blade tpi questions

[Chris Martin]

1. Took the Shad plans that I got from Jeff, ironed them with an iron on low heat to get the folds flatter. (probably overkill)

2. Cut the papers out and glued them on with the 3m Super 77 that Jeff says on pg 40 in his book. I was worried about the glue drying too fast and it does dry pretty quickly but if you work from the middle of the paper outward it goes down well without wrinkles or bubbles. You do need to be careful with position as peeling the paper back up did not seem like an option. Small lift backward of a couple inches maybe.

3. Anyway I used some 10 tpi Bosch "super clean" blades in the saber saw to rough the forms from the 5x5 sheet. I stayed about an inch away from the true line since I planned to use the Band Saw for more precision. I was not pleased with the amount of underside splintering so I am wondering if I should use a much higher tooth count maybe even use blades made for cutting steel with a very high tpi. I am thinking to even change out my Band saw blade to one for cutting steel before I do the final trimming to near the line.

Comments or ideas?

Chris Martin

Houston, Texas

[Hirilonde]

If you are getting a lot of splintering with a 10 tpi blade then something besides the tooth count is wrong. I use a 6 tpi blade on my bench top band saw for frames and have no issues. I was just playing around with my new (to me) 14" band saw with 3 tpi resaw blade and the splintering is minimal. I use a Bosch jig saw for the insides of frames with a 10 tpi finish blade and there is minor splintering, but the inside is all rounded over so I don't worry about it.

[Chris Martin]

Thanks for the feedback.

It was not excessive splintering ( 1/8 to 1/4) but was hoping for only a slight fuzz.

My Delta benchtop band saw needs a little tuning and attention so maybe that will help also before I get too close to the lines for the final cut.

[P Doug (WA)]

Personally, I think you will always get some small amount of splintering with baltic birch (if that is what you are cutting). Least I've never succeeded in not having some. Even drilling a hole through I always end up with some little amount of splintering. The project I am working on currently requires some very clean holes to prevent air leaking. I tried everything I know of to prevent splintering, sandwiches between board, sharp fornister bit, still got a little splintering. I could do it with Okume, but not BB. I finally coated around the holes with epxoy and than sanded, to get the clean holes I needed.

[Chris Martin]

Yes it is BB.

It also seemed to have something to do with how the 9 layers are glued.

If you looked at just one form several edges or sides would have virtually no splinters and other sides splinters.

I am off to Home Depot this morning for an 18 tpi 3/8 inch band saw blade and will be curious if it is better.

I also plan to try some saw blades made for cutting steel that I will try.

[P Doug (WA)]

I think the softness of the top layers affect it also. Okume is much harder, lwast what I have is.

[Hirilonde]

On the Janka scale for hardness, where higher is harder, Okoume is 380 and Balic or Russian Birch is between 1010 and 1200.

[P Doug (WA)]

On the Janka scale for hardness, where higher is harder, Okoume is 380 and Balic or Russian Birch is between 1010 and 1200.

Dang, that's the second time in my life I've been wrong!

[Hirilonde]

Dang, that's the second time in my life I've been wrong!

Actually, harder may be why it chips more as harder is often more brittle.

A good sharp fine tooth wood blade and careful even pressure while sawing are the key factors for minimizing tear out Chris. I think you will find that a metal blade burns the wood. You can score the line with a razor knife and cut on the scrap side of the line, but I think that is over kill and only works witha jig saw with an upstroke cutting blade. Also keep in mind that you will be rounding over just about every inch of cut edge, so perfection is not necessary. Only the notches where the stringers fit are not rounded over.