Deep Dado Cut Advice Requested - Woodworking Talk - Woodworkers Forum
 
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post #1 of 20 Old 10-05-2011, 02:47 AM Thread Starter
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Question Deep Dado Cut Advice Requested

I have a project that calls for a deep 2" x 3/8" wide dado cut in 1" thick stock. How much of this cut is safe to make at a time? At the center of the cut the blade will be fully enclosed by the stock. I know this can be done in small increments, but my concern is that repeated passes could possibly create a wider section at the outside. So my goal is to complete the cut in a minimum number of runs thru the dado stack.

Thanks.
Dave.
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post #2 of 20 Old 10-05-2011, 05:58 AM
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all most enough info

Cross grain or with the grain?
Stopped dado or open at one end like for a mortise?
Wood species?
Application.....like table leg mortise for apron?
Brand of dado head...Freud? Oshlun? other...

You can start with a slightly smaller kerf and for the final, use the full 3/8' stack.
You can use a stop block on a cross cut miter guage to make repetitive passes accurately.
Two passes should do it. Possibly 3.Trial and error. Listen to the saw for signs of binding, look at the cuts for signs of burning/overheating. The issue is getting rid of them sawdust efficiently to prevent overheating. It needs a place to exit.
That's my free advice... bill

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #3 of 20 Old 10-05-2011, 07:13 AM
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Quote:
Originally Posted by heinsite View Post
I have a project that calls for a deep 2" x 3/8" wide dado cut in 1" thick stock. How much of this cut is safe to make at a time? At the center of the cut the blade will be fully enclosed by the stock. I know this can be done in small increments, but my concern is that repeated passes could possibly create a wider section at the outside. So my goal is to complete the cut in a minimum number of runs thru the dado stack.

Thanks.
Dave.

I'm wondering how you can have a 2" deep dado in 1" thick stock. Is it a 3/8" wide dado in 1" wide stock, 2" deep, that would leave 5/16" as shoulders? Or is it a 2" wide dado 3/8" deep in 1" thick stock?

In any case I would do no more than 1/4" - 3/8" depth passes with a stack dado. Or, I would likely do the procedure with a router.








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post #4 of 20 Old 10-05-2011, 11:13 AM
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It depends on the power of your saw and the jig you set up to guide the pieces. 2" deep by 3/8" wide is doable in one pass with most cabinet saws, guessing the 1" thick stock is on edge and wider than 2". 3/8" deep by 2" wide will require more than one pass since you can't stack dadoes 2" wide.

I counted the cuts on this project once upon a time, it was over 2000, if I remember. 2" wide by 1" deep, half laps.
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post #5 of 20 Old 10-05-2011, 03:50 PM Thread Starter
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Thumbs up

Quote:
Originally Posted by woodnthings View Post
Cross grain or with the grain?
Stopped dado or open at one end like for a mortise?
Wood species?
Application.....like table leg mortise for apron?
Brand of dado head...Freud? Oshlun? other...

You can start with a slightly smaller kerf and for the final, use the full 3/8' stack.
You can use a stop block on a cross cut miter guage to make repetitive passes accurately.
Two passes should do it. Possibly 3.Trial and error. Listen to the saw for signs of binding, look at the cuts for signs of burning/overheating. The issue is getting rid of them sawdust efficiently to prevent overheating. It needs a place to exit.
That's my free advice... bill
I should have been more complete in the original, but this is what I'm doing:

Material is hard maple - for cutting boards. The 3/8" dado is being cut on the ends of a 12"w x 18"l x 1" thick piece of laminated stock to receive end splines, so the cuts are full width, 2" deep. I do not have a 220V cabinet saw, just 110/120 15A.

I used a custom push block with sacrificial material to prevent blowout on the ones I've done previously, and that worked well. But because of the repeated passes I got a slight outward tapering I didn't like.

I do like the suggestion of cutting a slightly smaller full depth cut first and then coming back later with the 3/8". With most of the material gone it would be much easier for the little safety elf on my shoulder to handle. I hadn't thought of that idea.

Thanks, guys!
Dave.
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post #6 of 20 Old 10-05-2011, 07:05 PM
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OK, but that sounds like overkill to me

Unless you know from experience, as in hindsight, that this depth is the best procedure I would think 1" deep would be plenty. Sounds essentially like "breadboard ends" to me or just a decorative end cap. Either way there is a movement issue in the cross long to cross grain joining. As was stated earlier a 3/8 dado in a 1" board leaves only 5/16" stock on either side which just doesn't seem right. bill

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #7 of 20 Old 10-06-2011, 04:06 AM Thread Starter
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Unless you know from experience, as in hindsight, that this depth is the best procedure I would think 1" deep would be plenty. Sounds essentially like "breadboard ends" to me or just a decorative end cap. Either way there is a movement issue in the cross long to cross grain joining. As was stated earlier a 3/8 dado in a 1" board leaves only 5/16" stock on either side which just doesn't seem right. bill
I think the posters here have provided enough help to get me safely and accurately thru my next project like this. This build did however require a 2" deep cut because of the curved design at each end of the board.

