https://www.youtube.com/watch?v=JLvDvG6U_Xw
This could be for future versions of the Peachy and would allow for more consistent drip.
Printable View
https://www.youtube.com/watch?v=JLvDvG6U_Xw
This could be for future versions of the Peachy and would allow for more consistent drip.
I see the potential.
:)
Very nice little variation on the Gear Bearing. I could see this going a step further and pausing the print to place the silicone tube mid-print and avoid problems with feeding it through the wheels. Also, putting a small hole down the middle of each planet gear to allow a small magnet or metal rod to be stuck through to get "pump count" out of it.
the water spray exiting the tube is much more nice and linear at higher speeds, but then the flowrate is much too fast. Maybe using a much smaller rubber tube would help with that (wikipedia's page on these types of pumps says "The flow is pulsed, particularly at low rotational speeds" which isn't exactly good for 3d printers)
They could also lasercut this design at the same time they are lasercutting the rest of the printer, since it's made of 2d shapes.
So we have been using a peristaltic pumps on one of our printers for quite some time now.
Its controlled via serial connection to an arduino.
here is what iv learned
- altho the pump pulses are abrupt they are also so very small that it doesn't affect the printing in a peachy printer with a large print tank ( over 20 cm x 20 cm aria ), as long as preconditions are taken to make sure that vibrations from the hose don't physically shake the printer head.
- using pwm we can get variable pump speeds
- putting a magnet in the pump and using a haul effect sensor could create a moving magnetic field, that could in turn cause the mirrors to move with the pump ( something to watch for)
- We use an optical encoder directly attached to the motor shaft, and doing this allows us 5-30 times more resolution( depending on the gear ratio to the pump)
-its tough to find inexpensive, peristaltic pumps that work reliably at lower than max rpm, they stall really easily.
- if the pump lifts water more than a 2 feet then the suction required to lift the water seems to be enough to cause oxygen dissolved in the water to bubble out. This could be a big problem because there we don't know much of the volume were pumping is oxygen and how much is water.
Placing the pump at the lowest point posible and pumping between tanks sitting at the same level are two things that help.
As for 3d printing one with the peachy printer, Well I love the idea peachy printers printing upgrades for them selves!
Ill definitely join the effort the get a 3d printed one working, but I may work untill we have more calibration maths implemented.
Laser cutting one is also very likely, James Townley was white boarding all the layers for one just 2 days ago :)
He seemed pretty pumped about it.
Oh, you:rolleyes:Quote:
Originally Posted by rylangrayston
This thread is old, but I like the idea very much.
I have spent about ½ year to develop my own pump, but in stainless steel, so prototypes does not come as easily and often :)
I just wanted to share some knowledge.
At my work we use peristaltic pumps a lot, for corrosive liquids. My work was a peristaltic pump that could be adjusted between 50mL to 2L over an hour.
To make this thing work, the inner pathway for the tube must be made specifically to the tube you want to use, actually a little smaller to make it shut tight in the hose. You need to have a very high pressure on the tube to shut tight. If it is too tight and there is too much pressure on the hose, the hose will be eaten (making holes/leaks) or collapse and not expand again.
Make the outer tooth ring thinner, so that it will make a spring effect and adjust for tiny hose wall thickness variations.
There should be something that prevents the hose to get too close the teeth on the gears, if it moves sideways.
There should be something that holds the hose in place, outside the pump head, else the hose will slowly be pushed through the pump. A cable tie can do, but when you have a 3d printer, you might as well make it more elegant.
A nice to have option, that will make it more complicated is a way to fast replace the hose
The trick with this pump in the video is that the gears mesh towards each other. This type of gearing can only be made with a 3d printer (or some other layer by layer method) and is made as one piece. So your point on something to prevent the hose from getting too close to the gears if the gears move sideways, is invalid. This is because by design the gears don't move sideways, and the hose is actually put into a track inside the gearing so it won't shift. Still it's a very good idea.
One thing that I've thought about is if there were a second tank with a hose connecting the first, and the drip was put into the second tank, then surface waves would be reduced. The second tank can be test tube sized, just so long as they are physically separated and only connected by a pipe and the liquid inside the pipe. Probably overthinking it, and it's a solution to a problem that doesn't exist.
If the pump delivers at the bottom at the tank, there properly wont be any waves at the top, but your idea will improve the design.
Regarding sideways movement, I was not talking about the gears, but the hose.
I like to explain out from my own experiments. I had a Ø8mm hose, 1,6mm wallthickness (3,2mm total). I used spring loaded bearings that pushed with 10Kg on the hose. I had a washer on each side of the bearing, so that the hose should not be able to move away from the bearing. In 2 of my experiments the hose managed to move past the washer, in only 1,5mm space. This of cause broke the hose.
It is very simple to adjust for that in the design.
It would be best to have a part between each roller, to align the hose in the center.
The easiest would be to have 6 planet gears, 3 acting as rollers and 3 between that dont push the hose but only aligns it.
I like the 6 planetary gears idea.
if you have a real peristaltic pump, you'll find that they use special tubing and plenty of lube to keep the tubing from getting destroyed by the pumping action. they also use barbed fittings, secured by hose clamps on each end of the tube that prevent the tube from moving out of the pump.
We deal a lot with real peristaltic pumps, I have not seen a small one that used glycerin. We have the fittings, the special hose and the glycerin in our stock, but I think the idea is to 3D print as much as possible.Quote:
Originally Posted by 3dspider
Am I the only one thinking that a pump like this can move the saline solution both ways? Imagine a dripper at both ends of this tube, one for counting drops raising the resin, and another one at the other end for lowering the resin. No need for a stepper motor anymore.
Technically you would need a T coupling from the reservoir and two check valves to direct the flow properly.
Yes it can move both ways. And if you deliver at the bottom of the tank, you maybe dont need the dripper, if your hose is thin enough, do that you can dose small amounts correctly.
I personally like steppers, it is very easy to control their position/speed and make accurate pump dosing. And you can easily find hardware/software to get anybody going with them. A RC servo driven pump could also be a nice solution.
Just the pumphead, with motor and control and a thin hose to reach between the 2 tanks. Then you can raise and lower the liquid level.
My 3D printer is not up and running yet, when it is, I will try to make this thing. I need it for my work anyway :)
If you dont mind using a stepper why not have a feed tank of water slightly lower than the build tank with a hose connecting to two. Then use a stepper to lower some displacing mass into the feed tank, the level of the saline in the build tank will also rise.
In-fact you don't even need a stepper, a roll of steel beads on a large reel being slowly unwound by a slow motor into the feed tank would slowly increase the saline level in both tanks
That is a great and simple idea
Use a bag of sand with a hole in it and you can do away with even the motor. It'll be like an hour glass
I apologise as this becomes a stream of my thoughts:
If you had a slowly unwinding spool of bbs (im thinking of these doodars: http://www.amazon.co.uk/ROLLER-ROMAN...tal+ball+chain ) then it could pass though a drip counter device too. a drinking straw with wires just poking though the walls, making contact as each little bb passes by.