DN NA Class

The Yahoo Iceboating Group 'files' section has a WORD file (insertrunnercrownplan.doc) with an embedded image of a drawing for a European 36 inch insert runner.  I'd like to make a new set of 'knock-about' 36 inch inserts for casual or pit use, and I can get 304 or 316SS water-jet cut locally for way less effort than my usual handraulic (hacksaw and grinder) approach to producing an insert blank with crown.  I don't want to simply buy 440inserts for this because it's way too painful to deal with the resulting knicks after sailing on some of our salt-water sites that run alongside sanded roads.

A friend here has already done a DXF and DWG of the Goodwin insert from Runner Tracks, but that drawing shows no crown, which negates the attraction of paying someone to water-jet a blank.

Has anyone produced a DXF or DWG of the Adsten insert from that WORD file that they would be prepared to share? 

Warren Nethercote
DN 3786

A word of warning...  the profile I had in my "How To" article was generated for the first set of inserts I made, and was based on the profile from a set of Russian T runners.  This was an old-school runner that had a lot of lead-in, and I would not recommend it for a mainstream insert runner.  Instead I would go for a lead-in profile close to a Sarns Bullnose runner.

I looked for the Jan Adsten drawing, but could not find it on my computer.  I don't remember the exact profile in the article, but I would caution using it to generate a profile for water jet cutting.  As I recall the bottom of the runner had an exaggerated crown to make it visible.  Most graphics for articles do not have the accuracy desired for a machine setup.

Paul,

Thank you for your comment.

If I am lucky I will be able to post the Adsten as a pdf here (converted from the WORD file).  Someone annotated it with 17 inches of 0.008 in. crown.  The 0.2mm offset at the after crown limit converts to 0.0079 thou, so it seems like a realistic drawing rather than an information sketch. 

I may have found someone to redraw it for me.  Whether the lead in is acceptable is the next question (Your opinion would be welcome).  It is probably no worse that anything I would do with my Mk 1 eyeball!  (Unfortunately, when I sold my previous boat this spring the buyer wanted my Sarns runners, so I don't have those for guidance)

Warren

Today I received a .dwg of the Adsten blade (courtesy of a friendly draftsman) and the crown based on the Adsten dimensions (not the drawn profile) is much less pronounced than as 'illustrated' by Jan Adsten.  I am getting a quotation for water jetting, and if the end result works out I will post the .dwg.  Paul's cautionary comment about exaggerated crown is more than apparent when you print the .dwg and compare it to the source illustration.

Today I received four water-jetted blanks for Adsten runners, two in 3/16 SS316 (at $51CDN plus HST ea)and two in 1/4 SS316 (at $59CDN plus HST ea).  I will attach the a photo plus a dwg (if I am allowed - NOT!).  You will see that the lifted exhaust has not been machined (or drawn).  I will do that by hand and eye.

I am happy with the end result.  The water-jetted blanks from plate are little more expensive than flat-bar stock, especially counted against the grief of shaping the forward end of the insert.

So, what do you think the overall cost per runner is going to be?

I try not to think about cost, but .....

I've got $105 CDN per pair(plus 15% HST)  invested in the SS316 blanks,

The runner bodies will be Baltic birch plywood, worth about 10 bucks on the basis of the fraction of a sheet that I already have

Say 15 dollars worth of epoxy

And $100 (WAG) for Carbon fibre that I have to order this week.  (For bow runners I often just use GRP since they are not subject to the same side loads as side runners)

So, rounding up for shop supplies (a grinding wheel, sanding belts, vinyl gloves, etc) I can do a set of inserts for about the cost of a single insert blade  from either Steve Duhammel or Ron Sherry.  Say $150 - $175CDN per runner.  My labour is free of course.

These runners are SS316 remember, so they require more frequent sharpening than 440C runners, but they are great for general knocking about or use on known dirty ice, since there is no concern about messing up the heat treatment when removing nicks arising from road sand or other ugliness.  I have a set of Northwind 440C runners that are way 'better' than anything I have ever made myself, and just got a set of Ron Sherry's 440C inserts (at $325 US ea), that I use for serious racing.  I am not advocating that 316 is a substitute for 440, but I routinely used  316 (or  304) home-made inserts for about 15 years before I invested in 'store-bought' 440 runners.  These softer stainless steels offer an economical way to control cost of entry to the class, and for a newbee I would argue they are more competitive than a set of plates in most conditions.  I still make them for bad ice or odd-ball configurations.  I have a home made set of 1/4 inch 304SS 100 degree inserts that are just lovely in soft spring ice that isn't quite slushy enough for angles.  To reduce cost further, I made most of my past side runners with GRP rather than carbon-fiber sheathing, together with 3/8 x 1 inch aluminum flat bar for stiffeners.  My future runners will be carbon sheathed to eliminate stiffeners and allow more efficient runner packing when travelling.

Following up on Paul Goodwin's earlier comment, I overlayed my Adsten water-jetted blanks (with Crown cut as specified by Adsten dimensions, NOT the illustration) slightly offset  with my recently-received Ron Sherry 440C inserts.  The entry to the measured crown portion (lead-in?) of the two designs is remarkably similar.  The Adsten runner has a very-much tighter radius on the front of the insert though, so it might be less happy on really bumpy ice - or is that in the noise?.

That sounds like a reasonable and cost effective way to get a set of runners. They may not be the ultimate for big races, but for smaller club racing and scrub racing they are perfect. It might not be a bad idea for Ron or Steve to offer that style of insert. It sounds like there could be a market for those.

I don't know.  I think that a big proportion of Ron or Steve's costs are process-related.  If they built runners in 316 as commercial ventures they would save money relative to 440C  on not doing heat treatment, and perhaps a bit of labour on post-heat treatment straightening.  As a WAG, Ron might have to charge $250 instead of $325 for an insert, commercially.  Would he sell many at that price, with such a small price differential to 440C?

On the other hand, few do-it-your-selfers will make their own 440C inserts because it takes a lot of similarly-minded friends to share in the cost of a whole 440C plate, which is generally the way you have to buy it.  Not to mention knowledge of what heat-treatment processes to use ....

But I agree that there is a place for 316 and 304 runners for those prepared to build their own.