It works. Took about 23 minutes to reach 50 degrees.
I want to thank everyone here for their help.

In case anybody wants to repeat my success, here is what I did:
this heater element:
https://www.mcmaster.com/3575K411/
with this fan:
https://www.mcmaster.com/1976K95/
this SSR:
https://www.amazon.com/gp/product/B07FVR37QN/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
this thermistor:
https://www.amazon.com/gp/product/B07V6YBFSY/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
and this TCO:
https://www.amazon.com/gp/product/B07JM2DB67/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Wired them up per this diagram

@mrehorstdmd said in Chamber heater plan:

Wiring:

this may be a stupid question, but why are you bothering to dry ABS?
I thought ABS was hydrophobic and therefore won't absorb water.

At the risk of dredging up a dead thread, i want to give one last update.
I didn't calibrate the MCU temperature sensor, so i'm going to do that and it should fix the issue i mentioned in my previous post.

I run a 3d printing user group out of the Improving Office at 10111 Richmond ave, Houston TX every 3rd monday starting at 6PM.
Our next meeting is the 16th, and we're talking about gears.

There is free pizza and beer.
All are welcome.

Here is a link to the meetup group.
https://www.meetup.com/3d-Printing-Concepts-to-Contraptions/

if it says its full just pm me and i'll delete some bots and let you in. Meetup has tons of bots join groups to get them to 50 so we have to upgrade to the more expensive plan.

Klein makes excellent wire strippers. Best I've ever used. Gotta strip before you crimp.
And I second the 'right tool for the right job' sentiment. especially regarding crimpers.

I think I fixed it.

I repositioned the fan blowing at the MCU so it aims underneath instead of directly at the board from the side(see picture). That fan was standing straight up vertically, now angled down under the maestro.
Haven't seen a warning since.

@mrehorstdmd said in Chamber heater plan:

@oryhara Photo of the assembly?

here's the SSR up top in the electronics area.

here's the heater and fan.
The brackets made acquaintance with a belt sander to clean up the bandsaw cuts, per CalvinX's suggestion.

and the tco

It's not exactly like the wiring diagram. I'd rather the TCO killed just the heater and not the heater and fan but that cabling would be much more complicated.

Now I'm testing how much warp i get on an ABS print by printing something that would totally warp without a chamber heater. This V-shaped shelf bracket:

I have a plan to build a chamber heater for my anycubic predator. I just want to run that plan by some folks that are smarter than me before I go and do something stupid.
I have an anycubic predator running a duet maestro and a smart effector. I have a fan on E1, so I can't use that pin. But I figured I could use output EXP_0 from the expansion header to control a 25 Amp SSR in bang-bang mode, with a 110V heat gun in the enclosure as the heating element. I picked a heat gun because its got heating element an fan and that seems like the best way to do a chamber heater.
Is this a terrible idea? If so, why, and do you have an alternative suggestion?

@dc42

I had a similar idea. its much bulkier than it needs to be for sure. I'm not obsessed with speed. I'd rather have rock-solid reliability.

In use, I found the cables wiggled enough for the conductor within to break at the point where they are 'clamped' to the strain relief part(the 2 flat bars pictured clamp wires to the strain relief piece). I think I was also clamping it too tightly.

I have observed numerous failures now of the 8-pin cable on my Smart Effector. I have seen this on 2 3.0 models and now a 4.0. The 4.0 has not completely failed yet, but I have seen some 'noise' in the temperature readings, especially when the printer is making small moves back and forth quickly, such as filling narrow areas.
I crimp the 8-pin JST connector with the following tool according to its instructions:
https://www.amazon.com/gp/product/B002AVVO7K/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

The readings are without issue for quite some time, months maybe depending on how much I use the printer, but eventually become noisy and cause spikes and temperature faults during a print.

Is there a way to glue the pins into the connector to provide some strain relief?
Silastic or hot glue, maybe?

The printer is an anycubic Predator, so the cable from the Duet 3 mini 5+ and the effector is about 1 meter long.

I can provide further details about the cable and my attempts at strain relief if that would be helpful.

@mrehorstdmd Yea i learned my lesson soldering the TCO doesn't work. did that with the first one.
I bought a pack of ten off amazon so no safety certification at all. but at least I have spares.

