Build platform woes.

[DBFIU]

I initially used the material pretty much every printer comes with. Borosilcate, 1/8" thick. It's flat, cheap, and pretty simple to mount with clips.

For the average user, it's perfectly fine once set up. For what I am trying to do, it is a terrible curse.

My intent is to be able to print, edge to edge along the entire surface. Glass is notoriously bad at transferring heat, so if your heater is not able to distribute heat evenly, don't count on the glass being the same temperature in any of the 4 corners. This leads to warping, and air prints in the corners of your job.

Glass also takes forever to heat up.

I then started to use the MK3 build platform, it is 3mm thick aluminum with heater circuit built into it. Perfect! It can accept either 12V or 24V and comes with mounting holes. Pretty much a direct replacement for my printers.

I have no complaints thus far with the MK3 heatbed. In fact, I run a 24v 350 watt power supply to this bed (on the 12V) circuit and it gets up to 125C in less then 3 minutes. Pretty sweet. The build surface REMAINS FLAT WHEN HOT. That is the key point.

Here is the problem though. I use auto bed level exclusively on my machines. I print 24 hours a day. And my auto bed level does save quite a bit of time. The only problem is that my z offset doesnt remain constant, it changes whenever it decides. So this causes my extruder nozzle to dig 3mm into the bed and when it goes to wipe the bugger off after a purge, you guessed it, creates a nice deep scar in the aluminum (I use swiss AVN nozzles and I believe those are nickel nozzles). The aluminum gets scratched up, and looks terrible.

A lot of my prints require that the bottom surface of the print remain flat and glossy, this is best accomplished with a glass surface.

Now I know you will say "just put kapton tape on your aluminum, durr!". If I do that, and my nozzle decides to dig, it will destroy the kapton tape and that is a process in itself to re-tape my bed.

I am looking for a bed with all the thermal properties of aluminum and the hardness of glass (so it doesnt get chewed up incase my printer decides to become possessed).

I was thinking of putting the glass on top of the aluminum, I can already see the problems with bed temperature. The thermistor will register the aluminum temp moreso then the glass temp and who knows what temp the corners of the glass will be if the aluminum and glass are not in direct contact everywhere.

This is my dilemma, I just want a suitable platform! Either that, or figure out a way to keep my machine from changing the z offset every other print.

/rant

[3dkarma]

If you Z offset does not remain constant, does that not indicate that you're missing steps on the Z axis? You've implied that you have multiple printers - does it happen with all of them? You say the problem tends to happen after a purge - can you give more detail about the circumstance? I'm assuming this is a purge at the start of a print. Can you make bed levelling and Z offset part of your print setup procedure? Does your Z axis suffer from overheating? Have you tried fettling the vref? Are your Z motors wired in series or parallel? Is it an issue with one or both of the Z axis stepper?

Sorry for all the questions, but it's an issue with many possible causes.

[DBFIU]

Hi,

Thank you for the help.

I am certain z axis is not missing steps, I can see both motors turn continuously in unison. Also, they are bone cold, like room temp cold.

The motors are wired separately to the ramps 1.4, the ramps has two rows of 4 pins each for a z axis motor. Each motor goes to one row of pins.

I am not sure what vref is.

Both steppers seem to be working just fine, print quality is fantastic once it gets the correct z offset.

I feel like I am chasing my tail, the z offset changes. Sometimes it will remain consistent for a few prints, and sometimes it wont even remain the same when I reset my ramps and go to restart a print. I can see my LCD screen, z offset always remains the same NUMERICALLY, but in reality something is causing my nozzle to either air print, or dig 3mm into the bed very frequently without notice or an understanding as to why.

I hope I can solve this problem soon.

[lakester]

Is it possible that something, perhaps setup or maintenance related, is displacing the z-rod nuts? I.e., is something "unloading" the x axis from the z-rod nuts?

People have mentioned something like this happening when they've homed on Z with the HE still oozing. As the HE cools, the plastic/HE/bed become somewhat bonded to each other. Then, if a +Z move is made before things have heated back up, the z-rod nuts can back out of their capture holes, since the HE is somewhat stuck to the bed.

That's one way, I imagine there are others.

0.02USD...

[Mjolinor]

You cannot "see" Z miss a step, you can hear it in a lot of cases but it is by no means guaranteed that you will.

[DBFIU]

Is it possible that something, perhaps setup or maintenance related, is displacing the z-rod nuts? I.e., is something "unloading" the x axis from the z-rod nuts?

People have mentioned something like this happening when they've homed on Z with the HE still oozing. As the HE cools, the plastic/HE/bed become somewhat bonded to each other. Then, if a +Z move is made before things have heated back up, the z-rod nuts can back out of their capture holes, since the HE is somewhat stuck to the bed.

That's one way, I imagine there are others.

0.02USD...

This is definitely not happening. The Z axis motors are not skipping either, I can clearly hear when that happens.

Something about this seems software related... I just have to figure out what it is.

[Roxy]

Where did you get your version of Marlin from? Which version are you running? Right now, the quickest way to get you fixed would be to take the BeckDac version for MakerFarm printers and put your Configuration.h settings into it. You can get that here: https://github.com/beckdac/Marlin

If you had a MakeFarm printer, you would just compile, load and go. But what you have is very similar and if you cross your important values from Configuration.h over into its Configuration.h file... It is very likely you can leave this problem behind.

[DBFIU]

Where did you get your version of Marlin from? Which version are you running? Right now, the quickest way to get you fixed would be to take the BeckDac version for MakerFarm printers and put your Configuration.h settings into it. You can get that here: https://github.com/beckdac/Marlin

If you had a MakeFarm printer, you would just compile, load and go. But what you have is very similar and if you cross your important values from Configuration.h over into its Configuration.h file... It is very likely you can leave this problem behind.

I think I am going to try that Roxy, that is probably my own hope as of now.
I will try this tonight, thank you!

[Roxy]

You didn't answer these questions:

Where did you get your version of Marlin from? Which version are you running?

That would be helpful information to know.

[DBFIU]

I got it from here.

https://github.com/MarlinFirmware/Marlin

I believe it is 1.0.5.