The OP said the table is 3.8m long....
On Thu, 4 Oct 2018 at 21:35, Chris Albertson <albertson.ch...@gmail.com> wrote: > 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 > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
