Hey @edf using an SK8 rail would be great for the X & Z. Before you put rails on though check out the mods I created to make it easier to brace the Toolhead and Z: https://forum.snapmaker.com/t/cnc-bracing-for-added-rigidity-other-mods/29444?u=elliot
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Those are pretty good, you should license the design to Snapmaker. If they were to sell aluminum parts with this design I would totally buy them.
I don’t have a reliable 3D printer at the moment. Might look into these as a future upgrade, though I am not too keen on using 3D printed components for the machine itself (too many failures of printed helper objects in the shop, but to be fair those were all PLA).
I see you rotated the touchscreen 90 degrees, which is also on my todo list for when I start drilling the base.
I selected and marked for cutting all of the metal stock this evening. It all came together surprisingly well, but we’ll see what happens once I start actually assembling things. It’s a bit too icy to go wandering to the shop in the dark, so I’ll start the cutting and such tomorrow
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Haha ya that would be awesome to see my parts officially sold by the company as an upgrade. Unfortunately I don’t think that would ever happen as they would be admitting that the machine is not not built adequately.
I was also not to keen on making these parts out of printed plastic and would prefer aluminum but I designed them in a way to maximize the strength and rigidity for 3D printing. The Z-axis roller is reinforced with aluminum bushings and the X-axis (toolhead) is reinforced with through bolts so it is almost as strong as a solid aluminum part.
as for the touch screen I didn’t actual drill a new hole as the single screw seems to hold it in place very well. Can’t wait so see some picture of your completed build!
Still in progress. The metalwork is taking a lot longer than I expected, and I only just this week started working in the machine shop again.
Hope to have it done over the weekend, but here’s a preview. Content warning: I do not shoot videos or photos, generally speaking, nor do I do things purty, so this will likely make the perfectionists out there all sick up a little.
Front. You can see the linear rails for the bed, the thick angle iron that rides on their carriages, and the 3/4x1/2" steel bar to support the front and back edges. Basically, the bar will bolt to the angle iron in a height-adjustable way, and the angle iron will bolt to the carriages.
Back. You can see the two end-caps for the X-axis, as well as the two end-caps for the Y-axis. The SK8 linear rail will bolt to these. To the right are the two aluminum pieces which will attach the Y-axis linear rail to the X-axis end cap. Mounted in place of the toolhead, on the X-axis, is the beefy hunk of aluminum that the linear rail carriage will bolt to. It may not be visible, but I milled a pocket the exact shape of the X-axis linear module carriage (5/16" radius if anyone is interested), so it registers on that nicely. Likewise, the two steel bars have pockets in which the bosses (well, nuts really) underneath the bed register.
So, most of the work is done. Just have to mark mount points for the linear module components, then drill and finally assemble everything. And I might re-do the Y-axis end cap: I’m not pleased with two of the holes.
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I wonder how much weight you’re adding for the system to handle. Any upgrades on bearings inside the rails?
I was concerned about that as well. The bulk of the weight is in the two steel bars, and I have aluminum ones to swap them out for is this proves to be too much. The weight on the Z-axis and Y-axis modules is pretty negligible - less than the carriage mounted to the X-axis, and the modules are interchangeable so they should be able to handle the weight easily. The parts together weigh less than the rotary module, though, so I don’t forsee any problems.
I seem to recall a forum thread which had the specs for the linear modules including how much weight they can handle, but could not find it doing a search. I did see this:
weight limit on snapmaker table
…which suggests 4 kg is safe.
When I next disassemble it (today likely) I’ll update this post with the actual weights.
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The two pieces of thick aluminum angle (now cut to size and drilled) and the 3/4 steel bar (ditto, plus with pockets milled) weigh in at 1.41 kg. Most of that weight is directly over the y-axis support rails, and the additional mass for the carriage shiouldn’t be to touch fr the bearings to handle.
Thanks for sharing,
About 700gr per rail, heavier then I thought it would be, frankly. Plus extra wight - extra energy to move - extra heat in motors.
I wonder with inertia, how much extra force is going to be applied at the start and end of motion. People report sloppy bearings without having the extra mass on them. But yet again, I didn’t see reports like this with the rail mods installed to help support the bearings.
So instead of bracing the bed frame, I wonder if replacing it with solid piece of aluminum would be more beneficial for wight/complexity. Adopting something like - https://www.amazon.com/Gulfcoast-Robotics-235x235mm-Aluminum-Silicone/dp/B08DTCGB6G
And applying the rails of course.
What’s wrong with leaving the rails on the bottom and attaching the sliders to the top?
If this addressed to me, I’m not sure what are you talking about?
I considered the solid aluminum bed as well. That follows the standard procedure, as it were, of bolting the liner rail cerriages directly to the bed, and under this approach it is probably the right thing to do.
My thinking on a design led me to the idea of constructing a metal frame on which the bed rests, and which bolts to the carriages. The frame would have to be fairly substantial (high-mass) along the X-axis as there is limited space, hence the steel. I had to forego the straightforward frame design because of the need for height adjustment (again, due to the limited space over the X axis). One could argue that the steel bars are now unnecessary, but I like having them as insurance against the bed warping during 3DP. EDIT: I forgot to mention that due to the limited space in the enclosure I built for the A350, I cannot have the linear rail mounts directly under the bed corners, which is what necessitated the frame design in the first place. The rails had 4" trimmed off the front and 2" trimmed off the rear, so the carriages are offset that much from the bed corners.
I hadn’t considered heat, because most of my use of the A350 has been 3DP and Laser, neither of which is improved by very fast movement. I’ll have to monitor this under CNC and see if limiting the speed will cause finish problems. Looking forward to using this thing for CNC finally - when I initially saw the rocking of the carriage, I lost all confidence that this machine would do CNC out of the box (but hey, people make it work, what do I know).
Finally drilled the base last night. Waiting for BoltDepot to deliver some on-size metric screws (threading metric on an imperial lathe … not fun) before final assembly. Everything seems good and the heftiness of the bed is, well, rather comforting for somebody who prefers good cast-iron machinery 
I wrote an email to a couple of companies , described the issue we have and provided info on solutions the community came up with.
May be they will be able to produce the bed frame replacement with mount points for the rails. Their custom beds for other printers are made to order anyway.
If there is enough demand I’m sure they would be keen on doing something like this.
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