rotarary vane pumps

[I.M. OUTAHEREParticipant @i-m-outahere]

Hi all.

Whilst not purely a model engineering question it could have relevance for those who use die grinders or the like .

I am currently building a petrol powered air pump that uses the internals from a 3/4 drive impact wrench as a pump .

Unfortunately the unit i scabbed from the steel bin at work was in pieces and the vanes are missing .

I remember years ago pulling a broken die grinder apart to salvage parts and the vanes looked like some sort of material similar to phenolic circuit boards but maybe with a fibreglass matrix .

This unit will only be used to pump up tyres on a 4wd – so used in short burst and only needs to raise the pressure from 12psi to 32psi max .

Any thoughts on suitable materials would be appreciated and please understand this is only an experiment !

IAN

[I.M. OUTAHEREParticipant @i-m-outahere]

what material to use for the vanes

[Michael GilliganParticipant @michaelgilligan61133]

Ian,

That sounds like a very interesting project.

This is only a guess really, but the vanes in your die grinder were probably made from one of the better grades of Tufnol  such as Carp Brand.

Beware: If making something like this [or particularly, gears] you should always work with suitably thick Sheet material, not Rod. …. The rods are made like a roll of fabric at the haberdasher's … and that puts the strength in all the wrong places.

MichaelG.

 

Edited By Michael Gilligan on 21/09/2012 09:05:46

Edited By Michael Gilligan on 21/09/2012 09:09:22

[Michael GilliganParticipant @michaelgilligan61133]

 

For ease of reference:

Tufnol's advice about machining Gears is here

… Much of this would be relevant to your Vanes.

 

 

MichaelG.

Edited By Michael Gilligan on 21/09/2012 09:20:09

[blowlampParticipant @blowlamp]

Ian.

Any motorised air tools that I've come across have never looked suitable for use as a pump – are you sure your conversion will work?

Martin.

[Clive HartlandParticipant @clivehartland94829]

My experience of Tufnol gears is entirely negative as twice I have had tufnol gears lose a tooth,

My Opel Kapitan had this–e larger tufnol timing gear strip a tooth when far out in the wild areas of Africa and the new gear came in aluminium. Later i enquired about tufnol gears and the best idea was to sandwich a sheet of steel between the two layers of tufnol, this being secured by screws through the matrix.

The second time was a small gear driven device with spiral tufnol gears which shed a tooth.

Clive

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Vane motors work well because the many leaks around the vanes don't matter too much with an overwhelming supply of air coming in .

Vane pumps on the other hand require very careful fitting of the vanes so as to reduce leaks to an absolute minimum otherwise the pump won't work at all . Conventional practice on higher quality commercially made pumps is to assemble the vanes with a transition fit and to 'run them in' before stripping down cleaning and reassembling – each van being numbered to match its slot position .

Tufnol is indeed commonly used but there is a slight problem of wear with (specifically) an air pump running dry . This is usually offset by having highly polished or chrome plated rubbing surfaces in the pump chamber .

On a comic note one of my fellow apprentices got married and mortgaged at a very young age and consequently never had any money . He was a resourceful fellow though and wanting an air compressor he fitted up an ordinary foot pump with a crank , flywheel and bigger treadle and put it under his lathe . When working away turning he used a spare foot to work the pump . Air went via DIY valve into an old fire extinguisher .

Regards ,

Michael Williams .

[KWILParticipant @kwil]

Vane pumps as air compressors, typical example Hydrovane, but these run with the vanes running in oil followed by an air/oil separator. Good compressors Hydrovanes, I have two, one small for spraying and the the other for workshop use. Does anyone have  a copy of theType 5/15 or 501/502 Hydrovane Service Manual?

Edited By KWIL on 21/09/2012 11:50:22

[I.M. OUTAHEREParticipant @i-m-outahere]

Hi all .

Thanks for the replies .

Michael G .

I will have a look at or for some tufnol sheet and check the specs for suitability but this sounds good .

Martin : as from what i have seen with air tools and rotary vane vacuum pumps that i use at work the main difference is the positioning of the exhaust and inlet ports.

For an air tool it is usually at 12o'clock and 6 o'clock from the inlet to exhaust or there abouts and for a vac pump which will also blow pressure the inlet would be at 10 o'clock and the exhaust at 2 o'clock or there abouts .

I plan to plug the exhaust holes that are drilled in the housing and machine a new set at aprrox 3'oclock and re- machine all internal surfaces .

Michael W.

There is no chrome plating on this unit and it was also used to try and stop the chatter effect that vane pumps develop – this was from over reving the pump which caused the vanes to bounce or from sticky vanes – i wish the hardchrome company i worked at 25yrs ago was still going as i could have got mates rates on a chrome bore !

The pump will mount directly to a new 50cc two stroke engine i picked up on E-bay for $75au inc clutch unit .

The bearings will be sealed units and ther will be no oil feed as i don't want oil in my tyres !

The pump will be reving at around 6000rpm for i hope less than 2 -3 min per tyre then back to idle .

There is no metal to metal contact and the only wearing parts are the vanes in which i can make a few sets for spares .

I wish i could go back ten yrs in time as my workplace threw out boxes of spare vanes for vacuum pumps in a workshop clean up .

I always wonderd what they were made of though .

Ian

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