Hey guys, still doing my research before buying, and one overall problem I’ve read about with ALL gantry style CNC routers is harmonics and general resonance. I’m dead set on a Shapeoko 3 XXL and had a sort of wild idea.
Has anyone tried (or thought to) filling the hollow frame / gantry pieces with expanding foam insulation? It’s cheap, it’s light, and would deaden a good bit of vibration.
Probably not necessary and probably wouldn’t do anything, but was something I sort of dreamed up.
I have no idea whether or not this would bring any noticeable change in vibration level, but I cannot see any drawback to doing this, general stiffness can only be improved (even if only by a tiny amount), and since I will soon disassemble my machine to install a new bed anyway, I think I’ll give it a try !
That was kind of my thought. Let me know what you think! May make it quieter if nothing else.
I believe this was discussed back in the SO1/2 days, but the idea was to use epoxy or cement I think it was.
I don’t think foam has anywhere near the density to matter in a meaningful way — maybe a high density sort — calculate out the volume of the interior, then determine the weight of that volume of foam, then compare that to the mass of the steel plates and wasteboard and rails. I’d be surprised if it isn’t a very great difference, possibly enough to make the foam seem inconsequential.
Before foaming everything up(not withstanding that it probably won’t hurt anything), I would want to narrow the perceived problem, and run the machine bare and add necessary items/steps until I clearly defined the thing(s) causing the problem. Then address the specifics of that problem.
If I were going to try to alter the harmonics of a machine with several moving masses, I would be considering adding mass, and maybe more important, what that additional mass would do to the rest of the system, transient response, Stepper load, belt stretch, Vwheel distortion, etc…
Having said that, There is always the pull of discovering Carbides version of teflon!
Long story short, I was doing some Pd’D research and found that a lot of machines use concrete (inside base castings) to add dampening to their products. So that’s my vote. (But that’s going to be tough on those little motors (acceleration and deceleration))
Yeah, just doing the Y-axis (non-moving) makes a lot of sense. Also, I think there was at least one epoxy pour of a wasteboard area, and another person who poured concrete as their tabletop and mounted the machine solidly to that.
The X-axis might require more powerful Y-axis motors.
A, I am stoked at these responses already!
B, I know concrete or just straight weight and generally dense and inert material (sand, lead shot, etc) is best but with the consumer nature of the machine and the motors, while beefy and best in it’s class already, there’s no way they’re holding up to that weight.
I want to do a good bit of aluminium and I’m considering all the vibration that will impart into the gantry, so wanting to minimize vibes (and therefore resonance and chatter) I was just thinking of something to deaden an aluminum extrusion. A high density foam insulation, or some sort of aerated silicone I think would be a good solution.
That said, as was already stated, maybe I am trying to solve a non-issue or answering an un-asked question?
Keep these ideas coming!
The products used to quiet steel panels on cars (for car audio enthusiasts) are pretty effective. They’re surprisingly heavy, too, for material that is 1/8" or so thick.
Application would be pretty straight-forward I think in that you’re just cutting rectangles, removing the self-adhesive backing, sliding it into the extrusion, then applying it to one of the four surfaces.
For that matter, the same material could also be applied to the OUTSIDE of the extrusions, if one keeps clear of the surfaces where wheels ride.
I’m not sure any of this actually makes sense on this level of machine, though. It seems like I can hold .001" pretty easily, not much more. I don’t think I’m going to make the jump to tenths by reducing vibration.
Thanks for those words! Made my day!
I know this is no Haas and I know I’m not chasing tenths, but just an exercise in “what if”
I am currently deployed so won’t be buying my machine for a good 8 months or so, but unless someone gets to it before me, or convinces me not to, I think a weighted table combined with sand or concrete in the two stationary rails and foam or some other vibe deadener in the moving rail is what I’m gonna try.
Only thinking sand over concrete cause I can remove it easier, but other than moving the machine, I can’t see a good reason not to try improving it.
Love these ideas and thoughts everyone! Someone go try it and convince me otherwise?
Different industry, but reminded me of Honda’s new dual sport motorcycle, with a urethane-filled swingarm to reduce vibration. Also used for motor mounts I believe and seems accessible to get in liquid form for curing into form.
All good ideas. When I was machining we used bags with lead shot to dampen the resonating vibrations . Like the previous post mentioning sand. It is a good start. Worked for us 20 years ago.
Yeah, I sort of had the idea from an old Ford commercial with their “silent steel” frame. Just makes sense.
The research continues…
this guy spent some effort doing a frame from scratch;
i’d look into his concoction
Oh that is exactly what i was looking for! i am not sure i will go quite as crazy, but i will be playing with something like that. great find. thanks!
Depending on the epoxy or concrete mix used, how would you plan on keeping it straight and negating issues with heat when curing?
I am not sure how much it would actually be an issue? Im sure it depends on the type of epoxy, but i dont feel most of those epoxies are extremely exothermic when drying, and i think the sand filler and rigidity of the aluminum extrusion would probably negate any issues.
…that said…who knows. could be a huge problem?
Was thinking about this, and I think a sand-fill would be a) easy b) fairly effective c) probably not require any significant changes to the machine.
Certainly no stepper changes for filling the Y rails. -MAYBE- a change in steppers if you fill the X axis, but I wouldn’t just assume so. If you fill with sand, it’s very easy to undo if it’s too heavy. I suspect it’ll be fine.
My only two concerns with JUST sand are a, moisture…youd have to like bake the sand to make sure its dry, and then hope it doesnt collect moisture, and b, keeping it in the frame. I dont know how well the frame seals to the end plates, but either filling the ends with silicon as a barrier, or something to that effect might be required just to keep sand from leaking out…thats where that epoxy mix sounds appealing. all that said…i think sand would do an awesome job.