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 Post subject: Sliding seat carriages
PostPosted: Sun Apr 10, 2011 6:43 pm 
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Joined: Tue Jun 02, 2009 8:22 pm
Posts: 98
Well I've spent the best part of 2 weeks making my first all carbon sear carriage. Not really sure yet if its worth the extra time and cost over a well made wooden carriage. Now I need advice on reducing the fiction between carbon surfaces, so that the carriage slides on its carbon tracks.


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 Post subject: Re: Sliding seat carriages
PostPosted: Sun Apr 10, 2011 7:27 pm 
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Joined: Sat Feb 02, 2008 12:24 pm
Posts: 250
Location: Plymouth, Devon, UK
I have a similar problem on Monkey. The seat is very resistant to being thrown across whilst tacking But it will move too easily when the boat heals.

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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 9:31 am 
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Joined: Fri Dec 22, 2006 10:32 pm
Posts: 511
Location: United Kingdom
Colin,

I assume you mean that the carbon surfaces are not involved in some literal exchange but they are binding :wink:

From my experience it is a combination or making sure there is adequate clearance between all the moving parts and tufnol where there is any load which may need to be roughened at the main point of contact. I actually have used a piece if ProGrip right at the end on the top surface to lock the frame more securely when weight is applied and it seems to work well enough. If the pieces are too tight, the weight of the seat when right out locks them in place more tightly being slightly angled and increases friction. You seem to need at about 2mm clearance top and bottom on the slidey bits to stop this from happening.

Main advantage with carbon is weight of course and tha ability to reproduce them easily from a mould but it is a hell of a faff of that there is no doubt.

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GBR324 "Hells Bells"
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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 9:54 am 
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Joined: Fri Jul 18, 2003 7:53 am
Posts: 142
Location: Emsworth Hants United Kingdom
Carbon running on carbon is a recipe for disaster. Carbon has very little abrasive resistance so you will need to protect both surfaces coming in contact with eachother with something that has, yet will slip enough, Tufnol is one option. Tufnol comes in various grades ie Carp, Whale, Lynx, Vole & Crow. These vary in hardness & abrasive resistance so keep away from the softer types ie. Lynx & try & stick to Carp, Whale or Crow. (Sounds like a pet soup). I use carp, 2mm thick by 10 wide strips of tufnol epoxied to the contact surfaces both on top & bottom of the seat & wider strips on the carriage to allow for slack tolerances that the seat must run in. The narrow strips on the seat allow it to slide smoothly with not too much friction whilst the slack fit will allow the seat not to slide through when the end is loaded. If the tolerances are fairly close then you'll have too much contact area when under load & find the seat is likley to slide through when you dont want it too, especially when your in the lead, so keep it sloppy. Obviously similar materials will wear but these usually will last the lifetime of the seat under normal use & can be replaced with similar if worn out. Better replacing these than the seat or carage. I can supply sets of Tufnol strip cut for the seat. So remember to allow for the thickness of the Tufnol & gap tolerances when building seats & carriages. For the vertical inner surfaces of the carriage I usually use mylar slot gasket material cut to size. Keeps the paint from wearing. I've got several sets of Tufnol seat strip in stock.
Contack Rob on 01243 430253 (evenings) or email razorbackboats@supanet.com


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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 10:20 am 
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Joined: Tue Jun 02, 2009 8:22 pm
Posts: 98
Sorry Guys its not the seat moving side to side , but the carriage moving fore and aft. I have an all carbon carriage and U sectioned tracks laid flat and glued to the hull ( similar to monkey, and most of the US canoes ). The problem does not exist with the alloy tracks and metal cars that Rob uses.


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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 12:10 pm 
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Joined: Fri Dec 22, 2006 10:32 pm
Posts: 511
Location: United Kingdom
Ok that makes more sense.

Interested in how that works out as i am debating whether to stick with Rob's aluminium tracks or make carbon ones with tufnol bonded to upper surface. Not sure if you save much weight but the fixing is a lot simpler. What is your experience?

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GBR324 "Hells Bells"
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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 1:40 pm 
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Joined: Sat Feb 02, 2008 12:24 pm
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Location: Plymouth, Devon, UK
Colin, Do you have a control line to pull the carriage back? I think when sat out on the seat trying to edge the carriage back it will twist and stick in place.

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 Post subject: Re: Sliding seat carriages
PostPosted: Mon Apr 11, 2011 2:44 pm 
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Joined: Fri Aug 01, 2003 2:26 pm
Posts: 163
If there is adequate clearance, then the biggest bugbear is probably the carriage getting out of alignment with the rails and binding.
My usual protocol calls for the outward flanges of the carriage to be several mm shy of bottoming out in the channels. This places the burden of keeping the carriage aligned on the inboard upper faces of the C channels and the vertical end pieces of the carriage.
Make sure that the upper inboard face of the "C" s are parallel.
If the ends of the carriage aren't, you can make different thickness pads at the 4 corners so the bearing surfaces are the right distances apart.
We have ski bottom plastic left over from our other stupid projects that works a treat.
I don't try for super fits because sand and other grotty stuff gets in there and you want it to flush out,
McLube is also a good friend.

I can't slide the carriage if I am sitting outboard. I have to squat on the rail and move it.
But I can move it with my legs if I am sitting inboard or on centerline. So I can shift my weight fore and aft when running in waves.
SHC

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 Post subject: Re: Sliding seat carriages
PostPosted: Wed Apr 13, 2011 4:23 pm 
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Posts: 98
Thanks for all the advice. On my old AC I had Rob's alloy tracks and stainless cars with the plastic inserts, and yes it would easily move fore and aft with my weight outboard with a 2:1 central puller.
I'll wait until all is complete then check it out again. I can easily ( in canoe terms) replace the carbon lateral tongues with 2 sections of high grade alloy angle, which will slide. If all else fails , I'll call Rob up buy some tracks and add a kilo to the weight. Some say I should have done this in the first place !

PS Have you noticed a picture of a ( very ) young Simon Allen on page 46 of this months Y & Y ?


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 Post subject: Re: Sliding seat carriages
PostPosted: Wed Apr 13, 2011 5:46 pm 
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Joined: Fri Jul 18, 2003 7:53 am
Posts: 142
Location: Emsworth Hants United Kingdom
colinbrown wrote:
Thanks for all the advice. On my old AC I had Rob's alloy tracks and stainless cars with the plastic inserts, and yes it would easily move fore and aft with my weight outboard with a 2:1 central puller.
I'll wait until all is complete then check it out again. I can easily ( in canoe terms) replace the carbon lateral tongues with 2 sections of high grade alloy angle, which will slide. If all else fails , I'll call Rob up buy some tracks and add a kilo to the weight. Some say I should have done this in the first place !

PS Have you noticed a picture of a ( very ) young Simon Allen on page 46 of this months Y & Y ?

You should have done this in the first place Colin :lol:


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 Post subject: Re: Sliding seat carriages
PostPosted: Mon May 23, 2011 2:38 am 
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Joined: Mon Dec 20, 2004 1:42 am
Posts: 79
Location: Australia
For both the carriage runners and the seat runners, I've used car floor carpet (black nylon type stuff) epoxied to one of the sliding surfaces. This provides a low friction fsurface when unloaded, but seems to grip reasonably well when loaded up. It also largely eliminates wear on the painted or epoxied mating surface.

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