Need 1/8 blade for incremental box joint jig ??

[glenn bradley]

Conclusion, I am now wondering if a FTG blade designed for ripping is never made to kerf spec tolerance suitable for my purpose, in which case it is luck of the purchase.

I just have Carbide Processors make all my blades to .125" kerf. The cost difference for custom is insignificant and all my jigs and accessories always line up and my fence is always correct. I guess I should have just mentioned that instead of pointing you at links but, I didn't want to sound like an advertisement. No affiliation, just a satisfied customer.

[Bill Adamsen]

... Conclusion, I am now wondering if a FTG blade designed for ripping is never made to kerf spec tolerance suitable for my purpose, in which case it is luck of the purchase.

Why not just use a good quality, full kerf ripping blade? You may have to get it resharpened to be exactly 0.125" width, but that doesn't cost much.

As John mentioned, you'd probably have to get the rip blade resharpened to get an accurate width. Though I am a little surprised it varies. I have had narrow rip blades that oscillate (not sure if that's the right term) and could produce inconsistent results. Not sure if that is something that is fixable, but some folks here seem to be getting satisfactory results.

Thanks for starting the thread because this is something I've had an interest in so I am watching closely.

[Alan Schaffter]

Just remember, to verify the setup of your SBOX8 (or any stacked dado blade), always measure the kerf that it makes. Do not rely on the manufacturer's published sizes (chippers + trimmers + shims)- Forrest grinds theirs slightly undersized. Also, do not attempt to measure the thickness (tip to tip) of the blade stack with calipers, the thickness may vary at different points around the blade and can be very hard to do accurately. And, of course, a slightly warped blade, a single, random carbide tooth that is wider than the others, or arbor runout will all affect the measurement and kerf width.

Of course, all this is totally unnecessary with an I-BOX. While the I-BOX's published range of finger sizes is 1/8" to 3/4", it will actually cut fingers that are slightly wider than 3/4" and thinner than 1/8" though this is not recommended. As an experiment, I enlarged the cutout in a pre-production I-BOX fence and was able to make 1-1/8" super wide fingers with a dado bit! I don't remember the absolute working minimum, but according to the I-BOX engineering drawings, the critical measurement of the pin plates is .090." The finger width must be wider to ensure adequate clearance between the blade and the pin plates, however. Typical thin kerf blades make a kerf somewhere around 3/32" (.09375") so I would think if you don't have runout and feed the stock very carefully, you might be able to use a thin kerf blade with the I-BOX, though, again, this is not recommended, since blade-to-pin plate clearance would be a very slim .00375"!

With respect to flat bottoms, as you know, you can buy flat grind blades. Also, Forrest will re-grind any one of their blades (and other brands?) with flat tops. While the feed rate and resulting production rate may be slower and you'll need a good backer board to prevent blowout and splintering, router bits do a better job making finger joints, if your jig will work on a router table.

[Alan Lightstone]

Personally, I use the same Freud BOX joint blade set with Alan's iBox, and it makes phenomenal joints. The blade has been great, over many usages.

I'd see if you can return the other blade.

[Lee Schierer]

Check out the Freud 10 In. 30 Tooth Glue Line Ripping Saw Blade with 5/8 In. Arbor (LM74R010). According to the specs the teeth are 1/8" and every other tooth is FTG. I doubt you would notice the bevel teeth in between. This blade is ~$63 from Amazon.

[Benjimin Young]

koodos to the vendor!! I returned the 1/8 blade and after a bit of measurement with their calipers they happily took back the blade and gave me a refund. It just goes to show that it pays to buy a brand you can trust and at a reputable vendor.

My Freud box joint blade set continues to work great on my incremental jig, I just have to get better at counting turns LOL. :-)

[Jim Tobias]

Another +1 on the Forrest 1/8" FT. I use it to cut flatbottom splines and it does a perfect job.

Jim