Narrowest possible kerfs

[Flint Miller]

I'd like to use my radial arm saw to cut a series of slots across an 8" width of hardwood, shallow (3/32") and the narrower the better. Considering using a 60-tooth aluminum-cutting blade, for its .0750 kerf, but worried that the triple chip grind may not give me a clean cross-cut. Is this a bad idea, and what would be a better one?

[Jamie Buxton]

You might consider a blade intended to cut fret slots in guitar necks. For instance, here's one that will go on your radial-ram, and cut .023" slots.

http://www.stewmac.com/shop/Tools/Saws/Fret_Slotting_Table_Saw_Blade.html

[Doug Shepard]

This has come up on a number of threads here in the past. Seems like one thread maybe a year or so ago had a few posts from a manufacturer that said they could custom grind blades similar to the StewMac one Jamie linked to at whatever kerf thickness you needed. Try the advanced or google search options. Sorry I don't have a link to the thread.

[Flint Miller]

Hey, thanks for the circular fret saw suggestion. I've skulked around the Stew-Mac site quite a bit, but was still unaware that there was such a thing.

.023 kerf would be nice, but seeing the 75 buck price tag, I think I may experiment some first.

I found one of the earlier discussions referred to, a fairly humorous one regarding thin kerfs, at http://www.sawmillcreek.org/showthread.php?p=800089&

Speaking of custom grinds, I wonder if you couldn't take a body grinder to a non-carbide plywood blade and create your own ultra-narrow blade.
This too may been discussed before -- I just haven't turned up the topic on the Creek.

[scott spencer]

The Freud LU79R007 (http://www.amazon.com/gp/product/B002IPHGA2/ref=ord_cart_shr?ie=UTF8&m=ATVPDKIKX0DER)7-1/4" 60T Hi-ATB has a 0.079" kerf and is ~ $40 shipped from Amazon.

[Matthew Hills]

Can you put a "backer board" on the top/back of the board, and cut through those? that might help to keep the cut edges on your workpiece a bit cleaner.

Matt

[Flint Miller]

Also just came across the Freud Diablo DO760X. It's their economy line, I guess, but this is definitely a light-duty application. It's also ATB, with a .059 kerf. The 10 degree hook wouldn't be my preference, but at $20 on Amazon, I might just pop for it.

Excellent suggestion, the sacrificial "backer board". Since there'll be multiple cuts within the length, I'm thinking attach it temporarily with double-sided tape, or possibly thin hide glue or other reversible adhesive.

[Brian Gumpper]

If you mean something like a dado when you say slots, the triple chip will not give you a flat bottom. The raker tooth is usually set a little below the other teeth. If that is not a concern, the quality of cut should be OK if it has enough teeth which I image it does being an aluminum blade.

I sometimes recommend TCG aluminum blades for miter saws cutting hard materials because the TCG will hold up better than anything, usually have a negative rake and enough teeth for a clean cut.

[Sam Layton]

A skill saw blade has a small kerf, a little over 7" in dia.

Sam

[Larry Fox]

How about a Japanese flush cut saw. I had one and it was very very thin and had no set at all. Not sure how much thinner than that you are going to be able to get.

http://www.leevalley.com/US/wood/page.aspx?p=32932&cat=1,42884

[Flint Miller]

FWIW, it was the Oshlun SBNF-072560 aluminum-cutting blade that I was first looking at, with 60 teeth, a .075 kerf, and- to judge from the picture - a slight negative hook, which would be particularly desirable for use with a radial saw, especially considering it would be making such a shallow cut.

In the old days I would have considered using a flush-cut saw, but I think it would require a high-precision guide such as Stew-Mac sells for their manual fret saws; and since I have multiple cuts to make, it also looks too much like work.

My current scheme is to take a skill-saw plywood blade, which is about .05 thick with a .06 kerf, and see if I can hollow-grind it down to .04 or so. And then see if it'll still cut! :cool:

Thanks for all the suggestions.

[Howard Klepper]

You might consider a blade intended to cut fret slots in guitar necks. For instance, here's one that will go on your radial-ram, and cut .023" slots.

http://www.stewmac.com/shop/Tools/Saws/Fret_Slotting_Table_Saw_Blade.html

You can only saw about 1/8" deep with one of those.

The 7-1/4" Freud Diablo blades take a .060" kerf and cut pretty smooth, espcially with blade stabilizers.

[Tony Joyce]

The Freud Diablo 7-1/4" is the most economical($14.97) and thinnest(.059 kerf) for the money at Amazon.

http://www.amazon.com/Freud-D0740X-Finishing-Knockout-PermaShield/dp/B00008WQ2H

(http://www.amazon.com/Freud-D0740X-Finishing-Knockout-PermaShield/dp/B00008WQ2H)

[Flint Miller]

My current scheme is to take a skill-saw plywood blade, which is about .05 thick with a .06 kerf, and see if I can hollow-grind it down to .04 or so. And then see if it'll still cut! :cool:

I did this, more or less. Started with a skil-saw plywood blade so worn out I'd been using it for cutting aluminum siding (i.e. running it backwards.) Nominal kerf (caliper across 3 teeth) was .08 or so, actual kerf (slot in board) .110, due to warped blade. By the time I got it into one plane, the actual kerf was down to about .65; by the time all remaining set was wiped out, about .58. I finally took it down to an actual .044 kerf, decided not to press my luck.

A radial arm saw is about perfect for reducing a blade this way. Align your HF benchtop grinder so side of tooth line touches wheel at 90 ATDC. Slide RAS motor away down arm to allow grinder to start (won't, under load), rotate blade quickly (by hand, mind you) as you re-engage with stone. Automatically hollow-grinds the thing.

Cuts just fine, by the way, at least for a 1/8" slot.

[John Coloccia]

I don't really have anything to add. I'm just curious what you're doing.

[Flint Miller]

I'm experimenting with kerf-bending thinner hardwood pieces into a tight radius, where steam/heat or ammonia techniques (or multi-ply laminations) are not an option. For strength, I was hoping to get the kerfs to close in the bend, but I need lots of closely-spaced kerfs to make a smooth curve, which minimizes the curvature/kerf ratio, so a very narrow kerf is required. Theoretically (i.e. CAD-wise), for 1" radius in 3/32" material the .023 of the circular fret-saw mentioned above should work, with kerfs spaced at .25", but my .044 is nowhere close to closing.

[John Coloccia]

I'm experimenting with kerf-bending thinner hardwood pieces into a tight radius, where steam/heat or ammonia techniques (or multi-ply laminations) are not an option. For strength, I was hoping to get the kerfs to close in the bend, but I need lots of closely-spaced kerfs to make a smooth curve, which minimizes the curvature/kerf ratio, so a very narrow kerf is required. Theoretically (i.e. CAD-wise), for 1" radius in 3/32" material the .023 of the circular fret-saw mentioned above should work, with kerfs spaced at .25", but my .044 is nowhere close to closing.

I don't think it helps you, but it's vaguely related, kind of clever, and very entertaining :)

http://www.youtube.com/watch?v=h-pdUWoNjPo

[Flint Miller]

Yeah, clever, and strangely entertaining. Seems there's a similar contraption at http://www.youtube.com/watch?v=yUOMmO09LvM&feature=fvw (w.better sound track.) Wonder who invented it? And one for a table saw at http://www.youtube.com/watch?v=wmonB49tQ_E&feature=related, but I may have to invent one for the RAS. Too bad the arm doesn't have cogs on it...:rolleyes: