honing 7" (180mm) bore.

[Gareth J]

I'm in the middle of tearing down and hopefully rebuilding a really tired vane vacuum pump. It's just snapped a vane and jammed up. Should've used the special inspection hole to inspect the vanes and noticed they were worn to about 2/3 their nominal thickness, replacing them in good time... But didn't.

Everything is pretty worn, the vane slots and the bore. The wear ridge on the bore must be over 0.5mm and the bore surface is pitted and ugly.

I'm never going to make this a pristine machine but think it's worth chucking a £100 rebuild kit at it. A brand new pump is £850 though so 3figure machine shop bills are going to be hard to justify.

So I was thinking I'd just try to clean it up a bit, but with what? Hone tools are surely going to be too small. Bear in mind the bore is 2' long and the central ports are a good 2" across too.

Best idea I've got is just to get my arm in there with some wet&dry...

Any ingenious ideas greatly received!

 

[Shox Dr]

Engine shop. Get them to bore and hone

 

[Gareth J]

Engine shop. Get them to bore and hone

Any idea on ballpark cost? There are a couple places I can ring but will be nice if I don't sound completely in the dark.

 

[mike 109444]

I think you have to be careful using JUST a hone in a worn bore as the hone will follow any irregularity. Honing is used to FINISH after boring. The boring removes any incorrectness in the bore then hone to give a surface to allow beading in

 

[Wendelspanswick]

Last rebore I had done was a Montessa Cota 348cc trials bike about 6 years ago, rebore and hone was £30.
I used Hamlins in Bridgwater:
http://www.hamlinsengineering.co.uk

 

[normspanners]

+1 for engine shop and get it cleaned and honed,

Just dont polish the bore to a mirror finish cause then it could end up a very vain pump!!

 

[Gareth J]

There's no way one of those toy hones would do. The blades would get swallowed by the ports.

I'll have a phone around and see. So long as it's not a 3 figure sum (well maybe just a 3 figure sum) it's probably worth it.

Just dont polish the bore to a mirror finish cause then it could end up a very vain pump!!

Groan....

 

[normspanners]

Best idea I've got is just to get my arm in there with some wet&dry...

ps that will take you years not hrs and it will end up all shapes and be worse than leaving it IMO
Vanes work on the basis, more so that the bore is parallel, for the blade edges to touch all along their sealing surface but also being even around the bore will help

 

[the snooper]

ps that will take you years not hrs and it will end up all shapes and be worse than leaving it IMO
Vanes work on the basis, more so that the bore is parallel, for the blade edges to touch all along their sealing surface but also being even around the bore will help

I agree with normski wet n dry by hand with doo more harm then good

 

[500e]

Hamlins as Wendle says ask for Mark, good bloke

http://www.hamlinsengineering.co.uk

Wendle it cant be that dark in your part of Somerset

 

[mike 109444]

Hamlins as Wendle says ask for Mark, good bloke

http://www.hamlinsengineering.co.uk

Wendle it cant be that dark in your part of Somerset

Not if they light the street gas lamps

 

[Wendelspanswick]

B'aint no new fangled street lights out ere, I just set lights to the cows farts!
Lost me eyebrows last time though!