded message ---------- > > From: Roger Whiteley via Discuss <discuss@lists.openscad.org> > > To: discuss@lists.openscad.org > > Cc: Roger Whiteley <roger.whiteley@me.com> > > Bcc: > > Date: Mon, 19 Jun 2023 09:21:29 +0100 > > Subject: [OpenSCAD] Re: Nut needed for nutless pot > > _______________________________________________ > > OpenSCAD mailing list > > To unsubscribe send an email to discuss-leave@lists.openscad.org > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org -- ** R.E.Wolff@BitWizard.nl ** https://www.BitWizard.nl/ ** +31-15-2049110 ** ** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 ** f equals m times a. When your f is steady, and your m is going down your a is going up. -- Chris Hadfield about flying up the space shuttle.