Aluminium bed upgrade.

So, I'm looking to upgrade my heated bed. Like most, I've started with a mk3 pcb heated bed with glass on top. It's great for PLA, rubbish for...everything else.
Whilst I'm at it, I thought, why not upgrade everything on the Y axis? I'm looking to make this an upgrade in almost every possible way, power, weight, accuracy etc. So, in the spirit of discussion i thought I'd make this thread and throw some ideas around.

So what have I got now? Its a mk3 heat bed, 2.5mm aluminium spreader, 4mm toughened glass, Printbite surface and a 3mm milled aluminium mounting plate (bought from openbuilds) on v-slot wheels. The wheels run in 2080 extrusion, 20 tooth pulley + gt2 belt on a 1.8deg nema17. This bed moves in the Y axis. All in all, I reckon this weighs around 1.2kg's.

So, my initial thoughts are to use extrusion instead of a mounting plate for the larger custom size. This will then be topped with a 5mm aluminium tooling plate. V slot extrusion weighs 458grams per meter. I may use cheaper extrusion as I don't need the v-track here, but its weight should be roughly similar. I'm thinking a frame such as---




This should weigh in around 450grams. And then an aluminium plate on top, + leveling screws. Interestingly The tooling plate only weighs slightly more than toughened glass of the same thickness. 300x300x5mm piece of aluminium should weigh around 1.2kg's. I'm thinking of going for a 240v mains powered silicone heater for this, and that should weigh maybe 200g? So all in all, 1.85kgs. Not bad really, considering the original bed weighs 1.2kg. Although, I feel like there may be some weight to be shaved off...

Any ideas for improvement of the design, or improvements in other areas, feel free to chime in.

Edited 1 time(s). Last edit at 07/06/2016 02:56PM by Origamib.

No comments? Would be interested to know peoples thoughts on 5mm tooling plate, will it be thick enough?

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Origamib
No comments? Would be interested to know peoples thoughts on 5mm tooling plate, will it be thick enough?

As you have invited comments, here is my twopence worth. Personally, I don't like the fact that you have effectively one linear guide in the centre of the bed. Admittedly it's 80mm wide but with a 300mm bed, you have a lot hanging over each side. I'd go for two parallel 2020 vslot, close to the sides. 2 lengths 2020 will be less weight than 1 length 2080 too. Have you thought about insulation under the bed? If it's moving in Y, you ought to try and keep the weight as low as possible. For bed heater, the consensus of opinion seems to be about 0.4 to 0.45W/cm^2. So for a 30 x 30 bed you'll need around 360 to 400 Watts. At 12v that's around 33 Amps, at 24V its around 17 amps and at 240v it's only about 1.7 amps. However, if you go for 240v you need to be very careful with your wiring if the bed is moving in Y.

Also, and this is just a personal thing, I like have 2 or 3 removable glass print surfaces as it enables me to start another print as soon as one job has finished without waiting for it to cool down. Aluminium is also quite soft and easily damaged and if its tooling plate, it can be expensive to replace. If it were me, I'd probably go with 4mm aluminium heat spread plus 4mm glass. If you don't want to use glass then I think you should consider 8mm aluminium.

That's just my personal opinion. What usually happens is that there will now be flurry of posts disagreeing with everything I have just said, so at least you should get some more responses.

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Origamib
So, I'm looking to upgrade my heated bed. Like most, I've started with a mk3 pcb heated bed with glass on top. It's great for PLA, rubbish for...everything else.

If the only issue you are having with it is that it can't reach higher temperatures fast enough, then there is a simpler solution: increase the voltage to the bed heater. But I guess you want to increase the print areas as well.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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deckingman

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Origamib
No comments? Would be interested to know peoples thoughts on 5mm tooling plate, will it be thick enough?

As you have invited comments, here is my twopence worth. Personally, I don't like the fact that you have effectively one linear guide in the centre of the bed. Admittedly it's 80mm wide but with a 300mm bed, you have a lot hanging over each side. I'd go for two parallel 2020 vslot, close to the sides. 2 lengths 2020 will be less weight than 1 length 2080 too. Have you thought about insulation under the bed? If it's moving in Y, you ought to try and keep the weight as low as possible. For bed heater, the consensus of opinion seems to be about 0.4 to 0.45W/cm^2. So for a 30 x 30 bed you'll need around 360 to 400 Watts. At 12v that's around 33 Amps, at 24V its around 17 amps and at 240v it's only about 1.7 amps. However, if you go for 240v you need to be very careful with your wiring if the bed is moving in Y.

