Print bed base.
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I can handle the drilling / slotting and such, it is getting the flat surface to a decent tolerance that's proving a struggle. I'm in between some major population centres - Manchester / Leeds but so far I've had a few decline to even quote the work.
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I've put 300x300 mm cast tooling plate beds into 3 printers, all supported on 3 points, and all of them can print edge to edge with no additional milling of the surfaces. You can cut the plate with almost any saw including a hack saw, but a table saw with a carbide blade will do a really good job on it. You can drill it with almost any drill. It's just aluminum...
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@Garfield Quote from the link I gave you " Ecocast is a fine milled and high precision continuous cast aluminium tooling plate".
I can verify that it is more than adequately flat.
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It is cast tooling plate I'm looking at but the supplier is quoting a 0.15mm surface flatness tolerance - which in my book is poor machine shop parctices if they're milling - but that's what they're quoting.
I just asked Aluminium Warehouse and they're quoting 0.5mm as a surface deviation !!!!!!!!
That said I may buy on your recommendation - there are techniques to flatten further but I'm really in no mood to if I don't need to.
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@Garfield I've been on this hunt recently too. Aluminium warehouse seems the go to but including shipping it got expensive quickly. I recently found these guys. They are much more reasonably priced with free shipping up to 500mm. The downside may be that the only thickness they have is 10mm which may be too heavy for you? However, it will be more stable when heated and it also means that it's easier to drill into the side to fit thermocouples or thermal fuses rather than milling slots in the face.
The tolerance they specify is 0.38mm but as someone pointed out to me recently that will be over the whole sheet, not the small cut that we would be after. I would expect significantly better on a small piece.
I haven't ordered yet but likely will.
https://www.zappautomation.co.uk/10mm-aluminium-cast-and-homogenised-tooling-plate.html
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This comment in their text is somewhat concerning ....
"Alloy 5083 also retains exceptional strength after welding. It has the highest strength of the non-heat treatable alloys but is not recommended for use in temperatures in excess of 65 °C."
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I have ordered from here before https://www.clickmetal.co.uk/aluminium-tooling-plate
They state tolerance of 0.1mm, however the sheet of 6mm I got for my delta was very flat.
I have just order 2 plates from Aluminium Warehouse, 5mm ECOCAST 330x330 and 330x400. Both are spot on thickness wise but they were ~2mm larger in width and length.
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Ordered from Click Metal
Not the cheapest but they're quoting 0.1 or better
May buy a surface plate just to satisfy curiosity - run my DTI over the plate - my project budget is well blown anyhow ....
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@Garfield I found Click Metal to have a cleaner cut edge to their plate as well but that's nothing that can't be fixed with a bit of sand paper.
Ha ha budget? I gave up on budgeting for this hobby a long time ago. Dread to think how much I've spent over the 3.5 years I've been at it.
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@Garfield Probably a bit late now but to prove the point with ECOCAST, I dug out this old video from 3 years ago. Admittedly there is 6mm of float glass on top of the aluminium but you'll need some sort of print surface in any case. https://www.youtube.com/watch?v=U733PMTou7M
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Never too late, I've ordered the plate, I will have a Wham Bam setup on top of it so any inaccuracy will get magnified. I'm going to check the surface before anything gets drilled or stuck down.
Might need to relook at my extruder - like your lighting ....
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@Garfield said in Print bed base.:
........................ - like your lighting ....
It's just a circular COB light - Ebay's finest. I think they are also known as "Angle Eyes". That's one of the few things that hasn't changed since I made that video about 3 years ago (that, and the Ecocast plate
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Probably a bit late, but the Australian supplier told me that they start guaranteeing real tolerances in flatness in the thicker sheets, 10mm up.
I bought from Calm Aluminium in Melbourne, and used the 1/4" plate, and it certainly isn't as flat as I'd like.
For a real factory fit I drew it all up in CAD and sent it to the water jet cutters. Cost more but with a Keenovo silicone heat mat under it and Printbite on top I've been very happy with it.
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I got some 6mm and I'll need to go at it a bit I think - put an engineers straight edge across the surface and looked for daylight under it - to the naked eye it is flat but the light tells a different tale.
Anything you put on top of an innacurate surface will magnify the error but this isn't a precision CNC machine so there's no point going mad. That said I want my surface deviation to be less than .1, preferrably much less.
Just need to figure the best way to do this, I've considered scraping or grinding but I've been busy with other aspects of the printer so I'm not really ready for the bed yet.
I'll be putting a wham bam system on mine but a Keenovo underneath, all supported on a Kinematic 3 point mount - constrained but not overconstrained.
Years gone by we would flat a cylinder head on a pane of glass with grinding paste.
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The problem with trying to make aluminum flat is that there is tension in the part causing it to be not flat. Removing material doesn't necessarily remove the tension evenly, IE you'll end up with a part warped in a slightly different manner.
I've been down that road before. I tried to lap a piece of aluminum flat -- it had a bow along the long axis. So I lapped and lapped and lapped until there was no more bow in the long axis, but a definite curve now on the short axis.
Cast aluminum is much better, but there is a reason it's not flat in the first place, and a reason they have a flatness spec of 0.15 mm. It's the truth.
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@Garfield In the past, I've thought about doing the final tramming and flatness by fitting some sort of abrasive to the print head carriage so that the printer laps it's own bed flat. Obviously, you'd need to start with the bed as level as possible and a nice rigid frame and rails. Thought about it but never tried it.......
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Yup - and then you add heat and aren't patient enough to let it equalise - hotter one side than the other = guaranteed bow.
The expansion in my bed at 90 Deg C will be 0.46mm in X and Y and .01 in the Z dimensions - that's why I'm using a Kinematic mount.
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@Garfield said in Print bed base.:
Yup - and then you add heat and aren't patient enough to let it equalise - hotter one side than the other = guaranteed bow.
One property of aluminium is that the hotter it gets, the better it becomes at conducting heat. Which means that it's very unlikely to get hotter one side than the other. Which is another reason why it is such a good material to use for a print bed. But of course if you use a very thin plate, and/or apply a lot of heat, and/or constrain the plate against thermal expansion, then anything can happen. Personally, I don't have any problems with my bed. The only time I check the level is when I transport the printer to a show, and I never use mesh or any other form of flatness compensation. Which is why my idea of using the printer itself to lap the bed flat never got any further than being an idea.
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I can recommend the website www.aluminyumburada.com for aluminium tooling plates / print bed base. Their unit price is cheaper than clickmetal, but their shipping prices higher since they are based in Turkey. So depending on where you are, this could be an interesting option. This is essentially the same product as Ecocast.
