Have you seen the new style ball screws? They are now cheaper then belts and have pretty "over kill" specs.
The problem with a 30mm wide belt drive is the need to resist the belt tension and a way to adjust it. Not only the tension between the two pulleys but there is side load on the motor shaft unless you use a flexible coupler and ball bearings on both sides of the drive pulley. The lead screw is mechanically simpler because the motor can be directly coupled to the screw and for $70 you get all the end blocks and mounting hardware. These have made router design nearly a "screw driver only" project. No design to even much thinking needed. I bought one for the vertical axis of a CNC milling machine and I can set there is zero backlash and not adjust needed or the life of the machine. Cost me about $35. A screw give the drive motor a larger mechanical deduction and you can likely skip the need for a reduction stage. A screw might advance the axis 4mm per revolution but a belt drive moves maybe 30 to 36mm per rev. You get more force the resolution with a 4mm pitch ball screw. You can make a one meter square X,Y router base or laser cutter today using two pair of supported rails and two screws for under $250 plus the motors and your z-axis. On Thu, Oct 4, 2018 at 11:41 AM Roland Jollivet <roland.jolli...@gmail.com> wrote: > The idea of using belts, and gearboxes, and rack and pinions, sounds like a > bad recipe. > > While I did suggest a bar across the gantry, the problem is that you're > carrying all those gears, and the motor. > I drew a quick concept sketch of how I would do it. Buy cut-to-length belt, > probably HTD M5 x 30mm wide for your application. > > I think this would be quite adequate for a wood router. At the far end of > the table, connect the two idler pulleys with a shaft too. Obviously all > the pulleys and motors will be below the table height. > > And; > - motor is no longer on the gantry > - no skew can happen > - easy to get your drive ratio > - single motor > > http://imgbox.com/ccZJF5nH > > > > On Thu, 4 Oct 2018 at 17:41, Leonardo Marsaglia <ldmarsag...@gmail.com> > wrote: > > > Hello Les, > > > > No, I plan to support 50 mm bars every 600 mm more or less. I'm attaching > > some pictures of the design I'm working on. (The adjustable stands for > > levelling are not in the assembly because I'm saving resources on this > > laptop) > > > > I like the idea of using the rectangular ways but unfortunately they are > > quite expensive for this project and also there's the aligning problem. > > With the setup I'm trying to do I can adjust the parallelism on every > > corner of the machine and also individually adjust every suport to level > > the guides perfectly. I'm sending pictures of everything to clarify what > > I'm intending to do. Please note this is under development and some > things > > are going to change a little bit. > > > > The idea of welding the frame is out of discussion because I plan to move > > and set up this thing in place. Also, I don't have the means to > guarantee a > > clean and squared welding for the frame. Instead I decided to do what you > > can see in the pictures, having an enormous amount of bolts to keep the > > parts rigid and firm. > > > > No problem about using tubing to lower the inertia. I also thought about > > reducing the 3000 max RPM with the worm and gear to 100 RPM on the shaft > > and then increase the size of the pinions to have the linear speed I > want. > > This way the long shaft doesn't have to withstand the high RPMs. > > > > I uploaded the pictures because the list doesn't allow me to attach them. > > Here's the link: > > > > https://imgur.com/a/7kLUWsq > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
