It also means that a unnoticed defect in the grain is unlikely to be highly important.
MIK
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It also means that a unnoticed defect in the grain is unlikely to be highly important.
MIK
You will spend a fortune buying 3 or 4 sanding sheets/discs in a pack. Go to your marine supply house (or auto paint suppy) and buy your sandpaper in quantity. A roll of sandpaper will be 30-50 dollars but will have 100 or more discs/sheets instead of 3-4.
Back when I was in the cabinet business I ran some tests on sandpaper brands. Mirka had just started being sold in the US and their prices undercut the usual suspects--3M and Norton. The Mirka Gold paper outlasted both of the favored brands by a noticeable amount so I've been a fan ever since.
One more tip for anyone who uses a sander with clamps instead of self-adhesive or hook-loop attachments. The old-timers who worked for me would put a half-dozen sheets on the sander and then rip off the outer one when it was worn out. My tests proved that doing this actually accelerates the wear on the layers. It might save a little time but your second, third, fourth, etc. sheets are already worn when you get around to using them.
Your tests proved that this practice was about the silliest thing I've ever heard of!:UQuote:
Originally Posted by MiddleAgesMan
I'm all for saving money. But speaking without the benefit of experience to back this question, just how long would that $90-$150 (a roll of each: 80, 150 and 220 grit) worth of sandpaper last me? Sound like a lifetime supply. :)Quote:
A roll of sandpaper will be 30-50 dollars but will have 100 or more discs/sheets instead of 3-4.
A bit of my experience sanding;
Indeed good quality sandpaper saves money, I use 3M because that's widely available here. Disc's are far more expensive than sheets or rolls. In professional use they are worth the costs, because labour is so much more expensive than the paper. In that perspective you need to see those professionals ripping off dozens of discs, to be able to speed up a sanding job.
I use square standard sheets of 3M paper, and bought a professional mini-square sander that uses exactly 1/4 sheet.
For hand-jobs ( rounding, round surfaces and corners.....there is a lot you can not do with an electric sander :~ ) I start to use parts of sanding belts ( It started since I bought a bunch of wrong sized belts for my sander :doh: ) . Even the cheapest sanding-belts are very good quality sanding "paper", they have a woven backing that lasts very long. You can cut ( actually tear) them into smaller pieces, but you can also use long pieces for a fast rounding job ( f.e. spars ) . It's amazing how long they last,comparing with ordinairy sanding paper.
Ofcourse most things are very depending on availabilty and pricing in your local market.
But do NOT underestimate these costs building a boat, there is much sanding to do :U
Even if you buy sheets the quality stuff is so much better - at least with the brands that are available here.
MIK
Hi MickQuote:
Originally Posted by Boatmik
I'm still toying with my flexi spars, and may glass them to stiffen them. Your plans mention to allow 50mm (2") deflection in the spars. How much weight would you say is needed to achieve this?
Hello Bruce,
I will try to make measurements soon of both my GIS yard and boom to see what the deflections are. My spars are exactly according to MIK's specs and made of fine grained oregon pine, coated with 3 coats of epoxy and varnished with 7 coats of Epifanes.
I was also amazed by the amount of flex in the spars when I had just made them. In use however, they seem to work fine (mine have held up fine in winds up to 25 knots). The sail will become very flat though when applying proper tension on the downhaul as both the yard and the boom will deflect a lot, thus flattening the sail (mine is a standard Duckworks sail with standard reef points).
As stated before, I am planning on making a second set of spars of larger diameter (50 mm rather than 40 mm). Time and testing will tell what works and what not. As it is becoming winter here in the Netherlands, we will have to wait until end of March 2010 for test results.
Best regards,
Joost
Howdy Joost,
Going up to 50mm will be about 2.5 times stiffer.
I am wondering if only part shaping the spars makes some sense. ie only radiusing the front face. This would mean that the back face could be planed down or have some extra material laminated on later to get the bend you wanted.
