exploring bed and autolevel sensors for self build.

I would appreciate some experienced assistance here. I have only a few months experience with an ME Creator and after feeling the limitations out I am ready to begin ordering some bits to make one from scratch based from a Ramps 1.4 setup.

So I am investigating options for a printer build. I am on a bit of information overload in trying to select parts. So much info and a lot of it is old so filtering out the newer ideas and experience is daunting.

I am fairly sure I want a PEI bed.
choices are .8mm thick 2mm thick - I would think 2mm would be better but then I read that PEI is not a consistent thickness so thinner would minimise this issue right?

I want to use an aluminum Hotbed all in one construction, from what I can gather from the wiki that means I want an MK3 construction right?

I want 300x200mm but will settle for 300x300mm IF it its cheaper... but then would the Ramps 1.4 be able to handle the larger heater?

I am trying to avoid the glass surface if I can and stick the PEI sheet directly to the aluminum surface. Is that a bad Idea?

I want to use self leveling, so many choices.....
I live in a coastal area of B.C. Canada so humidity varies HUGE... likely capacitive is not a good idea here...
and the choice of bed setup may greatly affect self leveling sensor choices. PEI thickness, glass or separate alum sheet, etc.

I am not worried much about mass as the Bed will either be stationary or I will use bed on Z axis setup so it wont be moving fast.

Plan at this stage is E3D V6 Bowden... I will cross details on that later, Bed choices are my biggest issue right now...

Thanx in advance for any assistance.

Most PCB bed heaters are under-powered and made to very poor power tolerances (the ones sold by E3D may be an exception).. A better solution is to use cast aluminium tooling plate for the bed, with a silicone heater underneath and your choice of bed surface on top. Another solution is to buy a PEI-coated aluminium plate such as the one from clever3D. They do a 300x200mm one, which some BigBox printer owners use.

Personally I prefer to have removable bed plates, mostly because prints sometimes stick to PEI too well and putting them in the fridge or freezer helps to detach them. It also makes it easier to experiment with different print surfaces. So I use PEI on top of glass, which is clamped to an aluminium bed. But some people prefer to use PEI glued directly to the aluminium bed plate.

If you have the budget, forget RAMPS and choose a modern 32-bit controller board. RAMPS is a very basic board for budget printers. With a 300x200mm bed you should be looking at 24V electronics, which most RAMPS boards can't handle without modification because the 11A polyfuse is rated at 16V, usually the capacitors are also rated at 16V, and the 5V regulator on the Arduino will fry if you feed it much more than 12V.

I recommend a bed heater power density of 0.4W per square cm. or a little more if you use a thick tooling plate. So for 300x200mm you need about 240W to 300W of heating power, which is 10 to 12.5A @ 24V. Good electronics can handle 15A or more.

There are lots of different height sensing technologies available. I sell a differential IR sensor (see [miscsolutions.wordpress.com]), which works really well with the PEI coated plate (especially the black version) from clever3D. However, if instead you use the IR sensor with a sheet of PEI, then the PEI needs to be backed by a black surface to reduce the reflection from the bottom of the sheet, which makes it less than ideal. Other sensing options include inductive sensors (if you use thin PEI attached directly to the aluminium) and nozzle-contact sensors.

HTH David

Edited 1 time(s). Last edit at 06/07/2017 04:59PM by dc42.

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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].

Thank you David this is exactly the kind of advise I was hoping for. Its funny how looking around shopping for bits I got the feeling the silicone heaters were old school rather than the newer tech

I chose the Ramps 1.4 because I have some Arduino Mega 2560 boards hanging around with no job to do.

My buddy and I are trying to work out the lowest cost large volume fast printer that can 'reasonably' be done. When complete we hope to post our setup with all build info and STL files and pray for a bit of monetary compensation lol
He has been printing for a few years now and this will be the 3rd I think printer he has built.

Together I think we are going to merge a lot of good ideas from all the experience we can glean from peeps like you, Google (always) and what we have to offer between us.

I was really exploring the 24v option but it shot the cost up way too high from what I was able to glean.

Exploring the IR sensor now!

Thanx again!

For a bed that size, if you use a piece of 1/4" cast aluminum tooling plate with 30 or 60 mil PEI it will be flat enough to print on edge to edge. If you mount it on 3 leveling screws, you won't need autoleveling- you'll set it up once and it will stay level (assuming you're building a reasonably rigid frame).

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

Quote
the_digital_dentist
... If you mount it on 3 leveling screws, you won't need autoleveling- you'll set it up once and it will stay level (assuming you're building a reasonably rigid frame).

That also assumes that the plane in which the nozzle moves is flat to within about 50um. On some printers, auto bed compensation is as much about compensating for sag in the X axis as it is about compensating for non-flat or non-level beds.

Edited 1 time(s). Last edit at 06/08/2017 02:48AM by dc42.

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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].

How true!

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