better heated bed for SD4? (Page 3 of 4)

Wow...I guess that leaves me in the "Bah Humbug" category for NOT posting a diagram today!

You got that right...tough day Better now with a Martini

I wouldn't bet on it
On a side note: anyone interested in starting a pool as to whether or not AZERATE screws this up? 

Fire, fire everywhere ... let's hope not

I'm placing a bunch of orders for various parts I need while I'm away from my machine. Some sort of heatpad and SSR are on the list for sure... Gonna have to heat that bed up well all around to fully utilize that volcano

Some SSRs will build up their own resistance and it's better to overkill on the rating...I got a 60A rated SSR to control a maximum 20A board.

I also bought the optional heat sink and put a fan on it to keep it cool.

With regard to the SSR, I fried a 30A rated version when my PCB heater was rated for 20A...so I ended up with a 60A SSR...it still gets warm, but with a heat sink and cooling fan it works great.

Really just trial and error...

The bed draws 18-20A during warmup...then draws about 16A to keep temp.  Bear in mind my PCB is 10" x 10"

When the SSR failed, it just heated up so much that it fried the MOSFET within and melted the outer casing.  It also failed in the ON condition which would have been pretty serious if I had not been supervising.

Nothing happened to the Motherboard.

My SD2 is stock with a glass bed; the 10" x 10" is my self-built Ord Bot Hadron...

Yup! More info if you're interested:

* Higher amp rating = cooler running. Note that the full rating is specified assuming a pretty serious heatsink.
* As ironman can attest, failure can be fail-on, which is potentially a fire hazard, so it's worth investing in headroom. The SSR isolates the motherboard from the heatbed current, so a massive SSR failure will usually not damage the motherboard - this is an advantage of a relay in general.
* Mechanical relays also fail-on in high current applications (contacts spark, resistance goes up, heat generated increases, finally enough to weld), so really you don't lose anything by picking an SSR.
* The SSR can switch on and off quite quickly, and has a near infinite cycle life, so is compatible with PWM control of the bed (a mechanical relay will buzz and not last very long!!). Note that it may run hotter in PWM mode than bang-bang, as heat is generated in the transition as it switches. I'm not actually sure what kind of frequency the bed PWM runs at, I think it's quite low so you might not notice this...

So I have to come back to this thread again.
Many people here suggested me to go with PCB beds instead of larger heater pads.
But I recently looked up some ir images of heated bed comparisons, and MK2B heatbed shows 10-15C difference between the center of the bed compared to closer to the edges.
While an aluminum with appropriately sized heater mat below provides more uniform heating.

So I have a question to those who suggested me and anyone else who would suggest the PCB beds...
Do you guys print anything large? Where the edges of your model reach the edges of the print bed? Does that 10-15C deviation in temp cause warping for you guys?

My PCB bed hasn't shipped yet and I'm seriously considering not using them now and going with 8''x8'' silicone heater mat instead, if the temperature deviation would be an issue with warping, which is the sole reason I want to switch the stock 6''x6'' mat with a larger heater in the first place...

It's not a concern as long as my prints don't warp.
So as long as middle of bed being 10C higher doesn't cause warping as long as the edges of the bed are still above a certain temp, then I don't have a problem.
If, however, warping will happen at any temp if there's a temperature variations on the bed, then yeah, that's an issue.

That's the reason I wanted to replace the stock heater as I mentioned in my first post.

What's the largest object you've printed so far IronMan?