low friction insert in snout for bow sprit.

[pratn0]

Right so I have now measured the pole.

S the diameters look like follows.

2.9m -- 7.98
2.8m -- 7.92
2.7m -- 7.70
2.6m -- 7.57
2.5m -- 7.38
2.4m -- 7.19
2.3m -- 7.00

2.0m -- 6.49

0.0m -- 3.91

So I'm Thinking of getting one tube with an ID of 80mm and a length of 60mm. And then a second tube of ID of 75mm to pad out the outer end. To deal with the taper.  Thoughts on this?

Once I get the tube I will build out some carbon around them before I put them into the bow. 

Having unwrapped the pole I have a total weight of 2.17kgs for the 3m tube. 

Our cloth/resin breakdown before the build is as follows. 

Cloth 1.05kg
Resin 1.254kg

So it came out very nicely.

Nick

[john_hamilton]

mine is 70mm at the launch tube

[Stuberry]

mine is 70mm at the launch tube

That's nothing to shout about mate. Hayley says she's not impressed.

[JimC]

Sorta related, I'm in the habit of using offcuts of kevlar in laminates in high wear places. On the sliding seat on the Canoe it seems to be wearing to a very high polish (too high actually which is embarrassing in that application) and I reckon its much longer lasting than carbon. The surface is smooth: it hasn't gone fuzzy like a sanded kevlar surface does.

[john_hamilton]

mine is 70mm at the launch tube

That's nothing to shout about mate. Hayley says she's not impressed.

she must be incredibly hard to impress then, fair play Mr trim

[Hayley_Trim]

I have incredibly high standards   

[john_hamilton]

jimc,

ill try that kevlar on the inboard pole rest, cheers!

[JimC]

ill try that kevlar on the inboard pole rest, cheers!

Don't forget you'll need to mould a polished bearing surface because you won't succeed in sanding a kevlar surface smooth unless you are a lot cleverer than me (not that big a challenge). At a guess some graphite powder in the resin at the surface will do no harm at all either...

[john_hamilton]

what would the graphite do?, i was thinking of taking an impression from my pole,l then making a male mould for the kevlar bearing surface from that with something cheap that can be polished up

[Graham Bridle]

Crikey you lot put me to shame. My insert fell out about 2 seasons ago, its on my desk here at work, should I bother putting it back in ?

[Phil Alderson]

what would the graphite do?, i was thinking of taking an impression from my pole,l then making a male mould for the kevlar bearing surface from that with something cheap that can be polished up

Graphite powder in an epoxy mix seems to leave a low friction surface, that also wears OK. I am not sure the mechanism but it seems to work. I have not tried the kevlar bearing surface.

Careful application of parcel tape to your pole will give a smooth surface, assuming the pole is fair.
There will always be some pole behind the support so molding the loop on the pole further down than the final position will give a bit of slack.

 

[Banshee Ambulance]

I have just machined a new jib turret for Banshee Ambulance out of Acetal. It seems to be a nice material to work with and gives a nice surface finish.
I dont currently have any inserts in the bow tube. We had a pole let go at the bow where the point loads are last year. I am wondering if inserts to match the pole taper may help stop this happening again? 

[john_hamilton]

yeh, i wish i could order some tapered ones without it being too expensive, i dont want to aftermarket machine taper into ones that ive bought for alot of cash, especially since the bank of dad has folded in the current economic climate!

[Phil Alderson]

Having a tapered pole support, with increasing flexibility towards the end of the support will be best. However with a tapered pole if you don't get it fully out then it won't fit the pole inserts properly and you get a point load.

if your pole is designed and constructed with a safety factor low enough for this to be critical then I suspect it won't last long in use.

[Will_Lee]

I would not recommend doing that - it suggests a tight fit at full extension. This may stick when the pole is out. Even if it does not, you are vulnerable to a single sand grain getting in there.

~5mm of space sorts that problem out, but leaves you with the point load issue. This can be minimised by flaring the inside (very slightly) and by increasing the distance between the front and back supports. I think we were at 340mm for this distance.

Lots of hoop fibres in the last ~400mm of pole is probably the major requirement though.