Modular Build Plate

I just installed the Lulzbot modular build plate on my TAZ 5 and tried it out by printing a small test model with ABS. I found the ABS would not stick to the build surface no matter what I tried. For the heck of it I checked the build plate temperature with an IR thermometer and found that the build surface was at 75 deg C while the bed thermistor was at 110 deg C. In doing some checks it looked like the heater plate was bowed down in the middle (away from the build plate) about 1.5mm, not making any contact over most of its surface. I added some binder clips around the build plate perimeter, but the bed temperature was still off by 30 deg C. Has anyone else seen this? It looks like the bed corner supports must be modified to remove a heater plate bind and some kind of support added under the heater plate center.

NZ

Did you print the new bed corners?
http://download.lulzbot.com/retail_parts/Completed_Parts/LulzBot_TAZ_Modular_Print_Bed_Heater_KT_HB0013/Production_parts/printed_parts/TAZ5_bed_corner_2pt_bed/

Yes I did. I think they may be part of the problem. It seems like they preload the corners of the heated plate and cause the plate to dish down or sag away from the glass build surface. When I get a chance I plan to open up the printed corners to provide more room for the heated plate.

NZ

That’s no good. I was just thinking about buying one of the modular plates. I have seen a couple other people complain about the droop.

I had to scrub the PEI quite a bit to get ABS to stick at 110C. Green scrub pad using a cross hatch pattern until the surface was hazy.

As for the gap, Lulzbot says its normal and should be compensated when heated by the spring metal… they should reverse the plate and let the glass “flatten” the plate for better contact. I use binder clips on each side to close the gap.

The removable plate opens a range a ideas for build plates. One of which is a removable 5mm PEI plate. The OEM PEI film on the plate will eventually bubble after use. I’m thinking about applying a thicker PEI sheet to the glass side to compare how it holds up and test if the bubbles will release from the film with the repeated heating against the metal plate.

Well, maybe I will pass on the modular plate.

If it helps you decide what to do, I have been running a 0.040" thick PEI sheet from CS Hyde on a gMax heated bed for a couple years with no bubbling issues. No issues at all, actually. It seems to be bulletproof.

I’ve had a pretty rotten experience with the modular build plate that I purchased. The combined thickness of the heat spreader and the glass+PEI surface ended up being 1.25 mm thicker than my original build surface. This doesn’t allow the washers to lay flat when secured.

Lulzbot support suggestions assumed operator error. Finally I made this video to illustrate that I was in fact installing the bed as per the installation guide. The said my installation looked OK and as long as the washers were tightened down in alternating order so that they are relatively flat, it won’t be an issue. They suggested compensating for the tilted washers by adjusting the z-offset. However, even when alternating tightening of the screws the washers remain at a severe tilt. I asked if they thought the fit was acceptable and if Aleph Objects would ship a Taz printer with a standard heat bed that fit so poorly.

They responded with: "The small slant you are seeing in the washers is within an acceptable range compared to what we see on the modular beds that we use in the office."

The modular print bed is advertised as a quick and easy upgrade, but this has not been my experience. I ended up printing 4 additional spacers at 1.25 mm thick that rest on top of the cylindrical spacers to allow the washers to lay parallel and flush to the build surface. The time investment involved in addressing the problem and having to derive a makeshift solution after spending $200 on a product is both frustrating and disappointing.

I went back to the original build plate and got back to having the ABS adhere to the build surface. As far as the modular build plate, I used binder clips around the edge and it closed up the gap at the edges, but I don’t know if the center still had a gap. My biggest concern was the IR thermometer checks which showed the 30 deg. temperature difference from the set point even after letting the bed preheat for 20 minutes.

Thanks for the tip on the surface preparation. Once I finish up a large job with the original bed, I’ll reinstall the modular bed and do some experiments to see if I can improve the temperature issue. I also need to verify if the IR thermometer is properly reading the build plate temperature because I noticed that the IR thermometer does not correctly read the temperature if it is pointed at the spring steel heat surface.

NZ

I was having the same issue with my TAZ5 with the heater plate sagging in the middle.

As work around until a permanent fix is implemented, support suggested that I use 4 of the TAZ 6 wiper pads to support the center of heat bed. With the wiper pads supporting the center of the heater plate, my bed temperature is within a couple of degrees of the display and uniform across the build plate.

You do need to print/use the bed corners in the TAZ 5 modular bed instructions. The link to the pads

I would also contact support about this issue if you haven’t done so already.

Here is the layout of the pads.

I’m going to wait until we get a better bed option, it being modular doesn’t do much good if it’s just the same print surface we already have. Spring steel with powder coated PEI like the Prusa MK3 would be awesome.

It would be nice, but it might be really long wait.

Prusa hit manufacturing issues with the PEI powder coated spring steel sheets and haven’t been able to produce them in large quantities yet. No solid ETA on when they will be able to resolve the problem and ship them. The MK3 is currently shipping with a spring steel sheet with PEI stickers on both sides.

I turned my TAZ 5 back on after a long period of not printing anything. I also saw a bunch of new accessories, and I went with the new Aerostruder. I like this printhead, but I also went with the new modular print bed. I think it was a mistake. My old print bed with buildtak coating did much better on helping items adhere to the print bed when printing with ABS, then I found this thread and now I see why. Thanks for bringing this up.

Well… if its any consolation, ABS will adhere to the removable glass/PEI. Just have to rough/scoff up the PEI. A green scotchbrite pad in a cross-hatch pattern works… but a fine grit sandpaper would have done it quicker. You want the surface to be hazy. Also may need a slightly closer initial nozzle height for ABS to stick well.

The bed is just another learning curve… In the end it will provide more options for print surfaces. I’ve stuck with just the PEI and glass, but I plan to get a second glass and put a thicker PEI sheet on both sides.


I think the steel bed and glass is too heavy for the stock springs… Probably need another set for to provide enough support.

I did some tinkering around and bought a set of assorted springs for $4.99 at Harbor Freight. Also used a few felt tabs from a furniture felt tab assortment from Costco. I found 4 of the lightest compression springs in the set and put some felt tabs at the top which contact the heat bed. I tried using the wiper pad solution but I found it difficult to level the bed once I had those in place. With these springs, leveling is much easier, and it doesn’t bow up the glass in the middle. It has solved my problem and I thought I’d share some photos.

This is the spring assortment I found at Harbor Freight


This is the Costco furniture felt tab assortment

These are the black felt circles I used from the felt tab assortment

I put them together like this and placed 4 of them on the aluminum plate below the heat bed. I spaced them evenly in a plus sign pattern.

Here is a shot of them sandwiched between the aluminum base plate and the head bed.

Both the wiper idea and the springs should help support the modular bed. I saw another mod recently using silicone tubing for the corners.

I’ll have to keep these in mind for the next bed overhaul. I’ve got a nice sweet spot going between the Dual V3 and modular bed.