Flattening aluminium hbp

Hello, I have an old makerbot thingomatic with a 12x12 cms aluminium bed. My original bed burnout and I bought a chinese replacemente, but now I noticed that the part is sightly bent and the adhesion is quite poor compared to my old bed.

How could I straighten the aluminium part? Is a 2 part construction, pcb + aluminium but the old part is not exactly the same to the new like to replace the unbent one.

Could I use heat? or a vise? I tried with C clamps and wood, but it is quite the struggle to get it perfectly straight

There isn't much chance of actually flattening it. You could get a piece of tooling plate, peel the heater off the bent plate, and cement it to the tooling plate and use it to replace the bed plate. That would be better than new in terms of flatness.

Then you still have to contend with a 4 corner leveling system that tends to bend the plate/undercarriage instead of leveling the plate anyway.

---

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

Just put a piece of glass on top of it?

you could use some thermal paste to even out bumps and holes
with good heat transfer to glass.
Glass would be flat if not tightened down to plate.

if the bend is not so much you can sand it down using a course sandpaper attached to a block. then mount 4 mm glass ( 2mm will bend ) on top of it using silicone thermal pads to take care of the rest of the bumps remaining.

Quote
ekaggrat
if the bend is not so much you can sand it down using a course sandpaper attached to a block. then mount 4 mm glass ( 2mm will bend ) on top of it using silicone thermal pads to take care of the rest of the bumps remaining.

A block of wood will probably not be flat enough. A granite tile might be, but check it first. This video has a good explanation of the lapping process: [www.youtube.com]

Quote
etfrench
A block of wood will probably not be flat enough. A granite tile might be, but check it first. This video has a good explanation of the lapping process: [www.youtube.com]

Thanks for the video!

Quote
ekaggrat
if the bend is not so much you can sand it down using a course sandpaper attached to a block. then mount 4 mm glass ( 2mm will bend ) on top of it using silicone thermal pads to take care of the rest of the bumps remaining.

Great idea!

Quote
ekaggrat
if the bend is not so much you can sand it down using a course sandpaper attached to a block. then mount 4 mm glass ( 2mm will bend ) on top of it using silicone thermal pads to take care of the rest of the bumps remaining.

I would look up the process of lapping!

Silicone is an insulator ---- Why insulate glass from the heated bed?

You can sand, lap, bend, and sacrifice small animals to the gods of your choice, but you won't have a flat print surface if the bed support/leveling system causes the bed to flex when it heats up. Let's say you save $20 by buying the thin, bent, flexible extruded sheet instead of a flat, much less flexible, cast tooling plate. How many hours of manual labor are you going to put in to get a questionable result, all in the interest of saving a lousy $20? Is your time really that worthless?

Cozmicray points out that silicone is an insulator and asks why insulate the glass from the heated bed? Following that logic to its correct conclusion should lead you to ask: "why insulate the print from the heated bed with a piece of glass?" Glass is often used because the too thin bed plate isn't flat, usually because it doesn't start flat, and then it is supported by a leveling system that guarantees it is going to bend if you try to level it. So you clamp on your glass plate then you try to print and can't get prints to stick to the bed without adding glue, hairspray, or other goop. Maybe the uneven heating is contributing to the problem of getting prints to stick.

How about addressing the real problem by using a flat, thermally conductive plate from the start? Sure it costs a few more $ for a piece of tooling plate up front, but the time it saves in failed prints makes it worth 10X the cost.

If you think and act like your time is worthless, it is worthless, because if you don't value your time, why should anyone else?

---

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