Custom Heat Pad and thermistor question
Well, this is the last component i need to order to finish this printer. I have my alum plate, the cork layer, the glass.. I just need to order my custom sized heat pad. (for duet wifi2, SSR setup)
In talking with a company that makes these, our translated conversations are a little confusing at times. They are asking if i want a 100k thermistor installed or something different but gave me no other options. Is he referring to a PT100? Thats not even a thermistor is it? After reading the wiki i just got even more confused as some sensors required an additional board while others didnt. What should i be asking them to install for a sensor inside when they make it for me?
Also they wanted to know what wattage. I would estimate normal operating temps would be anything from 45c-110c would work wouldnt it?
jens55 last edited by jens55
@wingtip, the 100k thermistor is the standard sensor.
Operating temperature and wattage are two different things. The recommended wattage is roughly 0.6W /cm^2 so a 300 * 300 mm bed would require 30x30x0.6 or 540W .... this is just a ballpark and I have I think 700W on a 300*300 bed.
my bed is 752x522. They wanted to know what wattage so i had no clue... so i was going to give them my desired operating temps...
For the bed heater just go with a simple 100k thermistor.
For heater wattage, given the size of the bed and the 0.6W/cm^2 rule of thumb that would be a rather powerful 2300 watts to achieve quick heat ups. which is too high for a single North American outlet to provide. All electric room heaters are limited to 1500 to 1800 watts to stay within the amperage limit of the circuit.
A 1500W heater would heat that large bed in a reasonable amount of time if insulated well.
Ask them if they can install a thermal cutout as well for safety sake. If not, install one yourself.
Heat pad is ordered, 1500 watts, and has a cutoff installed that cuts off at 120c, with 100k thermistor, 752mm x 522mm.
shipping: $52 lol
also, i just finished installing the bed plate today.
jens55 last edited by
A few comments:
Excellent price on a custom heat bed, too bad about the shipping cost (unless you decided to overnight it). Who was the vendor if I might ask?
What make/model of printer is this ... or is it a custom build?
If it is a custom build, what on earth made you choose to move the gantry and to really push the boat out, why did you put the heavy motors on the top where they would have the advantage of leverage ?
I do not have any experience with that kind of a printer but at first look, several red flags sprang up .....
@jens55 It's also lead screw driven, so I hope he has a fat nozzle to compensate for the low speeds.
Ordered the bed through http://www.alirubber.com/ and i had no options on shipping, its what they told me it would be and say its fedex freight. It is a custom build that i designed and built... its not perfect by any means... There are several areas that really need totally re designed but i just worked around it and found a solution.
As for the lead screw i dont mind losing speed for accuracy and detail. Which is one of the main reasons for the build.
jens55 last edited by
@wingtip, thanks for posting the supplier. I hope the printer works out for you, it is an interesting variation not seen before.
Ok gentlemen, the custom ordered silicone heated pad will be here tomorrow by noon according to fedex
so before i install the cork pads and silicone heat pad and glass and risk crashing into the glass, i want to get the bl touch lined out just on the alum bed.