?
MIK
If the section we a little oval you could radius the fwd face and plane the back side down...if it starts square, then you make it oval going athwartships if you plane the back side down. It's a good idea...we want to keep the spars flexible, but maybe this approach may be good when we are all using different wood species...even within species I have seen a lot of variation in stiffness/density. I'll get amazing tight grained spruce then I'll get this fat grained stuff that looks just like our pine.Quote:
Originally Posted by Boatmik
What about the boom? Maybe keep square or rectangular and sail with that and reduce dim's if necessary.
Clint
Two thoughts...don't glass the spars! It can cause issues...sheathing the wood keeps IN any water that finds it's way there...you want the wood to be able to breathe. This is why I don't like to heavy a coat of epoxy on oars and spars. I'd sail with what you have...that flex is making the rig able to withstand a great range of wind conditions. Make a second set of spars, maybe starting at 50mm and using the technique MIK suggests above to toy with them.Quote:
Originally Posted by woodeneye
The other thought was in a 10-15 kt breeze MIK may see the 50mm deflection.
Yes, I'm inclined to believe that glassing the spars is not the way to go, and I'll make a second set.Quote:
Originally Posted by Compass Project
I'm looking forward to the arrival of my marine ply so I can get stuck into building the hull. I'm using Joubert Okoume (Gaboon) marine ply, which I'm sourcing from Denman Marine in Tassie.
This weekend I completed a couple more fiddly bits.
The mast received its final coat of Marine polyurethane clear varnish (7 coats on top of the 3 coats of epoxy).
I made the stem from Paulownia. This needed careful planing with my no. 4 to get the taper right. If you look closely, you'll see the sort of "twist" that this taper induces. Clamping such a shape is impossible so I used long panel pins to hold it to my sawhorse while I planed. I was careful to punch the pins deep enough to prevent the plane blade striking the nails.
http://4.bp.blogspot.com/_EqNg3gNwXG...0/100_6717.jpg
I also made the tiller from Hoop pine with Paulownia infills. This will connect to the rudder stock when I make that. It now has 2 coats of epoxy.
http://4.bp.blogspot.com/_EqNg3gNwXG...0/100_6715.jpg
http://4.bp.blogspot.com/_EqNg3gNwXG...0/100_6722.jpg
Being short of stuff to do at the moment, I found my old chisels in the clutter of my tool cupboard. These did not receive the best of treatment when I was repairing cricket bats a few years ago and had built up a goodly layer of glue which had promoted rust. They cleaned up nicely with a wire wheel and then I took them to my diamond stones for sharpening, so now I have some nice, gleaming and sharp chisels, ready to take on the Goat :)
Hi Clint,Quote:
Originally Posted by Compass Project
I am considering to make a square hollow boom. I have ordered a loose-footed sail, so boom-stiffness is very critical for me. But also in general I like to have a boom as stiff as possible and use a flexible yard only.
I already made a square boom with rounded corners about 65x35 max in the center back to 50x35 in the front and 40x35 in the back end.......but I do not like the weight.
It's not a real issue ( will be around 4kg ) but it could be made better.
I have found a source of very nice 69x12 planks ( again cheap European Fir ) with 360 length. Two of these with 18mm infill and a spacers can make a very stiff and lighter boom. I am thinking to keep the top line straight and make a tapered bottum line with the max height somewere around 40% from the front of the boom. Sizes 42 x 69 max ( or slightly lower ) tapered towards 42x 40/50-ish in the ends.
Not the highest priority project yet, since I need to finish my hull first.
NB I have copied this into Joost interesting new Thread about GIS Spars !
A nice way of building a hollow boom is with timber on top and bottom and thin ply on the sides. The depth can be increased significantly without increasing weight.
MIK
Hi MIK,
I have thought about that too, but I like the looks of a more "classic" square with round corners. But I have to admit that these ply sides probably make a very light boom.