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mistergreen 10-13-2010 05:35 AM

DIY Peristaltic pump?
Have any of you tech heads thought about making one? I can see one being made with a servo, controller, teflon gear or wheel, and silicon tubing for under $50. But I can't see what I can use for the case that holds the tubing in place which is pretty important.

Any thoughts?

majstor76 10-13-2010 06:29 AM

Its tricky to make peristaltic pump in DIY and they are cheap so people does not want to bother with DIY. But i think that case could be made on cnc (im operator of one). For material i would use kerrock or max compact

mistergreen 10-13-2010 02:19 PM

They are cheap? do you have a link?

I was thinking last night and I guess I can make the body out of a chunk of wood. The circular hole can be drilled with a hole bit and then the face can be covered with a sheet of plexiglass/acrylic.

mistergreen 10-13-2010 03:40 PM

For this application, it would be a liquid fertilizer delivery device. With a servo or stepper motor, you can change the speed so you can control the amount.

I'm choosing a servo because it's a bit easier/cheaper to control.

Wasserpest 10-13-2010 03:46 PM

I tried a couple using a mechanical timer as the motor, for one complete rotation per day. In the end I gave up because it was tricky to exert enough pull/push to get the tubing pinched closed, but not too much to overwhelm the timer. Plus it wasn't very adjustable, just enough for adding concentrated micros to a smallish tank.

You need a little high-torque motor. This is where the cost side comes in... good if you have access to them. If not, I'd agree with majstor... might be more cost effective to go with the relatively inexpensive APT pumps.

Here's something
to get your creative DIY juices flowing...

MlDukes 10-13-2010 04:15 PM

The timer idea is clever.

If anythign rig up a simple unit not worrying about flow rate just consistency - then you can calculate how much is pumped per min/hr and in turn use a timer to control how long it runs each day.

mistergreen 10-13-2010 05:11 PM

haha, that autodoser is cool.

Yeah, I worry about the fudging to get it pumping too. A good stepper motor has enough torque. It's around $15... But the controller for it would be around $30. I'll have to compare a servo's torque.

5.2-6.5kg*cm is good torque right?

majstor76 10-13-2010 07:25 PM

You can seach on ebay for "dosing pump". Currently there are 6V/12V 50-100 ml/min mini peristaltic pumps for 30$ onwards. There are also medical pumps with digital controls, pumps for detergents for washing machines etc... I have just ordered one mini pump for 30$ to see how it works. It is just a peristaltic head with little motor

mistergreen 10-13-2010 07:58 PM

I think I can build a bump and a controller for ~$35..... That's pretty much the price of a pump alone.

Now we'll see if I have time to make it :)
If it fails, I can always use the motor to make a RC car or something! I'm thinking about buying the lego mindstorm for 'educational' purpose.

DarkCobra 10-14-2010 01:05 AM

How about a reciprocating/plunger style pump?

There's one shown on the page Wasserpest linked.

Use a syringe as the pump. Connect the nozzle to the center of a standard airline tee. Connect the two ends of the tee to the reservoir and aquarium via two check valves, so that solution always flows the proper way when the syringe's plunger is actuated.

You just need to pull, then push, the plunger.

If a mechanical timer doesn't suit or isn't strong enough, use a good servo. That would allow you to program in any dosage.

Or use any gearmotor with sufficient force, like a <$10 cordless screwdriver. Just like the horn on a servo, attach a disc to it, with a rigid mechanical linkage from the plunger to an off-center hole in the disc. There's no need to reverse the motor, which simplifies drive; all you need to do is turn the disc through one full rotation. A full rotation can be sensed with a microswitch that detects a protrusion or cutout on the disc. Dosage can be adjusted by the throw of the linkage, number of full rotations, and concentration of the solution. Just one digital input and one digital output (with a drive transistor) on an MCU for this. Easy.

With a little shopping around for inexpensive gearmotors, I'd think this could be built for $15/pump.

mistergreen 10-23-2010 08:15 PM

So I went ahead and started building one.

It's being controlled by my little arduino for now. It's kinda works but it should work better if I get another less rigid hose. I'm using a silicon hose but I think a latex hose would be better.

Does anybody know where to get a 1/4" latex hose besides online?
I might have to buy some online. I can't find it anywhere.

jeremyblevins 10-23-2010 08:17 PM

Home depot and lowes have it around me.

mistergreen 10-23-2010 08:20 PM

yeah, they have 1/2" hoses. Nothing smaller.

jeremyblevins 10-23-2010 08:30 PM

mistergreen 10-23-2010 08:56 PM

nice! But not available in my city! :(

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