Hi, how should I model this kind of thread (see attached video). It is a threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. Roman I have attached 1 file to this email: * Threaded_rod.3gp <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> Size: 41,0 MB Link souborů přes úložiště: Dropbox Link: https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0>

On 5/20/23 11:16, rr156 wrote: > Hi, > > how should I model this kind of thread (see attached video). It is a > threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. > > Roman > > I have attached 1 file to this email: > >  * Threaded_rod.3gp >    <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >    Size: 41,0 MB >    Link souborů přes úložiště: Dropbox >    Link: >    https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 >    <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> Pix not too clear, movie too shaky, looks like a multistart acme thread, how many starts is it? One method that has had fairly wide spread use for precise work like a lathes leadscrew is to slice a piece of acetel in two, clamp it back together and drill a hole thru it aligned with the slice, fit it in a vice so it grips the screw and heat the screw while closing the vise, forming very precise threads that are quite low backlash. Then carefully rewelding it while the screw is still in it to make it one piece again, using a hot air solder wand to supply the welding heat. Helpful to pad the vise jaws with a heat resistant insulator material. I'm printing quite usable 2 start 6mm tooth, 12mm pitch threads for a buttress thread with a .4 nozzle but at 2" diameter that is easy, at 8mm diameter for the screw you are are exceeding what the printer can do well even with a .2mm nozzle. Because my design is 2 start, both half nuts, printed face up, are identical. So I just do it twice in OpenSCAD, translating it for two locations on the printer bed. > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/>

On 5/20/23 12:09, gene heskett wrote: > On 5/20/23 11:16, rr156 wrote: >> Hi, >> >> how should I model this kind of thread (see attached video). It is a >> threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. >> >> Roman >> >> I have attached 1 file to this email: >> >>   * Threaded_rod.3gp >>     <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >>     Size: 41,0 MB >>     Link souborů přes úložiště: Dropbox >>     Link: >>     https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 >>     <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> > > Pix not too clear, movie too shaky, looks like a multistart acme thread, > how many starts is it? > > One method that has had fairly wide spread use for precise work like a > lathes leadscrew is to slice a piece of acetel in two, clamp it back > together and drill a hole thru it aligned with the slice, fit it in a > vice so it grips the screw and heat the screw while closing the vise, > forming very precise threads that are quite low backlash. Then carefully > rewelding it while the screw is still in it to make it one piece again, > using a hot air solder wand to supply the welding heat. Helpful to pad > the vise jaws with a heat resistant insulator material. > > I'm printing quite usable 2 start 6mm tooth, 12mm pitch threads for a > buttress thread with a .4 nozzle but at 2" diameter that is easy, at 8mm > diameter for the screw you are are exceeding what the printer can do > well even with a .2mm nozzle. Because my design is 2 start, both half > nuts, printed face up, are identical. So I just do it twice in OpenSCAD, > translating it for two locations on the printer bed. > > To give an idea how I generate the nuts, I first made a module for the shape of the tooth. And extruded 7 point polygon. Tilted slightly to match the pitch tilt. Then I made a cylinder at the root diameter of a phantom bolt. Then I used two for loops to wrap the tooth around the bolt at 1 degree intervals, 180 degrees apart. Several turns extra Then I added a clearance increase in the size, and rerendered the whole thing, then subtracted that from the form that is the nut. You see that "bolt" in red in this .png. Knowing what my printer can do, this same procedure could model your bolt, but I do not believe it would be printable using FDM tech like my modified sapphire-5. A high res photo-resin printer might do it, sure worth a try. I use PETG for this, but I've no clue as to the wearability of the photo resins such a printer might use. Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/>

