I have what looks like a similar oven I use for reflow. It has heating elements above and below the racks. I have a single sheet of aluminum in the middle position to hold my circuit board being reflowed. I use a thermocouple attached to a chunk of circuit board, screwed to the aluminum tray. I don't have a door actuator, but rely on me being there to open it during the cool-down cycle.
My controller is an arduino-style "ItsyBitsy M0", and it drives an optoisolated SSR between the wall power and the oven power cable.
My oven is un-modified, and I found that the heating and cooling rates with the heater 100% on and off were pretty close to the desired profile.
I have an auto-learning program that adjusts the on and off timing to hit my targets after a few calibration runs. There is no fancy PID loop or proportional heat control, it's just on and off.
I have the electronics in a small aluminum chassis, with a couple of buttons and a display, and I can control it with those. I also have a USB serial-port interface which lets me control the thing from a program running on a PC -- this gives me nice charting and logging. I also have duty-cycle heater control capability, and sometimes use that if I want to use the oven for medium-temperature thermal testing, but for soldering the on/off heater control works well. Duty-cycle control would only slow down the heating ramp, and it's already barely fast enough.
https://www.rocketscream.com/blog/product/tiny-reflow-controller-v2/ (https://www.rocketscream.com/blog/product/tiny-reflow-controller-v2/)
I installed the Solid State Relay in the right hand sidewall.
I also added high temperature mat insulation in the various cavities. Without the insulation, I couldn't get up to temperature fast enough. McMaster-Carr carries it but I don't remember which variant I used:
From my experience with toaster ovens, they never cool down fast enough, even when the door is fully open. The reflow profile is at the board level, not the air inside the oven. If you attach a thermocouple to the board, you’ll see that it stays at dangerous high temperatures for way too long if you don’t blow air on it.
if you open the door it won't be so bad.
I just ran some tests with my un-modified Black & Decker toaster oven:
I'm fairly comfortable with the cool-down when I open the door. This is in a garage, fairly cool but no particular airflow. I also think that the pre-heat, soak, and reflow are reasonable. I'm using a leaded solder paste and have a reflow target of 230 deg C. Perhaps with added insulation the cool-down might not be as rapid?
(is image in-lining still not working?)
More than 2 minutes above 200 C? Good luck!
MAX31856 thermocouple test
Thermocouple type: K Type
C = 22.0
F = 71.7
Turning OVEN on
C = 44.1
F = 111.4
monitoring OVEN
C = 44.1
F = 111.4
monitoring OVEN
<snip>
C = 89.9
F = 193.9
monitoring OVEN
C = 89.9
F = 193.9
monitoring OVEN
C = 90.0
F = 194.0
Turning OVEN off
I bought recently a T962 for 120CAD but it’s a piece of crap. The temperature difference between left and right is about 10 C.
Wire up the door actuator controls to the arduino and get code written that can open and close the door.
One open issue I have here is figuring out the door position at a moment in time, so I don't try to drive it beyond it's range of motion. Since the linear actuator works at fixed speed, I could just "do the math" and not worry about measuring the door position empirically. Or... dunno. Haven't given this part a ton of thought yet, TBH.
You might get some ideas from this Coffee Roasting firmware/hardware including PCB shield for SSR and fan controls. Coffee Roasting and PCB ovens share a similar temperature controlled ramp soak and rapid cooling process. In particular look at the slow PWM part of it to drive the SSR. https://github.com/greencardigan/TC4-shield (https://github.com/greencardigan/TC4-shield) People have used small turbo ovens with a Rotisserie and drum for roasting but the standard mod was always Insulate the body for better stability and control and generally adding some airflow from adding a fan and exhaust.
greencardigan is a member here too.
- First insulation is your friend. One of the gotchas with conversions is making sure the oven is easy to insulate. It makes a huge difference in the temperatures you can achieve and the power you will use to get there.
- If you are going to use SSR you might as well buy an optically isolated one. More so I believe that most on the market are isolated in some manner.
- Make sure your wires are temperature rated for the location they are in.
- Don't assume that the unit will never be run unattended, thus design in safety in case something of higher priority comes up and you get distracted. Your best intentions can be trumped by a kid crashing a bike and bleeding all over or the wife saying her water broke and you need to go to the hospital. Or if you are like me you can some times just focus on something to the exclusion of the entire world and forget what is going on. This goes back to over temp protection and frankly a limit on cycle time.
