DN NA Class

Hi,
I thought I would share some of the details of my recent build of insert runners.  Many of you don't need this, but if your new and pondering if you can do it I thought I would share.  I hemmed and hawed a lot about spending the money on built Sherry runners, which is clearly the way to go and I will some day, but since I bought a new sail, my slush fund was low, so I decided to build a set.  I did a lot of reading on this forum, and found that some people are using 304 stainless with success, it is softer and doesn't hold an edge as long and is susceptible to bending, but I found a 6 foot bar on line for $56, with shipping is was closer to $85.  I also found from US composites they had a discount section and I got 2 yards of 5.7 oz carbon for $50.  I got my wood from B &B heartwood in Ann Arbor planed to 7/8 ( just a hair thicker) for $50 that included wood and planing fee.
- I did the butcher block method and brought my finished bodies back to B&B and he ran them through the planer again and they were PERFECTly flat and brought to exactly 7/8.
- I had to ask a very generous friend to cut the steel with a plasma cutter, and he did and it looked perfect, had to make sure it was straight with a machinist. He also gave lots of advice as he has built many sets.
- I put the runners together referencing Paul Goodwin's plans on the DN site and also referenced WMIYCs building site.
- I did not use a jig. 
- the key part is the slot in the bottom, go very slowly and be very anal retentive.  When I started I had 3 perfect wood bodies, and trashed one making the slot because it did not go slow enough.
- make sure it fits tightly with the glass and you measure all along the edge with a good straight edge to ensure it is straight, if it is straight after you glue it you're MONEY!
- I did my carbon laminate last, and did one layer at a time.  I lined my really flat smooth bench with 2 layers of wax paper, wetted out the carbon, actually my first layer was 9 oz fiberglass tape.  Then layed the wood body on top and weighted it down I with dumbbells, that have not been lifted since I made my hull. I used a router with the trim bit on to cut the excess off and did the other side.
- the layers were:1- 9 oz glass layer, 2- 5.7 oz carbon fiber layers, and one final thin coat of epoxy after all the layers were done.  They easily slide snugly in my chalks.
- I think I was successful, at least enough to try again with higher grade 440 c steel next time.

Steel: www.metalsdepot.com
Carbon: www.uscomposites.com ( look for discount section)
Wood: Bandbheartwoods.com

Hope this helps someone.

.  Very nice article. If I may I'd like to add a couple of things. I've made a number of sets of runners like these. To save some effort and money, most of the sets I've made I've used Formica for the skins. The runners seem stiff enough and if you want them stiffer, add stiffeners. Even though 304 stainless is softer them 440C I've found if you hone them after each weekends use, the edges hold up a lot longer. Honing  304 is considerably easier the 440C. A plus  for 304 over 440 is that it's a lot easier to change profile or go to different edge angle (other then 90 degrees). I have several sets of both types and a pair of 304's is one of my favorite sets.
Bob

Better is the enemy of good enough, but regardless, an easy process upgrade would be to build a simple press which would allow you to get more carbon between the 7/8 body and the nominal 1 inch chock.  I my case I have 9 ozs of 45/45 carbon followed by 3 layers of 12 oz carbon uni on each side of the body, and I suspect I could squeeze in more.  I recall that a Kingston-based acquaintance got something like 54 oz in the same space.  I used 1x1 square aluminum extrusion for a spacer in my press and for the first time I got a series of runners with uniform thickness.  Please pardon the finger in the photo!

I have done runners both ways (carbon then blade or blade then carbon).  The casual side of me prefers leaving the slot and blade insertion until after the carbon fiber work is done, although I think there may be more merit in the other approach.

I have built four sets of runners with stiffeners, but once you get to a multiple runner program, stiffeners quickly multiply the volume of your gear on the road, and are that much harder to take out onto the ice (but almost no amount of carbon will give you the same stiffening effect as a nice big stiffener - if it matters that much).

"Great minds think alike", or "Fools seldom differ" - take your pick...  ;-)

I have a press that looks just like that!

Thanks for the jig picture, that is what I was looking to duplicate, so now I have a good idea of how to make it.  Can I assume that you are first dropping the blade in the wood body, ensuring straightness and letting cure first.  Then laying out your carbon, etc and placing in jig therefor the jig does not need anything to keep the blade straight? 

. I have a jig similar to the one pictured with one exception. One side has the 1" spacer while the other side has a top and bottom spacer of  13/32" each for 3/16" blades and 3/8" for 1/4" blades. This set up nicely centers the steel and gives a uniform thickness all in one operation. I take a one inch wide piece of hardwood and surface plane it to the desired thickness to make the spacers. Anyone with a surface planer could do this for you in a matter of minutes.
   I have 6 sets of 440 runners and they all have carbon sides and my 4 sets of 304 stainless have Formica. I really can't see much difference in stiffness between the two. I believe that only the center 18-20 inches of the runner is really subjected to bending forces and  7"to 9"of that are contained by the chock.

Pete,

I have generally 'finished' my runner bodies (added carbon fiber and let it cure in the press) and then cut the slot and fitted the blade afterwards.  In a couple of cases I have gone Bob's route and fitted and glued the blade into the bare body and then added the carbon fiber and pressed the runner, with shims to keep the blade aligned with the finished body faces.  Bob's approach is likely better, but I have generally found my usual route a little less like being a one-armed paper-hanger.

  I hate to beat a dead horse but one more thing. I have always made and cut the runners sides first then placed them in the jig like I would with Formica or Ron Sherry's carbon sides. Bob