Of course you can remove the nut. You just roll it onto a correctly sized former.
In fact it's a good idea to do this with the linear slides and ballscrews from china, to give them a wash. While they are greased up and wrapped in plastic, they are often covered in grinding grit which won't help the longevity of your drive system. On Sat, 6 Oct 2018 at 05:10, Chris Albertson <albertson.ch...@gmail.com> wrote: > They are on ebay. Yousearch for "ball screw" and they come up. > > Here is an example: https://www.ebay.com/itm/SFU1204-RM-Rolled-Ball-Screw > < > https://www.ebay.com/itm/SFU1204-RM-Rolled-Ball-Screw-C7-w-1204-Flange-Single-Ball-Nut-End-Machined-CNC/182984364227?hash=item2a9ab7d0c3:m:mRPMtPkRsQJgkW_GJutMw2Q&var=690294923392 > > > Here is another: ebay.com/itm/CNC-SFU1605-Ball-Screw > < > https://www.ebay.com/itm/CNC-SFU1605-Ball-Screw-SET-L300-2000mm-Ballnut-Housing-Coupler-BK-BF12-US/352275520560?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D52885%26meid%3D42d4afe676a5420b9da6da9c19401ec2%26pid%3D100005%26rk%3D5%26rkt%3D12%26sd%3D182984364227%26itm%3D352275520560&_trksid=p2047675.c100005.m1851 > > > > > Notice the number "1204" this means 12mm diameter by 4mm pitch. the other > common size is 1605. > > You can look up there specs on Google by searching for SFU1204 > specification and find the data. When you do yo find that even a 12mm > screw has some inside strength like 1,000 pounds or soothing but that does > not matter the real limit is how fast you can spin the screw before it > "whips". Yo can NEVER remove the nut. So design accordingly. > > the other thing is that the balls are held in compression. there is a > spring inside the nut so there is rolling resistance because the balls are > under load. This is good because it removes backlash but I bet you'd see > balls shooting all over the shop if the nut came off the end. > > The 1204 size is nice because with a normal 400 step motor it you run half > steps the each is exactly 0.005mm and that is good enough for a milling > machine. (works out to two 10ths in US units) > > One more "got-ya" the two "flats" on either side of the nut are not flat it > is a taper. It is good they did this but I did not notice at first. > > On Fri, Oct 5, 2018 at 8:11 AM Dave Cole <linuxcncro...@gmail.com> wrote: > > > Chris, > > > > Do you have a link for these "new style ball screws" ?? > > > > Thanks, Dave > > > > On 10/4/2018 3:33 PM, Chris Albertson 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 > > >> > > > > > > > > > _______________________________________________ > > 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