Again, guys, thanks! Great information and lots of experience on this site!

Dave.
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post #8 of 20 Old 10-06-2011, 04:20 AM
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Ah ha

2 pictures are worth 2000 words. Very nice detail and it looks great! bill

BTW another method to use which would allow a dado that's not as deep would be a router with a bearing bit to run the curve. Then a curved piece could be inserted. Probably a matter of choice, but it would avoid the 2" deep dado.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 10-06-2011 at 04:23 AM.
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post #9 of 20 Old 10-06-2011, 04:29 AM Thread Starter
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2 pictures are worth 2000 words. Very nice detail and it looks great! bill

BTW another method to use which would allow a dado that's not as deep would be a router with a bearing bit to run the curve. Then a curved piece could be inserted. Probably a matter of choice, but it would avoid the 2" deep dado.
The bearing slot bit idea would only work on the curved end. The handle end would still take another method because of the decorative curve. I opted to cut the dados while the stock was still square (rectangular) and then rounded the ends and installed the splines. The splines were glued only with a dab at the centers to allow a little freedom, and trim routed flush afterward.

I love how woodworking allows us to complete projects in so many different ways!

Thanks again!
Dave.
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post #10 of 20 Old 10-06-2011, 04:36 AM
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That's a very interesting design, looks very nice. I've got a few stack sets and haven't used them in years. For that type of procedure I would be using a router as I mentioned in my previous post. For me a router has a more tactile feel than using a stack dado.

With the handle being an insert, what steps do you take to prevent moisture or debris of any kind to seep in the fitting?








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post #11 of 20 Old 10-06-2011, 05:07 AM Thread Starter
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That's a very interesting design, looks very nice. I've got a few stack sets and haven't used them in years. For that type of procedure I would be using a router as I mentioned in my previous post. For me a router has a more tactile feel than using a stack dado.

With the handle being an insert, what steps do you take to prevent moisture or debris of any kind to seep in the fitting?
.
Well, none actually. It's the first time I've built this design. So we'll just have to see how much the maple moves over the course of a season. Here in Hawaii where one of the boards will live (I gave a copy to my neighbor as a gift) the humidity stays pretty constant over the course of the year (80-85%... sounds worse than it is) and I don't expect much of a problem. But another board I sent to my mom in Wisconsin and that's the one I'll want to watch over time. But this is part of the reason I've been concerned about that dado. The more accurate I can make it the better. Pushing a large panel like that thru the dado stack several times, even with a tall aux fence and custom push block, was still a little nerve wracking.

I did learn one thing doing this tho'... I should spend the money and get a high quality dado stack. Mine leaves a rather ragged bottom.

Dave
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post #12 of 20 Old 10-06-2011, 06:22 AM
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The picture makes what you are doing much more understandable. First I would assume that you are going to make the cut while the board is still square. That cut should be fairly simple with the board standing verticle and fastened to a universal (or any) jig on your table saw. You could use even a single 1/4" blade from your dado set and make the cut in two passes.

George
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post #13 of 20 Old 10-06-2011, 09:27 AM
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using a router?

I had in mind a shallow dado/groove, but that won't work on the decorative end as stated. I would have used a slot cutter in a table mounted router at the maximun depth of cut..close to 1".
Any other router application that I can think of would require a 2" long bit running in the edge of the board...not very stable and much could go wrong. Of course a special jig and set up could be made to make the process more stable and accurate.
The stacked dado in the table saw with a high supportive fence added would minimize any tendency for the board to tip in the procedure, my biggest concern. My next concern would be the necessity for a ZCI/ throat plate in the saw, of the dado width. This is to prevent an edge from going in to the throat plate and causing a big problem.
With those concerns accounted for the process should go well and be accurate. JMO of course. bill

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #14 of 20 Old 10-06-2011, 03:29 PM Thread Starter
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The picture makes what you are doing much more understandable. First I would assume that you are going to make the cut while the board is still square. That cut should be fairly simple with the board standing verticle and fastened to a universal (or any) jig on your table saw. You could use even a single 1/4" blade from your dado set and make the cut in two passes.

George
That's exactly how I cut this one, George. But you offer another great idea, to cut the dado with a single dado blade in several passes. Unfortunately on the dado set I have only the chippers have square tops. The outside blades both have slightly angled teeth. Are any dado stacks sold that have all square teeth? I mentioned above that I'm probably in the market for a better set.

