Originally Posted by Art Mann
I agree and use undersized router bits as well with good success. I assume Jamie is after a tablesaw solution for speed's sake.
I agree and use undersized router bits as well with good success. I assume Jamie is after a tablesaw solution for speed's sake.
"A hen is only an egg's way of making another egg".
– Samuel Butler
[OP]
Contributor
Yes, I am aware of making two passes with a standard blade. That's what I have to do now. But I want to do the job in one pass. That would be faster, and there's less opportunity for mistakes.
Lowell, it isn't obvious from looking at that page, but that PorterCable thing is a wobble blade. It gives a bad cut, with lots of chip-put along the edges of the dado.
Martin, I've looked at adjustable groovers, specifically from Amana. They do have one which will do my job, but they want $300 for it. Considering that standard stacked dado sets are less than $100, that seems more expensive than it should be.
So far, the best deal I've found is from Forrest. (Odd, saying "best deal" and "Forrest" in the same sentence.) But they do offer a Thin Kerf Dado Set which will do my job. They're asking $227 for it. That's still pretty spendy.
Member
I don't really recommend it but I have a Harbor Freight dado set and the outer cutters are well under 1/8. I think it could be set to cut a under 1/4 groove, I'm not sure really how small it could go. At least it's cheap.
A better idea, probably, would be to get inexpensive thin kerf blades, like 7.25 inch ones for circular saws, that are well under 1/8 and use washers and spacers to get to the width you need. You could try these out at a big box store. A 5/8 washer might be a reasonable spacer - or a couple. You could put them on a 5/8 bolt to try it out.
Member
I've had a similar situation as Jamie and used a couple thin kerf 7-1/4" or 8" blades and these blade spacers from Infinity:
https://www.infinitytools.com/thick-...FVJYDQodSnAEiQ
Contributor
Forest makes data set for cutting 1/4 plywood. Works great.
[OP]
Contributor
Why don't you recommend it?
Contributor
I've used the Forrest set and it works great for the undersized ply I get for drawer bottoms.
http://www.forrestblades.com/8-thin-...6-chipper.html
The outer blades from my regular set would leave them too sloppy.
[OP]
Contributor
I've tried that approach, and found that it is trickier than it seems. The shapes of the teeth and the plate must allow the two blades to stack together without the teeth touching. And the teeth must be wide enough that they still overlap with the spacers installed. If they don't overlap, they cut two kerfs, no one dado. I tried using 7 1/4" blades, but the width of the carbide teeth was so close to the width of the plate that I got the two-kerf result. I took another trip to the store, this time equipped with a micrometer and a calculator, but didn't find blades I thought would do the trick.
[OP]
Contributor
Yeah, that's the $227 set I mentioned. If I have to I'll get it, but I'm hoping for something that isn't so expensive.
Contributor
On approach I've used is simply making a skewed fence with whatever thickest blade I have lying around. This technique will allow for very small adjustments with no new tooling. Yes, technically the dadoes aren't perfectly square, but they're close enough.
Member
I recall trying a few different blades & configurations but could not recall what blades we settled on. I called my colleague who worked on that job with me (it was kinda driving me nuts not remembering). He said we used a Forrest Box Joint Blade with the spacer. I think it was this one:
http://www.forrestblades.com/2-piece...5-16-cuts.html
Contributor
Hi,
I've used one outside blade and the appropriate inside chipper from my stacked dado set to do this many times. For example, the outside blade plus the 3/32 chipper gives me 7/32 which is .21. Or you could use the outside blade and the 1/16 to get to .1875 and use shims to creep up from there. I heard it is not recommended to only use one of the outside blades in a dado set but I've never been sure what's bad about it so I tried it anyway. The only downside I have experienced is a slight bit of tear out on the side of the groove cut by the chipper. This is because the chipper tooth is not formed with a top bevel for scoring. So I try to orient that side of the cut in the less visible place, i.e. drawer side bottom. I think this will work better than trying to mate two separate blades and deal with the challenges you mention.
Contributor
I have been using a flat top grind ripping blade with a 1/8" kerf. Make multiple passes to get to the desired width (usually 2). Do a trial cut first to get the right distance from the blade to the fence, and you are good to go. I guess manufacturers use nominal sizing like framing lumber on plywood these days.
[OP]
Contributor
That Harbor Freight dado blade looked on the web site like a possibility, so I went to the store to look at it. Unfortunately, it doesn't do what I want. The teeth from the two outside blades cannot interlace with each other, so the narrowest dado it can cut is 1/4".
Member
I just don't think the HF dado set is very well made. The teeth are really small, it doesn't seem to be ground real well - to the same diameter for all the blades. I might try it again someday but the time or two I used it, I was not very happy with the results. So I got the least expensive Freud and it works great. But it won't cut less than 1/4 unless you used one outside blade and a thin cutter. I haven't tried that. Might work. I think I have a 1/16 chipper so that plus a spacer might work.
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