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rattle free 26X center board

Posted: Tue Jan 19, 2010 6:48 pm
by restless
Hi all
I've just dropped my CB out with a view to 'de-clunking' it, amongst the other 38 mods going on here.
I'm thinking of adding a sleeve to the cb pivot, then spacing it (@pivot point) out so that the hanger bracket is properly wedged into the hull when screwed in... then adding starboard (hdp/cutting board) on either side of the cb so it is a proper fit. Hmmm. think I'd better do a little diagram...
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Anyhoo... Is there any reason why this board is such a sloppy fit? other than economical fabrication? a 1/2 inch pin in a 3/4 inch hole??? :o :?
I'm sure that moving the board up/down when sailing will require a little more attention to going with the current. Obviously the engineering will need to be fairly precise. I'll also add something in on the trunk at the trailing edge so there shouldn't be any twisting going on either.
My braket is twisted too... I love our mac, but some of the fabrication is a bit irkesome :x

Re: rattle free 26X center board

Posted: Tue Jan 19, 2010 7:26 pm
by Don T
Hello,
1. You don't want the pivot pin to carry any side thrust. That's why the hole is bigger than the pin. The side thrust has to be held by the top and bottom edge of the trunk. This puts the fulcrum and the stop about a foot apart. You can imagine how much force a 5 foot long lever can exert on a 1/2" pin that's 3" long.

2. You have to watch setting zero tolerance. The board may bind, the adjustment window (when the board is hanging loose) during a tack is very small and growth & critters may jam it.

check out my mod so I don't have to retype all the info. :-)
http://www.macgregorsailors.com/modt/index.php?view=390

Re: rattle free 26X center board

Posted: Tue Jan 19, 2010 9:04 pm
by Erik Hardtle
I have a mod that I have NOT done yet that might solve the problem...

This is from my website:

Pivot Point Repair (not done... yet)
This was designed by Cliff Ainsworth and he installed it on his. Haven't heard anything about performance. Posted his mod here because his link is gone from the internet.

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END PLATES - 2 1/2" Diameter by 1/4" thick stainless steel, center hole 11/16" diameter; six holes drilled/tapped/countersink for 1/4" x 2" stainless steel bolts, 3 from each side.

WEAR SLEEVE - 3/4" OD x 1/2" ID x 1 15/16 L The outer diameter is machined down to 11/16" for a length of 1/4" on each side to create a shoulder that fits into the END PLATE center hole.

CENTER PIN - stock item, the diameter was machined down just enough to slide easily in the wear sleeve; alternately, the ID of the sleeve could be just larger.

END CAPS - As shown will not fit into the trunk area, the need to machined as a smaller ID. I have found that 1/4" plastic tubing ends available from hardware stores are perfect for the job.

CENTERBOARD - drill and/or repair the pivot hole to accommodate the assembly; the plate may be used as a drill guide.

Re: rattle free 26X center board

Posted: Tue Jan 19, 2010 10:24 pm
by Bill Reichert
The lost link might have been saved on the Way Back Machine. It's an internet archive. Just go to the wayback machine and type in the old url.

Re: rattle free 26X center board

Posted: Wed Jan 20, 2010 4:36 am
by restless
Hi Don
I've had a good look at your mod.. it's what made me drop the cb in the first place :) and thank you for pointing out the obvious.. of course you don't want the pin mashing a hole out. Duh! how did I not see that? :o
The idea is that it will be supported top n bottom with tight tolerances. and indeed not zero!

Eric.. love what you've done with yours.. sweet stuff!
My friend Jose has also done something similar to this, and he's happy.
There's a thing in me that just keeps trying to go that extra little bit when designing something. Usually it ends up with happily ever after... just sometimes one can overlook something almost too obvious?
I just wanted to make sure that I don't do something stupid.
Getting the cd to not clunk when full down easy enough with the donTmod.. so how about 1/2 down goes the brain...
Thanks for the help! 8)

Re: rattle free 26X center board

Posted: Wed Jan 20, 2010 9:09 am
by J.Teixeira
Hi Bjorn

I see you are very restless with your mods...

Check mi mod:

http://arianeoveleiro.blogspot.com/2009 ... d-pin.html

Try to reinforce the thing keeping flexibility...

Make the bolt 3" mod...

It's simple and very usefull.

Cheers

Jose

Re: rattle free 26X center board

Posted: Wed Jan 20, 2010 1:05 pm
by restless
Hi Jose
I've had a look at your pin setup too.
You're right about mod mode... the surgery is deep and drastic...

Galley rough concept...

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And here's how it is evolving... fridge and oven underneath. The stainless duct is temp heating outlet to set the grp a bit faster in the current winter conditions, as well as keeping me going!

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I saw one of my favourite posters put one of these smev units in...(thanks for the link!) we liked alot!
Catch up with you soon..

Re: rattle free 26X center board

Posted: Thu Jan 21, 2010 1:20 pm
by J.Teixeira
Did you finished the Shed? 8)

Or the Mac is more charming work ???? :evil:

:D :D :D

Re: rattle free 26X center board

Posted: Thu Jan 21, 2010 6:07 pm
by Erik Hardtle
Hmmm... would I happen to be his favorite poster? I just put in a new galley last year too... and I started by doing a cardboard mockup like his.... hmmmm.

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Cardboard Mock up

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Finished Product

Re: rattle free 26X center board

Posted: Thu Jan 21, 2010 7:58 pm
by restless
Eric.. yes
great stuff.
After some umming & arring we took the plunge and blew a quarter of this years mod budget on the sink/cooker.. £250 :( Thankfully I got an absorbtion fridge for £4 and the oven off ebay, so I may yet get to put in a mainsheet track n lines led aft for this season. We do like to eat well 8)
I'll post the mods when they're tried n tested.