Dave.
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post #15 of 20 Old 10-06-2011, 04:02 PM
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another great idea

Just use 2 rip blades which generally have "square teeth" and stack them together. Don't even think of using a chipper as a blade, at least I wouldn't do it unless it was an 8 tooth.
Oshlun makes a great dado set, at a reasonable price. Some are offered on Ebay for around $40.00 or so high bid. I have a 8" set I paid about $60.00 which is still reasonable in my opinion.
Infinity probably makes the best set, but it's Pricey! Deltas are good also. Some wood mag did a test for "squareness in the corners" and I think one of the members here did also. firemedic or knotscott. or both? I donno?

Another wild idea. I don't know if you took your "right" blade and put it on the left and vice versa if the corners would be more square, but it's worth a try since the bevels are pointed outward.
Just point them inward. bill

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #16 of 20 Old 10-06-2011, 04:46 PM
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That's exactly how I cut this one, George. But you offer another great idea, to cut the dado with a single dado blade in several passes. Unfortunately on the dado set I have only the chippers have square tops. The outside blades both have slightly angled teeth. Are any dado stacks sold that have all square teeth? I mentioned above that I'm probably in the market for a better set.

Dave.
Have you entertained the thought of using a router?








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post #17 of 20 Old 10-06-2011, 08:00 PM Thread Starter
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Just use 2 rip blades which generally have "square teeth" and stack them together. Don't even think of using a chipper as a blade, at least I wouldn't do it unless it was an 8 tooth.
Oshlun makes a great dado set, at a reasonable price. Some are offered on Ebay for around $40.00 or so high bid. I have a 8" set I paid about $60.00 which is still reasonable in my opinion.
Infinity probably makes the best set, but it's Pricey! Deltas are good also. Some wood mag did a test for "squareness in the corners" and I think one of the members here did also. firemedic or knotscott. or both? I donno?

Another wild idea. I don't know if you took your "right" blade and put it on the left and vice versa if the corners would be more square, but it's worth a try since the bevels are pointed outward.
Just point them inward. bill
I only did the "backward" blade setup early on when i didn't know any better! But it's another great suggestion in this particular case. (The hits just keep on comin'!)

I'll look for the reviews on dado stacks. I could still benefit from a better set than I have. I only have one rip blade in my shop too... so to use that idea would cost a few extra bucks as well. But that's another option. Very cool.

Dave.
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post #18 of 20 Old 10-06-2011, 08:03 PM Thread Starter
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Have you entertained the thought of using a router?
.
No. And it's because I only have a portable router table setup right now. For something this deep I just don't feel comfortable going that route. I tend to be super cautious with routers by nature.

Dave
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post #19 of 20 Old 10-06-2011, 08:24 PM
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I have a few of these

http://www.internationaltool.com/10-...tm_term=D1024X

http://www.amazon.com/D1024X-Diablo-10-Inch-24-Tooth-PermaShield/dp/B00008WQ2V/ref=sr_1_1?s=hi&ie=UTF8&qid=1317947553&sr=1-1
The advantage is you can get a pretty deep cut with 10" blades.

I still can't quite picture a router as the solution for a 3/8" x 2" deep Dado/groove on the edge /end of a 1" board..... when it can be dome easily on the table saw.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

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post #20 of 20 Old 10-07-2011, 03:55 AM Thread Starter
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http://www.internationaltool.com/10-...tm_term=D1024X

Amazon.com: Freud D1024X Diablo 10-Inch 24-Tooth ATB Ripping Saw Blade with 5/8-Inch Arbor and PermaShield Coating: Home Improvement

The advantage is you can get a pretty deep cut with 10" blades.

I still can't quite picture a router as the solution for a 3/8" x 2" deep Dado/groove on the edge /end of a 1" board..... when it can be dome easily on the table saw.
Just before I logged in here I placed an order tonite for a new Freud rip blade. But I went with a thin kerf LM75R010 10"x30T glue line blade and had to get it from Rockler because Amazon refused to ship a copy to Hawaii!!! For whatever reason, and this seems to come up more and more often now, Amazon's check out system classified it as "hazardous material", and simply would not (!) complete my order to any address, POB or street, that I provided!

Rockler however had no problem and will send it to my PO box address next week via USPS priority. Go figure.

As background, I'm an airports engineer who has to work around TSA and their ever changing rules on a regular basis. So part of it fits a pattern. It's common out here to have to go mail order for many things because variety in the local stores often just isn't what you might take for granted on the mainland. But with all the emphasis on security nowadays even mail ordering seems to be getting harder. I've had more and more examples like this recently, and they can be very frustrating.

Dave
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