Review of LulzBot Modular Print Bed Heater

So I broke my original Taz 4 Glass bed back before Christmas. I ordered a bunch of replacement parts, Modular bed (heater and glass), new silicone heater, and new borosilicate glass. Along with working on a plan B of an Aluminum plate.

This is my review of the new Modular bed for my Taz.
Let’s talk about weights first cause I know some of you guys are worried about that.
Heater with Stainless Steel heat spreader 1lb 9.4 oz
Modular Glass PEI - 1lb 8.4oz
Total 3lb 1.8oz

Original borosilicate glass 1lb 7.2oz (Minus PET Tape)
Silicone heater 6.8oz
Total 1lb 14oz

1/8thk Aluminum Plate 1lb 4.6 oz
Total 1lb 12oz

So you are gaining about a full pound of weight on the Y-axis. I haven’t seen any negative effects, but I run my machine at conservative speeds. I’m sure this extra weight will cause some of you guys issues at higher speeds.

Heat Mat
One thing that Lulzbot didn’t mention is they have changed the heat mat for this Modular bed system, or have at least used a different heat mat from the original one that came with my Taz 4. On this new heat mat, the resistive elements are thinner but are more evenly spaced across the bed, as shown in the pictures below.

New Heat Mat

Old Heat Mat

Temperature Accuracy
With the printer up to operating temp and allowing enough time for the temperature to stabilize I am seeing about 25C difference between what the printer is indicating and what I am measuring on the glass surface.

I haven’t had time to take a comparative measurement of an original glass bed. If someone has these values please let me know.

Temperature Distribution
I am seeing about a 2C across the bed with the colder areas being in the middle of the bed (Measured after 5hr print job). This is caused by the sagging of the 22 Gauge (0.0310"thk ) stainless sheet not contacting the glass in the center of the bed. I understand this is a compromise, a thicker sheet would not sag, but would increase the weight of the assembly. I am going to apply some small springs to help hold up the stainless plate and hopefully even out the temperature across the glass.

I’ve been running this printer continuous for 3 days now and not having to prep the bed with ABS/acetone slurry has been amazing. I have been running batches of small parts and they have been adhering well, I have yet to try a large ABS part. I worry that a large part may warp more on PEI than PET due to low holding force that PEI has (With PET I could load the bed down with ABS glue to ensure a solid bond).

Interesting, especially the new heater bit. I’ll have to see if I can get a raw unadhered one to put on a plate and shoot it with my thermal camera side by side. Thank you for the review!

I’m noticed the same temperature difference with my modular bed also. ABS sticks at 110C, so I didn’t think much about it. Wrote it off as the infrared not working properly with the translucent PEI & glass. Maybe putting a sheet of paper the PEI then taking the temp might produce more accurate results. One of these days I’ll check with the thermal camera…

To help with the sagging plate, I used binder clips on each side. It holds the glass to the plate… at least on the edges. May I ask the approximate gap on the leading edge of the bed? This apparently is by design, and the gap diminishes when heated… I haven’t removed the binder clips to verify.