Domed build platform / bed help...

[cassetti]

Although I've only done one print, the Lexan build plate supplied by SeeMe was amazing. At 75C the ABS stuck like glue, and after cooling, you can remove the Lexan and simply flex slightly. POP and it's off! It's almost too simple. No noticeable residue or damage to the plate that I can see. Buy a few, and you can rotate them...

Hey there friend! Happy to see you posting on the board! According to SeeMeCNC, the Lexan panels you mentioned won't be available on sale for a few weeks - consider yourself lucky! I look forward to using a flexible build surface.

FYI, after reading this thread and several others, I was really concerned about my build surface. I found the middle would bow up by around 0.25 to 0.5 mm. I compensated for this by calibrating the adjustment screws using a thick piece of card stock directly in front of each rail. Once my G1 Z0 was just close enough to grip the card, I'd switch to another rail. I'd finish my testing by using a piece of thin printer paper and testing the center of the board.

I believe by using a thicker card stock (instead of thin paper) for calibrating at the rails, I can compensate for the very slight warping on my bed. So far all my prints since calibrating in this manner have been very promising - I have had no issue with delamination of the first layer.

[rs50pilot]

I still can't get my bed leveled to my liking. Without the onyx the top of the base is bowed downward in the middle. Seems to be flat at the mounting points which is good. When the onyx is put on with the snowflake and spacers it is high in the center without the bed heated.
So I made some springs to try to get the bed level.

Put the springs under the onyx on top of the spacers no snowflake. Then placed the alum plate on top. I used a stack of feeler gages at each mounting point to get these points close.
Placed the glass on top. Guess what its still high in the center. Adjusting the mounting screws up and down while holding the glass at one point still won't bring the bed flat enough. Need a way to pull the center of the bed down.

So I clipped the glass onto the alum plate in two spots which should hold the glass flat between the two clamps. The edges that are not clamped down are raised above the bed about .015 to .020 thous. But it takes a lot of pressure to push these floating edges down so this should work. I quit before I could verify if this will work but I'm out of ideas aside from jb welding a ring to the center of the bed and using a screw assembly to pull the center down.

Frustrating because I need to print something 7 inches long and since the middle is high the outer edges of the print are way off.

[MorbidSlowBurn]

If you are able to get good adhesion and can print with quality there is a work around if you need the bottom of the part flat.

First ensure that after a couple of layers the printed surface is flat. Maybe 3 to 5 layers.

Then print with a raft. At the same height as you just verified flatness (3 to 5 layers). Once the print is done you can remove the raft.

I know it doesn't fix the bowing, but it will allow you to get consistent flat prints.

I do find it odd that the onyx is bending the aluminum. Have you checked the flatness of the aluminum when it is not installed?

[cassetti]

Yeah, I agree with MorbidSlowBurn - with Slic3r 0.9.9 you can now add rafts to models.

I haven't checked, but it appears my onyx is relatively flat (though I should test with a straightedge at some point). I do know my Aluminum heat dissipator plate from Mhackney does have a slight bow in the middle. I've tried using a heat gun to heat the plate, then bend it into shape with a 45# kettlebell in the center of the plate resting on carpet with me standing on the kettlebell. I don't think I did anything at all! Hoping a piece of borosilicite glass on top of the aluminum will help account for the this.

For now, I have resolved my warping issues using a 3mm brim and 6 layers of rafts. Not the best solution - but rafts work GREAT if you have an unlevel bed.

[rs50pilot]

I can't see the bed moving the plate either. My plate seems bowed in the middle a little as well. Even without heating it. I didn't think about using a raft. Guess im going to have to it. I'm just pissed because it seems impossible to get the platform level to the bed because I can't get it leveled.
I'm pretty sure I'm going to be closer to being level by camping the glass in two spots that are close to being flat and just letting the unclamped edges float. The glass isn't going to bend. I'll post my findings later after work.

[cassetti]

FYI

I am currently contacting several waterjet vendors to see if I can get Mhackney's Onyx heat dissapator cut out of something more precise such as 1/4" thick MIC6 Cast Aluminum - Pricey, but flatness tolerance within 0.036. (If anyone is interested in one, send me a PM). Might try the borosilicite glass first and see how it does.

