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Delta Tower heated bed upgrade

Posted: January 19th, 2017, 11:34 am
by Anders Olsson
So, finally I found some time to document the heated bed upgrade we did on the Delta Tower printer, just in case someone else has this rather nice machine and thinking of doing something similar.

Here is how it looked before.
A bed that large made from metal, without heating, is not really working at all I can tell you.
People at work eventually developed all sorts of workarounds, like hot gluing warping things to the plate while printing :-? and we had to find a better solution.

I don't think Delta Tower sells this model anymore by the way, they appear only to sell larger and even more expensive models now days, but for anyone sitting with one of this or another large delta-machine this might be interesting.

Some of these machines were actually sold with heated bed, but it was underpowered and had very high mass, I think it was something like 20 mm thick aluminium (!) powered by 100 Watts. This made heating very show, according to sources reaching 90 C in 30 minutes, which corresponded to 60 C on the bed.
So that upgrade route was not an alternative for us.

After some searching the only suitable 400 mm heated bed kit we could find was sold by Ultibots in the US:
Unfortunately they don't ship it outside the US, so we had to wait until one of our colleagues was going there on a business trip and ship it to his hotel room :-)

Our workshop at the University made a 4 mm aluminium plate. They apparently had to roll the aluminium to make it flat, which is probably the reason for the extremely thick plate on the Delta Tower genuine heated bed.

When it comes to mounting the heating film, if anyone else attempts this, make sure you make the heating film flat BEFORE you start sticking it to the metal plate.
Once it is glued it is not coming off again, I can tell you that :-)
I did not manage to stick it 100%, but it was just a few small spots that did not stick.
I thought this would create hot-spots that could destroy the heater, but looking with the thermal camera the temperature difference between the parts sticking and the parts not sticking decreased with increased temperature, which makes sense when one thinks about it, so it is probably not an issue.
Still though, I recommend to try to make the heating film as flat as possible before you start sticking it!

The temperature sensor is mounted with a screw in the center of the plate just because there was a suitable hole in the heater film to drill a hole there.

Electronics before:
And after the upgrade:
The heated bed power supply is a MEAN WELL HRP-600-36 (630W / 36V) with adjustable output voltage.
I set the voltage to 33V since I thought 36V was a bit more than needed.
This power supply has the disadvantage of having a very noisy fan and goes on/off with the bed power, it is fine in our lab but you probably want to look for another PSU if your printer is staying in your living room :-)

The original heated bed output now just send its 12V output to the input of a solid state DC relay (Celduc SOM02060, 60VDC/20A), which switches the power from the 36V power supply to the heated bed.

I also upgraded the printer with a proper on/off-switch, since it was not equipped with such device upon delivery (!). One simply had to pull the plug when something went wrong, which was nether quick or convenient.
Three bed clips proved not to be enough, so I added another three to make sure the glass is touching the metal plate all way around.

The heated bed appears to work fine, even though I haven't tested it on any really large object yet.
It heats to 60C in ~4 minutes and 90C in ~8 minutes and will reach ~135 C in ambient 20 C.

If anyone is doing a heater bed upgrade on an identical machine, contact me if you want a copy of the heated bed firmware :-)

Re: Delta Tower heated bed upgrade

Posted: February 3rd, 2017, 2:55 am
by jonnybischof
Looks quite nice! Is that the Swiss Delta Tower ( ? These are really, really expensive for what they can do :D
(The RTA 500 - which is not the biggest model - weighs 75 kg o.O)

A tip for the heating foil: You can sting the bubbles with a needle and remove the air. But ofc it's best to place it so that there are as little bubbles as possible in the first place.

Re: Delta Tower heated bed upgrade

Posted: February 3rd, 2017, 10:59 am
by Anders Olsson
I think this one was much less expensive than the current models, I remember seeing something like 5kEuro for a kit (?), which is still quite a lot though.
They don't offer these "small" models anymore though as far as I can see.

I did try to cut holes in the bubbles with a razor blade, but it was still difficult to get the film completely flat, thank you for the advice though! :-)

Re: Delta Tower heated bed upgrade

Posted: August 15th, 2017, 3:14 am
by jonnybischof
Playing around with my own delta printer design again...
I really like the idea of delta 3D printers. They look so much cooler than cartesian printers while working, and they can also be made cheaper than cartesian ones since they don't need a lot of components.

I'm trying to work out the details of "how to best design the trapezoidal effector arms", but I don't really find any information about this :(
Things like optimal length vs. build platform size, and whether or not the trapeze shape is important.