Stacked dado set for "quarter-inch" plywood?

[Jamie Buxton]

Does anybody know of a stacked dado set that will cut a dado for "quarter-inch" plywood? That is, it would get down to .19" or so. And it would need to be adjustable, because "quarter-inch" plywood is not all the same thickness.

[glenn bradley]

I think you'll have more success simply buying a blade that cuts the width your after from 'carbide processors' or some other blade maker.

[Jamie Buxton]

I think you'll have more success simply buying a blade that cuts the width your after from 'carbide processors' or some other blade maker.

Plywood from my hardwood dealers ranges from .18" to .24". A single fixed-width blade won't do what I need.

[Mel Fulks]

Haven't used any in several years, but the way I remember it that would just be the two saws with a small spacer. Since the only thing that two kinds of 1/4 plywood have in common is niether measure a real 1/4

[Andrew J. Coholic]

Plywood from my hardwood dealers ranges from .18" to .24". A single fixed-width blade won't do what I need.

All the bigger tooling suppliers will custom make and/or grind what you need. I had a custom dado set made for some specific cuts I use, from Royce Ayr, (for my Euro slider) and it wasn't a whole lot more than a stock set of blades.

I guess I'm just used to always dealing with a supplier that actually makes their product - but when I need something I just call one of them and they are always able to come up with a solution.

[Frederick Skelly]

Jamie, what if you bought a single blade that was flat ground, and made 2 passes? It's tedious, but it should work.

[Charles Lent]

With a DRO on your table saw and a good 0.125 blade on your saw you can get the width you want in two slightly overlapping passes. I can , and do, get that width in two passes without any setup. No need to buy anything, except maybe a DRO for he saw, which will greatly improve everything that you cut in the future. Oh, it will take a little math too, but it's simple math.

Charley

[daryl moses]

The Freud box joint cutter set can be set for 1/4" or 3/8".

[Doug Hepler]

Jamie, I agree with Frederick, except to say that you usually need a slight bit of slop in a groove when it comes time to assemble it with glue in the joint. So before you buy new equipment, experiment with what you have.

To elaborate a bit on Frederick's suggestion, use one 1/8" outside blade from a dado stack. If you don't have one you can use any flat-top blade. Set the fence on your table saw or a stop in the miter gauge, etc. to the distance of the dado to the reference edge. Then move it over the required distance to complete the dado. For example if the dado needs to be .20" wide you would move it over (.2-.125 = .075" or about 1/16". If you have many to do, make a spacer.

Charles Lent, you are too hip for me. What is a DRO? Google says it might be a Debt Relief Order, a Domestic Relations Order, or hydroponically grown marijuana.// I can see how the latter might help.

Doug

[larry senen]

Digital read out???

[lowell holmes]

Check this site.

https://www.amazon.com/Porter-Cable-7005012-Oldham-Adjustable-Blade/dp/B0000DD1BU/ref=sr_1_5?s=hi&ie=UTF8&qid=1497233971&sr=1-5&keywords=dado+blade+set

[Martin Wasner]

You want an adjustable groover, not a dado set.

[Doug Garson]

Use a flat ground blade like Frederick suggested to give you a flat bottom joint and a kermaker from bridge city tools or a shop made version to match the width using two passes http://www.bridgecitytools.com/default/featured/km-1-kerfmaker.html.

[glenn bradley]

Plywood from my hardwood dealers ranges from .18" to .24". A single fixed-width blade won't do what I need.


Ah, there's the rub. I'm betting custom job. May not be as bad as one might think. I have my blades all ground to .125" so that all my jigs and measuring tools stay consistent through cutter swaps. The occasional bargain aside, I find the made to order prices to be within a few bucks of a mass marketed cutter of equal quality. Maybe two thinner outer blades (custom) where the teeth overlap like a dado and a few shims(?). It wouldn't take too many lineal feet at one pass to make up the investment.

[Art Mann]

I know this is a simple minded approach but it has worked for me. I have a router bit set that is made for plywood and the bits are a little narrower than nominal. I have used them many times on 1/4 and 3/4 and I have never gotten a fit I considered unsatisfactory.

[glenn bradley]

I know this is a simple minded approach but it has worked for me. I have a router bit set that is made for plywood and the bits are a little narrower than nominal. I have used them many times on 1/4 and 3/4 and I have never gotten a fit I considered unsatisfactory.


I agree and use undersized router bits as well with good success. I assume Jamie is after a tablesaw solution for speed's sake.

[Jamie Buxton]

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.

[Jim Dwight]

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.

[Todd Davidson]

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-kerf-flat-top-saw-blades?gclid=CIKW6ZKmuNQCFVJYDQodSnAEiQ

[eugene thomas]

Forest makes data set for cutting 1/4 plywood. Works great.

[Jamie Buxton]

I don't really recommend it but I have a Harbor Freight dado set and the outer cutters are well under 1/8...

Why don't you recommend it?

[Charles P. Wright]

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-kerf-dados-3-piece-set-with-1-16-chipper.html

The outer blades from my regular set would leave them too sloppy.

[Jamie Buxton]

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-kerf-flat-top-saw-blades?gclid=CIKW6ZKmuNQCFVJYDQodSnAEiQ

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.

[Jamie Buxton]

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-kerf-dados-3-piece-set-with-1-16-chipper.html

The outer blades from my regular set would leave them too sloppy.

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.

[johnny means]

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.

[Todd Davidson]

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-finger-joint-set-3-16-and-5-16-cuts.html


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.

[Edwin Santos]

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.

[Mike Wilkins]

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.

[Jamie Buxton]

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".

[Jim Dwight]

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.

[Mel Fulks]

I remember seeing saw HF saws marked c2. Had never seen anything under c3 before. Think it was a 10 saw,haven't looked closely at the dado sets.