Fin Material Suggestion

[kurtschachner]

Carl,

You didn't ask, but I think it would be a great idea if Semroc sold your laser cut fins (and/or the kits as well) with the option of basswood fins. Every time I fill balsa fins I am reminded of how much I hate doing that - and every time I make fins myself out of basswood I am reminded of how much better they are.

I don't know what an appropriate price multiplier would be (2X? 3X?) as that would be determined by the added cost of basswood plus no doubt a longer laser time, but whatever it is I would likely be more than willing to pay it.

Thanks.

Kurt

[ghrocketman]

I would choose basswood fins over balsa everytime given the choice even if the laser cut versions would cost 2 to 2.5 times that of balsa due to the lower amount of sanding sealer/balsa fillercoat coats that would be required as well.
I would not mind the slight weight penalty.
I realize it would probably be too painful to offer all Semroc kits with either fin type from a production standpoint, but it would be nice if one could order basswood fins separately for all Semroc kits.

[Carl@Semroc]

We have looked at that. I like basswood as well. The penalty is about 3 times the cost. Basswood is 4 times as dense as balsa and most early models would not be stable without lots of nose weight. Since basswood sheets have much more imperfections, we cut the fins out completely, hoping to get about three of the four or so with no flaws. We were throwing away too many sheets in the early days because one of the fins was not good enough to sell.

Cutting them out means we have to bag them up in sets to get the count right. That adds time as well. Since it takes about 2.5 times as long to cut them and the raw materials cost is about 2 times balsa, we use basswood only on our most expensive kits.

Substituting 1/16" basswood for 3/32" balsa helps some, but 1/16" basswood warps before we get it, before we cut it, or after it is cut. That adds to the cost. 1/16" plywood also has major warping problems. We have much waste with it as well.

I don't worry about anyone on this group, but the general public would buy a set, launch it, and complain that" it looped three or four times before it became stable."

[ghrocketman]

Somehow I knew Carl would have a reasonable explanation to why he does not offer them for every kit.
Usually Semroc already has things available for us before we even think we want them if it is practical to do so.
In this case it does not appear practical to offer basswood for anything but the SLS line.

[kurtschachner]

Yeah, that is too bad. Besides *really* liking basswood fins, I also *really* like laser-cut fins. A combination of the two was, well, IMHO a marriage made in Knightdale.

As an aside I also like the idea of the fins completely cut from the sheet. Alas I see that is also a problem. I'm awfully picky I know, but I don't like having to sand off those little uncut doo-hickeys :o

The biggest problem with cutting your own basswood fins (again IMHO) is that since the wood is more dense, the X-Acto knife blade has a tendency to wander or especially twist while cutting. This causes the root edges to be "unsquare" and they don't glue onto the tube as nicely. This is of course eliminated with your laser cutter. I do try to sand them all stacked together but this is harder to accomplish with bass.

[barone]

X-Acto.......I thought everyone was using a band saw or scroll saw to cut the basswood? :D

[ghrocketman]

I always have used a razor saw in my X-Acto #6 handle to cut basswood fins.
Using a #1 knife with a #11 blade takes WAAAAYYYYY too long.

[Mark II]

I use an X-Acto #2 blade in a #2 handle to cut basswood up to 1/8" thick without any difficulty. A new #2 blade slices right through it. I can't imagine cutting out fins from a sheet using a hand (razor) saw. How on Earth do you get a precise, straight cut with a saw blade that can only make either a 5/8" or a 7/8" long cut? :confused: For thicker basswood, and for thin plywood up to 1/8" thick, I use a utility knife with a thin blade.

Mark \\

[kurtschachner]

I use an X-Acto #2 blade in a #2 handle to cut basswood up to 1/8" thick without any difficulty. A new #2 blade slices right through it. I can't imagine cutting out fins from a sheet using a hand (razor) saw. How on Earth do you get a precise, straight cut with a saw blade that can only make either a 5/8" or a 7/8" long cut? :confused: For thicker basswood, and for thin plywood up to 1/8" thick, I use a utility knife with a thin blade.

Mark \\

This is exactly what I was going to say but you beat me to it. I use a new #11 blade and if you hold the knife upright so the point is doing most of the cutting, it does just fine. It takes several passes but you get the job done. The grain on basswood does cause the blade to wander a bit more but I try to cut with the ruler covering the "good" part of the fin.

I can't even imagine using a saw to cut fins.