I never saw the original message, but if you need a multistart acme threaded rod you could do that with BOSL2. See https://github.com/revarbat/BOSL2/wiki/threading.scad#module-acme_threaded_rod I have printed functioning threads at 1/4-20 size, so 6mm diam and 1.3mm pitch using my FDM prusa, though you wouldn't want to hang heavy weights from such a printed bolt. Printing a truncate bolt sideways may give a stronger result. include<BOSL2-fork/std.scad> include<BOSL2-fork/threading.scad> $fn=48; acme_threaded_rod(length=20, d=8, pitch=2, starts=3); [image: image.png] On Sat, May 20, 2023 at 1:20 PM gene heskett <gheskett@shentel.net> wrote: > On 5/20/23 12:09, gene heskett wrote: > > On 5/20/23 11:16, rr156 wrote: > >> Hi, > >> > >> how should I model this kind of thread (see attached video). It is a > >> threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. > >> > >> Roman > >> > >> I have attached 1 file to this email: > >> > >> * Threaded_rod.3gp > >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> > >> Size: 41,0 MB > >> Link souborů přes úložiště: Dropbox > >> Link: > >> https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 > >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> > > > > Pix not too clear, movie too shaky, looks like a multistart acme thread, > > how many starts is it? > > > > One method that has had fairly wide spread use for precise work like a > > lathes leadscrew is to slice a piece of acetel in two, clamp it back > > together and drill a hole thru it aligned with the slice, fit it in a > > vice so it grips the screw and heat the screw while closing the vise, > > forming very precise threads that are quite low backlash. Then carefully > > rewelding it while the screw is still in it to make it one piece again, > > using a hot air solder wand to supply the welding heat. Helpful to pad > > the vise jaws with a heat resistant insulator material. > > > > I'm printing quite usable 2 start 6mm tooth, 12mm pitch threads for a > > buttress thread with a .4 nozzle but at 2" diameter that is easy, at 8mm > > diameter for the screw you are are exceeding what the printer can do > > well even with a .2mm nozzle. Because my design is 2 start, both half > > nuts, printed face up, are identical. So I just do it twice in OpenSCAD, > > translating it for two locations on the printer bed. > > > > > To give an idea how I generate the nuts, I first made a module for the > shape of the tooth. And extruded 7 point polygon. Tilted slightly to > match the pitch tilt. > > Then I made a cylinder at the root diameter of a phantom bolt. > > Then I used two for loops to wrap the tooth around the bolt at 1 degree > intervals, 180 degrees apart. Several turns extra > > Then I added a clearance increase in the size, and rerendered the whole > thing, then subtracted that from the form that is the nut. You see that > "bolt" in red in this .png. > > Knowing what my printer can do, this same procedure could model your > bolt, but I do not believe it would be printable using FDM tech like my > modified sapphire-5. A high res photo-resin printer might do it, sure > worth a try. I use PETG for this, but I've no clue as to the wearability > of the photo resins such a printer might use. > > Cheers, Gene Heskett. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

