I want a thick, milled flat, magnetic bed with thermistor ports on both sides. I'm going to explore getting one from https://713maker.com/. Either custom for the E3D Tool Changer or cutting one of their Rail Core beds to size. I have a track saw that cuts aluminum and a router so I could "make it work". There are a lot of parts of this printer that are projects and I was 100% on board for that when I bought it (just like Sanjay said). But the bed is not a thing I can turn into a project. Ultimately, you need a mill with a fly cutter or a surface grinder and I have neither of those tools so I have to sub this out.
If it helps, and ordering more than 1 impacts price per unit, I'd be potentially interested too. I'm running a sticky back magnetic sheet on top of the standard bed at the moment, but it's far from satisfactory.
I will ask them if quantity makes a difference. I am also making the design open so they can offer a bed for sale through their store, if they want to do that. alternately any of you can submit the design tot hem or any other job shop. The CAD only took a couple of hours to do. Design: https://cad.onshape.com/documents/8d39fa86f828e9049e311f0a/w/1b143dfc829362336d52c230/e/cc90854da771fc50efdb384d Extending the lip on the front of the heat bed from ~8mm to 25mm. This should give a slight increase in printable area or just more space for purge/wipers. Front corners of the bed are inset and notched (like the Prusa bed) to allow the build plate to be lifted up easily. Mounting slots are shortened to 1mm inwards from the nominal mounting hole locations. The bed will expand slightly corner to corner (my layman's math say ~0.7mm from 25C to 150C), so 2mm should be enough play. The oversized 4mm holes are retained and there is a countersink so you can use a 3mm socket head cap screw and washer for mounting and that will all fit below the print surface. Thermistor slot in the top of the plate so it is closer to the print surface and therefor more accurate. The nominal build plate dimensions would be: 318 x 233. I don't actually know of any commercial ones that size. I'm using 300x300 plates. Top: Bottom:
@garethky Did you ever hear back from them? I'm interested as well, though I would want the rectangular magnets.
They are being impacted by the covid-19 situation I think. So I bid the job out through Xometry. It was expensive. By the time I have a bed it will probably be 2x what 713 sells them for. But I will have a bed. It will be here later on this month and I will let you know how it works out.
I got my prototype. It was about 2x the cost of one of the 713 Maker beds to have this cut as a 1-off through Xometry. It is MIC-6 tooling plate (same as 713 Maker uses) which is a more expensive material than standard T6 Aluminum, but not THAT much more. Choosing MIC-6 caused the job not to be auto-quotable and the price jumped 4x over the same .step file in T6. When I asked why and offered to alter the design to help bring costs down, Xometry cut the price of the job in half. I chose the cheapest grade of machining with tolerances of +/- 0.005" (0.13mm). The magnets I was able to source had a similar tolerance so I opted to increase all of the magnet pocket dimensions by 0.015" (0.39mm). I didn't want to get a part with the holes too small and have to re-work it by hand. So hats off to 713 Maker, their product looks great and the price is very reasonable from what I can see. Honestly I could have done this cheaper by buying one of their beds and cutting it down to fit the Toolchanger. Magnets: I could not find a cheap supplier of high temp magnets so I opted to get them from McMaster. Those come from China and I have no idea on the supplier but clearly there is a huge markup. Going direct to the source would be a massive cost savings. Initial assessment is that it could use more magnetic force. I can slide the bed around without too much effort. Its stronger than the flat magnetic sheets I was using, but maybe only 1/2 as strong as the Prusa beds. It should work fine in practice. Weight wise this is ~450g heavier than the stock plate + glass bed. Hopefully that's not an issue as the machine should be able to handle a print that involves at least a couple Kg of filament being dropped on the bed. The heater pad adhesive and the magnets max temp is 150C. Realistically this get us all the common filaments, PLA, PETG, ASA/ABS, Nylon and maybe PC. If you want to print ULTEM etc the glass bed is probably right for you. This was expensive and it was something of a learning experience for me using Xometry. If you have a home shop with a mill, you can make your own for a reasonable price using MIC-6 plate. But for most owners that want a magnetic bed I think using a company like 713 Maker that has the supply chain, jigs, fixtures and machines dialed in for this work would be way cheaper.
For those of you looking for a commercial option, Mandala Rose Works is now producing a magnetic bed: https://www.mandalaroseworks.com/shop/home/magbed-for-e3d-toolchanger Also there is a thread here that's trying to get 713 maker to also make one: https://forum.e3d-online.com/threads/magnetic-heated-bed-713maker-style.3923 For my part I'm working on code to probe these beds with an inductive sensor. Turns out that the normal G29 grid based probing can hit the magnets if your grid parameters are not lucky enough to miss them all. Prusa had to tweak their probe positions to fix this in the MK3. We now have enough pieces of software in RRF, an extension and Python to do one better than that. We can probe completely arbitrary points and still build a height map that RRF can use. Probably another week or two before I get all the kinks worked out.
I have one coming as well. My bed is flat-is but not ground like these. I'm interested to see how this "big magnets in the middle" vs "small magnets around the outside" approach works.
I just got mine delivered. It is beefy! Are you planning on just putting this new magnetic bed on top of the E3D bed that has the silicone pad on it or were you going to try and transfer the silicone pad to this new bed? Edit: I just put it on top of E3D original bed. Sorry about the blurred image.
I got mine as well at it looks awesome! I've ordered a 200mm x 300mm, 600W heater pad: https://keenovo.store/collections/s...ate-heatbed-heating-pad?variant=8337135730743 Same as I have on my bed now, works well. China post, will take a few weeks to show up.
I have mine up and running and its great! Those magnets are strong and even with a thin build plate they are keeping it flat. I'm seeing less than 0.2mm variation with a build plate installed, which is fantastic. Without the plate its even lower. Very precise piece of equipment. I've developed an extension for RRF that allows you to probe around the magnets with an inductive probe: https://github.com/garethky/rrf-mesh-level You need a Duet 3 with the Pi attached though so its not as accessible as I would like. I did open a request with the devs to add support for these kinds of beds and I think they are going to do it by skipping probe points, similar to what Prusa's firmware does. I'm using the Panasonic GX-6FB (digikey) probe that is small enough to fit under the tool head where the micro switch is normally. I also modded the Mandala Rose bed to add an additional thermistor on top of the bed (I cut a channel in it with a track saw! ). I also wrote a short script to have the printer wait for the temperature in that thermistor to stabilize before starting the print: https://forum.duet3d.com/topic/21277/wait-for-passive-thermistor-temprature-to-stabilize Stabilize means it doesn't have a specific target temp, it just waits for it to stop climbing and level off. This is something that works on any of the new versions of RRF.
Is anyone interested in a group buy on Texture Coated PEI build sheet for the Toolchanger? I have tried about 6 different suppliers so far and they have all been underwhelming in some way: sheet metal is too thin so it curls up, not enough PEI on the plate, PEI comes off, PETG sticks to the "PEI" etc. So I haven't wanted to recommend a plate yet, but I tried a 300x300 plate on my Voron 2.4 from BD3D Customs: https://bd3dcustoms.com/ The spring steel is thick enough that it doesn't curl up at the edges. There is enough PEI granules on the plate that its fully covered Lots of testing with PETG hasn't shown any lifting of the coating or tendency for PETG to stick. I'm in contact with the owner and they need to order at least 10 plates to make it worth having a custom size of us. Who wants a plate for $35?
Have you tried the energetic 3d ones? I am using their plain smooth PEI one and am happy with it. Was thinking of springing for a powder one from them.