- Kinda related to the above add a buzzer or bell to alert you to the end of cycle or other program steps. You might not need it all the time but it can really help when developing recipes and doing things like manually opening the door.
- Data logging can be a great diagnostic tool. Even if it is a file on secondary storage that get over written with each run, it can be a bit help. So consider that when writing your oven control software. The only trick here is to find the right sample time to catch glitches yet not blow up file size.
I had to buy fiber glass silicone wire (the same kind as in the oven) to make the power and fan control extensions to my control box which was bolted to the side of the top chassis. I usex like a 10x10x5 box on the side, and the lid of the box I made from 3/16 thick preforated steel sheet, so the PID and SSR are sure to get good cooling (like old HP equipment, but bigger preforations since its a power device without a internal heatsink).
Don't miss the detail, match the same type of wire they have in the oven side cabinet to the wire you are leading out, it gets pretty hot. They used the same type of wire for everything in mine, including the low power fan, until it got to a distribution block inside of the metal box, where I switched to conventional wire, since that are does not get hot.
Because I was too cheap to get a big base plate, to get stiff/ridgid mechanical assembly, its built for service by a octopus (i.e. mirrors and right angle key to service some things), thankfully my PID comes in a sleeve so theoretically I can swap out every part without undoing the wires, so long nothing in the oven breaks, then I will be cursing hard, well maybe if it broke right after I made it, but its been a year so I think I won't be too upset doing a bit of difficult disassembly.
That is similar, but I went with color coding and 12awg for a premium lol,
you can put heat shrink on the ends of the wire going into the chassis with the correct color code
MAX31856 thermocouple test
Thermocouple type: K Type
Turning OVEN on
6094,38.70
8095,38.74
10096,38.92
12097,39.48
14098,40.01
16099,40.76
18100,41.38
20101,42.32
22102,43.68
24103,44.92
26104,46.48
28105,48.45
30105,50.43
32107,52.88
34108,55.23
36109,56.72
38110,58.66
40110,60.77
42111,62.39
44113,64.33
46114,66.89
48115,69.15
50116,71.81
52117,74.73
54118,77.52
56119,80.40
58120,83.06
60121,85.89
62122,88.76
64122,91.73
66123,94.66
68124,97.58
70125,99.91
72126,102.75
74127,105.54
76128,108.15
78129,110.71
80130,113.55
82131,115.97
84132,118.54
86134,120.90
88135,123.23
90136,125.71
92137,128.09
94138,130.46
96139,133.08
98140,135.23
100141,137.30
102142,139.69
104143,142.20
106144,144.77
108145,147.09
110146,149.40
112147,151.77
114148,153.75
116149,155.80
118150,157.81
120151,160.20
122152,162.41
124153,164.43
126154,165.95
128155,167.55
130156,169.28
132157,171.14
134158,172.90
136159,174.64
138160,176.48
140161,178.12
142162,179.54
144163,180.73
146164,182.05
148166,183.74
150167,185.57
152168,187.45
154169,189.18
156170,190.81
158171,192.52
160172,194.12
162173,195.80
164174,196.96
166175,198.50
168176,199.80
170177,200.97
172178,201.88
174179,203.13
176180,204.23
178181,205.58
180182,206.45
182183,208.28
184184,209.75
186185,210.84
188186,212.09
190187,212.93
192188,214.21
194189,215.20
196190,215.73
198191,216.87
200192,218.16
202193,219.02
204194,220.09
206195,220.93
208196,221.87
210197,222.83
212199,223.62
214200,224.29
216201,224.83
218202,225.88
220203,226.89
222204,227.71
224205,229.41
226206,230.29
228207,230.56
230208,231.59
232209,232.15
234210,233.00
236211,233.88
238212,234.80
240213,235.68
242214,235.87
244215,236.47
246216,237.03
248217,237.43
250218,237.94
252219,238.37
254220,238.89
256221,239.70
258222,240.63
260223,241.34
262224,241.95
264225,242.40
266226,243.06
268227,243.29
270228,243.59
272229,244.30
274230,244.66
276231,244.95
278232,246.23
280233,247.23
282235,247.55
284236,247.79
286237,248.37
288238,249.31
290239,250.00
Turning OVEN off
Good progress! I would be interested in the temperature ramp after you turn off the heater. On mine, the temperature continues to rise for quite a while.