Metric trapezoidal threads are not exactly the same as ACME thread. https://en.wikipedia.org/wiki/Trapezoidal_thread_form#Metric_trapezoidal_thread_characteristics ACME uses 29 degree angle between flanks and metric trapezoidal uses 30 degree. I can't be sure from the source video, i'm guessing it is a 4 start. I think the standard way this is denoted is: Tr8x8(P2) Which stands for: (Tr)apezoidal thread, 8mm nominal diameter, 8mm lead (travel per revolution), 2mm (P)itch lead = (# of starts)*pitch On Sat, May 20, 2023 at 2:59 PM Adrian Mariano <avm4@cornell.edu> wrote: > I never saw the original message, but if you need a multistart acme > threaded rod you could do that with BOSL2. See > https://github.com/revarbat/BOSL2/wiki/threading.scad#module-acme_threaded_rod > I have printed functioning threads at 1/4-20 size, so 6mm diam and 1.3mm > pitch using my FDM prusa, though you wouldn't want to hang heavy weights > from such a printed bolt. Printing a truncate bolt sideways may give a > stronger result. > > include<BOSL2-fork/std.scad> > include<BOSL2-fork/threading.scad> > > $fn=48; > > acme_threaded_rod(length=20, d=8, pitch=2, starts=3); > > [image: image.png] > > > On Sat, May 20, 2023 at 1:20 PM gene heskett <gheskett@shentel.net> wrote: > >> On 5/20/23 12:09, gene heskett wrote: >> > On 5/20/23 11:16, rr156 wrote: >> >> Hi, >> >> >> >> how should I model this kind of thread (see attached video). It is a >> >> threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. >> >> >> >> Roman >> >> >> >> I have attached 1 file to this email: >> >> >> >> * Threaded_rod.3gp >> >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >> >> Size: 41,0 MB >> >> Link souborů přes úložiště: Dropbox >> >> Link: >> >> https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 >> >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >> > >> > Pix not too clear, movie too shaky, looks like a multistart acme >> thread, >> > how many starts is it? >> > >> > One method that has had fairly wide spread use for precise work like a >> > lathes leadscrew is to slice a piece of acetel in two, clamp it back >> > together and drill a hole thru it aligned with the slice, fit it in a >> > vice so it grips the screw and heat the screw while closing the vise, >> > forming very precise threads that are quite low backlash. Then >> carefully >> > rewelding it while the screw is still in it to make it one piece again, >> > using a hot air solder wand to supply the welding heat. Helpful to pad >> > the vise jaws with a heat resistant insulator material. >> > >> > I'm printing quite usable 2 start 6mm tooth, 12mm pitch threads for a >> > buttress thread with a .4 nozzle but at 2" diameter that is easy, at >> 8mm >> > diameter for the screw you are are exceeding what the printer can do >> > well even with a .2mm nozzle. Because my design is 2 start, both half >> > nuts, printed face up, are identical. So I just do it twice in >> OpenSCAD, >> > translating it for two locations on the printer bed. >> > >> > >> To give an idea how I generate the nuts, I first made a module for the >> shape of the tooth. And extruded 7 point polygon. Tilted slightly to >> match the pitch tilt. >> >> Then I made a cylinder at the root diameter of a phantom bolt. >> >> Then I used two for loops to wrap the tooth around the bolt at 1 degree >> intervals, 180 degrees apart. Several turns extra >> >> Then I added a clearance increase in the size, and rerendered the whole >> thing, then subtracted that from the form that is the nut. You see that >> "bolt" in red in this .png. >> >> Knowing what my printer can do, this same procedure could model your >> bolt, but I do not believe it would be printable using FDM tech like my >> modified sapphire-5. A high res photo-resin printer might do it, sure >> worth a try. I use PETG for this, but I've no clue as to the wearability >> of the photo resins such a printer might use. >> >> Cheers, Gene Heskett. >> -- >> "There are four boxes to be used in defense of liberty: >> soap, ballot, jury, and ammo. Please use in that order." >> -Ed Howdershelt (Author, 1940) >> If we desire respect for the law, we must first make the law respectable. >> - Louis D. Brandeis >> Genes Web page <http://geneslinuxbox.net:6309/> >> _______________________________________________ >> 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 >

* Threaded_rod.3gp
  <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0>
  Size: 41,0 MB
  Link souborů přes úložiště: Dropbox
  Link:
  https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0
  <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0>

