It’s all off of Amazon and I have prime.
I also took a second look at the CNC on my workbench. It’s using NEMA23’s throughout. I’m thinking the NEMA34’s night not be necessary afterall. That would lower the cost about $200.
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Screwed around in Fusion 360 today to get an idea of what this might look like. Decided to take a look at 8020 extrusion. It’s not “too” terribly expensive.
Fusion makes it pretty easy to grab CAD drawings and throw together a design. It’s pretty much your typical cartesian style machine. Main Spoilboard is 3/4" MDF. I’d have a second spoilboard bolted to the top of this one. Total cut size would be 1400mm x 1000mm (55" x 39"). Right now I have the z height at about 1.75" (sorry for the mixed measurements), but would probably adjust it to get about a 2.5".
Total pricing including the 2.2kw water cooled spindle, NEMA23 steppers and drivers (but not all the M5 and 1/4-20 bolts or shipping) is ~$2400. You’d still need some way of getting the signal to the drivers.
I still need to design some adapters to bolt the 20UU rails and ball-screw mounts to the 8020 extrusion. That should just be some 1/4" steel plates, though and I don’t want to design those until I have some of the parts in my hand to verify/validate the amazon parts match the ones pulled in by Fusion.
I also need to figure out how I’d attach the pre-made Z axis to the ball screw on the back of the gantry. (more design as I go stuff)
I think I’ll probably start collecting parts while working on the next project so that I can jump in to this one later this spring.
back
front
bottom with spoilboard removed to show rails.
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I have some of those rails you have on the Y axis, and they have a pretty nasty dip built in. I tried to loosen and shim them and the screw stripped out. I got like 6-8 of them and I held them rail to rail and didn’t find any that were particularly straight. Probably and straight as a linear rail bolted to extrusion but you might want to start there and see if you have better luck.
Thanks for the heads up. I keep going back and forth between using the 20uu vs linear rails on the Y axis.
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ME too. For those prices I think people expect more accuracy. You will surely get more speed/rigidity, but if you have a wobble in the rails it will always be there. A little easier to dismiss at $500 and conduit based. But I am not sure, this is one of those things I am always up against.
So if you do, please give a mpcnc to new lr build plan 
Oops that was to Ryan’s comment:
Bitter sweet, cool that you got to mess around with it a bit though. Hopefully I can come up with a new LR…but if the ideas don’t work out I will revise the current one. So hopefully there will be a new LR of some sort in Jan-Feb? So save some space for that, don’t build anything new until then
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I keep going back and forth between the 20u rails or linear rails. One thing I like about the linear rails is that they can mount to the extrusion easier than the 20u ones. I think I’ll end up with those for both x and y axis.
I thought the 20UU slides were going to be awesome, but The straightness is one factor, but really the ones I got were just as cruddy as the lm8uu bearings started to be. Kinda choppy, cheap plastic inserts, just didn’t seem worth it.
The MGN style rails have been pretty good. The worst I had was a couple with poorly tapped threaded holes. I chased them out with a bottoming M3 tap and they were fine. They are dead simple to mount to the extrusions as well M3x8, done.
I am thinking the new LR might use them for the Z instead of the tubes. That will mean less unique parts between sizes and not real possibility of rocking.
My experiences are not very through, though. You might want to grab one of the SBR rails and just see what you think. Turns out some of the sizes have mounting holes the right width for double or triple extrusions. They might be awesome if you get some decent ones.
The 20u rails line up with the size 40 8020, but that extrusion is pretty expensive. I’m trying to stick with the size 25 extrusion.
I’m looking at using 20mm hgr rails. Amazon has the rails with a ball screw for a really good price. I’d just need to get a second ball screw for the Y axis. The combo comes with a 1605 ballscrew and I was considering 1610 for quicker rapids. I was also thinking 2010 ballscrew for the x axis to reduce any flex in the screw.
So many choices, but I have plenty of time to decide.
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Alright. I ordered the hgr linear rails. I also made a design change. I’m going to build a 1500x1500 machine. This should allow me to put 4’x4’ stock on the machine to cut.
I went ahead and ordered the rails because a lot of the other design decisions are based on the rails themselves.
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Rails arrived. Good news is, nothing looks bent.
Still can’t decide if I want to do a welded steel frame or 8020.
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Last of the expensive parts showed up today. Now I can take measurements and start really designing something.
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Monster, wow!
Did you ever get this machine together and running?
Nope.
Collected a few more parts for it, but that’s about it. I keep waffling on what to make it out of. Part of me wants to use extruded aluminum. Part of me wants to weld something.
I think part of the problem is I don’t have defined end goals for what it is I really want to do with it.
The other issue is, I’ve been doing a lot of non-shop stuff this year. We picked up a travel trailer and have been using that a bunch. I also finally finished re-painting one of my Harleys, which took me a few months. I can’t really do anything else in the shop while I’m painting as the paint booth takes up a good portion of the middle of the shop.
I have a few more projects that the wife wants that I need to do, but I’m sure when it starts to get cold outside I’ll start playing with this more again.
Another excuse is that I really haven’t had a need for a CNC this year. I don’t think I’ve even ran the MPCNC since last winter. I did one or two laser projects this year, but that’s been it.
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When the goal becomes clear, you’ll be able to decide on a path to get there. There are no deadlines in hobby land (I wish).