Home made peristaltic pumps

[Dadrick]

Remember that from day 1 if needs be, or after a bit of wear has set in, more squeeze can easily be had by fitting a bit of flexible shim stock behind the tube, for the entire width and length of the wall.

I've been quietly following this thread. To me this seems like the best KISS solution possible. The ability to fine tune the wheel pressure without going to some extreme engineering solution with springs or tensioning screw adjustments. When it comes time to replace the tube remove the shims and start over.

 

[BrewBeemer]

For my 2 cents worth, I think .010" to .015" extra compression is a bit too much. I think that as soon as the wheel squeezes the tube enough to prime at near zero revs (IE by hand) and stay primed if you stop rotating it, then that is enough. Any more pressure will just make the pump harder to turn.

Remember that from day 1 if needs be, or after a bit of wear has set in, more squeeze can easily be had by fitting a bit of flexible shim stock behind the tube, for the entire width and length of the wall. In fact, any adjustment required can be done this way, as long as the wheel is made wide enough in the first place, unlike mine, which was limited from the outset by a bad wheel purchase (£10 skateboard)

The .010" to .015" of compression on the tubing compressing thru two wall thicknesses of the tubing so the tubing wall thickness as a wild example of
.090" is rather thin compressing the material .005" to .0075" on .090" of a soft flexible material at a very little amount of compression. Sorry I don't buy your reply, again it is a forum and all replies are your right so I will respect yours.

 

[silverbrewer]

Hi Brewbeemer...I didn't mean to offend or critisize. As you say ,we are all on the same side here , and we are all guessing to some extent, although from your interesting and constructive comments it does seem you have experience of these pumps, or silicone tube. I was just trying to say that I think that "a seal" may be obtained with a bit less pressure.

Today I bought a 5 1/2" length of 12" od 1/4" wall thickness aluminium tube for £10. With a bit of luck I may be able to cram 4 bits of 1/2" tube in there to get 4 pumps.

This should give me the ability to use all 4 pumps at once to give a high flow rate without a high RPM, or, in the event of a catastropy, there is going to be other useable pumps to rescue the situation if this silicone tube proves to be un-reliable, which I doubt.

Looking at the tube on the dining room table, it looks massive for a bit of alloy tube!

 

[silverbrewer]

Here are photos of the Mk1 pump taken apart. There are two thin plastic layers that are not in the exploded pics. They are there to get the width of the central layer to the correct width. I needed 27 mm wide and the MDF sheet was only 25 mm wide. The skateboard wheels run on standard skate bearings and the wheel carrying spider has two Oilite plain bearings in its centre. They were put there so the pin that picks up drive from the shaft could be removed so the pump would be disabled but the shaft could still be driven while in the stationary spider.

 

[Yorg]

Any updates??

 

[silverbrewer]

I am getting on with the Mk 2 pump, but have been a bit tied up with other brewery related tasks...

To get ready for the brewery build (Shed extension), I have chopped down two of next doors large trees, dismantled and re-assembled a small shed to elsewhere in the garden, dug up and re-positioned one of those bloody heavy 8' tall concrete fence posts and had a general tidy up. The extention will give me a 10' x 23' covered area, with a 16' x 5' covered corridor along the back. Got to go buy the wood soon.....

Anyway, back to pumps.

I have trimmed the ends of the alloy tube (12"od 11 3/4" id 5 1/2" long)
I have two bits of 10 mm thick 12" square Perspex that I have to turn a 11 3/4" diameter shoulder onto and bore holes for bearings. These will sit into the tube ends and provide concentric bearings for the shaft.
I have sorted out how to machine the three arms for the rollers, but cannot finalize the dimensions until I make the rollers.
I have got the steel tube for the rollers and am now searching for some round alloy stock to make the six end caps/bearing holders that will go in each end of each roller and hold concentric bearings for the rollers.

To machine the larger stuff I need to visit my mate who lives 100 miles away! but I will get to do that soon I hope.

This pump will have three separate 1/2" silicone tubes, getting squeezed by rollers that are about 4" long and 2" diameter. This will give me the 2 pumps I need for sparging operations and an instantly available spare for emergencies. With all three tubes in use for high flow needs, I do not expect this pump to need to be turning at much over 50 to 75 RPM during use....

 

[BrewBeemer]

I am getting on with the Mk 2 pump, but have been a bit tied up with other brewery related tasks...

