For a CNC router used primarily for wood and some aluminum I would not consider anything other than a profile linear bearing such as these for the ways. https://www.ebay.com/itm/2-sets-HGR25-2000mm-Hiwin-Liner-rail-4-pcs-HGH25CA-Block-Bearing/142629148212?hash=item21355c1634:g:AP0AAOSwfGdbRtAw
I don’t think 1kw is over kill for a wood router especially if you are only using one to move the gantry. Wood routers need to move pretty fast, and having too low acceleration can be a big problem. Also don’t skimp on the spindle, 5kw minimum and 8-12kw is nice. (Unless your just building a light duty wood carver, which it doesn't sound like you are.) Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: Leonardo Marsaglia <ldmarsag...@gmail.com> Sent: Thursday, October 04, 2018 8:47 AM To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Yet another topic about gantry homing First of all, thank you guys for your advices as always! I'm gonna try an asnwer this on one message because sadly gmail doesn't have the quote selected text feature anymore. About the oversized motors. Yes, I also think that for a normal router 1 kw per side is too much. But the thing is, I'm planning to use round guides with bronze adjustable bearings. I decided this because I want more rigidity for an eventual need of machining aluminum, and also because I think this kind of guides with whipers are much more reliable than the recirculating ball ones. Also, I don't think I can have the adjustable feature with the slotted ball bearings. I'm attaching a picture of the bearing I plan to make, there are no lube channels on the model but they will be on the final part. So, to sum up, with these kind of bearings I expect more resistance on the joints, and also the router is 2 meters x 3,8 meters long so to have enough rigidity I'm planning to use steel and cast iron, so that's why I'm oversizing the motors. Besides, there's no much difference between a 400W and a 1Kw chinese servo motor and drive on ebay. About how to drive and home the gantry. From what we've been talking and thinking it through a little more, I'm thinking that the best solution is the one Gregg suggested. To have a transversal shaft on the gantry driven by the servo motor by a worm and gear reduction with the timing pulleys on each end of the shaft driving the pinions. This way I can adjust and square the two columns and it should stay squared at any time. This is really important because this is going to be used by a regular operator, so this has to be as reliable and fail proof as possible. About the last question. Is there any disadvantage other than may be a little more mechanical complexity with the one motor and shaft approach? Because I've seen lots of routers driven with two motors that I almost think it's mandatory for some reason. Thanks again! Leonardo El jue., 4 oct. 2018 a las 0:03, Gregg Eshelman via Emc-users (< emc-users@lists.sourceforge.net>) escribió: > The easiest method is mechanically connect the two sides with a shaft > along the gantry and use one motor. Then it *cannot rack* or have any > of the other issues that can happen with driving both sides of a > constrained axis with two motors. > If you need more Z height, you can elevate the racks on the sides. Or > run chains or belts from the cross shaft ends down to stub shafts with > the pinion gears. > > On Wednesday, October 3, 2018, 4:03:48 AM MDT, Leonardo Marsaglia > < ldmarsag...@gmail.com> wrote: > > Hello to all! > <clip> > > About how to drive both Y joints as one axis: I've read that there's a > way of simply adding two Y joints for the Y axis in the 2.8 master > branch but I don't know if there's documentation available already. > _______________________________________________ > 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
