sleeving steel pipe over other pipe

[ash_on_mtb]

I know this isn't really the forum for this kinda stuff, but everyone loves fabrication, and I figure ya'll suggest ways to make it tough enough, so why not. I'm making a high pole for the boat, and hit a bit of a hurdle. I've built the grounds that go between the bearers to support the lower 'stub', to which the pole slides over, but there is the problem

I need to find two bits of pipe/tube that sleeve over each other neatly. Off the shelf... Basically, I need a 600mm tube with an OD the same as a 2.2m pieces' ID. I've been to 2 places now that tell me its not really possible, but I call BS, and the outers Oracle. I'd like the 2.2m pole @ 3mm wall, about 50mm diameter or a shade more, and then the 600mm bit to be about 4mm wall thickness and an OD to suit the pole.

Anyone know how I can make this happen, without having to machine down a heavy wall 600mm bit to suit...?! Inner SE Melbs if possible, but if you know of somewhere else...!!

Thanks,

[mickbeny]

Hi all...ash-on-mtb,Pipe is measured by the I.D. while tube is measured by its O.D..So if you can get a catalogue you should be able to work something out.

[ANDREWGQ 351]

Can bo done
Use 40 nom bore extra light structural pipe for the pole 48.3 OD 2.3mm this gives an ID of 43.7mm
Then use 32 nom bore medium black pipe for the support 42.4 OD 3.2mm
Therefore a loose fit of 1.3mm, the inside seam will reduce this to a nice fit.
2.3mm wall pole will be more than strong enough and at 2.2m tall only 5.7KG.
Use a strap from the top of the pole to the front of the boat to stop pole from bending.
Galvanise then powder coat

[ozy1]

Can bo done
Use 40 nom bore extra light structural pipe for the pole 48.3 OD 2.3mm this gives an ID of 43.7mm
Then use 32 nom bore medium black pipe for the support 42.4 OD 3.2mm
Therefore a loose fit of 1.3mm, the inside seam will reduce this to a nice fit.
2.3mm wall pole will be more than strong enough and at 2.2m tall only 5.7KG.
Use a strap from the top of the pole to the front of the boat to stop pole from bending.
Galvanise then powder coat

remember if you galvanise and powder coat the od of the stub will change and the longer pole may not slide over it,

[ash_on_mtb]

Thats very true ozi, and I'm a little bit wary of getting the fit too tight, but I do need to be within cooee... I was thinking of another idea - perhaps I could get something about 2-3mm undersize, and run some beads of weld around and around, then con a mate into machining them back to pretty and neat. So in effect they would be perpenent shims.

I was thinking of about 4 bands, and make the stub only about 500 long - Like an extension on the coke can shim idea. Only thing is the 'load' will be localised on the bands, not spread the length of the stub, but I'm sure that wouldn't be an issue if the bands are nice and wide...

just a thought..?

[PJ.zook]

Or you could get an oversize piece of pipe with really thick wall, and machine it down to right diameter. Easier than the welding idea.

[ash_on_mtb]

that was the original idea, but I don't have easy access to a lathe, so its easier for me to weld a butload of rings off site, then con someone to just bring them down to the same diameter, rather than ripping down a whole length @500mm for basically the same outcome...

[PJ.zook]

Ask around some engineering shops, one might lathe it up for a six pack. Its not a hard job and wouldnt take long if theyres not much material to remove.

[ash_on_mtb]

out of curiosity, what would be a resonable measured allowance for gal and powdercoating?? What thickness would they be on average??

ta.

[awill4x4]

We deal in and use Chrome Moly tubing at work for motorsport use and it comes in telescoping sizes.
So lets get it straight. The long tube (2.2 metres) needs to be around 50mm outside diameter and approx 3mm wall. If thats the case then 2" (51mm) Cro/Mo with .120" wall gets pretty close to the mark. (and it's the right size for telescoping)
The smaller one (600 mm) then needs to slide inside the long one?
If so, then 1.3/4" (44.5mm) will slide neatly inside the other but note: there's no allowance for galvanising/powder coating. You could possibly get by with zinc plating but that would be about it.
You could then get the 1.3/4" tubing in any thickness you like, .156" would get you close to 4mm wall thickness.
These sizes will do what you want, but they're not going to be cheap so be warned.
If you want prices then ring my boss Greg Foster at D&F Racing Products and he should be able to quote you prices and availability.
Regards Andrew.