Be aware - Actual buildplate temp lower than temp setting

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EldRick
Posts: 167
Joined: Thu Jun 22, 2017 5:55 am

Be aware - Actual buildplate temp lower than temp setting

Postby EldRick » Thu Jan 11, 2018 9:52 pm

Be aware that while the heated aluminum plate under the buildplate glass may reach the temperature you set, the actual temperature of the surface on which you print will be substantially lower.

I set the buildplate temperature to 100C with the cover on the machine, and waited an hour for temps to completely stabilize. I pointed my pyrometer (which I believe to be accurate to around +/-3C) at the glass buildplate with a good coat of gluestick on it. The temperature read within +/-1C, at various locations on the plate, except near the Home position, where the printhead fan apparently cools the area by several degrees. So I lowered the bed a couple of inches and waited another half-hour before measuring.

Unfortunately, the reading was 87C, thirteen degrees lower than the 100C I had set. When I used a plate with Buildtak on it, the temp only read 84C, as the Buildtak material insulates the heater even more.

So the message is, if you are having bed adhesion problems, it is very possibly because you don't have the buildplate as hot as you think you set. I found that when I set the buildplate temp to 106C using gluestick instead of the recommended 100C, I got substantially better print adhesion with ABS and PC without any problems with removal when cooled.

I'll use this information in a couple of days, when I receive the Ultem I ordered. I'll also modify the end-of-print gcode to lower the bed a couple of inches after printing, for more even bed temps on the next print.

BTW, here is a good source for Ultem - better than Mcmaster.com:
http://catalog.cshyde.com/viewitems/3d- ... /ultem-pei
Their Ultem comes with 3M adhesive pre-applied, and you can request both precut exact size (331mm X 339mm for the N2) and whether the shiny or matte side is up, in addition to thickness. I chose .020" (=.5mm) because I hope it will be easier to apply to the glass without bubbles vs. a thinner sheet.

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Casale8
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Re: Be aware - Actual buildplate temp lower than temp setting

Postby Casale8 » Fri Jan 12, 2018 4:18 pm

Add materials between the source of heat and there will be dissipation. An engineering given.

I have purchased a bunch of temperature indicating labels for the platform. I place them on the buildtak in various locations during print to observe the difference as I need. McM: https://www.mcmaster.com/#stickers/=1b3guoj

I also took a gauge and noted that the bed varied at random locations ±.3° max, so I know that the heating is fine in my case.
-SCC
“One man's "magic" is another man's engineering. "Supernatural" is a null word.” -R.A.Heinlein

EldRick
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Re: Be aware - Actual buildplate temp lower than temp setting

Postby EldRick » Fri Jan 12, 2018 4:46 pm

Once it stabilized, heating on mine was very even, but quite low compared to the set-point.
Clearly it needs correction, and I'm glad I took the time to investigate.

Vice Chief
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Re: Be aware - Actual buildplate temp lower than temp setting

Postby Vice Chief » Tue Jan 16, 2018 2:29 am

I saw the same thing with a piece of glass painted black, measured with a thermal camera, Casel8 is right, I set my bed to 108C to hit a desired temp of 100C. There is a +/- 5 deg C variation across the bed.

zemlin
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Re: Be aware - Actual buildplate temp lower than temp setting

Postby zemlin » Tue Jan 16, 2018 4:23 am

I get a good ABS print with my bed temp set to 105C. Does it matter that the surface may actually be 100C?

firesped
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Re: Be aware - Actual buildplate temp lower than temp setting

Postby firesped » Tue Jan 16, 2018 6:41 am

bed adhesion is far more complicated then just reaching a target temperature. your surface needs to be level or the printer has to have sensors to compensate for it not being level. When you heat metal, it bends and warps. the more you heat it, the more it bends and warps. using clips to keep the glass in place will cause the glass to also bend and warp with the heated bed.

It should also be pointed out that the borosilicate glass build plate is a high heat resistant material. so the glass build plate is not really intended to actually hit 100C itself. This is also why letting it have time to actually get to temperature helps with printing.

Raise3D attempts to keep the bed level are by installing a massive number of screws that have counter screws to keep it in place. This is a very time consuming process to re-level after it goes out of level from the factory install.

some people have switched to 4 point leveling. I think one owner has put in a new 3 point heated bed. personally I switched to a 4 point leveling system. I recently switched over to wing nuts versus using thumb screws. I was not able to turn the thumb screws without releasing tension on the bed. the wing nut for this bed actually let me make controlled movements to level it. The technique that I learned to level it works. 100C was sufficient for me to print ePC with no problems at all.

Stating that there is a major issue with the heated build plate heating element on all Raise3D printer is not really valid. If you thing you have an issue with your printer, you should contact Raise3D tech support and work out the problem.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2

EldRick
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Joined: Thu Jun 22, 2017 5:55 am

Re: Be aware - Actual buildplate temp lower than temp setting

Postby EldRick » Tue Jan 16, 2018 4:24 pm

Stating that there is a major issue with the heated build plate heating element on all Raise3D printer is not really valid.

Did someone say that?

I, at least, just said "be aware" that the buildplate heater temp is not equal to buildplate surface temp. So, to get to the usually-recommended 100C buildplate temp for ABS, you will need to set 105-110C.

This does seem to me to be a significant issue with buildplate adhesion, but I'm pretty sure it would afflict any 3D printer with a heated glass plate (including all Raise3D printers).


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