Thanks Doug that makes sense but I have 360mm arms and 300mm calipers, so what I wondered is whether there is a trick to measure something that is longer than the calipers? I could use the metal rod that protrudes from the caliper, but how to measure to high accuracy like this I don't know.
Just clap a block to the edge of your desk, butt the rod up against it, mark the end, then repeat for each rod, see if all your lines are in the exact same place
I would be so excited if you found a way to make this work. Right now SLA is taking off and the field of printers is so small mostly because of the difficulty of driving a galvo/the fact that arduino boards can't do it at proper resolution. All the solutions are proprietary and expensive. If you can get a duet and a duet branded DAC on the market that could drive a galvo they would sell like hotcakes.
Came here to post this exact suggestion.
Could be HUGE for the duet, as Arduino lacks the tech to drive a galvo currently and a lot of people are looking to drive galvos in 3dp
Haha thank you! 70lpm was just an example of one of the more powerful units. I certainly don't need that much through a berd air…it'd probably blow my effector up to my home switches! I would consider that unit for hotend cooling though, if I make a super heated chamber.
What's the best way to integrate this to my system I wonder. Can pumps be pwm? Is it possible to do some sorcery like hot to a power supply and negative to the duet and get pwm? Or get an ssr and hook it up like a bed?
Hi Mr. 42 & Co.,
I'm considering a "berd air" cooling setup. I planned on using 110v and a solid state relay like my bed to control the pump. Now though, I'm stumbling on 12v DC air pumps with some impressive specs! Unfortunately my electrical knowledge ends somewhere around operating a light switch. The pump feature specs like this:
OUTPUT: 70LPM /Min POWER: 35W VOLTAGE: DC 12V PRESSURE: 0.10MPa
If I hook this thing up directly to a duet wifi does it ( a ) blow cool air across my prints surface or (b) explode
Thanks!
Stefan
Note that the extruder doesn't have to be directly fixed to the carriage…. the fourth tower could reach out over the print area. If if it was just an upside down L that held the extruder fixed downward over the center of the bed and just high enough to be out of the way of any printer moves you could have a fairly short Bowden with no mass on real carriages. The firmware capability is the tricky part. I haven't bothered thinking through exactly how I'm going to work out the mechanics until I have a way of moving a fourth axis pretty in tune with the effector. My other idea is a long worm-gear looking thing that spans across the top of the printer and suspends the extruder, as it rotates the string/wire/whatever you're suspending with follows the path around the gear (at a constant steps/mm) effectively reeling the extruder up the print goes.
That is the point – this intended for a large delta, like mine. My carriages -- under normal conditions park at the top -- engage breaks (servos driven by an arduino) and printer powers down, if the breaks don't engage, the effector will fall down. If assuming normal conditions, we are assuming perfect knowledge in all cases -- I can't always assume that. If I have a hall effect sensor -- -- and I have 1 small tube and a large tube -- and a universal joint at the effector -- I can track small tube going in and out and know if I have to move the extruder axis up or down -- if you can bake that into the firmware - -great, but I plan on implementing it as a standalone feature -- like the piezo board. It will use the sensor to keep the rigid arm between the effector and the extruder carriage at a predefined distance -- it's actually fairly simple, your output of the hall effect sensor must be 512 -- you have a magnet at one end of the tube, and as the value decreases, that means the distance between the extruder and the effector is decreasing, so you move away -- which is up...as the value is increasing, which means the distance is increasing also, so you move the effector down
My delta is 1m tall with a 350mm bed, and my carriages don't fall when I turn my printer off.
In other words, rods+ (radius of ballstud * 2)
If you purchased them from Haydn/ultibots etc, the number on the rod will be correct. The actual measurement is from the pivot point of both ends, which is the distance between the center of each ball-stud.
I saw this post, and I'll throw in my 2c. I implemented a Z traveling tower on my delta – (my delta runs smoothieware) -- with my own code to control the independent axis for Z -- it's original purpose was to be a place where the effector would go to wipe during color changes. I have a silicone sponge there, and in general it worked for the volcano chimera setup, on each tool change the effector would go to the wiper, do temperature change -- cool off the inactive tool and heat up the active tool, and then wipe over the silicone pad. However I ran into an issue which is inherent to chimera style setups -- the inactive head would hit the printed part and cause a layer shift. So basically unless you can get the 2nd nozzle out of the way somehow, there is no way to make this system work. I've since switched to developing my quad idex, which is nearly finished -- doing a true first 4 color print -- a 4 color benchy. But going back to the delta. I wanted to still print multi color on the delta being that I have 2 bondech QR extruders, a flying extruder on rubber bands is out of the question, so I wanted to use the extra tower I have to mount my dual bondechs, and use the distech automation multi material heat break for color changes. I'd be able to shorten my currently 1.2m bowden tubes going into Y coupler ( I ditched the chimera in favor of a single volcano) -- so after brainstorming for a few months this summer, I came up with an idea to implement this "extruder platform" -- but it would not be using the printer firmware -- for 2 simple reasons, the printer doesn't always know where the effector is. It needs to home, and homing the 4th point which is attached to the effector is a recipe for disaster. So my idea involves essentially running the platform stepper using an arduino pro mini (or regular arduino, doesn't matter) and a hall effect sensor to keep track of the distance between the platform and the effector -- there will be a rigid carbon fiber rod going to the effector from the platform, fairly short -- around 100-200mm, basically the length of the bowden tube with the Y coupler and it would be moved by the stepper as the hall effect sensor indicates -- I may need 2, either way the platform must maintain a certain distance from the effector, having it done in printer firmware would be impossible without the additional sensors.