BLT installed, lights up, goes through a self check when powered up, but i have set nothing else up. I will post the g code if someone can look and see if it needs tweaked. I did download a bunch of macros as suggested and they are on the duet. I have no idea how to use it. Most youtube videos ive watched are all about wire installation ... but dont walk you through steps needed to safely test it... they usually just skip to some great prints and say get a bltouch lol.. Can someone walk me through this without just quoting dozuki links which makes my brain hurt at times? Thank you
; Configuration file for Duet WiFi (firmware version 3) ; executed by the firmware on start-up ; ; generated by RepRapFirmware Configuration Tool v3.2.3 on Wed Mar 03 2021 15:26:56 GMT-0600 (Central Standard Time) ; General preferences G90 ; send absolute coordinates... M83 ; ...but relative extruder moves M550 P"The Big One" ; set printer name ; Network M552 S1 ; enable network M586 P0 S1 ; enable HTTP M586 P1 S0 ; disable FTP M586 P2 S0 ; disable Telnet ; Drives M569 P0 S0 ; physical drive 0 goes reverse M569 P1 S0 ; physical drive 1 goes reverse M569 P2 S1 ; physical drive 2 goes forwards M569 P3 S0 ; physical drive 3 goes reverse M569 P4 S1 ; physical drive 4 goes forwards M569 P5 S0 ; physical drive 5 goes reverse M584 X0:3 Y1 Z2:5 E4 ; set drive mapping M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation M92 X395.52 Y80.00 Z400.00 E420.00 ; set steps per mm M566 X300.00 Y900.00 Z180.00 E120.00 ; set maximum instantaneous speed changes (mm/min) M203 X4000.00 Y4000.00 Z400.00 E1200.00 ; set maximum speeds (mm/min) M201 X400.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2) M906 X1400 Y1000 Z1200 E800 I30 ; set motor currents (mA) and motor idle factor in per cent M84 S30 ; Set idle timeout ; Axis Limits M208 X0 Y0 Z0 S1 ; set axis minima M208 X800 Y440 Z400 S0 ; set axis maxima ; Endstops M574 X1 S1 P"!xstop+!e0stop" ; configure active-high endstop for low end on X via pin xstop M574 Y1 S1 P"!ystop" ; configure active-high endstop for low end on Y via pin ystop M574 Z1 S2 ; configure Z-probe endstop for low end on Z ; Z-Probe M950 S0 C"exp.heater3" ; create servo pin 0 for BLTouch M558 P9 C"^zprobe.in" H5 F120 T6000 ; set Z probe type to bltouch and the dive height + speeds G31 P500 X0 Y0 Z2.5 ; set Z probe trigger value, offset and trigger height M557 X15:215 Y15:195 S20 ; define mesh grid ; Heaters M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin bedtemp M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0 M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit M140 H0 ; map heated bed to heater 0 M143 H0 S120 ; set temperature limit for heater 0 to 120C M308 S1 P"e1temp" Y"thermistor" T100000 B4725 C7.06e-8 ; define E1 temperature sensor M950 H1 C"e1heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1 M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit M143 H1 S280 ; set temperature limit for heater 1 to 280C ; Fans M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency M106 P0 S0 H-1 ; set fan 0 value. Thermostatic control is turned off M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency M106 P1 S1 H1 T45 ; set fan 1 value. Thermostatic control is turned on ; Tools M563 P0 D0 H1 F0 ; define tool 0 G10 P0 X0 Y0 Z0 ; set tool 0 axis offsets G10 P0 R0 S0 ; set initial tool 0 active and standby temperatures to 0C ; Custom settings are not defined ; Miscellaneous M575 P1 S1 B57600 ; enable support for PanelDue T0
and the home z:
; homez.g ; called to home the Z axis ; ; generated by RepRapFirmware Configuration Tool v2.1.1 on Sun Nov 03 2019 09:32:24 GMT-0500 (Eastern Standard Time) G91 ; relative positioning G1 H2 Z5 F6000 ; lift Z relative to current position G1 H1 Z-400 F900 ; move quickly to z and axis endstops and stop there (first pass) G1 H2 Z5 F1800 ; go back a few mm G1 H1 Z-10 F360 ; move slowly to z axis endstops once more (second pass) G92 Z0 ; sets current position as zero G90 ; absolute positioning ;G1 s2 X15 Y15 F6000 ; go to first probe point ;G30 ; home Z by probing the bed ; Uncomment the following lines to lift Z after probing ;G91 ; relative positioning ;G1 H2 Z5 F100 ; lift Z relative to current position ;G90 ; absolute positioning
; Z-Probe M950 S0 C"exp.heater3" ; create servo pin 0 for BLTouch M558 P9 C"^zprobe.in" H5 F120 T6000 ; set Z probe type to bltouch and the dive height + speeds G31 P500 X0 Y0 Z2.5 ; set Z probe trigger value, offset and trigger height M557 X15:215 Y15:195 S20 ; define mesh grid
Looks ok assuming you are using heater pin 3 on the expansion port for the servo control wire. (yellow wire I believe.)
For home Z you need to make some changes. You can basically replace everything in there now with this.