0,29.21
2,29.25
4,29.25
6,29.21
8,29.21
10,29.23
12,29.30
14,29.44
16,29.68
18,29.91
20,30.30
22,30.75
24,31.33
26,31.98
28,32.79
30,33.71
32,34.79
34,35.91
36,36.99
38,38.45
40,39.77
42,41.46
44,43.19
46,44.95
48,46.70
50,48.57
52,50.59
54,52.70
56,54.86
58,57.18
60,59.40
62,61.76
64,64.00
66,66.50
68,69.02
70,71.49
72,74.17
74,76.94
76,79.66
78,82.38
80,85.20
82,88.01
84,90.89
86,93.78
88,96.70
90,99.67
92,102.68
94,105.45
96,108.47
98,111.59
100,114.45
102,117.34
104,120.23
106,123.29
108,126.22
110,129.09
112,131.96
114,134.71
116,137.52
118,140.55
120,143.35
122,146.27
124,148.97
126,151.77
128,154.49
130,157.11
132,159.80
134,162.45
136,165.24
138,168.12
140,170.59
142,173.07
144,175.52
146,178.14
148,180.67
150,183.06
152,185.30
154,187.61
156,190.00
158,192.35
160,194.48
162,196.81
164,199.04
166,201.21
168,203.29
170,205.52
172,207.52
174,209.66
176,211.77
178,213.76
180,215.70
182,217.84
184,219.87
186,221.84
188,223.83
190,225.77
192,227.60
194,229.45
196,231.41
198,233.20
200,234.97
202,236.46
204,238.06
206,239.95
208,241.79
210,243.52
213,245.16
215,246.80
217,248.16
219,249.65
221,251.42 # elements turned off here, as soon as temp > 250.0
223,252.95
225,254.27
227,255.27
229,255.77
231,256.19
233,256.43
235,256.75
237,257.18
239,257.54
241,257.59
243,257.71 # temperature peaks here, 22 seconds after the elements are turned off
245,257.67 # and declines from here on
247,257.34
249,257.02
251,256.62
253,256.20
255,255.62
Unlikely it is the bead type thermocouple lagging so it is more just a case of some thermal inertia carrying you past what you are aiming for. In Coffee Roasting we have a different set of issues as the beans go exothermic during the roast but if we need to bring the ramp down a quick blip of air through the chamber is way faster than waiting for the Element and Metal/Bean mass to respond.
Is your code written to work from actual temperature data only or does it look at a Rate of Rise/Fall as well? RoR or some sort of Temperature average over a few seconds is sometimes a better thing to run from.
Again, I'm not seeing the value in using a proportional heater drive. I do this when doing thermal testing of components and I want to maintain a fairly low temperature in the toaster, but for the reflow even 100% on / 100% off barely gets me to the desired thermal ramp rate. Using anything less than 100% is only going to slow down the rate of change. Perhaps if I added insulation a proportional control would make sense.
do you have the fan in your oven? It makes a big difference, even a small slow fan
I thought there was a fan in the oven, based on your picture.
I see a motor and some kinda vents in the side of the oven in the opening pictures in your thread. What am I looking at?
https://lh3.googleusercontent.com/pw/ACtC-3en77W0POn-RK16h_JZ2_LsB2ruJMBqGtA-JGGH6liVDBJRKC-_dlcBIdCFZGUCJPs9bT6etZf53wocdq4lBrfRc5DzyTUNW0X6xj2Rws_dt5OxKHtBWoktv4rUaSdeQxlRyrjh598n_k2_PZgPNq31=w1244-h933-no?authuser=0
at the bottom, that looks like a circulation motor.
Well you are not turning the fan on and off on the SSR are you? Thats why I put its own mechanical switch, for instance if I am preheating parts for soldering, welding, painting, curing epoxy at some random elevated temperature, etc, I keep the fan off. I might be useful to not have a fan going if you are just doing a warming cure of saying potting compound. You get more out of your oven IMO if you have the option to disable the fan, it seems unnecessary for some times, and you can experiment which thermal profile is better.
I thought to add a speed controller for the fan too, it should fit in my oversized chassis, but its already pretty weak as it is, and I am not sure how much it will like a controller since its already operating in pretty extreme conditions for a fan, I am not sure about those cheap AC motor speed control circuits and how they do with heat and what the effect on the coils is.
I have an external SSR in the middle of a short extension cord that the oven is plugged into. The SSR, and my controller are all powered via the USB interface to the controller.
