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rswabsin
Joined: 14 May 2000 Posts: 444 Location: New Jersey
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Posted: Fri Dec 14, 2018 9:30 am Post subject: Power Box Fin too Snug - Where to Sand? |
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So I have a new power box fin that sits about 3-4 mm too high in the box - the top of the fin base sits several mm above the deck of the board. I don't have access to a caliper so its hard to really tell where to sand for a better fit. I have a very good fitting fin to compare it too and visually I can't see any noticeable difference. I sanded a few mm off the bottom edge of the fin base thinking the depth was slightly too large but really no change in fit after that. Anyone have some simple method or guidelines on how I can determine where to sand the base other than educated guessing and trial and error?
Rob |
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dhmark
Joined: 04 Sep 2007 Posts: 376
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Posted: Fri Dec 14, 2018 11:03 am Post subject: |
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If the fin base was too deep, then the fin would have wiggled from side to side, since a power box is tapered and you would have hit bottom before the sides are flush. You have to sand. If you can't tell if its fore/aft or the sides, I'd try fore/aft first if it looks tight in that dimension, as there is no harm if oversanded in that dimension. If nothing changes with a little bit of sanding, then its the sides. I've had to do this before, not difficult, just takes some time. Just gradually work on it until it sinks to the right level. (you didn't mean deck of board, did you? that is the side you stand on). |
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rswabsin
Joined: 14 May 2000 Posts: 444 Location: New Jersey
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Posted: Fri Dec 14, 2018 12:10 pm Post subject: |
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Yes - sorry, I meant the bottom side of the board not the deck. When I set the fin in the box, there is still about 1mm of space between the top edge of the fin box and the perimeter of the fin base top so it appears the lower third of the fin base is the issue. My plan is to start there with the sanding. |
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westender
Joined: 02 Aug 2007 Posts: 1288 Location: Portland / Gorge
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Posted: Fri Dec 14, 2018 12:13 pm Post subject: |
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I usually try to rub a pencil to leave something on the inside of the box so you can see where it's rubbing. Use a heavy grit sandpaper to make the work go fast. |
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dllee
Joined: 03 Jul 2009 Posts: 5329 Location: East Bay
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Posted: Fri Dec 14, 2018 1:00 pm Post subject: |
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With Westender, flip board upside down, WET the PB, stuff it into box, pull out and LOOK at the finhead...and sand with 36-60 grit. |
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lturkevich
Joined: 11 May 2000 Posts: 68
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Posted: Fri Dec 14, 2018 1:26 pm Post subject: |
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I recently had to adjust a new fin for my powerbox: flip the board upside down, and check whether you have two tabs protruding from the bottom of the box and keeping you from getting the fin fully seated; if so, you can file down on the fin base two notches that match the protruding tabs so you can get the fin fully seated. |
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joethewindsufa
Joined: 10 Oct 2010 Posts: 1190 Location: Montréal
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Posted: Fri Dec 14, 2018 4:15 pm Post subject: |
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as i do not have a caliper either ...
when i compare fins i use a compass (the one that makes circles)
thus i can measure fin that slide in versus the protruder ...
then comes the part that requires patience - gently sanding
until it all fits ... |
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bred2shred
Joined: 02 May 2000 Posts: 989 Location: Jersey Shore
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Posted: Fri Dec 14, 2018 7:17 pm Post subject: |
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I was going to recommend the same as a few posts up - rub the fin base with a pencil or grease pencil. Install the fin in the box and wherever the pencil rubs off the base is where it’s contacting. Also, make sure you put the fin in the box and actually install and torque the screw before starting to sand. I recently purchased a new fin (also powerbox) and it was sitting pretty high when I just dropped it in the box. After tightening the screw, it pulled down nearly flush.
Definitely only remove a little at a time and check the fit often.
sm |
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isobars
Joined: 12 Dec 1999 Posts: 20935
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Posted: Fri Dec 14, 2018 11:10 pm Post subject: |
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Rub a dry soap bar on the fin head. Stick the fin in the board and remove it. High spots on the fin will be black. Sand the black marks down until they disappear. Repeat until the fin fits right.
If I mis-remember the color (I think it was black), SEARCH for the last time this was discussed here last year. That's where I got that invaluable tip, which worked like a charm.
Here's another power box tip: if you ever remove your fin, make its screw captive and just leave it in the board all the time. Put the screw in the board and twist a cm-or-so-long piece of 7/32th (inside diameter) rubber windshield wiper or vacuum tubing down over the bolt all the way. Any auto parts store carries it in packages for about the price of a SS bolt.
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manuel
Joined: 08 Oct 2007 Posts: 1158
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Posted: Sat Dec 15, 2018 8:33 am Post subject: |
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If the fin base is too thick? Then put a tiny bit of flour or powered sugar around, you'll see exactly where it rubs. Just make sure it's dry! _________________ *NEW* - Manu's Windsurfing Blog, The STORE! |
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