Here’s the deal.
I can sand boards adequately but I’ve only found out how to do by trying it - never been propely instructed.
Here’s the problem - I’ve got close over the 7 years I’ve been trying but I want absolute perfection.
I want a board that has NO bends in the reflection when sanded.
I would very much appreciate tips to help.
I currently use a hard pad on the rail laps and fins/plugs then go at the bottom and deck with a medium pad running slow with 80 grit…keeping the sander moving.
I then finish off with 120 and then 240 on softpads.
I’m sure having never even seen a pro sander in action that I’m missing some real basic tips…
Any advice would be appreciated.
And yes I’ve searched the archives but just cant seem to fine the golden tip that makes sense.
Cheers
Rich
www.thirdshade.com
After machine sanding with 100 grit, I then block sand rail to rail on a diagonal in opposit directions. Then nose to tail block sanding, followed by more diagonal sanding, and linear sanding. Beginning with 120 grit, followed by another cycle using 150 grit. I dont go any finer than 150 grit, because I want to leave some ''tooth'' to the surface for the gloss resin to bond to. Does this description make sense?
thirdshade, Before blocking as Bill has described you can put some lines on the board with a soft lead pencil. Kind of a rough version of a “guide coat” that the car guys do before block sanding. When you start block sanding this will give you a visual as to how effective your sanding is. I bet you will be surprised at what you have been missing.
regards, Dave
Bill nailed it, while I have very limited experience building boards I have done my fair share of panel work in my time and to get that panel flat you need to use flat tools.
A disc sander is used to take down the lumps and bumps left from application of your medium, be it bondo or resin, keeping the sander as flat as possible and work through your grades to get it ‘just before’ flat, don’t try to chase the perfect finish yet, you need some material left for the nect step/s.
As Bill said, use a block to cut the rest down flat as he described. You can buy a good plastic with rubber based block with spring type clips that takes half a sheet of paper from your auto supplier or hardware, these are a good size. The bigger/longer the block the better to get the flattest finish as longer blocks don’t ride up and down the hollows left from the sander, they ride over them taking down the high spots with it, this is the key. Obviously you will need smaller blocks for tighter curves such as in the nose area of the deck or you can turn your block like you would your planer.
For your first grades of blocking you may be able to use an orbital sander but if you’ve done a good job with the sander it won’t take long by hand with the right paper grades.
Another tip from the panel shop that may help, grab a can of spray paint (a contrasting colour to your board) and lightly dust coat the whole board on your final grade, this is what they call a ‘guide coat’.
The idea here is you need to rub all that dust coat off, if your surface is well blocked out it will be an easy job, if not you will see patches of colour left and you still have some hollow spots, use your descretion on how to deal with these depending on where they are 
Hope that helps,
Mick.
edit: Dave beat me to the guide coat while I was typing this up (hence the repeated info), another good idea with the pencil.
That’s some gold, right there. Thanks for the tips.
Yes
I might add (though I’m no expert)- having a really tight, smooth lamination helps heaps.
as Bill says
Block it
and iw ill then add that if you want a smoot lam, you definately want a smooth shaped blank to start with!
if your shape is shit, so will your shine/straightness
Just sand the shit out of it. Sand it flat. use 60 grit. Buzzzzzzz
I had to jump in on this one. Sanders are a Shapers best friend. The key is speed and control plus a whole lot of practice. First its true ya need a tight lam pulling to all four corners. Then a good paste and hot coat. If its a tanker in volan dub the HC. To sand it to mirror glass ya need Speed 5000 rpms. Grinding disk 50 grit, blue hard power pad and a soft pad. You grind all your high points laps, boxes, patches and plugs. Then put your hard pad on and slap some 40 or 60 grit on starting on the bottom. Walking your machine nose to tail never stopping crossing or overlaping your last one. The thing with Speed and hard pad is the pad is its blocking the deck flat. You have to keep the pad flat only a slight angle. Holding the machine at a 45 in front of you on racks set at the right height. Think ergonomics. A smart way to sand is the opposite side of the board. Its much easier to reach a little with control. when ya have it under your chest you have little contro. Control is in the wrist. When the machine is in front of you just a little lift on the handle you sand right, a little down ya go left. Once the machines spinning you can twist of the wrist you change directions. Try it on the garage floor with a old used peice of paper. learn to control your sander with one hand. So back to sanding Now that bottom is flat if ya think you sanded enough keep sanding over in even passes done right all you need to do is block out your edges. Deck same thing just beware of the nose. You do have to pound the deck flats a lot blending into the nose area. depending on the board nose you should be able to drag the trailing edge of the pad through the nose area. If you learn to use the trailing edge of the pad it fits in wings and fish tails real well. Now put that same paper on a soft pad at lower speeds and sand to the apex of the rail all the flats and at a real slow speed machine your rails very lite touch. When sanding work like a CNC machine and think how ya move from nose to tail never stopping. Thats sand for gloss. If its a fine finish start with 120, 180 hard pad. Fine sand as you like. Block the nose good to before your 220 or 320. Speed and hard pads make things very flat. I’ll post some pic once I figure out how
priceless info, great thread
beautiful board there Sano
and I see you use a disc sander as a shaping tool as well as a finishing tool... (this pic should come with the proviso: "don't try this at home - paid professional in a controlled environment" LOL)
Tanks Huckleberry. The point of the pic was to show a little control can help in other ways. I reshape a lot of older programs that I tweak like this one. It has a big beak and right after the program was made we changed the design to flip thin tip nose. So to blend it out I use a disk at a about 1600 half throttle. Sanders make reshaping and shaping as fun as sanding. The Sanders keep things even and blends decks into rails so much better then a old block of wood. You really do want to try this alone the first time. I haven’t ever chopped a rail with one yet. Master your tools is how ya make thing flat and true.
well i have said it before so may as well say it again dont like the idea in any way
and yes i have used sanders and grinders and understand your point. but as a master boatbuilder was trained to make and use tools
for the best application. never found the need to use sanders or grinders in shaping
theres a lot of newbys on here and that pic will prbly lead to more prblms than gains
and before you blow up on me i am just saying it how i see it (interweb you know)
**cheers for coming on here **
** huie
**
Well theres fins, and then theres that thing! Geezzzz.
Sanders are not for foam!
Hey guys many thanks…this is exactly what I need. I realise my errors now and I’ll be using your advice on the next board…I’ll let you know how it goes…time to search out my rubber sanding block,
Cheers
Rich
I’m sure thats what Dale Velzy said when he had to give up his draw knife for that damm Skill 100? I’m sure he said I never needed it before and Planners are for building boats. Time to sharpen my ax and get back to the roots a little better? Keep it real
Chicks play with Vibrator’s and plastic squeegees. Men work with machines and rubber! I’m a Oldschool Dick so never take me for my word sometime I mean it!
some gold information here, thanks guys