Basic considerations about Delta printers

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fma
Yes, sure. But is it a reliable method? Or does it introduce some issues?

I haven't used FSRs, but as there has been a lack of response, here goes. I am aware of these potential issues:

1. Some bed materials (e.g. BuildTak) don't take kindly to being probed with the nozzle hot. So with those, you need to probe before heating the nozzle. Then if the Z height changes slightly when the nozzle is hot, you can allow for that when you set the trigger height.

2. ..but if you probe when the nozzle is cold, then any filament stuck to the nozzle will affect the trigger height.

3. It's quite difficult to keep the bed secure so that it can't shift sideways, while supporting its weight on FSRs. There are probably designs that solve this problem.

4. The trigger height (i.e. how hard you have to push on the bed to trigger the FSRs) tends to vary with XY position. In RepRapFirmware you can correct for this by specifying a trigger height correction parameter at each probe point.

General advice seems to be that if you do use FSRs, then use one of John's trinket boards to process the signal. In principle, with Duet electronics you could generate a signal for the analog Z probe input using just the 3 FSRs connected in parallel and a resistor and capacitor to ground, but I haven't tried that. The trinket board would probably be more reliable because it monitors the FSRs individually.

I guess the advantage of FSRs is that they work with any bed surface that can tolerate being prodded, and that any tilting of the nozzle as it translates doesn't affect the trigger height.

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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].

Thanks for this complete answer! If I go that way, I will use a dedicated board to monitor the FSR, like John's trinket board.

Did anyone tried to mount the FSR on the hotend, instead of the bed? This is something I wanted to try for years, but never did... The problem is to maintain the hotend, and allow it to change the resistor of the FSR when hitting the bed.

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Frédéric

Definitely use the trinket or JohnSL boards. As DC42 said stabilizing the bed while allowing it to float enough for the FSR's can get tricky. I don't have the link handy but MHackney posted what I think is one of the best solutions to that over on the SeeMeCNC forums. His approach is to make a cup that holds the FSR and then a plunger that attaches to the bed. The walls of the cup keep the plunger in place and since the plunger is attached to the bed it cannot rotate even though its free floating. The cup part is attached to your frame. Simple and elegant, now if I could just get my printer going well enough to print a set

Quote
fma
Thanks for this complete answer! If I go that way, I will use a dedicated board to monitor the FSR, like John's trinket board.

Did anyone tried to mount the FSR on the hotend, instead of the bed? This is something I wanted to try for years, but never did... The problem is to maintain the hotend, and allow it to change the resistor of the FSR when hitting the bed.

This:

[repables.com]
[forum.seemecnc.com]

?

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Frédéric

Yes. I have not tried them myself but I have spoken to mhackney about them and they work great for him. I'm planning to print a set as an upgrade to my printer since I get inconsistent results with my FSRs using the stock holders.

hello, there is a interesting use of magnets to resolve the rapid changing of printheads that could allow a user to hotswap even for use with a laser cutter attachment.

perhaps this will evolve further.

congrats to the thoughtful designer of The Flux 3d swiss army knife of printers.


there is clearly much room for improvements in the design of printers and other machines and devices.

the electronic components involved in 3d printers currently show a need for this.

as cryptic as things can be, they often are.
this will no doubt be a set back for anyone attempting the transition from owning a 3d printer, to actually being able to get the most out of it.
much time will be dedicated to trying to sort out factory level and or preset programming defects within these early version sometimes rather beta released kits and even fully factory assembled ones.

perhaps it makes sense to wish to start out using the most ideal processor, sometime at raspberry pi level or more capable, that would allow for very detailed versions of customer walk-throughs in one screen tutorials built into the printers onboard permanent memory.
the tutorials would have enough storage set into a larger capacity onboard memory, that memory could even be a series of populated micro sd sockets if not more permanently fixed memory chips.
different pre installed firmwares could be allowed to exist at the same time on the same controller card.
a user might choose to try different firmwares without frustrations included.
remove the frustrations and the product is a real winner.
so simple that house pets could just about operate it, rather than the a more detailed online based education in order to reach productive results, especially if anything about the machine or the software or firmware does any modifications.
a library of modifications and their proper variables would be found scrolling through the printers onboard vastly improved more detailed and simplified database.

the motors drivers would also be recommended as removable.
should one driver, or other component on the printing devices controller card ever need replacing, it would save further costs for someone to have to purchase a entire replacement controller card.
this could also allow for more specific upgrades by its scalable design.

true this useful and exciting technology is advancing, and its expected to keep getting better while becoming more affordable.

next will be the inclusion of a material recycler built into the framework of the printer itself. as affordable an option as the commonly known paper shredder is easily possible.

@megamicro
These onboard tutorials should then be in Chinese, English, French, German and ten other languages??? I wonder, who would pay for such amount of work?

Online [how-to]'s are the only way to go here. Made for free from enthusiasts in their native language.
-Olaf