Today I mounted my MK3 heatbed. At first, I had the heatbed on top of the build platform, with some insulating cork under from reprap.me and a piece of glass on top (not the Vertex one).
It ended up being a really thick sandwich even with the thinner glass and printing wasn’t that big a succes, so instead I decided to risk my heatbed, it’s not that expensive, so if I destroyed it, it wouldn’t be the end of the world.
I removed the build platform, used epoxy glue to put some screws directly on the headbed and mounted it on the arms, put the Vertex glass with buildtak on top and bazinga, everything fit’s perfectly and it’s the same thickness as before. So now I can pretty easily swap the heatbed with the normal build platform if I ever need to.
Here are a couple of images of my work and a little “guide”
First I put the screws in place, put the heatbed on top and leveled it out, to make sure the screws would sit straight under the heatbed.
Carefully I put a little epoxy glue under the screws and made sure the heatbed was centered. The glue is extra strong and very hard after just two hours.
When the first drop of glue was hard, I removed the heatbed again to glue the screws even better.
I mounted the heatbed back to the arm and it fit’s perfectly. Slides right in. With the Vertex glass and buildtak on top of the heatbed, everything is 1mm less than the stock platform. I could use the Vertex clamps if I had bend them a little, but I didn’t want to do that now, I’d rather buy some new clamps and then mount them. Instead I used the known paperclamps, which I hammered down, to reduce the height. Not that I think it would be a problem, but now I’m 100% safe
Looks good! I might copy this procedure since I want to keep the glass plate for quick changes and easier removal of prints. Does the heatbed reach your desired temperatures now that you do not have any insulation? I guess you could glue the cork sheet to the heatbed as well, it looks like you might have enough space for it in the pictures.
I have a dedicated power supply for the heatbed and it only takes 1-2 minutes longer now to heat up with the glass on. I was afraid the glass would make it take forever, but that is not the case
It’s a good idear with the cork underneath, might try and glue that on, there is enough space for it.
The left part of the bed is not used (it’s the rest place for the heads when using two heads and they’re waiting for their filament to reach the right temperature). So you have to mount the MK3 on the right side.
Maybe someone could comment on this :
The 2x12V 105W halogen electronic transformers I used sag to 18V, unstable. Will not go beyond 57°C (the AC SSR is on 220V side)
Could I use a toroid 225W 24V AC or would it do ‘boooiiinnggg’ on each switch-on from SSR ?
Is there a hysteresis of the temperature i.e. make it 1°C so there will be less on-off cycles ?
[quote=“benoitmabille”]Could I use a toroid 225W 24V AC or would it do ‘boooiiinnggg’ on each switch-on from SSR ?[/quote]What kind of SSR do you use? You can’t use an AC device on the usual (MosFET) power expander and the power output must be regulated. With a bare transformer, the output will probably be way over 24V and spike on switch on.
Finally I choose a 24V 150W power supply, controlled by a 220V zero cross SSR (on the primary side).
3mm glass (same dimension as original) on top of MK3.
Works fine ! It is a delight to easily remove the objects.
However whatever the temperature (50-60°c for PLA), the sides of medium to large PLA objects do not stay flat
Is your buildplate perfectly flat? Most often it’s sagging a bit on the corners where the clamps are holding it, hence bulging in the center. So with large objects, the adhesion is not sufficient near the corners…
hhmmm… I’ll check but it is 3mm thick glass and even with small objects (5cm), the sides are not really sticked to the glass.
Therefore the bottom of the part is not perfectly flat.
If I stick buildtak on the glass, would heated buildtak stick too much ?
Alternatively, a sheet of 3mm inox wouldn’t be better for sticking PLA ?
[quote=“benoitmabille”]
If I stick buildtak on the glass, would heated buildtak stick too much ?[/quote]Probably.
You can remove the glass (or not) and try printing with blue painter tape directly on the bed. PLA sticks very well on it.
Also check the nozzle-bed distance : it should not exceed 0.2 mm.
I’m installing it the same way as you are, which brand and type of epoxy glue have you used?
Cause there are so many and some of them only have a temperature range to 60°C which is obvious to low.
[quote=“JNicholaas”]So this one (link) is also good? Cause that’s the one I find in shops here in the neighbourhood.
Also this one is available link.[/quote]
Both should do the job but the UHU is stronger - 300kg/cm² (and even stronger if you heat it during the hardening process). You can buy it on line.
