Hello Dave, Well, to avoid the backlash is that or may be using timing belts and pulleys to drive the shaft too. The gearbox is a good idea but I think that can raise the cost too much. Anyway I'll give it a look because I don't want to discard any option.
In any case I'm still not sure about wheter use two motors or one motor with a shaft. The latter option makes me feel more secure because it can't go out of squaress easily, unless you have loose belt or something breaks. By the way I just re send another message that was rejected by the list because of the size of the pictures, I don't know if now you can see it. El jue., 4 oct. 2018 a las 12:04, Leonardo Marsaglia (<ldmarsag...@gmail.com>) escribió: > 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. > > (Second attempt to attach the pictures) > > El jue., 4 oct. 2018 a las 12:00, Dave Cole (<linuxcncro...@gmail.com>) > escribió: > >> I'd avoid a worm gear drive. They are prone to wear and backlash. >> I'd look for a good deal on a servo grade planetary 10:1 gearbox that >> fits your Chinese motor. >> Probably the easiest and most rigid drive solution is to use two motors >> each with a planetary gear box and direct drive a pinion on a rack. >> If you want to mill aluminum and need rigidity, that's the way I would go. >> You might want to weld the frame in sections and then bolt it together. >> If you don't have a platen to weld it on, you might want to contract out >> part of the frame welding. >> >> Dave >> >> On 10/4/2018 10:41 AM, Leonardo Marsaglia wrote: >> > By the way, on the pictures there are missing details I didn't draw yet, >> > like setscrews for parallel regulation and things like that. Also, I >> have >> > yet to modify the design for the one motor and shaft approach and see >> wich >> > is better. >> > >> > El jue., 4 oct. 2018 a las 11:37, Leonardo Marsaglia (< >> ldmarsag...@gmail.com>) >> > escribió: >> > >> >> 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. >> >> >> >> Let me know if you can see the pictures. >> >> >> >> >> >> >> >> El jue., 4 oct. 2018 a las 10:52, Les Newell (< >> les.new...@fastmail.co.uk>) >> >> escribió: >> >> >> >>> Using two motors is mechanically simpler and has lower rotational >> >>> inertia but I am not a fan of this setup. If you use a tube rather >> than >> >>> a solid shaft, you won't add a lot of inertia. I'm thinking of >> building >> >>> another plasma cutter and it will probably use a shaft rather than 2 >> >>> motors. >> >>> >> >>>> But the thing is, I'm planning to use round guides >> >>>> with bronze adjustable bearings. >> >>> Do you mean guides that are only supported at the ends? This is a very >> >>> bad idea. They'll flex and bounce all over the place. You are also >> >>> likely to get a lot of wear unless you pressure feed lubricant. If you >> >>> do that oil will go everywhere. My router uses box ways on the Y and Z >> >>> axes with oil feed. It gets pretty messy at times. >> >>> >> >>> Most modern commercial routers and many machining centres use >> >>> rectangular linear ways, such as this >> >>> < >> >>> >> https://www.qualitybearingsonline.com/lwl25r240bhs2-iko-maintenance-free-linear-guide-rail/ >> >. >> >>> >> >>> They are very rigid and lasts a long time with very little wear. The >> >>> only disadvantage is that you need to be careful to make sure >> everything >> >>> is perfectly aligned. These have very little give in them. Another >> >>> option is supported round rail such as this >> >>> < >> >>> >> https://www.amazon.co.uk/TEN-HIGH-Supported-SBR40UU-BlockBearing-Bearing/dp/B01N10JF5N >> >. >> >>> >> >>> For the sort of size machine you are talking about you'll need at >> least >> >>> 40mm round rail. Round rails wear faster than rectangular but are a >> lot >> >>> less fussy about alignment. >> >>> >> >>>> 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. >> >>> To give you an idea about motor sizing the motors on my router (1 per >> >>> axis) are about 1.8kw and it's scary. My tool changer is mounted on a >> >>> bracket made from 50mmx50mm box section. I messed up the tool change >> >>> sequencing a while back and it pushed the tool changer out of the way >> >>> without breaking a sweat. It tool a lot of effort with big levers to >> >>> twist it straight again. Here is a link to a similar machine to mine >> but >> >>> without a tool changer >> >>> < >> >>> >> https://www.bidspotter.co.uk/en-gb/auction-catalogues/cjm-asset/catalogue-id-cjm10389/lot-47df49af-bf1a-4676-ab88-a75a00f5f92b >> >. >> >>> >> >>> Lots of heavy steel and cast iron. Mine originally had 4 drill heads >> and >> >>> 2 spindles. If it was easy to dial back the power I would. If >> something >> >>> goes wrong the machine will keep pushing until something breaks. >> >>> >> >>> I do maintenance work on a router with 750W motors. A while back the >> >>> spindle stalled while it was cutting. It bent the 1/2" cutter nearly >> 90 >> >>> degrees and carried on. >> >>> >> >>> Les >> >>> >> >>> On 04/10/2018 13:47, Leonardo Marsaglia wrote: >> >>>> 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 >> >>>> >> >>>> >> >>> >> >>> >> >>> _______________________________________________ >> >>> 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 >> >> >> _______________________________________________ >> 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
