So after weeks of scratching my head...

[bob64]

I've realized that the top base melamine plate is warped like crazy. In the process of tearing apart the printer now to see if I can figure out wtf is causing it to be warped so bad. Anyone else see this before? You really notice it when trying to see if your towers are square.

[bob64]

Ok. Taking apart the printer just to get to the base is a huge pain in the ass.

But I have it now removed from my printer. Holding one corner down on my glass table (totally flat), I measure about 3-4mm of displacement along the opposite edges. The center is bowed upwards toward the heated bed. Anyone got any suggestions?

Edit: the snowflake is also bowed.

[Eaglezsoar]

Ok. Taking apart the printer just to get to the base is a huge pain in the ass.

But I have it now removed from my printer. Holding one corner down on my glass table (totally flat), I measure about 3-4mm of displacement along the opposite edges. The center is bowed upwards toward the heated bed. Anyone got any suggestions?

Edit: the snowflake is also bowed.

If the printer is new I would ask SeeMeCNC for new parts.
Best way to contact them is to go to their website and click on the chat button on the bottom right. They will take care of you.

[bob64]

Unfortunately it's not new. Got it approximately around august 2014... However I've done barely any printing on it. Maybe 2 month's worth of total print time was tallied before the eeprom got corrupted due to a unstable 12v issue. (Reflashing it fixed that problem). After flashing I've racked up maybe another 30 hours before upgrading recently to the duet. So if it happened to me with my level of printing done on it then maybe others that followed gene's assembly guide also has the same issue?

Anyway, according to more research in the forum this might have been caused by the heated bed being overconstrained. I'm really curious if anyone else's snowflake/top base plate is also warped like mine. You can easily tell when you put a square to the side of the aluminum extrusion, if it's bowed, it'll read that extrusion is leaning away from both sides rather than just towards one side or the other. Best way to see if people have the same issue is probably just to remove the snowflake/bed or set it aside with the wires still going through the plate, and run a straightedge across the top plate/snowflake.

[TN Yankee]

I bought my V2 new in December of '14. Last winter, after pulling it out of storage from a recent move and re-doing the cals, I discovered the Onyx was warped to the point it would pull the glass with it. Below that, the snowflake is also warped (high towards the center). After a LOT of time spent with shims, varying screw tension, number and placement of binder clips, and running a couple hundred 13-point cal runs with a digital height gauge, I've gotten it acceptable enough in the center area encompassing about half the diameter of the plate.

Concurrently, I've slowly acquired a 5/16" MIC-6 aluminum plate, four 100W @ 110VAC PTC heaters (1 is a spare), more PEI and some Crydom D2425 relays. The plate is with some buddies at the community college machine shop getting trimmed down to 310mm. Once it is back, it will replace the Onyx and glass. I may or may not leave the snowflake, but if so, just as a spacer and possibly a point to attach the 3 stand-off bolts for the plate. There will also be a 6mm/0.24" piece of Aerogel/Spaceloft insulation under the aluminum to minimize the heat radiated back into the base.

I'll drill & place a thermistor somewhere in the plate, with the RAMBO controlling heating via the relay.

Many people here have commented on how AC-powered heaters are not desirable due to a higher shock hazard. However, do not for a second discount the 20-24 amps required by the 24 volt DC heaters - that is still a very dangerously high amount of current that can cause respiratory paralysis or ventricular fibrillation.

Most of these ideas came from this forum. These are my sources, though there are likely many more:

Heaters: http://www.ebay.com/itm/110V-100W-PTC-H ... Swg3FUgT8W

Aerogel: http://www.ebay.com/itm/Aspen-Aerogel-S ... xynwlTcnZL

MIC-6 aluminum: http://www.sandsmachine.com/alumweb.htm

PEI (12"x24" was $5 shipping): https://www.zoro.com/search?q=pei&varia ... s.1196=PEI

[jason128]

I struggled for months trying to get it calibrated before realising I had the same issue.
I ended up removing the snow flake completely, fixed the onyx on spacers through the same holes.
Also holding the bed onto the onyx, which was also warped, with 3 big blobs of silicone.
Was intended as a tempory fix, but worked so well it's Permiant. I'm now able to print over the full bed perfectly.
It's actually really nice having no clips, much easier to wipe down.

[Johncoffee]

I struggled for months trying to get it calibrated before realising I had the same issue.
I ended up removing the snow flake completely, fixed the onyx on spacers through the same holes.
Also holding the bed onto the onyx, which was also warped, with 3 big blobs of silicone.
Was intended as a tempory fix, but worked so well it's Permiant. I'm now able to print over the full bed perfectly.
It's actually really nice having no clips, much easier to wipe down.

Awesome Jason128. Would you mind showing some pictures and details of your setup? E.g. do you use oval holes for mounting the onyx onto the base as mhackney suggested in another thread? (or is this not necessary when using your method?

Best regards
John

[jason128]

ill grab some photos when i get a chance.
i just used the existing holes in the base that are there for the snowflake.
i used longer screws, and the plastic washers off the snowflake to space the bed up (i think I used 2 or 3 each screw)
I think this setup nicely gives the onyx bed the ability to move expand by just bending the scews out very slightly. (they were only very slightly tight with a little locktite to hold it.
so the onyx is only held in 3 places....
The glass was held with 3 big blobs of black silicone directly above the fixing screws, with the glass very very lightly pressed down on top.
this allowed the onyx bed to remain warped by about 1.5mm at the edges, while the glass is still flat.- so what i'm saying is theres around a 1.5mm gap between the glass and the bed in places on mine..
it heats up fine, slightly slower, but at least the glass is flat!

The glass cannot straighten out the onyx if it is warped- as it bends it self, remember .05mm here is enough to stuff op the first layer.
I have heard people say it will on here- but i know from experience it will not!

good luck

[Johncoffee]

Jason128 - even I can follow your explanations it would be great if you could post some pics of what you have done for others to do the same!

Thanks a lot!
John

[jason128]

here you go

[Johncoffee]

Thanks Jason128 - I assume this is one of the big blop of silicon between the ONYX bed and the glass?

[jason128]

yep - that's the silicone- i might have got a little carried away!
A little blob spreads a long way when squished down.