Faster Heated Bed

[Tincho85]

IF it doesn't work I wont buy a Fotek again.
Would this one work? http://www.ebay.com/itm/CRYDOM-SOLID-ST ... r#shpCntId

Just want to have a good alt option.
Thanks for your feedback.

[Tincho85]

Btw the heatsink is bigger than expected

[img]https://farm9.staticflickr.com/8708/163 ... b5e8_o.jpg[/img]

[dpmacri]

IF it doesn't work I wont buy a Fotek again.
Would this one work? http://www.ebay.com/itm/CRYDOM-SOLID-ST ... r#shpCntId

Just want to have a good alt option.
Thanks for your feedback.

I'm using a Crydom D1D40 and it's working great (I got mine for $15 off ebay which was a SUPER bargain). My heatsink is just a 1/4" piece of aluminum plate although it doesn't get hot at all (I can touch it without even noticing a temperature delta while the bed is heating). I go from 20c to 100c in about 3 minutes using a 24v power supply (Meanwell 600W version which I have dialed down to about 20v).

[Tincho85]

I'm using a Crydom D1D40 and it's working great (I got mine for $15 off ebay which was a SUPER bargain). My heatsink is just a 1/4" piece of aluminum plate although it doesn't get hot at all (I can touch it without even noticing a temperature delta while the bed is heating). I go from 20c to 100c in about 3 minutes using a 24v power supply (Meanwell 600W version which I have dialed down to about 20v).

Thanks dpmacri, if the Fotek goes on fire I will try to get a Crydom.
About the heatsink, maybe the one you have doesn't need a big one, but I've heard that the Fotek for example does need one.

Why did you dial it down to 20v? I've read about that but can't recall where.

[dpmacri]

I'm using a Crydom D1D40 and it's working great (I got mine for $15 off ebay which was a SUPER bargain). My heatsink is just a 1/4" piece of aluminum plate although it doesn't get hot at all (I can touch it without even noticing a temperature delta while the bed is heating). I go from 20c to 100c in about 3 minutes using a 24v power supply (Meanwell 600W version which I have dialed down to about 20v).

Thanks dpmacri, if the Fotek goes on fire I will try to get a Crydom.
About the heatsink, maybe the one you have doesn't need a big one, but I've heard that the Fotek for example does need one.

Why did you dial it down to 20v? I've read about that but can't recall where.

My power supply is a Meanwell 600W. I've read that continuous operation shouldn't exceed 80% (or something like that) which would be ~480W. Assuming my Onyx bed resistance is ~1 ohm that means I'll use 400W at 20V/20A, so I'm making sure to not be over taxing my power supply. I could probably leave it at 24v but it's heating up fine at 20 so hopefully I'll get longer life out of the power supply.

[Tincho85]

A little update... Today the PSU finally arrived!!!
It's a little bit big. Not a Meanwell though, maybe those are smaller.

[img]https://farm9.staticflickr.com/8742/172 ... 9216_o.jpg[/img]
Yup, it's sitting on top of the onyx...


Lets hope this weekend I can make the upgrade.

[Tincho85]

I'm kinda scared to do the 24v update. So please, excuse the silly question, but why does my SSR have different outputs?
Both will handle a + load so... does it matter where to connect the + psu or the + bed?


rpress SSR (Albertus Magnus thread http://forum.seemecnc.com/viewtopic.php?f=42&t=6539):
OUTPUT 1 (-)
OUTPUT 2 (+)
[img]https://lh6.googleusercontent.com/-CbDt ... 153842.jpg[/img]

My SSR:
OUTPUT 1 (+)
OUTPUT 2 (-)
[img]https://farm9.staticflickr.com/8753/163 ... 7d19dc.jpg[/img]


and another thing, It's recommended to add a fuse between the SSR and the PSU.
But of how many amps? and what kind of fuse? a car fuse will work?

[stevewm]

Have you just tried using a better ATX PSU first?

On my v2 with the stock power supply it took almost 15 minutes for the bed to reach 90. I switched it out for a nice Corsair CX750M rated for 60A on its single 12v rail. Bed now gets to 90 in less than 5 minutes. It seems to me the stock PSU just isn't up to the task.

[dpmacri]

I'm kinda scared to do the 24v update. So please, excuse the silly question, but why does my SSR have different outputs?
Both will handle a + load so... does it matter where to connect the + psu or the + bed?


rpress SSR (Albertus Magnus thread http://forum.seemecnc.com/viewtopic.php?f=42&t=6539):
OUTPUT 1 (-)
OUTPUT 2 (+)
[img]https://lh6.googleusercontent.com/-CbDt ... 153842.jpg[/img]

My SSR:
OUTPUT 1 (+)
OUTPUT 2 (-)
[img]https://farm9.staticflickr.com/8753/163 ... 7d19dc.jpg[/img]

and another thing, It's recommended to add a fuse between the SSR and the PSU.
But of how many amps? and what kind of fuse? a car fuse will work?

For the output of the SSR, put it between the ground (-) of the power supply and the bed. The positive (+) connection from the power supply should go directly to the bed. So think of the connection like this Power Supply (-) -> Wire -> SSR (+) -> SSR (-) -> Wire ->Bed -> Wire -> Power Supply (+).