Just for fun, I've been trying to model the thermal behavior of the oven, and I've come pretty close with an electrical equivalent in LTSpice. I ran some tests with the heater at 10% and 30% duty-cycle to see what the steady-state chamber temperature was for a given heater power, and logged the door-closed cool-down cycle to find the chamber thermal mass (capacitance) and the chamber-to-ambient thermal leakage (resistance). I also empirically added a second R-C delay to the circuit to model the heating/cooling lag in the heater element. This gives me my overshoot. The component values look strange because I've been playing with time-scaling and other normalizations. Now the scale is 1 second = 1 second, and a heater voltage of 10,000V = 100% duty-cycle. It comes pretty close to matching my oven, but if I ever want to use the model for anything practical I will need to dial it in a bit more.
I am actually using an SSR wired into an extension cord as well, but I consider that to be "just for the prototyping phase."I usually keep my "prototyping phase" lash-ups as long as I don't have to look at them. Mine is behind and underneath the oven (the oven is standing off the bench, sitting on a couple of red bricks.)
[...]
It would never have occurred to me to model thermal mass as capacitance, and so on. Very clever. I wonder if that's been done before?
did you measure temperature with the housing on to see what temperature that stuff in there will operate at?
Before you do more work, I suggest putting the lid on and measuring the temperature in that cavity.
You might be really disappointed by the temperature you will get in that cavity now that you put work into it.
if you add an exhaust fan without insulation its going to cool the oven and make a thermal gradient because its like putting a big flat heat exchanger on the side of the oven wall, minor, but the wider the PCB the more an effect it will have
also for deburring the vent, there is NO better tool then a abrasive rubber point for a dremel, they wear quick but your vents will be like, ultra smooth
https://www.amazon.com/Dremel-463-Rubber-Polishing-Point/dp/B00004UDHR (https://www.amazon.com/Dremel-463-Rubber-Polishing-Point/dp/B00004UDHR)
also, this is the video where dave jones has problems with his reflow oven overheating the controller
https://www.youtube.com/watch?v=FNNRoXZom30 (https://www.youtube.com/watch?v=FNNRoXZom30)
For my oven I used a $50 panasonic SSR, you want to treat the cheap ones real well, and downrate to ~50% of their real rating, some people going down to 25% on the forum
I think I read one mod where the control electronics had the wrong temp because of the heat, did dave jones not have this problem when he left his controller on top of the oven also?
oh yeah, beware, the ebay one needs a smaller collet, so only do it if you got the dremel collets that are smaller size.
a worthy investment because that is a stupid thing that can really hurt you, a wire shorting to a chassis
0,32.07 # Turning OVEN on
2,32.02
4,32.00
6,32.14
8,32.19
10,32.27
12,32.58
14,32.73
16,33.04
18,33.50
20,34.02
22,34.76
24,35.52
26,36.57
28,37.66
30,38.92
32,40.30
34,41.87
36,43.73
38,45.73
40,47.59
42,49.76
44,52.20
46,54.50
48,57.03
50,59.53
52,62.30
54,65.22
56,68.00
58,70.88
60,73.99
62,77.14
64,80.24
66,83.70
68,86.94
70,90.18
72,93.50
74,96.86
76,100.28
78,103.61
80,107.03
82,110.55
84,113.97
86,117.37
88,120.83
90,124.18
92,127.52
94,130.96
96,134.51
98,137.98
100,141.34
102,144.68
104,147.96
106,151.04
108,154.31
110,157.45
112,160.57
114,163.62
116,166.90
118,170.00
120,173.01
122,175.91
124,178.99
126,181.87
128,184.95
130,187.66
132,190.41
134,193.12
136,195.82
138,198.71
140,201.43
142,203.96
144,206.62
146,209.16
148,211.86
150,214.37
152,216.88
154,219.20
156,221.53
158,224.07
160,226.59
162,229.07
164,231.50
166,233.75
168,236.12
170,238.33
172,240.43
174,242.69
176,244.88
178,246.95
180,249.17 # Turning OVEN off
182,251.67
184,253.84
186,255.20
188,256.70
190,257.71
192,258.92
194,260.00
196,260.85
198,261.16
200,261.45
202,261.39
204,260.24
206,257.87
208,255.59
210,252.52
213,249.80
215,247.70
217,245.39
219,243.34
221,241.15
223,239.01
225,237.31
227,235.59
229,234.06
231,232.01
233,230.41
235,228.35
237,226.08
239,224.27
[snip]
823,39.70
825,39.62
827,39.50
829,39.41
What insulation is good for being thin, and clean? I thought about this but I am worried about dust contamination, particularly with the fan.
the temperature you achieved in the side chamber is a game changer, so long the crimps or welds are not under higher temperature
Then I'll do something similar to what user @fourfathom was doing, where I'll just rely on timing for the various states, based on the expected change in temp over time. I'm just going to hard-code the timings into my control program for a trial run, and test that approach and see how close I can get to matching a published "official" soldering profile.
