M303

In my unending impatience, I've started using an aluminum heater under my heat-spreader while I wait for an appropriate silicone heater from China. Alls well, fits perfectly, certainly gets hot, heat dispersion is the clear weak point, but thats what the heat spreader is for I suppose. Only problem is the default bed settings are def no good. It takes a few seconds to get cooking, but then it soars wayyy above the set temp long after the bang bang kills it. I'm using an SSR btw and the heater is mains powered. I tried running m303, at 5 it crashed, at .5 it crashed, at .1 however its been running and doing its thing. Only problem is its been 2 hours! When I run a blank m303 command it reports that its in phase three. It's been reporting so for at least an hour. Ideas?

For reference, the heater I'm using is similar to this, but round

It's not unusual for the current tuning algorithm to take nearly an hour when tuning the bed. What temperature has it reached? If it's less than about 80C then I suggest you restart with higher PWM, because that may speed it up a bit.

I'm planning a new tuning algorithm for a future firmware release, which will avoid the need to guess a suitable PWM value when using high-powered heaters like yours.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Haha I have gave up a few hours in assuming it glitched out. In cases where it takes hours, does that time usually take place in phase 3?

I haven't heard of it taking over an hour before - and yes, most of the time taken is in phase 3. It's waiting for the rate of temperature rise to slow down enough for it to calculate the gain and time constant. If the printer is enclosed or poorly ventilated, then it's possible that it's gradually heating up the environment, so that the temperature rise doesn't slow down enough.

The wiki page at duet3d.com describes an alternative way of estimating the M307 parameters.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].