[dpmacri]

I'm kinda scared to do the 24v update. So please, excuse the silly question, but why does my SSR have different outputs?
Both will handle a + load so... does it matter where to connect the + psu or the + bed?


rpress SSR (Albertus Magnus thread http://forum.seemecnc.com/viewtopic.php?f=42&t=6539):
OUTPUT 1 (-)
OUTPUT 2 (+)
[img]https://lh6.googleusercontent.com/-CbDt ... 153842.jpg[/img]

My SSR:
OUTPUT 1 (+)
OUTPUT 2 (-)
[img]https://farm9.staticflickr.com/8753/163 ... 7d19dc.jpg[/img]

and another thing, It's recommended to add a fuse between the SSR and the PSU.
But of how many amps? and what kind of fuse? a car fuse will work?

For the output of the SSR, put it between the ground (-) of the power supply and the bed. The positive (+) connection from the power supply should go directly to the bed. So think of the connection like this Power Supply (-) -> Wire -> SSR (+) -> SSR (-) -> Wire ->Bed -> Wire -> Power Supply (+).

Oh, and I should have mentioned that I found out this configuration the hard way Originally I had the SSR between the PSU + and the Bed. But that doesn't work -- the SSR ends up always "connected" (I initially assumed I had received a bad SSR) so the bed begins heating immediately. Anyway, once I switched mine around it worked (and is working) great

[Tincho85]

So insted of interrupting the + you are interrupting the - with the SSR?

[dpmacri]

So insted of interrupting the + you are interrupting the - with the SSR?

Correct. I know it sounds strange, but that's the way it works

[dpmacri]

After posting my reply, I went out and searched on how to hook up a DC-DC relay and found this: http://www.crydom.com/en/tech/tips/dc%2 ... elines.pdf which seems to indicate that the SSR can be either on the + side or - side of the load. However, for me it didn't work when I had the SSR on the + side. Maybe I had something else wrong, but it's a pretty simple hookup so I'm not sure

[Tincho85]

I would buy you a beer but we are a bit far away
It is connected like you said, and everything is working like charm. The PSU was dialed down to 21v just in case.

Now it take less than 5 min to get to 110ºc
The SSR is not getting hot at all, maybe because I only tested the time that takes to heat the bed and did not print anything yet, but time will tell.

In a few min I will be posting this wire config.


Thanks again for your help.

[Tincho85]

So, this is what I did, and its working... for now

[Tincho85]

The SSR heatsink was way too big, so I used an old heatsink from a PC, I think it was for AM2. Removed the fan and the support.
[img]https://farm9.staticflickr.com/8744/173 ... e312_o.jpg[/img]


Drilled some holes and tap them.
Two 12v fans connected in series so they can be wired to the 24v psu.
[img]https://farm6.staticflickr.com/5346/175 ... 45a8_o.jpg[/img]
[img]https://farm9.staticflickr.com/8849/175 ... 2a41_o.jpg[/img]


And because I'm a bit paranoic, the 24v update was hanged above my working table. This way I can monitor the SSR in case of fire
[img]https://farm6.staticflickr.com/5323/175 ... 2415_o.jpg[/img]


How it's wired:
[img]https://farm8.staticflickr.com/7685/169 ... 36c3_o.jpg[/img]



Hope this helps.
If you do make this upgrade, please share your results.

[Tincho85]

Still don't where to add the fuse. Any help on that matter would be great.
How many amps? and what kind of fuse? a car fuse will work?

[Heflin]

Automotive fuse is fine. The fuse just goes in line with the load. Positive or negative leg, before or after the ssr does not matter. Fuses are only used to protect the wiring! By the time the current exceeds the design of the load, the load has already suffered failure so the fuse prevents fire by not allowing the wiring to overheat.
Just as an fyi, remember the glass fuses that used to be in automotive and are still sometimes found under the post in automotive power port plugs, that glas fuse is rated for 250v but works equally well in 12v applications.

[Heflin]

On the fuse size, here is some content of a great post at http://www.oznium.com/forum/topic15761

[BenTheRighteous]

Fuse placement does matter. If the circuit problem is the load, then the fuse can blow anywhere in the circuit and it will be fine.

However if the problem is anything else, you want to fuse as close to the positive voltage source as possible.

Let's say you're working on the machine and accidentally pinch the positive lead of your heated bed with the ground of another circuit. If your heated bed's fuse is on the ground wire, the fuse won't blow and you've got a problem.

[BuckeyeVolunteer]

voltage goes up current goes down this is the law.

[BuckeyeVolunteer]

I actually think a good PWM power supply would work better to heat the bed up and there would alot more control.

[IMBoring25]

voltage goes up current goes down this is the law.

We covered this in this thread already. Only true when designing a circuit from scratch for a constant wattage. Putting more voltage through an existing circuit without increasing its resistance to compensate will raise current and wattage.

[bot]

voltage goes up current goes down this is the law.

We covered this in this thread already. Only true when designing a circuit from scratch for a constant wattage. Putting more voltage through an existing circuit without increasing its resistance to compensate will raise current and wattage.

Yup. I was proved wrong for making the same mistake. The onyx bed is a fixed 1.1 ohm resistance. 24 v makes that over 500 w, over 20 amps!! about 4 times what 12v is, like someone mentioned.

[IT_Cowboy]

Hey guys what crydom SSR would you suggest?