Apply calibration settings to MAX31855 temps #241
Conversation
|
Hi, I’ve got a T962 reflow oven and have done most of the MODS to it, including uploading this firmware, though I did this several years ago, so there’s likely new firmware now. I also added a couple more small heating elements under the tray to make the oven heat up more evenly and be able to keep up with the reflow profile. But I would like to add the external TC board with the MAX TC chips on it, and have ordered them and the board from OSHPark already. I’m wondering how the firmware handles the extra TC? If I use 4 will it just take an average of all 4? I’d like to put 2 on the tray with little clips that will hold them on 2 different edges of the board I’m reflowing, or maybe just barely above the board. I am not familiar with GitHub nor firmware making, so I’m wondering if there is a version of firmware that will let me use these extra TC’s in this fashion? If the two on the board work well, I may not need the OEM ones the are up in the air too high, so I wouldn’t really want them factored in to when the oven does it’s PID control of the profile. Thanks. |
|
Nice. You might also want to try smoker grill seals on the front - made a hide difference in evenness for me. |
|
Thanks. Is there a firmware that will work with calibration of the external TC’s? Charlie KerrOn Dec 31, 2023, at 9:02 PM, George Harker ***@***.***> wrote:
Nice. You might also want to try smoker grill seals on the front - made a hide difference in evenness for me.
—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you commented.Message ID: ***@***.***>
|
|
Thanks. |
|
It looks like a lot of folks fork the firmware and make tweaks. I did also. However the stock firmware here does recognize the breakout and reads it. It ignores two (I forget which, you can add extra thermocouples and hack the firmware if desired) - which is what i did. I measured on-pcb temps at a few locations and calibrated the other thermocouple coefficients against that with linear regression in a spreadsheet. I then take effectively a weighted average of each. |
|
Ok thanks. I’m not fluent enough in this code to modify anything but I can upload the latest one via the tutorial. The one you made does it work better with the TC daughter board? I’ll have to experiment with them once I get all the parts. |
|
Once I calibrated, sealed the front airflow to keep better temps inside and added extra thermocouples and made a profile for my paste I can get decant reflow even on large boards. So yes it works decently. It’s definitely an iterative process though. |
|
To Georgeharker - for those of us not in the US what is a smoke grill seal and where can I get something similar please?. Dimensions, approx profile and softness and material would help greatly. Thanks. |
|
I used this Smoker Chef XXL 20 FT Grill... https://www.amazon.com/dp/B09KY9DRD6?ref=ppx_pop_mob_ap_share Which is just high temp adhesive and a high temp fine felt / brush like material that blocks airflow. I’ll put a blog post together. I’m not sure I took many pictures when I did it. |
|
Thank you George. It turns out Amazon Uk has loads of the stuff too, such as : https://www.amazon.co.uk/LANUCN-Gasket-Synthetic-Replacement-Accessories/dp/B07SX859NQ I should've looked first! |
|
Wrote up approximately what I did here |
As per #240 this allows the calibration settings to be used with the external TC board, allowing tuning of the readings to reflect on-pcb measurements.