Then I'll do something similar to what user @fourfathom was doing, where I'll just rely on timing for the various states, based on the expected change in temp over time. I'm just going to hard-code the timings into my control program for a trial run, and test that approach and see how close I can get to matching a published "official" soldering profile.
Looks good. Have you done any door-open cool-down measurements with the new insulation?
You probably know this, but my method is temperature threshold-triggered timing, not just blind timing. The ambient and starting chamber temperature still have some effect on the heating curves, but with the temperature thresholds the results are reasonably accurate.
Not sure if I realized that earlier or not, but that's good to know. I plan to try the dumbest possible approach first just to see what happens, and then gradually add complexity as needed to get a good track against the desired profile. If we're talking about the same thing, then "temperature threshold-triggered timing" sounds like what I'm guessing with be the best combination of "simplest thing that could possibly work" AND "achieves reasonably good compliance with the desired profile". :D
Yeah, I mentioned this a couple of times, but probably not clearly. I have three temperature trigger points:
My post with the explanation and some plots:
https://www.eevblog.com/forum/projects/finally-starting-on-this-convection-oven-gt-reflow-oven-conversion-project/msg3573697/#msg3573697 (https://www.eevblog.com/forum/projects/finally-starting-on-this-convection-oven-gt-reflow-oven-conversion-project/msg3573697/#msg3573697)
For the soak phase at what temperature did you shut off the heater? How long after that did the chamber temperature start to fall? As you zero in on this, remember that the temperature won't start climbing again the instant you turn the heater back on -- there is a delay as the heating elements warm up.
It does look like a bit of duty-cycle control on the heater would help you during the soak phase. I have a duty-cycle option in my oven controller, although I don't use it for reflow. My duty-cycle technique uses a one-second interval, with the heat ON or OFF one second at a time.
116,145.83
118,149.03
120,151.84
SOAK: Turning oven OFF
122,154.62
124,157.16
126,159.62
128,161.96
130,163.93
132,165.64
134,167.30
136,168.76
138,170.00
140,171.10
142,171.94
144,172.79
146,173.45
148,174.10
150,174.65
152,175.12
154,175.45
156,175.87
158,176.11
160,176.43
162,176.63
164,176.70
166,176.74
168,176.73
SOAK: Turning oven ON
SOAK: Turning oven OFF
175,175.05
SOAK: Turning oven ON
SOAK: Turning oven OFF
182,174.84
SOAK: Turning oven ON
SOAK: Turning oven OFF
189,175.41
191,175.83
193,176.37
195,177.06
197,177.64
199,178.23
REFLOW: Turning oven ON
201,178.57
203,178.77
I have a "Bresenham" algorithm (quite simple, really) that keeps the on/off cycle spacing as fast as practical. For example, a 30% duty-cycle results in a repeating on/off (1/0) sequence of "0010010001", rather than "0000000111". The thermal inertia of the system is enough that this probably makes no practical difference, but I have a thing for Bresenham, having used it a lot in frequency synthesis and other problems. I'm using the 1-second rate since I don't want to stress my SSR more than necessary.
For my complicated boards I use a stencil, but for one-off simple stuff I use a toothpick or small wire to transfer solder paste to the pads. I can't use the syringe that came with my solder paste, the needle is too large to dispense small-enough drops of paste. Perhaps a smaller-diameter needle would work, but the one I have already takes too much finger pressure to operate easily.
When hand-pasting the 0.5mm QFN packages, I essentially drag a thin line of paste across all the pads on a side, and the melting solder wicks to the pads and leaves a clean gap in-between. It's extremely seldom that I have a short or open.
Bur a stencil is really the way to go for any significant board.
I had thought about trying the "lay a line across the row of pads" approach. When you do that, do you just put the line on and then place the component? Or is it necessary to take a razor blade or something thin and divide the line between the pads?