I tried a 220V fan initially but it wasn't 'cooling' the heater adequately. The back wall got too hot(for my comfort) and the thermistor didn't rise above 36C. So now its a 110V fan and yes it runs at full speed. 34CFM iirc the specs. Could be what was causing the warp since that happened 'downwind' of the general direction the fan is blowing. Maybe i'll move the whole assembly up a bit on that extrusion so its not blowing at the bottom of the print area there where it can cause problems with this object.

I agree first layer adhesion is a different issue. that's why im trying again after cleaning the build surface well. It hadn't been done in a while so probably might have contributed to the adhesion problem.

the leads on the TCO aren't long enough to move it further out of the anderson connectors.
Good idea on connecting the heater from below I'll get on that.
But i can't put the heater in another orientation or it won't fit(without compromizing build volume) unless I move it to the top of the enclosure.
The fan keeps the back wall cool by moving hot air off the heater so it doesn't make the back wall hot. It's really not that close despite the angle of the picture.
The TCO should trip before the back wall melts according its melting temp. Granted I haven't tested that scenario. It doesn't get more than 'warm' to touch. you can see my hand smudges on the outside of the window in this picture.

That's taken with my phone right against the plexiglass.
Though I guess if the fan fails then I might be in a pickle.

My test print was a failure. It still warped. THen when I tried it with a brim it wouldn't even get the first layer down without peeling up.
I'll try again later with a PEI build surface instead of this whatever-material that came with the printer. Or maybe I'll put down some ABS juice.

@mrehorstdmd said in Chamber heater plan:

@oryhara Photo of the assembly?

here's the SSR up top in the electronics area.

here's the heater and fan.
The brackets made acquaintance with a belt sander to clean up the bandsaw cuts, per CalvinX's suggestion.

and the tco

It's not exactly like the wiring diagram. I'd rather the TCO killed just the heater and not the heater and fan but that cabling would be much more complicated.

Now I'm testing how much warp i get on an ABS print by printing something that would totally warp without a chamber heater. This V-shaped shelf bracket:

It works. Took about 23 minutes to reach 50 degrees.
I want to thank everyone here for their help.

In case anybody wants to repeat my success, here is what I did:
this heater element:
https://www.mcmaster.com/3575K411/
with this fan:
https://www.mcmaster.com/1976K95/
this SSR:
https://www.amazon.com/gp/product/B07FVR37QN/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
this thermistor:
https://www.amazon.com/gp/product/B07V6YBFSY/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
and this TCO:
https://www.amazon.com/gp/product/B07JM2DB67/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Wired them up per this diagram

@mrehorstdmd said in Chamber heater plan:

Wiring:

this may be a stupid question, but why are you bothering to dry ABS?
I thought ABS was hydrophobic and therefore won't absorb water.

Yea bang-bang mode with manually-configured heater model worked ok.
Well I say ok. The firmware ran it without complaint. But 20 minutes later and my chamber temp didn't read more than 36degrees. Running both bed and heater I expected more.
And the clear panel nearest the heater element got too hot to touch and started to bow inward. Probably is too close.
I think I need a more powerful fan on the heater element. the 220V is moving but probably not enough if its radiating heat like that and not getting hot air to the thermistor.

Also my thermistor is in a metal casing which might be throwing off the reading by acting as a heat sink. maybe? I'm no expert. I bought this: https://www.amazon.com/DROK-Waterproof-Temperature-Thermistor-Transimitter/dp/B01MR37GOQ/ref=sr_1_6?dchild=1&keywords=thermistor&qid=1608467027&sr=8-6
for my chamber heater sensor. maybe I should have bought a bare thermistor.

Im going to order a 110V fan and see if that improves the chamber heater performance. 'cooling' the heater element faster should raise the ambient air temp in my enclosure faster. until they reach equilibrium. This base on my imperfect memory of high school science class. Of course there are losses to the air outside my enclosure based on the insulation effectiveness. My 1/8" clear plexiglass panels are not as good as corrugated ones. And my enclosure isn't perfectly airtight. There are holes for cabling.

still no joy with M303 but with a gain set nice and low M141 seems to be working ok. I set the model parameters manually per the instructions:
https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control#Section_Setting_the_model_parameters_manually

so now I get to make it pretty.
@CaLviNx you said something about a file? what needs filing?
you want I should round off the corners of the mounting bracket?

@CaLviNx form follows function

like i said I'll make it pretty when it works.
which it doesn't at the moment. I can't get M303 to run because it heats so slowly, even with the bed at 100 degrees.

@mrehorstdmd I'm curious how you got your chamber heater model to work, given you said it takes 20 minutes to get to 50C