Heated Bed Build Plate

[msdevstep]

I think I may be doing something wrong. I have my Rostock MAX printing, and it's printing on what feels like a plexi glass build plate that was included (and is being held on by the binder clips). My problem however is my prints are literally fusing to the build plate. Like I have to actually use a grinder to get the plastic off of it. My Phebe I has been running at 70 C, and I've tried pulling my prints off while it's still hot, and after letting it cool down. Either way it's completely destroying everything I print. What am I doing wrong?

[kometen]

Hi,

You need to have some tape between the plate and your model. I have learned that most people use 'blue painter tape'.
I am using standard painter masking tape, and so far it works for me. However, some of the filament goes still goes through the tape and adhere to the plate.

I have replaced the pvc plate with a heat resistant glass. It is easier to clean, but takes longer time to heat.

[jimrk]

try running the bed at 50 c. I think I heard John say that.

[Polygonhell]

I destroyed my plate, but John suggested using a much lower bed temperature when I discussed it with him afterwards.
I'd probably start with a cold build surface, then move up in 10degree increments, but John suggested 50 degrees, I'm unclear though if he meant 50 on the surface of the build plate or a thermister reading of 50, because there is a big difference .

I'm currently printing on PET tape on a glass build plate, just a $2 piece of window glass cut by my local hardware store.

[msdevstep]

In their videos, I see them printing right on the plate. That's what I'm after. What are they doing differently?

Thank you everyone for your replies.

[v8tony]

I'm not using the plate that came with the kit. I was assuming that was for PLA and not ABS. Since I have the ONYX round plate I'm using a piece of glass (pretty thick) that I had cut a local shop (since I couldn't find a 280mm piece of round Borosilicate anywhere). I printed some clips to hold it down and I use blue painters tape.

If your first build layer is set so low that your cutting through the painters tape and some of the ABS is getting on the glass I think your doing something wrong. I'm able to reuse the tape that I lay down for 3 or 4 prints most of the time...

I'm only printing ABS and I run the bed temperature at 100 deg C for the first layer and crank it down to 80 for the rest of the print. So far I've printed silver, red and natural ABS and they have all acted pretty similar.

Here is a quick picture of what my setup looks like. I replaced 3 of the 6-32 screws that hold the base together with longer ones so they could serve double purpose for clamping the galss and holding the base together. I only have 2 screws that aren't under the glass holding down the actual ONYX plate since I didn't want the heads of those screws to hold up the glass. I poked my thermistor throught he center hole and RTV'd it in so that it was proud by about 2mm from the surface (so the glass pushes it back down). That way I'm getting a good reading on the bottom of the glass. For what it's worth my IR termometer says the blue tape gets to about 200 deg F when I have the plate set to 100 deg C (212F).

The 2 smaller pieces of tape are there to have a consistant distance to level the print head at all 3 post (FYI)...

If someone has a better system or suggestions for me I'm listenting...

Tony

[msdevstep]

Thanks, that helps. Perhaps that PVC plate is only for PLA. I noticed it doesn't sit very flat either when clamped down. I think I'm going to try the glass setup, similar to what you showed me. Thanks for the detailed feedback.

[dgirard]

I too had a problem with the pvc plate.

Mine was fine for the first print or two, then while I was trying to work out other issues, I noticed that it was warping, and ultimately it "etched" itself on the underside in the pattern of the heating elements (and quite badly warped)

I got out my laser temp probe and saw that my heated bed was *way* hotter than the thermister was indicating...Not sure if the thermister is reading differently than originally (i suspect it is)...but now if I set my temp to 60c I get a heated bed temp of ~100c...If I see much further variance I may have to replace the thermister...

So, I now have a piece of glass with blue painters tape...with the temp actually at 100c my prints are starting to stick as I would expect....now I just need to get the extruder tuned in...

[fredini]

Yeah, I noted elsewhere that the thermister positioning is not a real reflection of the center of the plate's temperature. My other printer uses a thermister under the center of the plate, rather than off to the side. On my Rostock Max, I cannot get the bed's temp reading to go much higher than 90, but my IR thermometer reads more like 148 in the center of the plate.

[Polygonhell]

Yeah, I noted elsewhere that the thermister positioning is not a real reflection of the center of the plate's temperature. My other printer uses a thermister under the center of the plate, rather than off to the side. On my Rostock Max, I cannot get the bed's temp reading to go much higher than 90, but my IR thermometer reads more like 148 in the center of the plate.

It's extremely common for bed temperature to be massively under reported by the thermister, regardless of the bed type or printer type.
I checked mine when I first wired it, it's ~30 degrees low @ 100 degrees measured on the bed, my mendel max with a "Mk2" heated bed is a bit closer ~20 degrees low.
It's not really surprising if you look at the position of the thermister and the contact area.

It doesn't matter as long as you realize this and set the temperature to whatever the thermister will report when the bed is at the temperature you desire.