So far, rafting has proven very successful at preventing warping

[rs50pilot]

.036 is not very flat. I'll have to measure this plate but it's probably close to that. You want flat you need something thats been ground flat. I thin I'll stick with the raft until I find a better way to do it.

[cambo3d]

mic6 is ground flat to +/- .005, .036 is definitely not good.

[rs50pilot]

FYI

I am currently contacting several waterjet vendors to see if I can get Mhackney's Onyx heat dissapator cut out of something more precise such as 1/4" thick MIC6 Cast Aluminum - Pricey, but flatness tolerance within 0.036. (If anyone is interested in one, send me a PM). Might try the borosilicite glass first and see how it does.

So far, rafting has proven very successful at preventing warping

I guess I read something wrong? Sorry but looks like you posted .036 flatness.

[easybeans]

Currently suffering from the same problem... My Rostock Max base is bowed downwards and the Onyx is bowed upwards when installed... I'm gonna try some things when I get home from work... But I'm concerned about the fitment of tue base in general

[cassetti]

Hmm, you're right guys. It's Flatness tolerance is 0.015" - which would be 0.381mm. hmm, according to Mcmaster I'd get a flatness of 0.005" for anything over 3/4 - guess that won't work - 3/4 is probably too thick. Looks like I need Tool&Jig aluminum - anyone know a good source to buy a few plates of it? McMaster doesn't seem to list that.

http://www.mcmaster.com/#aluminum-alloy-mic-6/=m6a0k3

Has anyone tested glass on top of the aluminum - how's that working with the bow in the middle of the aluminum? Does the glass plate sit flat?

[MorbidSlowBurn]

I am actually using glass on top of the aluminum. I do have a slight bow in my plate but the glass does seem to get rid of it. Depending on how significant the bow is you may also bow the glass based on how you retain the glass. My glass heats up fairly even. I would have to check again but I only saw a degree or two variation over the majority of the plate.

[cassetti]

I am actually using glass on top of the aluminum. I do have a slight bow in my plate but the glass does seem to get rid of it. Depending on how significant the bow is you may also bow the glass based on how you retain the glass. My glass heats up fairly even. I would have to check again but I only saw a degree or two variation over the majority of the plate.

What about the actual heat - have you tested the temps - I bet you're probably right on temp in the center, but the outer edges probably drop by 10C or more. That could cause warping issues on larger prints.

I'm awaiting a price for the tool&jig plates and a flatness tolerance, I might opt for that with a piece of Lexan on top.

[rs50pilot]

I found a place on the bed that had the least amount of bow. Used a straight edge and a feeler gage. Then I placed the glass on top and clipped it in two places on that line. Now with the straightedge on top of the glass it is pretty damn flat. I just let the other egdes of the glass hang out in space over the plate.
Takes a reasonable amount of force to pull the glass down so I think it will work.
Even a huge model doesn't weigh enough to bend the glass.

I printed a part and it looks good. I'm going to print something from edge to edge and see how that turns out.
Otherwise im going to make a plate out of steel and grind it. That way I know it within .0005.

[USMCPelto]

Anyone end up getting a nicely level bed? My bows quite a bit in center. Significantly enough to skew a few things.

[cambo3d]

there's couple of things that can cause this,

1, make sure that your rostock base is flat as can be, or else anything that you mount to it will try to bow to that surface when heated. If you didn't check your laser cut parts for squareness and alignment, you really should. the current manual does not discuss how important it is to check squareness of the laser cut parts.

2, torque all mounting hardware evenly.

once its as flat as can be, placing the boro glass on top of the onyx will hide most of the slight variations, boro will stay flat no matter what temperature.

i've had problems with bowing before as noted in my build log, and I found that having a perfectly flat base solved most of my issues.

[cassetti]

Anyone end up getting a nicely level bed? My bows quite a bit in center. Significantly enough to skew a few things.

Still fighting with mine - but I'm playing with the Delta Radius settings in the firmware - I set mine to -0.2, but think I might try -0.5 and see how well that does