Also, and this is just a personal thing, I like have 2 or 3 removable glass print surfaces as it enables me to start another print as soon as one job has finished without waiting for it to cool down. Aluminium is also quite soft and easily damaged and if its tooling plate, it can be expensive to replace. If it were me, I'd probably go with 4mm aluminium heat spread plus 4mm glass. If you don't want to use glass then I think you should consider 8mm aluminium.

That's just my personal opinion. What usually happens is that there will now be flurry of posts disagreeing with everything I have just said, so at least you should get some more responses.

Thanks for the responses, the point about one single guide is a good one to make. I'm not fussed about weight of this, as it's a static piece. I may look into using 2 lengths of 2060 or 2080. However, more wheels will add more weight so any design must take this into account. If possible, I would like this design to weigh as much as my current bed (1.2kg) as I know my printer is capable of moving this at 50mm/s and maintain high print quality.

I currently use a thick piece of silicone under my bed used for protecting counter tops from saucepans as insulation, it has made a difference. I can get to 120c, but I'm looking at a 20 minute wait. Totally unacceptable really... Thus a change to 240v,or at least 24v for the bed is a natural progression.

As for glass print surfaces, I'm not that fussed. I use print bite, and I can just run the fan on it when the print is done to remove a print in less than 3 minutes. I will be using print bite on this 300mm bed. Using aluminium makes sense to me, it distributes heat in a far superior way, and you can use counter sunk holes and screws for neat installation and maximum print area. Print bite will stop any damage to the aluminium. Interestingly, aluminium only weighs slightly more than glass, and since I can get rid of heat spreaders and others fixings needed for glass, potentially slightly lighter in the end. I can get a piece of ecocast tooling plate that measures 300x300x5mm for only £15.

Do you have a reason for stating 8mm aluminium plate? This will increase the weight by alot.

@DC42 - the only issue I'm having is that it does not maintain temps well. I'm constantly upgrading this machine, so if I'm buying a new power supply or heat source that is more capable, why not upgrade something else at the same time?

nevermind

Edited 2 time(s). Last edit at 07/11/2016 02:42PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Interesting to hear that you only use 6.35mm aluminium, perhaps I can get away with 5mm. A link to 5mm toolplate as well - [www.aluminiumwarehouse.co.uk]

I've had some thoughts on using more than one linear guide.... Why does it need it? other applications use them, as linear guides are relatively thin compared to mine. The larger the build plate gets, the more movement you'll see towards the edge of that bed. (eg, 1 degree of movement is amplified the further away from the center it gets. even a fraction of a degree may start to become a problem over longer distances) 2 guides helps you stop this, minimizing movement. There are also weight issues, as 2 guides distributes the weight more evenly.

With 2080 extrusion, neither of these are a problem. V slot wheels use concentric spacers, removing any play whatsoever, and I believe 2080 is strong enough, especially if I supported the extrusion from underneath.

The 2020 extrusion should also hold up to this task of being a frame for the bed, even with a single linear guide. I use 2020 for my X axis and I have seen no sag. This has not been measured in any meaningful way except with feeler gauges but it has made good prints.

I think I will just have to go ahead with it anyway, £15 for a piece of tooling plate is not expensive and if it fails i'll upgrade to 6 or 7mm. I'll keep you all updated.

nevermind

Edited 1 time(s). Last edit at 07/11/2016 02:42PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Nice to know that I was right when I said there would be a flurry of posts disagreeing with everything I'd said.

@the_digital_dentist. Why do you do that every time? Do I know you? Have I wronged you in a previous life? I understand that you have an aversion for using glass as a print surface. I disagree but respect your opinion. I don't launch into a diatribe of sarcastic comments or hypothetical reasons why something that I have not tried might not work, every time you mention something. Why all the comments about Yoda heads and tug boats? That is totally uncalled for.

If you are just trying to drive everyone off of these forums so that your opinions are the only ones that people will read, then you are certainly going the right way about it.

I'm not sure what beef you guys have got with each other, but save it for PM's.

I don't use these forums much, I'm more of a lurker who posts when the actual info can't be found via google. Its topics like this, but made by other people that have helped me to build my printer to the high quality that it is now (with no prior experience in high precision machines). Removing the information from posts doesn't help at all.

I didn't join these forums for pettiness, I joined it for knowledge.