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
