FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
If you're not already aware of the Z temperature shifts with the Prusa Mini, do a first layer calibration from a cold printer, then preheat and re-do the first layer calibration. WARNING: Keep a close eye on the nozzle height or you will damage your build plate.
REQUEST DETAILS:
Problem: MINDA Probe (PINDA V1) does not have a temperature sensor so temperature drift cannot be adjusted for.
Requested Solution: Provide a feature in the firmware to automatically account for temperature drift through a preheat process
Functional Application:
1. Each print will have a minimum preheat time where the probe is centered over the build plate and at a known ~1mm (Aut0-home height) nozzle height. This will stabilize the temperature of the probe
2. The preheat temperature will be used with a built-in table for the probe that will estimate temperature drift at different bed and nozzle preheat temperatures. (This can be developed in-house and automated by customizing firmware and using a touch-off z-height probe, then cycling through a wide range of temperatures)
3. The estimated drift will be applied to the Z height before the print begins.
That will solve the issue and save Prusa the entire $1.63 per printer by not using a probe with a temperature sensor.
Alternatively: Just incorporate the information from the Mk3s into the firmware and let us upgrade the probes ourselves without voiding the warranty.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
The best place to submit any request like this is on Prusa's github pages. While the devs to occasionally check in here, that is the official place where changes are identified, prioritized and rejected or accepted for implementation. I suspect similar issues have already been submitted, in which case you can add your voice to the chorus asking for a change.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
@bobstro
That is true for all firmware-only related issues, but this would require they develop a solution in coordination with other teams. I'd rather not push this on the bugfix team, especially if other users don't want it.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
given the board appears to be designed to support an actual PINDA, and not just a MINDA, I'd really like to see a PINDA upgrade in the future. Even if it added $20 USD to the cost it would be welcome.
But, people are being very successful with the current PINDA, so is it worth changing? Time will tell.
I'm not a mad scientist, I'm an angry engineer in training.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
given the board appears to be designed to support an actual PINDA, and not just a MINDA, I'd really like to see a PINDA upgrade in the future. Even if it added $20 USD to the cost it would be welcome.
But, people are being very successful with the current PINDA, so is it worth changing? Time will tell.
Successful but with extra effort that shouldn't be necessary. I dislike having to remember to lower the Z before the first print of the day then raising it for the next print. I would gladly pay $20 to fix this.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
@drkmstr
On the first page of the firmware issues there are something like 12 feature requests. As Bobstro said, Github is the place that will get the attention of the people who can get the right people within Prusa to decide if they want to include the feature on their roadmap.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
given the board appears to be designed to support an actual PINDA, and not just a MINDA, I'd really like to see a PINDA upgrade in the future. Even if it added $20 USD to the cost it would be welcome.
But, people are being very successful with the current PINDA, so is it worth changing? Time will tell.
Maybe MINI S next year or MINI MK2 in 2022 will have it. Given there's also usually a roadmap for older printers, there will be MINI MK1.5(S) upgrade kit available which may feature PINDAv2 support 🤣
Jokes aside, I'd welcome it too. Especially when printing PETG, it seems to be very sensitive on getting first layer just right, else the first solid infill above it crumbles. Or not. Then it does again. Next print it's OK. I thought I just can't adjust it properly and it may be from temperature.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
With PETG as my primary filament, I would like to see a solution too.
A little odd that a problem found and fixed on the MK3 pops up again on a new printer model.
Have a look at my models on Printables.com 😉
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
Pretty standard really, the desire to reduce cost often means features are left out. It seems to be a rule of marketing that the more expensive model must be better in all areas, even if the feature makes little difference to the actual cost, it's the perception that counts.
There are several features on the Mini that are done differently for no obvious reason, and don't perform as well as tried and tested solutions. We can only speculate what Prusa's reasons were. Several people, including me, are modding or building their own Mini clones which don't have these flaws.
Of course, if Prusa's intent was to build a printer that is cheaper but not as good as MK3S then they have achieved that. Presumably the BOM is nice and low so that they are making a healthy profit.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
I'd be interested in thoughts on using the nozzle temperature sensor as a stand-in for the sensor for the PINDA hardware. Through either an external script (e.g. Octoprint) or firmware mod (Team Prusa) to modify gcode handling, a "wait for UNHEATED nozzle temperature" would allow Mk3-like sensor warmup without any hardware changes required. In testing on my Mk3, the UNHEATED nozzle temp closely follows the PINDA temp, including when physically positioned close to the heated bed for warmup. I put more notes in this thread.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
Sure, why not? Easy for me to say while I am not volunteering to write the code 🙂 The hotend thermistor should work as a general temp probe with a fairly high thermal mass.
I don't use Octoprint, but either way it seems to require persuading someone to write a code fix.
RE: FEATURE REQUEST - Z Height Calibration with temperature offset built-in to the firmware (See within)
@bobcousins
The smaller print volume already differentiated the mini from the Mk3, so I don't see how including this (PINDA) would have changed the sales of either unit. We can only speculate at this point.
I'm not a mad scientist, I'm an angry engineer in training.