Cut out my third EPS blank the other day, and for the second time, I “scalloped” the end cut. I pulled the bow out front of the template at the end of the blank and, I believe, lost control over where the wire cut. I believe I should be pulling more perpendicular to the template at the end. Should I be more perpendicular the whole way? Overall the blank looks good, and I must be living right, cuz the guy I cut the blank for called me and asked if he could go from a 7-6 semi-gun to a 6-8 Fish. Lucky or what???
I run my cutting templates longer that the finished length of the board. It allows a much cleaner end cut.
Same as Dan.
Also, the tighter the wire on your bow, the less it will wander, and also cutting with the wire hotter helps (to a point, don’t go too hot).
But then you increase the chance of snapping the wire of course.
Just make the templates a little oversize in length and thickness of foil. Takes a little bit more shaping though.
Nice luck with the dimension change eh.
Blanks are so cheap for you now though right! 
if necessary you could just keep that one for yourself and cut another! Love that, custom size at such a good price…
Kit
Try adding 2" run out tabs onto both ends of the template, works good for controlling the position of the wire for starting and as it wants to drop off the end of the template out the end of the block. For the scallop problem, use some wire tension but be careful about breakage, I did break testing to find out just where that wire will start to think about breaking, then of course it broke mid real cut!! Rest the wire gently on the template surface to help the breakage problem. Go very slow on the curve portions of the cuts, those are the areas where wire lag will cause the big scallop effect.
Hey, don’t cut down that blank yet! Maybe you’re on to a new design concept… “The wire is the wave”. The rational goes something like this. As the wire takes the path of least resistance through the foam, so too does the water. Maybe accellerating concave out the tail is a good thing. Rides on the flatter rail rocker line when out in the flats but when you put it on rail during a bottom turn you get the effect of the increased tail rocker along the stringer!
With all three previous posts in agreement, I had to do something to stir the pot.
Alan:
As has been said, I also run my templates 2"+ longer off the tail. Also helps to slow your momentum down as you near the tail and let your wire become perpendicular or squared up with the templates as you clear that last 6" of foam.
Tom S.
Thanks everyone for the responses. I still have it in my head that I need to turn the bow more perp to the template near the end of the run.
As for the “path of least resistance,” it was in the nose, so the entry rocker concave may be the latest greatest, who knows???
I’d be interested to see a pic of this.
the wire shouldnt touch the foam …
the wire has to hang in space , the heat from the wire , melts the foam ahead of it … the amount of foam it burns away , or the distance from the wire to the foam that has already been cut is refered to as the burn out area , any more than 1/8th of an inch and your cooking it, a 16th and your a machine , any less and it means your dragging your wire …
you have to nail the right speed for the heat your wire is set at …
when the wire comes in contact with the foam , it loses heat quickly and can get bogged …
so you either have to make it hotter or slow down your cut …
watch to much heat , because if you slow a fraction you can get large burn out grooves across your blank , and they are a pain to shape out when they go like hard melted plastic …
like everything else in board making its an art and you can only get better the more you do it …
regards
BERT
Quote:
the wire shouldnt touch the foam …
the wire has to hang in space , the heat from the wire , melts the foam ahead of it … the amount of foam it burns away , or the distance from the wire to the foam that has already been cut is refered to as the burn out area , any more than 1/8th of an inch and your cooking it, a 16th and your a machine , any less and it means your dragging your wire …
you have to nail the right speed for the heat your wire is set at …
when the wire comes in contact with the foam , it loses heat quickly and can get bogged …
so you either have to make it hotter or slow down your cut …
watch to much heat , because if you slow a fraction you can get large burn out grooves across your blank , and they are a pain to shape out when they go like hard melted plastic …
like everything else in board making its an art and you can only get better the more you do it …
regards
BERT
So true!! That’s what my buddy and I that went in halves on a big block of foam are finding out! Having always bought my blanks, it’s a new learning curve to cut my own out of the block. Finding that happy medium where all the elements are working right is a bit of a trick (read art).
BTW- thanks Bert and Drewtang for inspiration on my last couple of boards, not vac-bagged, but perimeter and/or parabolic stringers. I’m going to post pics of my new fish when I get a chance.
Airframe (Ken) gave me a great tip for telling when you got the heat perfect - when the wire exits the foam it will leave behind little “foam hairs”. All my best cuts seem to have the foam hairs.
get a variable dc power supply
then you can up the amps if your in a hurry
i can do aboard pretty damm quick
nichrome runs a lot hoter without fatigue
it retains it tensile properties at high temperatures
i tension it with a guitar head tuner
hate those burn groves
always when im rushing
Quote:
get a variable dc power supply
then you can up the amps if your in a hurry
i can do aboard pretty damm quick
nichrome runs a lot hoter without fatigue
it retains it tensile properties at high temperatures
i tension it with a guitar head tuner
hate those burn groves
always when im rushing
I like the guitar tuner idea. I thought about doing that, but the bow my buddy came up with has the tensioning spring on the backside, not in line with the hotwire. The “variac” I sort of inherited works great for fine tuning the voltage. I’ve been using stainless fishing leader material, but may soon switch to NiChrome.
As for the foam “hair,” is it doing that when cutting into the deeper section of the blank?