To get ready for the brewery build (Shed extension), I have chopped down two of next doors large trees, dismantled and re-assembled a small shed to elsewhere in the garden, dug up and re-positioned one of those bloody heavy 8' tall concrete fence posts and had a general tidy up. The extention will give me a 10' x 23' covered area, with a 16' x 5' covered corridor along the back. Got to go buy the wood soon.....

Anyway, back to pumps.

I have trimmed the ends of the alloy tube (12"od 11 3/4" id 5 1/2" long)
I have two bits of 10 mm thick 12" square Perspex that I have to turn a 11 3/4" diameter shoulder onto and bore holes for bearings. These will sit into the tube ends and provide concentric bearings for the shaft.
I have sorted out how to machine the three arms for the rollers, but cannot finalize the dimensions until I make the rollers.
I have got the steel tube for the rollers and am now searching for some round alloy stock to make the six end caps/bearing holders that will go in each end of each roller and hold concentric bearings for the rollers.

To machine the larger stuff I need to visit my mate who lives 100 miles away! but I will get to do that soon I hope.

This pump will have three separate 1/2" silicone tubes, getting squeezed by rollers that are about 4" long and 2" diameter. This will give me the 2 pumps I need for sparging operations and an instantly available spare for emergencies. With all three tubes in use for high flow needs, I do not expect this pump to need to be turning at much over 50 to 75 RPM during use....

All I can add is your on the mark with your pump building and drive until you'll get the results your after in due time.
I believe with the tubing diameters plus the low rpm's your at a "have a winner" coming together. Hats off mate. I'm going off pumps my machine shop was designing back in late 1969 thru early 73 when I finished my college and started working for the airlines as I had my FAA licenses by then. I must ask on your tubing what is the wall thickness and how much crush less than the two wall thickness are you at now in this last pumps design? This has sparked my intrest beyond spending any money purchasing any March pumps with all their priming problems plus the perfect sparge with two pumps working as one. I'm just adding what I never forgot when I was younger as these pumps were built in a prototype one off type machine shop I worked in while in college classes on swing shift. My dad helped this shop owner he made a short loan to him as dad purchased two new Bridgeport mills with optics at 0.0001" table scale readings for him. This was in 1969 I recall.
We also did production runs and machined cast aluminum electrocardiograph
machine bases as well pneumatic hand probe air blast units used to test
for the eye pressure glaucoma disease. My aviation job took me away from the machine shop but have a old Bridgeport and lathe in the shop at home.

On the pumps they had a stainless tube stub tig welded to a threaded nut, a bulb before the end of the stainless tube prevented the tubing in the pump from being pulled off as there was a collar to prevent the tubing from creeping off the stainless stub bulb from the nylon roll pulling inside the pump. Mind you this was 38 years ago. With your unit a 90 VDC motor like they use on those jogging tread mills will have the rpm's your looking for if a poly "V" belt reduction were used as well they should have a trigger wheel and LED to maintain a constant speed control under different motor loads. I just picked up a "KEYS" manufacture jogging unit due to the owner drilling into the side frame and ripping apart 12 wires of 26 gauge hence it a curb side rubbish unit. I stripped it apart, rewired the controller and motor which is 1 1/2 hp 12.7 amp @100 VDC motor. App 115 to 4,460 rpm's constant speed control under different motor loads due to that LED trigger assembly. I was also thinking this a perfect grain mill motor after a poly "V" belt reduction then a direct drive to a the grain mill without large pulley bushing side loading.
Keep posting your progress as i'll be watching. Take care. Carl.....

 

[silverbrewer]

Today, just for the hell of it, I set up the Mk1 pump and circulated boiling water for a couple of hours, at about what I am guessing will be the flow rate RIMS requires.. about 45 RPM and 2.5 USPintsPM. The silicone tube seemed to take it in it's stride, so there is another hurdle passed off the check list of potential problems! The test stopped when it started raining all over my electrics!!

Carl:- The tubes ID is 12.7 mm and the wall thickness is 3.2 mm. I am setting the pump clearance to 6.4 mm. If I find I need more "crush" than that, I will fit shim stock inside my alloy tube, behind the silicone tube....That way I can set the crush to whatever I like, and the surface finish on the shim stock will probably be better than the surface finish of my alloy tube, so the silicone will be happier.

