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I think your 3D printing company basically exists because of Therac-25 indifference in the 3D printing community. We could put motor position encoders on the a

I think your 3D printing company basically exists because of Therac-25 indifference in the 3D printing community. We could put motor position encoders on the axes to actually detect crashes. But those things are like $20 per axis, and your microcontroller needs a quadrature encoder, so we say "fuck it, we'll do it with OpenCV". It's good when it's good, I guess!

Palomides 3y ago
3d printers are very safe and reliable, mine detects crashes via the current through the motor controller with no extra hardware (not that it's ever crashed) cost/benefit analysis is the heart of engineering, and that applies to redundant safety and error detection hardware as well
grepLeigh 3y ago
Defects in 3D print jobs are usually usually related to model design, slicing parameter decisions, and occasionally a printer part needs replacement/servicing (like belts). So far, firmware crashing hasn't been an issue. I'm supporting open source firmwares though (Marlin, Klipper, and soon RepRap/Duet) so they're VERY battle-tested. Maybe this is an issue for proprietary closed-source firmware?
horsawlarway 3y ago
I mean... the ones that are any good are about twice that price. Ex: I personally prefer CUI encoders: https://www.cuidevices.com/amt-modular-encoders https://www.cuidevices.com/amt-modular-encoders and they run about $50 each (with bulk ordering able to get you closer to $40). But I think you're not really considering the problem space from all the appropriate angles. Ex: The main reasons you avoid putting encoders on a 3d printer... 1. Weight - Hands down the biggest in most cases (excluding CoreXY setups). Each of those CUI encoders is about 16 grams. Total moving weight matters a lot in printer design. Go too high and you have to bulk up every other part of the machine to account for it and reduce shake/wobble and ensure you can maintain the correct accel. Or you have to print much slower, which makes the machine less capable (and valuable). It also adds wear and tear and increases friction. 2. Safety - They aren't worth very much in terms of safety. You can detect a lot of bad things by just setting sane current limits in your motor controllers. Combined with the thermal runaway protection available in most firmware... that covers most of the same things you can detect with encoders. 3. Value - Steppers are already incredibly precise. There is limited value in adding the extra encoder feedback into the system. Most of the cases where it matters are already detectable (and without any need for OpenCV...). So encoders are nifty - but this isn't really the best case for using them. No big win and lots of downsides (not the least of which is the extra $150 for adding them - which is 50% of the total cost of my first printer).

Palomides 3y ago

3d printers are very safe and reliable, mine detects crashes via the current through the motor controller with no extra hardware (not that it's ever crashed) cost/benefit analysis is the heart of engineering, and that applies to redundant safety and error detection hardware as well

grepLeigh 3y ago

Defects in 3D print jobs are usually usually related to model design, slicing parameter decisions, and occasionally a printer part needs replacement/servicing (like belts). So far, firmware crashing hasn't been an issue. I'm supporting open source firmwares though (Marlin, Klipper, and soon RepRap/Duet) so they're VERY battle-tested. Maybe this is an issue for proprietary closed-source firmware?

horsawlarway 3y ago

I mean... the ones that are any good are about twice that price. Ex: I personally prefer CUI encoders: https://www.cuidevices.com/amt-modular-encoders https://www.cuidevices.com/amt-modular-encoders and they run about $50 each (with bulk ordering able to get you closer to $40). But I think you're not really considering the problem space from all the appropriate angles. Ex: The main reasons you avoid putting encoders on a 3d printer... 1. Weight - Hands down the biggest in most cases (excluding CoreXY setups). Each of those CUI encoders is about 16 grams. Total moving weight matters a lot in printer design. Go too high and you have to bulk up every other part of the machine to account for it and reduce shake/wobble and ensure you can maintain the correct accel. Or you have to print much slower, which makes the machine less capable (and valuable). It also adds wear and tear and increases friction. 2. Safety - They aren't worth very much in terms of safety. You can detect a lot of bad things by just setting sane current limits in your motor controllers. Combined with the thermal runaway protection available in most firmware... that covers most of the same things you can detect with encoders. 3. Value - Steppers are already incredibly precise. There is limited value in adding the extra encoder feedback into the system. Most of the cases where it matters are already detectable (and without any need for OpenCV...). So encoders are nifty - but this isn't really the best case for using them. No big win and lots of downsides (not the least of which is the extra $150 for adding them - which is 50% of the total cost of my first printer).