A new board has begun and this one is special. Thefishexpert (TFE) and I, along with many other sways members were deeply saddened by the passing of our friend, mentor and inspiration - Ben Shipman. While niether of us physically met Ben we were both inspired by him and blessed to have been around to ask him questions and receive his lessons while he was amoungst us.
With that thought in mind we decided to colaborate and make a board to honor Ben. The plan is a bonzer style 5 fin from EPS/Epoxy. TFE recently finished rocker templates and a plan shape template and this weekend I started cutting the foam.
I used a hotwire cutter I made for next to nothing an is in the pics below. The thought is to cut a series of rockered planks, then glue these together so they make up the width of the blank. Then cut the planshape. Shape the concaves, chanels and then the rails and wings before art and glassing.
I’ll add pics as we progress and here is the first installment showing the hotwiring of the first couple of planks.
ask if you have any questions - as Ben would have - we’ll answer anything with detail, honesty and our whole understanding of what we think we are doing.
the photos are big so I have posted them remotely. The links will apear within the next 5 mins.
This pic shows the hotwire cutter. Ni-chrome wire attached directly to the crocodile clamps of the charger that powers it. A spring at the other end to maintain tension. One of the arms pivots on the cross member the other is fixed. Its small and light and can be used with one hand quite easily.
This is the second plank I cut. The brown is the wooden template made by TFE, the other template is opposite “sandwiching” the foam. you can see here the skewers used to hold the templates in position as well. A square was used as a guide to make sure the skewers were inserted correctly and thus avoiding paralex error which could mess up the rocker. Each plank is 75mm wide.
Another pic of the second plank showing the quality of the cut. Its nice and clean with only a couple of imperfections where the wire snagged a splinter or two along the template causing a burn or a lump here and there. Nothing that a light sand wont remove when it comes to shaping so over all I was happy with the result.
This pic shows the plank held against one of my stock panels. I should be able to cut about 9 planks from a panel and will need 7 planks per board. If you look at the background you can see the first plank I cut leaning against the wall behind the foam. In the foreground, on the panel I cut it from you can see a burn where the wire got caught on a splinter in the template.
The last pic for now - this shows the first two planks side by side as they will be glued. They match well and gluing the entire board this way will alow for flexible arrangements with multiple stringers or stingers of different materials etc. That said TFE and I are thinking that we might attempt a stingerless for this particular board.
In total I cut 7 planks today - enough for 1 board… they got better as I went and by the end I had found a good technique that was quite fast and resulted in a nice smooth finish with minimal burns. Now I need to find some glue and finished making the blank by lining up all of the planks and joining them with the glue…
Sorry about the splinters in the rocker templates, that batch of ply I got was pretty hard to work with.
I think I’ll stick to MDF next time
If you havn’t already knocked the splinters off with some sandpaper, maybe for future cuts:
Start from the apex of the rocker and cut outwards towards the nose,
Then from the apex again cut towards the tail.
The splinters were all in the curve where the line of the rocker went across the grain of the outside layers of the ply in the template, so starting fromthe apex and moving out should avoid snags… but as you say, once the shaping starts, the bumps won’t last long.
Cam, I say if your can get your desired width with six planks instead of seven go for it. The five joints/ stringers will look much more symmetrical, and you could possibly even use a thicker stringer for the middle than the rest to accentuate the symmetry as I am doing with one the blanks I glued up recently (1/4” center, 1/8” to the sides).
Now what’s this metric system you speak of?
Oh is that the vastly superior measuring system based on increments of ten. lol.
Logic. We don’t need no stinkin’ logic. We are Americans!
Sorry about the splinters in the rocker templates, that batch of ply I got was pretty hard to work with.
I think I’ll stick to MDF next time
No probs Cam,
I think I found a way around it - I have masked the edges with green masking tape and it seems to work well. The snags were minor at worst so it really didnt make it hard. I was worried that the wire might snap under tension when it got caught but it seems pretty strong!
Ive finished glueing the blank but my camera is out of batteries so photos will come later. Its looking pretty good though… The deck is a little uneven - max 2mm (i.e + or - 1mm from intent) but I glued it with the bottom as priority so its matched well on the bottom… there is one step about .5mm but otherwise its nice and flat.
Hey guys, When I first saw the strips you were cutting, I was immediately thinking , “They should throw some balsa stringers in there.” Actually, I was thinking of LOB’s fish shaped from an old blank with a 3" stringer thrown in. That was a cool board.
On second thought, if you’re shaping one pound EPS, my biggest problem (one of many) was shaping different densities. For example, I have a 3 poiund foam insert around the fin box area. After trying many different tools I found the surform cut both densities with creating any ridges or valleys. But when I went to sand, obviously the high density started raising. It wasn’t a problem for me because the insert was covered by wood so I just went back and surformed it. I didn’t need a nice finish.
I guess what I’m trying to say is whatever you put in as a stringer should be more or less the same density as the foam. If not, you’ll have a hell of a time getting a smooth finish on the foam without raising the stringers. Does that make sense? Or, if you figure a way to get a smooth finish on the foam WITHOUT raising the stringers, please let me know so I can employ the technique on future projects.
Regarding snags… cruise by a sewing/craft store or raid your mom’s sewing kit. Get a couple of bobbins and thread them on your wire. They track along the edges of your profile pattern allowing your wire to roll right over any splinters or snags.
I remember reading that a while back and thinking “Great idea… must do that…” but I completely forgot… thanks for the reminder John! I’ll try it tonight.
The first blank is now glued without stringers and ready to cut the plan shape. I went to a craft store and a hardware store (bunnings) looking for elmers glue and couldnt find it so I bought a modified PVA to test and also had some 5min epoxy lyng around. I setteled for the 5min epoxy as the modified PVA didnt set - surprise surprise! (I had read that it wouldnt but wanted to have some to play with - I’d like to try a PVA/sawdust slurry and see if that bonds as the sawdust will help it set).
For the moment I used the 5min epoxy and spot glued the blanks every 4 inches or so using an ice cream stick to apply by mixing small amounts in catalyst measuring cups (30ml cup). I lay the planks on their sides and glued 2 at a time, then placed weights on top to act as a clamp while they set. When the epoxy had hardened I then repeated the process glueing the sets of two together to finish the blank and hotwire cut the nose and tail to clean it up a little.
Ive also started cutting planks for a second blank and they are comming out really well, better than the first lot.
My sheat yeild was better than calculated too. I was able to cut 11 planks from one panel so that means 9 blanks can be made from the foam I have if I use the same rocker profile.