I have yet to decide whether to lubricate the tubes within the pump case with anything? The pump case will be not quite "water tight" but should be Grease tight, so I was thinking "silicone grease" may be a good starting point? Perhaps I can get PTFE shim stock and then not need any lubrication...

Any "sensible" advice out there on lubrication !?

 

[Yorg]

What is shim stock?
Any links?

 

[silverbrewer]

Hi Yorg,

"Shim stock" is standard thickness sheet material available from stock, for making up thin spacers. (shim) It is readily available and does not need to be manufactured. It comes in a multitude of thicknesses from sheet metal suppliers, and can be steel, brass, copper, whatever.

There are weird differences in what we call engineering things each side of the pond...over here, the swirly cuttings that come off a metal lathe are called "swarf" and high carbon steel ground bar in 13" lengths is called "silver steel"

 

[BrewBeemer]

Kind of like driving on the wrong side of the bloody road mate?
I was across the Pond during the "Storm of the Centry" in London
heading north on holiday for an additional two weeks, cut it short
and headed back to California. So sad no Matchless and Velo single
parts. Ya still shut your pubs at 11 PM? So used to 2 AM in the states.
No worries, shim stock is our standard wording state side, now the propeller
shafts a hoot as well a "hearty tug with a one foot Tommy Bar" for a torque
spec on a head bolt. The bonnet and boot plus anti-clockwise are fun to read
about. My wife was asked "what time do you want to be knocked up?" That we laughed for years onward. Driving in the states, horn standard equipment, blinkers optional use. Still 17% VAT? Not 17% ABV, now go get pissed chap.

 

[silverbrewer]

Here are the three arms of my Mk 2 peristaltic pump wheel spider

The component parts are here.

Here is the aluminium tube that the spider will be put in, It is 11,1/2" id 1/4" wall thickness. The inside of this tube will be the "outer" wall that the three 1/2" silicone tubes will be squeezed against by the three rollers.

 

[jcdillin]

Whoa, that's sweet!

 

[cyberbackpacker]

Wow, that thing is going to be HUGE!

 

[silverbrewer]

I've never had any complaints about "hugeness" before!!

Seriously though......It is going to end up 12" diameter and 6" long, but remember that it is THREE pumps combined.

It will/can sit high up in the brewery (shoulder height), as it can prime itself.

It will be mounted on a wall, with the drive coming from the other side of that wall, so a very neat setup. I intend setting up the keggles so that each one has a stainless 1/2" tube going down into it from the pump, so I will not need any holes in the side of the keggles at all, just a straight keg with the 12" hole cut out of the top. Temp probes, and all inlet or outlet tubes will come in from the top. Well, that's the plan anyway!

Now, will someone perleeeeese tell me the outside diameters of Blickmans punched false bottoms, so I can order one to go into my mash keggle.....

 

[Hang Glider]

Those are some incredible engineering skilz

 

[cyberbackpacker]

I intend setting up the keggles so that each one has a stainless 1/2" tube going down into it from the pump, so I will not need any holes in the side of the keggles at all, just a straight keg with the 12" hole cut out of the top. Temp probes, and all inlet or outlet tubes will come in from the top. Well, that's the plan anyway!

I have a peristaltic pump with 4 heads that I plan on utilizing in the same way. Draw from the bottom up without a need for excess holes, or even a ball valve in my case.


Good luck.



...

 

[Catt22]

Now, will someone perleeeeese tell me the outside diameters of Blichmans punched false bottoms, so I can order one to go into my mash keggle.....

The Blickman false bottoms are designed specifically for use with their kettles. The Blichman kettles have a stepped side near the bottom that supports the FB. You could probably modify the Blichman FB to work with other kettles by adding some feet to it or figure out some other way to support it.

 

[Yorg]

You are a friggin legend.
Once built and tested, can you post some CAD drawings and some part specs and sources?

 

[bendavanza]

That thing is going to be a beauty. Super clean looking parts!

 

[silverbrewer]

The parts for this Mk 2 pump are so far pretty much hand made. All of this could be done if you enrolled in an evening course at the local engineering college, which shouldn't cost much. The Mk 2 pump build will indeed need some access to engineering equipment, but down the line, once this Mk 2 pump has been well and truly tested, there is no reason why a Mk 3 pump cannot be designed that uses only simple readily to hand parts.... so that anyone can make one, with a tad of ingenuity and a simple toolkit!

