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What is it with prints raising up on one edge? Most of my prints are doing this now. I'm using a light coat of hairspray on the hot bed. Seems to be happening more often for some reason.

Bed not evenly hot?

Print with a brim. It's easy to remove at the end and keeps edges from warping.

Jay,

Are you printing with ABS or PLA ?

As a side note.... what is the ideal bed temp for ABS ? , I am using 80 Deg, I feel it should be hotter but my onyx wont go up higher unless i go for a higher voltage power supply.

barry99705 the bed doesn't seem consistent, i have an infrared handheld thermometer and it fluctuates. The printer is brand new. I'm doubting its a bed issue but could be wrong.

MDMD I have printed with a brim before and the only problem I have with that is I really want to know why this is happening.

MAXMAN, put a shirt or heavy cotton cloth over your bed when you're heating, it'll rise in temperature faster and you should get to 90C easily.

Jay, what you're seeing is a symptom of shrinkage with ABS. The easiest way to minimize that is to add a brim on the part or "mouse ears" on the corners that are pulling up. It gives more surface area for the part to stick to the bed with.

I've been running Blue Max with an 80C bed temp on ABS for a couple of weeks with zero issue. As long as you're properly calibrated, that's plenty hot enough to allow the first layer to properly stick. I use "Aqua Net" extreme hold hairspray (unscented or your office will smell like a brothel...) and it works really well.

g.

geneb wrote:Jay, what you're seeing is a symptom of shrinkage with ABS. The easiest way to minimize that is to add a brim on the part or "mouse ears" on the corners that are pulling up. It gives more surface area for the part to stick to the bed with.

I've been running Blue Max with an 80C bed temp on ABS for a couple of weeks with zero issue. As long as you're properly calibrated, that's plenty hot enough to allow the first layer to properly stick. I use "Aqua Net" extreme hold hairspray (unscented or your office will smell like a brothel...) and it works really well.

g.

So what is wrong smelling like a brothel?
I'll have to try the scented so I'll know what a brothel smells like.

Odd how that smell with a little acetone turns it into smelling like a hair salon. Maybe I have been looking at those all wrong all these years.

As for the bed temp, for printing ABS I was able to lower mine to 60°C with hairspray on glass. I forgot the brand but it had the specific vinyl copolymer that was stated as being the necessary ingredient for the hairspray to work well.

I tried printing with a skirt at my usual 90C and yes it worked great. I can deal with that. Funny comments about the brothel and hair salon. Thanks for the help!

I'm having a problem with the corners of prints separating from the hot bed or rising up again. Used to not have this problem and I posted about it here and you guy suggested to add a skirt. I have been doing this, I have an 8 loop skirt with a height of 2 layers and a 9mm brim width and the corner of the print still rises up! This usually happens with larger prints(6" in diameter or more) and with prints that are on the hot bed for a long time(6 or 7 hrs). I'm not sure if my bed is or is not heating evenly. I've even been thinking about putting up plexiglass walls because I think it might be drafty on one side of the printer.. Any suggestions?

A piece of aluminum 1/8" between the Onyx and the glass can help to distribute the temperature. A wall you mentioned is also a good idea to minimize drafts. Some use a section
of Sonotube (not sure of the spelling) but it is for concrete, can work also. Heating the Onyx with a 24v supply can get you to temperature faster and you could try a hotter bed
temperature but I recommend a DC-DC SSR feeding the 24V into the Onyx although I have received arguments on that. (Some would rather run the 24V through the Rambo).
Just throwing out some ideas.

Thank you very much for the suggestions. I like the aluminum sheet idea.

Have you had these same issues and applied these ideas yourself? I'm wondering if it actually is uneven heat and a drafty basement.

-Jay

JAY wrote:Thank you very much for the suggestions. I like the aluminum sheet idea.

Have you had these same issues and applied these ideas yourself? I'm wondering if it actually is uneven heat and a drafty basement.