G91 ; relative positioning G1 H2 Z5 F2000 ; lift z for clearance G90 ; absolute positioning G1 X100 Y100 F6000 ; move probe to bed center. Adjust coordinates as needed. G30 ; probe the bed G1 X0 Y0 Z5 ; return to origin position
Nothing fancy. Just moves the probe to the center of the bed and probes it and then moves back to a parking position.
You'll need to modify it to move the probe to your actual bed center.
In addition to the changes in config.g you already have you'll need the deployprobe.g and retractprobe.g macros setup if you haven't already.
; deployprobe.g ; called to deploy a physical Z probe ; ; generated by RepRapFirmware Configuration Tool v3.2.3 on Wed Apr 14 2021 18:38:44 GMT-0600 (Central Standard Time) M280 P0 S10 ; deploy BLTouch
; retractprobe.g ; called to retract a physical Z probe ; ; generated by RepRapFirmware Configuration Tool v3.2.3 on Wed Apr 14 2021 18:38:57 GMT-0600 (Central Standard Time) M280 P0 S90 ; retract BLTouch
Then test them by sending M401 and M402 to deploy and retract the pin.
If that works, you can do the tests described here and measure your XYZ probe offsets as well.
3DPMicro last edited by
@wingtip what is the lead on your lead screws? Not apples to apples but 18k mm/m is doable with (the right) .9deg motors, 16x ms, and10mm lead on ball screws tossing around 3kg. Lead screws will be a bit more draggy though.
25k mm/m with external 2130's and higher voltage
@phaedrux Something isnt working right.. I tried to enter the M401 and 402 and nothing happens. Looking at the pic below, my signal wire (the yellow from the bltouch) is red in this photo on the pwm3 connector. do i need to flip it 180 or is my signal wire on the correct pin for pwm3?
@3dpmicro almost everything came from openbuilds.com except a few steppers which i matched to the open builds ones i had and i believe their steppers and leadscrews are only one type (for nema17)... This is just a big experiment so it is what it is at this point lol... its either going to work or be a colossal (expensive) failure.
Ah ok, so you're using the Duex PWM headers. In that case you'll need to change a line in config.g to use the pin name for that pwm port on the duex instead of the pin on the expansion header (since the duex is using the expansion header).
M950 S0 C"exp.heater3" ; create servo pin 0 for BLTouch
M950 S0 C"duex.pwm3" ; create servo pin 0 for BLTouch
Then M401 and M402 should work if the deploy and retract macros match what I posted above.
If it still doesn't work, check wiring continuity, or try the PWM5 header instead.
The deploy and retract is working via the macros but not by the direct M401 and 402 in the console. Is that normal? What should i test next or have as a macro?
The macros must be in the system folder for M401 and M402 to work. If you have them in the macros folder only, they won't.
wingtip last edited by wingtip
@phaedrux So what directory should the two macro's go in? At the moment i have them directly in the macro directory. I do have a BL Touch folder/directory created within the macro directory but havent placed those two files in there yet.
Nevermind i see your last message says in the main directory... but then what is the point of being able to make other directories and keeping things less cluttered?
but then what is the point of being able to make other directories and keeping things less cluttered?
You still can do that, but the firmware is looking in the /sys folder for the probe deploy and retract macros. That's just the way it is.
In other words, the macros folder is your to do with as you wish, but the sys folder is for the firmware and you must play by it's rules.
Ok, so if the macros are working now from the macro directory then i can leave it that way right? So what should i test or add next to the directory... Thank you for all the help!
You can leave a COPY of those deploy and retract macros in the macros folder, but if you want the probe to deploy and retract when you send G30, a copy of those macros must also be in the /sys folder.
Now working from the console with the m401 and m402. I had to remove a space in the name of the files and now they work. Ok what now?
Ok what now?
If that works, you can do the tests described here and measure your XYZ probe offsets as well.
Custom heat pad just arrived. 752mm x 522mm, 110vac, 1500 watt.
45c-110c with safety cut at 120c.
In this pic you can just see the heating element pattern
Looks really good. Not sure if they included instructions for mounting it, but here's what Keenovo recommends. High temp silicone is the way to go. You don't want that thing coming off mid print.