I was being shown a brand new brake drum the other day that would have been a good starting point, but the bloke at work was only showing it to me because he had recently put a .22 bullet through it with his rifle! While he was chuffed that it had gone right through one side and dented the other, I was looking at it and thinking "****, I could have used that you berk"....My point here is that brand new brake drums cost very little and give a perfectly machined circular surface.

On my Mk 2, all the shafts are silver steel, which is already ground to exacting tolerances, so it fits the bearings exactly with no work required except cutting them to length. (Note here that metric silver steel is machined to a plus nothing, minus a couple of thousanths, while imperial sizes might be a plus or minus tollerance, so bearings may not fit and you will have to go with metric) I was lucky with the steel tube for the rollers....that is also ground, so cleaning it up to get a good surface took a few minutes with 800 grit paper.

The arms on my Mk 2 are cut out of a very hard foam that our 5 axis guys use to carve car models out of....... but they could just as easy be made from wood. The shapes were drawn by hand and cut on a simple band-saw. The round hole cut in the middle of each part is so I could hold each part down on the top slide of my lathe, using the tool post bolt. I then drilled one of the shaft holes with a 15 mm drill stuck into the lathe head. I then indexed the cross slide the appropriate amount and drilled the other shaft hole. that way, the shaft holes were all drilled exactly the right distance apart, and they were parallel, and not skewed either. Fine slots were cut in the bases of each leg and holes drilled for the clamping screws.

The end plates for the big tube will have to be made on a BIG lathe, so that could be a stumbling block for this design to be made by one and all, so those without access to a machine shop will have to wait until Mk 3

 

[ajwillys]

Hey, any updates on this project? I'm very interested in seeing how this turns out.

 

[BrewBeemer]

A lathe of 16" is available, made by the Pratt & Whitney radial engine manufacture. My Atlas is only a 12" swing. For drums look into big rig
18 wheelers as they have an ID of 16 1/2" by 7 3/8" deep shoe depth.
One problem your dealing with app 55 pounds of steel. I have used them as grinder and buffer stand bases. Big rig drivers as friends with worn out drums
available. F250 Ford pick ups of the 67 thru 76 era have 12" x 3" drums ortherwise look into F350 truck drums as they are wider. Cast in steel with finned aluminum drums on my 56 300C Mercedes drums are app 4 1/2" wide at the shoes.
Anything is better than having a collection of March pumps with what they are
the asking for them, this just rubs me wrong. I sold my last brewery with two March pumps with their priming PITA plus their high cost even used. I will explore the use of other pumps.

 

[JVD_X]

One last thing... you need to make sure the tubing can be replaced in a matter of minutes. I have peristaltic pump using high-temp silicone tubing that occasionally bursts during use. I think a the regular use of hit liquids and cleaning fluids causes the silicone to become brittle. Luckily - I have never had the tubing split while pumping my beer or mash.

 

[silverbrewer]

Just to update on progress, I have now fitted bearings in each end of the three rollers and they are all fitted to the "spider".
The 12" aluminum tube and 10 mm thick Perspex end plates are all at my mates house waiting to be machined on his big lathe. The trouble is, he is in bloody Mexico!!! The only good thing about that is he is bringing me back a couple of propane gas rings, and one of "Derrins" stir plates.

JVD-X :- To combat emergency down time I have three tubes in the single pump body, so if a tube fails I can switch to the spare to get out of trouble, plus if needs be, I always have my MK1 model close to hand, even if it is only made of wood!! Although this is a "how long is a bit of string" type question, how often do you reckon the tubes will need replacing?

Regarding popularizing this type of pump, I think that would be a great idea. I still think making one based on a readily available brake drum is a good starting point, to keep the engineering simple. The trouble there is that what is a popular drum Stateside is not available here, so one of you lot needs to join in and do some development. I think that once the design has been finalized they should be really cheap to make, so the plan would be for everyone to have two or three of them driven off a single shaft.

