It varies too much to say very precisely, but months to a couple years are known. I’m guessing, but only guessing, that the subbase will relieve sooner than later because its cross-section is rather small. If you’ve used the FDM head, each heating cycle for the bed would relieve some stress. The Wikipedia page isn’t very detailed, but it’s a start. I’ll add only that if the casting cools non-uniformly, say if one side cools before the other, or if the edges cool before the middle, that’s a situation for residual stresses in the casting.
I can make a guess about time frame to relieve stress, but I’m going to completely pass on guessing a process temperature. The alloy determines most everything there. It’s some kind of aluminum alloy, but that’s a pretty wide variety. I do know that heating aluminum above a threshold temperature causes it to become brittle and to lose strength, so this isn’t something to guess at.
I don’t know who at SM would be able to comment on the alloy. It’s entirely possible that it varies batch to batch, given what we’ve been able to infer about some of their other contracting practices. And I’m not optimistic that they’d even have records to be able to trace something like that. If you’ve got access to an XRF machine, that’d get you enough data to identify the alloy (or at least get very close).
Yes, Support are sending me one with another linear module as I just had my second one fail, lucky I had a support ticket raised for the bed and was able to add the rail to it.
I was thinking of a way that would help everyone if we could measure the height of each point correctly with the sensor on the 3d Print head, I am working on a minor change so it will work on a glass bed and on Aluminium by touching the surface with a plastic spring moving a metal plate. We could then work out the measurements and then shim the bed.
I haven’t had the time to take my carriage to the shop yet. But I was thinking that we should be able too use the CNC head with a metal cutting bit to surface the attachment points of the carriage while it’s in place.
Thoughts?
With it being aluminum it could work, might be asking for a lot but its a relatively small job so probably doable at least
i dont know if you will be able to lower the head far enough for that, the machine might not like being under the top platform level?
Im not sure if it monitors that or not, it certainly does for 3d printing. perhaps if you had a longer bit, but it would have to be a bigger shank i would imagine
If you go slow enough with .1mm steps.
I didn’t use a waste board with my original SM the first few times. The carbide bit cut nice little grooves in the aluminum bed plate. I’m going to draw up a cut path to see if its doable. I have some 1/4" shank diameter carbide end mills to try with. I also have some small pieces of cast aluminum I can test with.
Biggest “challenge” would be that you’ll push the carriage out of place a lot of the time. If you push down on it on the sides, it doesn’t require a lot of force for it to move down. So if you’re trying to mill it flat, there’s a good chance you’ll just push it out of place.
Likely creating a lot of vibrations too. Possibly rotating the plate one way or another in the process. (so needing realignment after some holes, especially those on the far corners.
Would it work, maybe yes. I would assume you’ll need to use a very small stepdown and multiple passes at the same height. And that might then heat up the frame causing new distortions etc.
I’ve used this in my mounting plate project and can confirm those are correct
If you’re an openscad user you can reuse some of the code to create those cutouts: snapmaker-quickchange-bed/mountingplates.scad at main · brvdboss/snapmaker-quickchange-bed · GitHub lines 186-220 include the layout of those mountingholes. (you’ll need to adjust the diameter of the cut you want to make)
But it might be more convenient to just recreate that layout in Fusio360
I have tried this but not with a mill I used a flat grindigbit like they come with a Dremel.
I wrote a CNC programm to do the job. Test was ok but I am a little bit yellow and stopt it.
But it is doable. Needs many Z Steps at 0,1mm.
Will the CNC do .05mm? Really not concerned with how long it takes but I would like to keep heat to a minimum. Will probably start the cut without the bit over the boss and have it gradually move over it in very thin slices.
I thought this was a variable speed spindle. Is it not?
Yes, or at least attempt to. I have done that kind of step down (0.04mm actually) when experimenting with pcb milling and it works. Don’t know if it’s exact at that point. but it does go down in very small steps
Where is the speed adjustment? Does it have to be hooked via USB or can the speed be set via Luban and saved to the file on a USB?
Do you know the spindle wattage?
What command is the spindle speed and where should I insert it?
Found it. Is the spindle speed code supposed to rpm based (S6000) or percentage based (S50) like on the touchpad?
I haven’t use F360 for CNC yet. I do use it for all my printing though. I am reading up on the CNC functions of it now.
I drew a picture, saved it as an svg, opened it with Luban, sized it, then generated the g-code. I have the g-code open in note++ to add the spindle speed manually. So I’ve added the line S P50 after the M3 line. Is this correct?
Those chip load and Feed/Speed pages are going to come in very handy. Thanks.
If the file is generated by Luban, you most likely have one line like this in it: M3 P100
Change the 100 to the value you want (50-100). That should be enough. M3 P75
That being said, I have the impression you should do a lot more experimenting with the cnc function before you’re trying to mill your carriage. A lot can go wrong, and as someone who was new to cnc as well I can only confirm I did make a lot of silly mistakes and a lot went wrong in my first projects!
It wouldn’t be that difficult to just have your bit run into the module and just going right through the thin metal strip and ruining your module and lead screw in the process by getting some of the parameters wrong. Be careful!, triple check everything, run everything in the air 3 times at different heights before you try for real, wear the protective glasses etc.
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