On 5/20/23 19:25, Hans L wrote: > Metric trapezoidal threads are not exactly the same as ACME thread. > https://en.wikipedia.org/wiki/Trapezoidal_thread_form#Metric_trapezoidal_thread_characteristics > ACME uses 29 degree angle between flanks and metric trapezoidal uses 30 > degree. > I can't be sure from the source video, i'm guessing it is a 4 start. > I think the standard way this is denoted is: Tr8x8(P2) > Which stands for: (Tr)apezoidal thread, 8mm nominal diameter, 8mm lead > (travel per revolution), 2mm (P)itch > lead = (# of starts)*pitch > That can be done in OpenSCAD with much the same code idea as I am using for 2 start, but the end result seems like a fdm printer is beyond its limits for good detail. The higher resolution photo resin based stuff might be able to do it though. That's the reason I mentioned the heat molding using acetal, the screw will be perfectly matched and will not have appreciable backlash until its worn by dragging in dirt. One of the reasons I enclosed both ball screws to keep them clean on my Sheldon conversion. Z with bellows on both sides of the nut with an air passage thru the nut, x by sealing up the channel in the cross slide. > > > On Sat, May 20, 2023 at 2:59 PM Adrian Mariano <avm4@cornell.edu> wrote: > >> I never saw the original message, but if you need a multistart acme >> threaded rod you could do that with BOSL2. See >> https://github.com/revarbat/BOSL2/wiki/threading.scad#module-acme_threaded_rod >> I have printed functioning threads at 1/4-20 size, so 6mm diam and 1.3mm >> pitch using my FDM prusa, though you wouldn't want to hang heavy weights >> from such a printed bolt. Printing a truncate bolt sideways may give a >> stronger result. >> >> include<BOSL2-fork/std.scad> >> include<BOSL2-fork/threading.scad> >> >> $fn=48; >> >> acme_threaded_rod(length=20, d=8, pitch=2, starts=3); >> >> [image: image.png] >> >> >> On Sat, May 20, 2023 at 1:20 PM gene heskett <gheskett@shentel.net> wrote: >> >>> On 5/20/23 12:09, gene heskett wrote: >>>> On 5/20/23 11:16, rr156 wrote: >>>>> Hi, >>>>> >>>>> how should I model this kind of thread (see attached video). It is a >>>>> threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. >>>>> >>>>> Roman >>>>> >>>>> I have attached 1 file to this email: >>>>> >>>>> * Threaded_rod.3gp >>>>> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >>>>> Size: 41,0 MB >>>>> Link souborů přes úložiště: Dropbox >>>>> Link: >>>>> https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 >>>>> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >>>> >>>> Pix not too clear, movie too shaky, looks like a multistart acme >>> thread, >>>> how many starts is it? >>>> >>>> One method that has had fairly wide spread use for precise work like a >>>> lathes leadscrew is to slice a piece of acetel in two, clamp it back >>>> together and drill a hole thru it aligned with the slice, fit it in a >>>> vice so it grips the screw and heat the screw while closing the vise, >>>> forming very precise threads that are quite low backlash. Then >>> carefully >>>> rewelding it while the screw is still in it to make it one piece again, >>>> using a hot air solder wand to supply the welding heat. Helpful to pad >>>> the vise jaws with a heat resistant insulator material. >>>> >>>> I'm printing quite usable 2 start 6mm tooth, 12mm pitch threads for a >>>> buttress thread with a .4 nozzle but at 2" diameter that is easy, at >>> 8mm >>>> diameter for the screw you are are exceeding what the printer can do >>>> well even with a .2mm nozzle. Because my design is 2 start, both half >>>> nuts, printed face up, are identical. So I just do it twice in >>> OpenSCAD, >>>> translating it for two locations on the printer bed. >>>> >>>> >>> To give an idea how I generate the nuts, I first made a module for the >>> shape of the tooth. And extruded 7 point polygon. Tilted slightly to >>> match the pitch tilt. >>> >>> Then I made a cylinder at the root diameter of a phantom bolt. >>> >>> Then I used two for loops to wrap the tooth around the bolt at 1 degree >>> intervals, 180 degrees apart. Several turns extra >>> >>> Then I added a clearance increase in the size, and rerendered the whole >>> thing, then subtracted that from the form that is the nut. You see that >>> "bolt" in red in this .png. >>> >>> Knowing what my printer can do, this same procedure could model your >>> bolt, but I do not believe it would be printable using FDM tech like my >>> modified sapphire-5. A high res photo-resin printer might do it, sure >>> worth a try. I use PETG for this, but I've no clue as to the wearability >>> of the photo resins such a printer might use. >>> >>> Cheers, Gene Heskett. >>> -- >>> "There are four boxes to be used in defense of liberty: >>> soap, ballot, jury, and ammo. Please use in that order." >>> -Ed Howdershelt (Author, 1940) >>> If we desire respect for the law, we must first make the law respectable. >>> - Louis D. Brandeis >>> Genes Web page <http://geneslinuxbox.net:6309/> >>> _______________________________________________ >>> 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 >> > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/>

Thank you all for your support and ideas. Roman Dne 20.5.2023 v 17:16 rr156 napsal(a): > Hi, > > how should I model this kind of thread (see attached video). It is a > threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. > > Roman > > I have attached 1 file to this email: > >  * Threaded_rod.3gp > <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >    Size: 41,0 MB >    Link souborů přes úložiště: Dropbox >    Link: >    https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 > <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org

Hi, I have one question please: When I need to screw the acme nut counter-clockwise, is it enough to enter a negative pitch angle or is it more complicated? Roman Dne 22.5.2023 v 10:56 rr156 napsal(a): > Thank you all for your support and ideas. > > Roman > > Dne 20.5.2023 v 17:16 rr156 napsal(a): >> Hi, >> >> how should I model this kind of thread (see attached video). It is a >> threaded rod d = 8 (exactly 7.8) mm, pitch 2 mm. >> >> Roman >> >> I have attached 1 file to this email: >> >>  * Threaded_rod.3gp >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >>    Size: 41,0 MB >>    Link souborů přes úložiště: Dropbox >>    Link: >> https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0 >> <https://www.dropbox.com/s/lctxv4zdrntdsla/Threaded_rod.3gp?dl=0> >> >> >> _______________________________________________ >> 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