Heat bed for semi large printer

I am looking to make a Heat bed for my in the design stage printer. Heat bed is .6M x 1M I would like to only do this once as the budget is getting more and more strapped by the day. However I am not willing to cut any corners. Would like to make this printer as reliable as possible as I don't want it screwing up half way through large prints. So if you have any experience I would love you to chime in. I see PCB heaters seem to be the love of everyone However they are not available or readily available at that size. What have you had success with? Heat bed will be machined AL plate Possible steel. Some specs on machine Servo drive x and y Stepper Z precision ball screws on all axis. Bowden extruder dual Micron hot ends both .4mm (hoping to make one closer to 1mm). All motors out of heated chamber expecting 70 deg C. Linear rails on all axises except Z. As Z has three ball screws securing it. 50mm extruded frame. Smoothie board running off an SD card. Also has I thought smoothie was updating their board. Anyone hear any news on this?

Joe

Use an AC mains voltage silicone heater on the underside of the aluminium plate. I suggest you choose a heater a little smaller than the bed so that you have a margin around it for bed support ribs. For that size bed, I guess you will need additional supporting ribs in the middle unless the plate is very thick (which would increase the heating and cooling times). So choose the arrangement of supporting ribs, then order silicone heaters to fit between them. Connect all the heaters in parallel and drive them from the electronics via a zero crossing DC-AC SSR.

I haven't built a bed that large, but my best guess is that you need 2 to 3kW of bed heating power in total, and aluminium at least 7mm thick to spread the heat well.

This company [www.aliexpress.com] will make silicone heaters to your size, voltage and power specification, at very reasonable prices.

Smoothie 2 is under development, but I haven't heard any release date mentioned. Currently my preferred controller is Duet 0.8.5, which is comparable to the Smoothie 5XC but costs less, has a better web interface, and supports the PanelDue colour touch screen (full disclosure: I manufacture the PanelDue).

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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].

Slightly off topic: You're using an aluminum frame and steel linear guides. When the machine heats up to 70C, you'll have aluminum expanding more than steel. That will move the two Y axis guides apart. Are you doing anything to prevent the mechanism from binding? Steel guides screwed to aluminum may warp when the temperature rises because of the difference in the expansion. Are you doing anything to mitigate that?

I've started on a smaller CoreXY design and have been thinking through the thermal problems and the best solution I can come up with is to make the rectangular frame to which the linear guides attach out of steel so that the coefficients of expansion of the frame and the guides will be about the same. The rest of the frame can be aluminum.

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

Thanks for the good Info and the Disclosure haha!. Will definitely check those parts out. and the silicone heater link.

Digital Dentist, Those points have been worrying me the whole design process. My work around is The XY axis is only attached to the AL at 4 points the corners. And from math the Steel will expand .4 mm and AL .9 mm over a meter length. .5mm seems pretty small over a meter. (I'm an engineer not a physicist) My second thought is that if the machine is calibrated and clamped down at operating temperature. It should square up at temperature. What are your thoughts? And thanks for a lot of good advice back in Nov. Have put a lot what you said into the design. Making a steel frame seems great idea but I know what happens when you try to weld steel and try to make thing precision. Generally a nightmare.

Also, currently looking for a large GT2 belt that is single sided. Have any sources for that? 3 Meters?

Edited 1 time(s). Last edit at 01/08/2016 12:01AM by audioman7.