Seeking a source for milling
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To say I do it every day would be a bit of an overstatement but I do work within these tolerances regularly. It's my vocation. A primary attribute of the cast tooling plate is its lack of internal or sometimes referred to residual stress with other processing methods. There is machine induced stress from localized heat or cold working but it's unlikely especially when taking skim cuts with the appropriate tooling. If I where to true up a piece like this I would tape it down with double sided tape. The main concern would be what actually happens to it at 100c. Probably loose some of the flatness. I have tried hand lapping too. The problem is a humans cant control downward force ( or the lack there of) accurately enough. A pure lateral force is required.
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@fcwilt What do you put on top of the aluminum plate for print adhesion? If you're having problems with flatness, maybe it's that surface (or underlying adhesive) that isn't flat enough, or maybe the XY positioning mechanism is sagging, which can make the plate look like it's bowed. Or maybe whatever the plate is mounted on is deforming when the plate is heated- are you using a kinematic mount for the plate?
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Depending how distorted the plate is to start with, lapping is certainly an option, and inexpensive, if you have access to a sufficiently large known flat surface. The "right way" is to use a granite slab or surface plate, but that's usually not available unless you can "rent" one for a weekend from a shop. That, some sheets of wet/dry sandpaper, water, and a few hours should get you there if it not too far off. It also has the benefit of clearly showing progress as the high points are ground down, and when you're done.
Given the goal though, a variation of the above may be in order. That is, since you support the bed on three points, to make it really flat means that it should be ground when mounted to the same supports. That way, any sagging is accounted for. It also means making a 3-point jig and moving the grinding surface, not the bed.
Zooming out a bit, why is it necessary to reach such perfection for the surface? I understand wanting to make the printer as good as it can be, but at some point, the costs may outweigh the gains. Do you have an estimation of its current distortion? Also, since you're applying a 400-point bed compensation, what does the error end up being then?
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@kb58 said in Seeking a source for milling:
Zooming out a bit, why is it necessary to reach such perfection for the surface?
Because I am somewhat OC and it is satisfying to have a nice flat bed.
Here is one I am satisfied with:
Here is the one that I am not satisfied with:
However it's possible that it is a gantry issue but my ability to measure for that is limited.
I'm still working on it.
Frederick
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@fcwilt said in Seeking a source for milling:
Here is the one that I am not satisfied with:
I print with that one all the time. Nothing a little mesh can't fix.
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@phaedrux said in Seeking a source for milling:
@fcwilt said in Seeking a source for milling:
Here is the one that I am not satisfied with:
I print with that one all the time. Nothing a little mesh can't fix.
I do understand that - it's just my somewhat OC nature makes it unsatisfying and thus I strive for flatter.
But you must admit that first image is pretty nice.
Frederick
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@fcwilt, first image is obscene, second image is about as good as you can expect unless you won the bed plate lottery!
Unfortunately, my beds are nowhere near as nice .... but I can dream -
@jens55 said in Seeking a source for milling:
@fcwilt, first image is obscene, second image is about as good as you can expect unless you won the bed plate lottery!
You must be using "obscene" in a way I am not familiar with.
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@fcwilt .... probably ..... from Merriam-Webster: so excessive as to be offensive
Or put another way ..... <sigh>, I wish I could come even half way close to that .... or "you dog" .... or just <sigh> -
@fcwilt said in Seeking a source for milling:
... However it's possible that it is a gantry issue but my ability to measure for that is limited.
Frederick <
It can be done with a known flat surface. It needs to be propped up at a level approximating the bed position, then do a profile sweep of that. Any deviations from perfection will be gantry deflection. It'll work even if it's not perfectly level, as the profile map might show a tilt, but it should be straight.