I may give that a try tonight after work. That or try the approach of just globbing some solder out on a scrap piece of board and then transfer it in small dabs with a piece of wire, or something along those lines, as you mentioned above.
I can only stand veroboard and all the other ones are torture to useVeroboard with the copper strips, right? That's never seemed handy to me. I always needed so many cuts and jumpers that I would rather just strip and solder wire-wrap wire between isolated pads, and lay down / tack-solder a few bare wires as ground and power busses.
just leave it on a breadboard and melt the first pcb with it
if you use the stripping tool and its sharp for veroboard (or a drill if you don't mind it being weaker), it is efficient
if you use an exacto instead of a rotary cutter then thats your problem.
The few boards like Mindcrime used here I had got trashed for assorted Spacers in woodworking jigs and non Electronics use.
Could those be "M2" screws (2 mm dia, slightly smaller than "#2")? These days a lot of small boards use the metric M2 hardware. Me, I grew up using #6 and #4 screws for this stuff, but recently I was assimilated and bought some M2 assortments: various screw, nut, washer, standoff, etc kits in stainless, brass, and plastic. Cheap, from China, via Amazon.
Arduino sizes and screw placements generally SUCK. I keep some 2 and 2.5mm plastic hardware principally for them. In the case of the UNO you risk shorting bits out with metal fastners and in particular if you enlarge the holes.
As an R/C flier and being of a certain Age and an Aussie I still talk 2-56 and 4-40 and have even been known to have conversations with farmers in Rods and Chains ;D
Strange but some of your images are blocked for me ;D
(https://i.imgur.com/uYsPzXY.gif)
And some of them really are too. Whoever or wherever you are hosting your pictures seems to be bandwidth limiting :-//
I can't see the images in this post: https://www.eevblog.com/forum/projects/finally-starting-on-this-convection-oven-gt-reflow-oven-conversion-project/msg3592043/#msg3592043 (https://www.eevblog.com/forum/projects/finally-starting-on-this-convection-oven-gt-reflow-oven-conversion-project/msg3592043/#msg3592043)
All the others, including your latest, look fine.
I finally got a small-diameter syringe tip for the solder paste, and while it takes a whole lot of force to work the syringe I can put small dots of paste on the pads. I hand-soldered the SMA connectors, but I'm going to try a few in the oven to see how they hold up.
You have a scrap of metal in one of your banana plug holes that can potentially come lose and make a short circuit, get that fixed ASAP. Typical drilling near metal stampings problem, take a close look
If you want 'cleaner' holes in shitty metal, you can think about this tool:
https://www.amazon.com/Astro-Pneumatic-Tool-1442-Setter/dp/B003TODXQW/ref=asc_df_B003TODXQW/?tag=hyprod-20&linkCode=df0&hvadid=312174136943&hvpos=&hvnetw=g&hvrand=13597386352196417469&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004235&hvtargid=pla-338189070626&psc=1&tag=&ref=&adgrpid=63790029762&hvpone=&hvptwo=&hvadid=312174136943&hvpos=&hvnetw=g&hvrand=13597386352196417469&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004235&hvtargid=pla-338189070626 (https://www.amazon.com/Astro-Pneumatic-Tool-1442-Setter/dp/B003TODXQW/ref=asc_df_B003TODXQW/?tag=hyprod-20&linkCode=df0&hvadid=312174136943&hvpos=&hvnetw=g&hvrand=13597386352196417469&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004235&hvtargid=pla-338189070626&psc=1&tag=&ref=&adgrpid=63790029762&hvpone=&hvptwo=&hvadid=312174136943&hvpos=&hvnetw=g&hvrand=13597386352196417469&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9004235&hvtargid=pla-338189070626)
you can put nuts into the chassis, drill out the thread, and seat the banana plug in it, if you want it in a neat grommet
you might want to look at getting cable harnesses or at least looking at pin and socket for those wires so you can unhook the boards without a soldering iron, its starting to look hairy. You don't need the cable housing, you can put aviation pins on the PCB and crimp or solder sockets on the wires. not sure whats going on in there, maybe you soldered them to headers
then its fine, too many pictures failed to load and I thought it was soldered together. if the wiring in mine was all soldered together I would possibly throw it out if it breaks because its just too much
If I had the tool I linked you when I made it, I could put thick stable deformed metal nuts into the thin crappy metal to have a really good place to put the connectors on stable surfaces. I would just need to drill the nuts out a little bit.