To start the ball rolling, I see some kind of cheap standard brake drum cut away so only half of the drums surface is intact forming a semi-circle, but cut so the centrally machined circle where the drive shaft enters is still intact.
The ends of the drum surface are carefully rounded so as to not damage the tube.
Next, a bearing holder is manufactured that holds a couple of ball races, and that assembly sits tightly within the drums shaft entry hole so as to pick up on the concentricity that has already been provided for us. A suitable shaft is placed through this bearing holder and a two roller arm is fitted within what is left of the drums swept surface, to crush the tube.
As mentioned before, over here, metric sized ground shafts have a negative tolerance, so they fit very exactly, (but with a clearance) into metric bearings, but I think imperial ground stock has a plus or minus tolerance, so a good fit cannot be guaranteed. Do you guys work in metric? I work in metric all the time, but I still think in thousandths of an inch as soon as small stuff is encountered, but that's just cos I'm an old git.

The sort of motor that is used for grain mills should be able to be utilized if one is available, or the sort of geared motor commonly found driving industrial roller shutter doors will be well up to the task.....

Having said all this, trying to cover all bases is a big task as everyone has different abilities and equipment. A DIY build of this complexity should be aimed at peeps who either have suitable equipment, or can enroll in a model engineering class at a local college..where there are always people ready and willing to help....I suppose there is always the option to bulk buy in the manufactured bits from a small engineering company! This is after all a very well attended forum!

Discuss!!!!!!!!!

 

[ajwillys]

Wow, quite an update! I think the idea of using a brake drum would be good. I have no expertise on the engineering that would be required but I would very much like to get my hands on the finished product. Most of the peristaltic pumps I find are either very precise and small or absolutely huge. Seems like there is a big market for a general purpose P-pump like this.

 

[bendavanza]

Stateside there has to be a ton of cheap drums for chevy trucks. Measurements are done in either metric or inches, depending on who's doing the work.

 

[BrewBeemer]

Using a complete front drum with hub assembly including the tapered bearings then all you would need is a machined center axle that fits the two different cone bearing bores for a concentric mounting point for your roller spider to mount onto. Threaded axle with jam nuts for slight bearing preload. With the drum mounted on a bracket off the hub lug studs it would then be easy if you have the axle extended past the outboard side of the hub for a connecting means to a 90 VDC gearmotor with speed control. For holding the tubing in their channels or pockets machine oversize aluminum rings with the proper spacers, freeze the rings or use dry ice then install the rings. Once expanded into the drum remove the spacers between the aluminum rings these channels for your tubes to set in. Like you mentioned before, cut away what's needed to pass the tubing in and out of the drum which can just be holes in the channels angles into the direction of the tubing and radiused to prevent any tube chafing. building the pump body this way 90% of it is from a automotive breaker just pick the diameter drum you want, make the spider to your drum and rollers as well the aluminum rings. Surely those tapered greased wheel bearings will outlast a lifetime of use going from 1,000 pounds plus loading to almost zero bearing loading just rotating. This is how I would build one as there are many drums available at 12" ID and smaller, my lathe can only swing 12" for the aluminum tubing support rings. I would build it to allow for grease seals at both ends of the hub.

 

[BrewBeemer]

Stateside there has to be a ton of cheap drums for chevy trucks. Measurements are done in either metric or inches, depending on who's doing the work.

You got that right after going thru 3 chebbie trucks until I got smart and changed brands. Dodge still a no. Went Blue Oval sold the last truck at 922K miles it passed 1,032,000 two years ago second owner now.
Those miles with the Blue Oval since 1972 with a 69, never looked back. A mint 68 F250 Camper Special with 69K original miles I had to have but the 390 had to go the 520 FE filled my needs.

 

[JVD_X]

JVD-X :- To combat emergency down time I have three tubes in the single pump body, so if a tube fails I can switch to the spare to get out of trouble, plus if needs be, I always have my MK1 model close to hand, even if it is only made of wood!! Although this is a "how long is a bit of string" type question, how often do you reckon the tubes will need replacing?

I have found that I get about 10 batches out of tubing. The tubing is not cheap but the length is really short, so it doesn't cost much. In addition, I use the pump for cleaning and sanitizing as well. For example, I use it to pump PBW and Starsan through my counterflow chiller; I also use it for my RIMS. This means it is easily running 2-4 hours each brew session.

So - as a guesstimate I would say you would need to replace the tubing every 30 hours of use. The point being, you can't really be sure when it's going to split - I have been lucky. Also - I have started taking the tube off the rollers between batches to minimize the strain on the tubing. I don't know if this will make a difference but I haven't gotten to my 30 hours since starting this practice.

BTW - here is the pump I use.