-Jay

I certainly have had the same issues. I ended up using a 5/16" Mic-6 aluminum plate which took care of the uneven heat and I run the Onyx at 24V through
a DC-DC ssr. I have not used the tube to prevent drafts but I do use the Aqua Net unscented Super Hold hair spray at a bed temp of 90c. I still get some
shrinkage of the ABS and lifted corners on the larger parts. ABS can be a bear to stop curling edges but it's benefits make it worthwhile to work at minimizing
the curling.

Ok I tried several aluminum foil sheets cut to 300mm in diameter in an attempt to even out my heat on the bed to combat raising corners on my prints. As I laid the aluminum sheets down I noticed some odd behavior with the printer. The screen of my RostockMax was not displaying anything I could read. I then noticed my bed temperature display was reading 82C. This was absolutely incorrect because it wasn't hot at all. As I took the aluminum foil sheet off the bed I then noticed the power and thermistor nodes! Crap I had shorted them out or something. I'm not sure what I've done but I can say that everything else works and connect just fine.

Here's the thing, my bed temperature displays 86C as soon as I open RepetierHost. I can hit the "heatbed" and it heats up but it's way off. I think I measured that when it's displaying 107C then I'm actually at 90C. I know that the RostockMax has PID control for heating the bed and hot end. I've definitely messed that whole closed control loop up.

The good new is that I've noticed I can take the bed thermistor input and connect it to the hot end input on the rambo and the temp displays correctly. I've also noticed that there are 4 total thermistor inputs of which only two I'm using (hotend and bed). I want to change my firmware and plug the bed input currently in T2 and put it in T1. I think this would be simply enough but as I downloaded the firmware and I'm going through it, I can't seem to find the T2 analogReads and swap that for T1. Any help???

there is also some other points besides the bed pads that needs to get a layer of kapton tape to electrically insulate.

Putting Kapton on the exposed vias on the Onyx are part of the instructions.

You've likely shorted out the thermistor port on the RAMBo and killed it.

g.

Yes thanks for the email! I've found the pins.h and the Rambo board temperature pin assignments. I believe I'll change #define TEMP_BED_PIN 2. Not sure what to change "2" to though. I've debugged a little and this is what I've found.
Changing pin 2 to "1" made the temp stay at 76.03C.
Changing pin 2 to "-1" made the temp stay at 89C.

The correct Celsius temperature it should read is around 23C. Like I said earlier, I can plug the bed thermistor where the extruder input is and it'll read around 23C.

Ouch just checked the price of a new Rambo board. $185. Any other suggestions?

JAY wrote:Ouch just checked the price of a new Rambo board. $185. Any other suggestions?

Gene's assembly manual tells you to cover those areas with Kapton, I think you missed that section but their are solutions.
Ultimachine will repair those boards. They are the manufacturer. Go to the ultimachine.com site and send
a note to support asking how to send the board in for repair. It's under the about us - contact us.
It is also possible to change the firmware to use a different input for the bed thermistor. Can one of our upper
level users help Jay remap his pins.h and configuration.h? I am not good on the remaps.

Yes I changed the inputs and the bed temperature did not resemble the correct Celsius temp after the changes and uploads to my Rambo board. I have four total thermistor temp inputs, one is the extruder, one is the bed, and the other two are open so I tried the two open ports with no success. The extruder temp is reading fine through RepetierHost, furthermore the bed thermistor plugged into the extruder port reads out fine on Repetier Host as well.

I just find it odd that I've fired 3 out of 4 ports. Hell, I find it odd that I've fried 3 ports in one quick swoop. I can't imagine 3 analog ports using the same analog to digital converter, maybe two yes but three seems like a jump.

Are you sure you used the correct pin number? RAMBo has some pretty funky pin assignments. Even with my RAMPS and marlin, I used a pre set up configuration and it had the bed assigned to the wrong pin, what should have been Extruder 2 pin, and I don't think the pins were used in numerical order... (T0 is like 2, T1 is 4, T2 is 5, pretty sure RAMBo is even more scrambled)

JAY wrote:Yes I changed the inputs and the bed temperature did not resemble the correct Celsius temp after the changes and uploads to my Rambo board. I have four total thermistor temp inputs, one is the extruder, one is the bed, and the other two are open so I tried the two open ports with no success. The extruder temp is reading fine through RepetierHost, furthermore the bed thermistor plugged into the extruder port reads out fine on Repetier Host as well.