This sounds unduly complicated. You see, smoothie doesn't have a DC42 to help come up with the easiest way to implement his customers ideas 
Of course the printer knows where the effector is, otherwise the G-code wouldn't mean anything. G1 Z+1 works exactly because the firmware knows where that is lol. Nonetheless, DCs idea will work out fine, I'm confident! Homing shouldn't be a problem, if it needs to be done at all. Even without a homing switch just push the thing where you want it relative to the effector and hit it with a G92. This would work better if we could use the actual effector Z height instead of a 4th axis rod solution, but it'll still get it close enough, doesn't need to be that precise.
Which is another question for you David. would it be possible to average all 3 existing towers? That plus or minus some offset should get us close to the height of the effector!
Hi DC, wondering if you've put any thought into the fourth axis idea to keep a forth carriage floating somewhere around the same z height as the effector? I've got the mechanical bits all sorted and am going to test it with the setup of just mirroring another tower, but it'll still require the bowden to be pretty long to reach the effector when it's very close to that tower or pretty far from it. I'm tossing around some other ideas too like basically winding it up a long worm gear so it can be suspended from the top and centered closer to the effector without the weight on the carriages which would require the firmware to actually know the z height of the printer to know how high the effector is, but for now I'm just checking in on our earlier 4th carriage ideal! Thanks!
My original plan was to run the extruder drive on a carriage on an additional tower, probably situated midway between two of the other towers. The "diagonal rod length" to the additional carriage would be configured to be a little less than the length of the Bowden tube, and possibly somewhat shorter than the lengths of the real diagonal rods.
The 4th carriage would need its own homing switch. During homing, the motor current for the 4th carriage drive could be reduced, so that it its position is a long way off where it should be, the motor can skip steps in either direction. Then the motor current could be restored before fine homing.
Works for me. How do it do it? haha
Hi DC, wondering if you've put any thought into the fourth axis idea to keep a forth carriage floating somewhere around the same z height as the effector? I've got the mechanical bits all sorted and am going to test it with the setup of just mirroring another tower, but it'll still require the bowden to be pretty long to reach the effector when it's very close to that tower or pretty far from it. I'm tossing around some other ideas too like basically winding it up a long worm gear so it can be suspended from the top and centered closer to the effector without the weight on the carriages which would require the firmware to actually know the z height of the printer to know how high the effector is, but for now I'm just checking in on our earlier 4th carriage ideal! Thanks!
Understood. Thanks as always, you guys are the best in the business!
Great. Is there any way to set it up to track (either via separate rod theory as you planned, or just tracking Z height of the effector) Z height yet, or is my best plan to just clone a tower for now.
Ok, so lets move forward on this. Lets say I want to set up an extruder carriage on a fourth rail to just mirror one of the x y z towers until firmware supports the new axis thing DC was talking about. How might I go about doing this. Anything I'm missing homing wise? Do I even need to home it, will the computer treat it like a new axis, or will it be treated like a second motor on one axis (like a dual z setup with one endstop), if I could just tell it to mirror X without setting up homing stuff that'd be ideal, as I'd just mount it a little lower than that carriage and it'd stay in sync.
Hey DC and Co,
What'd be the easiest way of running multiple configurations on one duet? For instance, if I have two configs, one for my e3d v6 and another for my volcano, with different heights, steps/mm and motor power etc. Can I make copy and paste config.G into a macro titled configvolcano and simply run that macro after powerup to set all the settings up for the volcano?
Well sh!t!
My replacement effector doesn't work either! Only options= cables or config.g - Cables worked well enough to set the sensitivity, so what am I missing!?!
This raises another question for me David. I have my hotend cooling fan as a thermo-controlled fan (as default on I wanna say slot two? something like that). Would it be possible to insert gcode into bed.g that stops that fan before probing and starts at again after probing? I don't think heatcreep for the 15 seconds it takes to probe would matter much and I can use a lower sensitivity when probing without the fan. In fact, I usually probe with only the bed hot, then heat up the heater, then set my height manually with G92 Z.
I'm at work at the moment but I'll give it a thorough look when I get home. I gave it a once over before and didn't see damage excepting what I posted earlier. I was unable to replicate it working without magnets attached however; it was non-responsive with or without magnets the second go-round.