Mount and Reservoir Discussion

[Toasterboy]

How big of a build area have you actually tested?

What is the maximum deflection angle for the peachy like? I'd like to get an idea of how high the printer needs to be mounted as related to desired build area dimensions. (i.e. height above top of build area container).

If it works (even if somewhat slowly) with the dripper for larger volumes (i.e. 2'x2'x2'), then it could make sense to look at ways to increase the fill rate of the build container (a pump hack, or whatever, to make the print times less painful). Maybe something involving a pair of motorized ball valves and a continuously running small pump to facilitate "scaling up" the drips for larger containers. With an adjustable size holding reservoir between the valves (i.e. with a diaphragm or something like a syringe + stepper motor so it can be controlled, and with open air overflow so the holding tank always fills to the exact correct volume), it might be fully automated (just enter the build volume size in the software and it can solve for the correct settings), and provide extremely consistent Z on the scaled up "drips".

If the printer angle is narrow, it may make trying to print a lifesize canoe require an impractical mounting height though=)

And with napkin math, at 2 liters per hour, something like the ~24"x22.5"x14.5" build area I suggested above would only take about 64 hours to fill (if I calculated correctly), which isn't that much worse than print times I've heard of for other large build area printers. Definitely would want to look at increasing the fill rate if I try to print at that size though...

This thread is insightful. You've been fantastically open about the details of this project and it's been fun watching as you have brought the Peachy to life... Thanks!

[jontelling]

....... then it could make sense to look at ways to increase the fill rate of the build container.........

I'm not sure this is the case, bigger build area, bigger build therefore more resin to cure, as with all lasers the power is limited this means the laser will take longer to cure each layer. Which means it needs to be kept slow.

If the current limiting factors on build speed are related to the moving the mirrors (slow and steady to avoid vibrations etc) then you can up the Z-axis speed. If the laser is the limiter then the z-axis will need to be kept just as slow.

I could be totally wrong though…

[Toasterboy]

I'm not suggesting scaling up the fill rate with small containers; only for large containers. Keep the fill rate proportional to what works in small containers. They used water drops in the design because they are consistent in volume and provided an extremely cheap , easy to sense z mechanism.

Rylan mentioned in another thread that they are working on a software modification to allow the laser to stay on continuously; right now it shuts off and pauses waiting for the z level to reach the desired level between layers. That suggests that the z-level rate is a strong limiting factor. It's also a good question what the deflection speed performance of the laser is. The videos are sped up, but they seem to show the laser moving fast enough so as to appear to be a continuous line... I would expect the surface dynamics (i.e. the interface between water, resin, and laser) to behave similarly to the small scale build reservoir; I expect you would need to account for additional travel time on the laser for curing for larger objects, but that should essentially scale linearly with the surface trace path length. It seems like the z-level rise rate is the larger limiting factor in a large container. Using a calibrated valve system for z-filling essentially makes it digital, and with digital 2-way control, it could be software controlled rather than depending on sensing the drip rate. It only makes sense with containers above some size threshold though, as it's harder to calibrate and deliver smaller water volumes approaching water drop size, making the drops a better choice for small containers.

Certainly you will use more resin on larger objects, although with hollow shells, that is still pretty economical.

Perhaps this a is a feature that the Pro could explore. I'm definitely going to play around with this concept though. If only I had the printer in hand. I missed the original Kickstarter window and ordered my Peachy through BackerKit. =)

[Toasterboy]

Aha, didn't know about peristaltic pumps. One of those would work great and be much cheaper than I was thinking.

[jontelling]

Aha, didn't know about peristaltic pumps. One of those would work great and be much cheaper than I was thinking.

I may make a syringe pump one day

[Toasterboy]

Reading the peachy beta kit instructions, it looks like the calibration step is smart enough to scale the Z per "drip" based on the height provided. Is that correct?

If so, and we replace the basic dripper with a peristaltic pump, it seems like the drip contact detection mechanism should still work about the same. If the volume of the pulses from the peristaltic pump is small enough that the z-level rise in the container per pulse is appropriate for the target layer height (i.e. operates at a similar scale to dripping in a small container does), I would think it would be OK. Looks like I can get an appropriate 12V pump (one which pushes 20-100ml per minute) for about $10 plus power supply (I have a 12v dc controller for a train that should work for testing). May be a very easy mod?

So....that still leaves the question of what the maximum deflection angles the printer can support are, so it doesn't have to be mounted 30' in the air to get larger build volumes.

[jontelling]

Reading the peachy beta kit instructions, it looks like the calibration step is smart enough to scale the Z per "drip" based on the height provided. Is that correct?

If so, and we replace the basic dripper with a peristaltic pump, it seems like the drip contact detection mechanism should still work about the same. If the volume of the pulses from the peristaltic pump is small enough that the z-level rise in the container per pulse is appropriate for the target layer height (i.e. operates at a similar scale to dripping in a small container does), I would think it would be OK. Looks like I can get an appropriate 12V pump (one which pushes 20-100ml per minute) for about $10 plus power supply (I have a 12v dc controller for a train that should work for testing). May be a very easy mod?

So....that still leaves the question of what the maximum deflection angles the printer can support are, so it doesn't have to be mounted 30' in the air to get larger build volumes.

From the other thread Rylan said the drips as the z-axis can be out by 5%, but a peristaltic pump is 1%. As you say the drip detector should be be the same so it should work great and better than a passive dripper.

I can see speed printing becoming a thing,