hello,
has someone already finished a heatbed on the k8400.
is it posibble to make a power expander by myself?
[quote=“3Design”]hello,
has someone already finished a heatbed on the k8400.
is it posibble to make a power expander by myself?[/quote]
It should be doable if you are familliar with soldering.
Somwhere here on the forum is a design of such, including a layout for stripe PCB.
It’s very easy to do but has some limitation.
I got the headbed MK3 with alu core from reprap. Also the power expander. Got another 24V 150W power supply. It looks just like the original the vertex has just different voltage. Mounted the PSU near the original one. Only needs 4 holes in the bottom plate of the printer.
You do have to solder the thermistor and the wires to the bed.
I can give you a full description if you need it.
I have tried printing both directly on the bed and on the original glass with buildtak. I like the glass buildtak with heated bed underneath the most.
Hi,
It would be nice if you can post some picture of your vertex
I would like to see them as well
i will take some pics tomorrow and put them here with a more detailed description.
Well it’s an ok heatbed. Printing on the alu directly is easy and works with a little bit of glue (i used glue sticks because of the easy way to use them).
However after about 20-30 prints i do see more and more scratches. If you are very very careful you can get the print of without scratching however you cannot remove the bed as it is now wired to the printer and that makes taking off larger prints quite hard. So for me it got more and more scratches.
So i put the original glass back on top of the MK3 bed. It works however the temp is no longer accurate as the glass takes longer to heat up. Also max temp i get with 150W 24V power supply is about 90 degree. It gets a little higher but takes more then 15 minutes and i find that it’s not practical to wait that long for the bed to heat up. Without the glass i get a max temp of 115 but usable temp of 100-105 degree. However with the original glass and buildtak it seems that even 80-90 degree are enough for ABS.
Now some negative points. I use bulldog clamps to hold the bed or the glass to the original metal frame of the vertex. With this you lose some overall build volumes. Depending on where you put the clamps you can choose which axis you sacrifice but there is always a part missing. Specially with dual extruder setup. If you don’t setup the new build surface and adjust travel your head will hit the clamps. Don’t ask how i know that 
Another minor inconvenience is that you have to recalibrate the Z axis and with MK3 and glass i was almost at the maximum i could get from the screw on the back of the printer.
One big advantage of using glass is that you can just take off the clamps and take of the glass. On large prints with a big surface area sticking to the buildtak that is really helpful as it makes removing the print much easier.
Sorry for the long post. More to come tomorrow with pics 
I’m going to munt the heatbed using bolts and spacers so that the heatbed can’t ove over the alu plate of the vrtex and then i’m going to use bulldog clamps to hold a mirror with kapton tape on the heatbed.
The start point of the extruder can you change in the software. And the max z value can you also adjust so that you can still use the screws to level te bed
I did mount a MK3 heatbed and I’m using it without a glass. It fits in the stock clamps so I only needed to use one small bulldog clamp and I’m not loosing any space nor height.
To print ABS I’m coating PVC diluted glue on the bed. It’s easy to remove once cooling down.
I’m printing at 85-90°.
The power extender I did myself as it’s quite elementary.
How have you made the power expander?
There is a design here on the forum :
control circuit :http://forum.velleman.be/viewtopic.php?f=53&t=9598&hilit=24v+power&sid=389515d45bc179e673cd8bda894beb7e&sid=389515d45bc179e673cd8bda894beb7e#p37991
Easy to build if you are familliar to soldering electronics.
Another method can be to connect a relay to the heatbed output to switch the external power.
Like this :
viewtopic.php?f=53&t=9598&p=57390&hilit=flyback#p57390
I used this design :
It’s from the topic quoted by ichbinsnur.
Here is what’s needed (+ a 24V PSU) :
You can see the power expander inside my printer :
And the heatbed while printing ABS :
Edit : typo
That cork sheet is a nice idea to prvent heat loss.
Did it come with your heatbed PCB?
I tried a sheet of felt before but is was too soft to get the bed leveled.
cheers,
Christian
No I had a roll lying around but you can buy one with the bed.
Can you post some photos how you mounted the PCB heated bed?
Cheers,
Dylan
I just swapped it with the glass plate. I had to add a small bulldog clip on the front left.
sur l’une de tes photos je pense distinguer un circuit c’est bien le power extander que tu as relié a l’alimentation et au mk3 ?
Oui sur la vue interne de la Vertex. Il est pourvu d’un large radiateur (récup), tout à fait inutile en fait car cela ne chauffe pas du tout.
Why use every one th mk3?
Would it be possible to use a mk2 heatbed?
[quote=“3Design”]Why use every one th mk3?
Would it be possible to use a mk2 heatbed?[/quote]
The MK2 is a PCB heatbead (not flat you have to use a glass plate). The MK3 Is glued on a rigid aluminum plate.
The MK2 has only the 12V option the MK3 can be used with 12 and 24 V.
But yes it’s possible to use a MK2, even with a 15V PSU but then it drains 150W.