I just find it odd that I've fired 3 out of 4 ports. Hell, I find it odd that I've fried 3 ports in one quick swoop. I can't imagine 3 analog ports using the same analog to digital converter, maybe two yes but three seems like a jump.

I doubt that they are all fried also but I don't see anyone offering to help you remap the pins. Sent it in to Ultimachine and get it repaired. If your budget allows it I always recommend
having a good card in the printer and a good card as a spare.

I got this reply in my email from John Oly with Seemecnc:

_______________________________________________________________________________________________________________________________________________________
Jay,

Nope, not hard at all actually!

Open up the repetier.ino in arduino, which opens a bunch of other files. The top right drop down will list them all. Go to pins.h and once there, do a ctrl-F and search for RAMBo pin assignments. Underneath that, look for the #define TEMP_BED_PIN 2 and change the 2 to a 1 and save/upload. You'll now be using the number 1 pin (it goes 0, 1, 2, 3) which is the one next to the hotend thermistor
_______________________________________________________________________________________________________________________________________________________

Up to this point I have tried "1" and "-1" with no luck. I got John's email at work so I remoted home and changed pin 2 to 3 and uploaded to the printer. I'm not there sitting in front of the rambo board so I couldnt physically unplug the thermistor from port 2 and try in port 3 but as I connected with Repetier host, the bed temperature wasn't right again. It was acting dependent on the extruder temp with an offset of +3C. So if the extruder read 23C, the bed read 26C. As a test I turned only the extruder on and the bed temperature would rise as well always 3C above the extruder. I believe pin 0 is the extruder.

Anything popping out at anyone here? Shouldn't one of the other two unused thermistor inputs work? Does anyone know how many DAC's the 2560mega has and to what pins they are assigned to?

-Thanks

Not sure what's going on with my Rambo board. John Oly replied again and said that it was odd that switching the #define TEMP_BED_PIN 2 to "1" didn't work. I wasn't sure what else I could do, thanks for your help Geneb and John. I have bought another rambo board, it shipped out today.

Eaglezsoar what power source are you using for the 24V heating and where did you get your aluminum disk? Do you have a link to your dc-dc SSR? And what about wiring? Also what are the side effects of the 24V power source for your bed.

Thanks.

JAY wrote:Not sure what's going on with my Rambo board. John Oly replied again and said that it was odd that switching the #define TEMP_BED_PIN 2 to "1" didn't work. I wasn't sure what else I could do, thanks for your help Geneb and John. I have bought another rambo board, it shipped out today.

Eaglezsoar what power source are you using for the 24V heating and where did you get your aluminum disk? Do you have a link to your dc-dc SSR? And what about wiring? Also what are the side effects of the 24V power source for your bed.

Thanks.

Link to power supply used: http://www.ebay.com/itm/Meanwell-Power- ... 3f2cebec8f

The aluminum disk was purchased and a machine shop cut it to size here is the link: http://www.sandsmachine.com/alumweb.htm

DC-DC SSRs are quite common, I just did a search on Amazon. I also recommend a heat sink for it which are also sold at Amazon.

As far as wiring, the output from the Rambo heatbed goes into the input of the SSR The output of the 24V power supply goes to the output of the SSR and then to the Onyx.
When the Rambo turns on the heatbed it actually turns on the SSR and the SSR passes the 24V at approximately 17-18 Amps to the heatbed. The advantage is that the
current passes through the SSR instead of the thin copper traces and the cheap screws connectors on the Rambo.

The side effects is a faster warmup time and higher temperatures for the heatbed. No cons that I have seen.
Please everyone, I am well aware that the Rambo can handle the 24v, I chose not to do it this way. I have seen pictures of melted connectors on the Rambo from having
that much current going through it. You do yours anyway you want, I chose the SSR route.