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flat bottom dado

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Forum topic by Grumpymike posted 09-12-2012 06:56 PM 2029 views 0 times favorited 32 replies Add to Favorites Watch
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Grumpymike

1180 posts in 1063 days


09-12-2012 06:56 PM

Topic tags/keywords: question

I don’t know if this has ever been discussed here or not but I had a Freud 8” stack dado set and could never get a nice flat bottom dado, it looked like a beaver chewed it out. Each tooth mark was maybe a 1/32” to 1/16” different than that adjacent blade.
I gave that set away and bought an Oshlun 8” stack dado set and I still have the same problem; leading me to believe that the problem is with me.
I am a hobby woodworker using this set for making tennons and dados, right now I have to rework each cut with a shoulder plane or sanding block.
Is there a way to get flat bottom dados? i am reluctant to buy yet another expensive set for fear that i will still have the same problem.

-- Grumpy old guy, and lookin' good Doin' it. ... Surprise Az.


32 replies so far

View knotscott's profile

knotscott

5601 posts in 2123 days


#1 posted 09-12-2012 06:59 PM

Both of the dado sets you mentioned are considered to be pretty good sets. It could be your saw….what saw do you have? Some of the TTI/Ryobi made Craftsman and Ridgid contractor saws are known to have miscut arbors that cause problems with dado stacks.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View Dennisgrosen's profile

Dennisgrosen

10850 posts in 1863 days


#2 posted 09-12-2012 07:03 PM

no its not you that is the problem its just the way the dado is made on a tablesaw
if you get a handrouter in iron or wood your problem will be solved in a snap
since you can get a dead on flat bottom with that and with the correct debth all the way
some call the router … granny tooth

Dennis

View BinghamtonEd's profile

BinghamtonEd

1593 posts in 1117 days


#3 posted 09-12-2012 07:05 PM

I have the Freud 8” stacked dado set, and I get some marks when cutting tenons wider than the width of the dado, due to the slight bat-ear cut on the outside of the outer blades and having to make multiple passes, but my chippers leave pretty even bottom. Every once in a while I will see some variation, but not on the order of 1/32 to 1/16 like you’re seeing.

I would ask if your chippers had been sharpened, but it looks like you bought the set new. Do they fit, without any play, on the arbor? If you know somebody with a dado set that does not have the same issues as you, you could swap sets and each do a test cut, that might tell you if there is an issue with your saw.

-- - The mightiest oak in the forest is just a little nut that held its ground.

View BinghamtonEd's profile

BinghamtonEd

1593 posts in 1117 days


#4 posted 09-12-2012 07:07 PM

Dennis, I would agree that a table saw isn’t going to leave the same cut as a router or plane, however I don’t think a 1/16” difference between chippers should be considered “just the way the dado is made on a tablesaw”. If my Freud set gave me that, I’d be returning it.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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knotscott

5601 posts in 2123 days


#5 posted 09-12-2012 07:17 PM

It sounds to me like its far more than just the nature of dado made with a TS. Many of us get such good results with a TS, that it’s debatable which is the preferred method…TS or router.

These cuts were made with 4 different stacked dado sets on a TS…3 of them are sub-$100 sets:


-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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Dennisgrosen

10850 posts in 1863 days


#6 posted 09-12-2012 07:22 PM

Bingham
I don´t have a Ts and we ain´t alowed to use dadoblades here in europe
I just saw a videoclip on ( I thoink it was woodwisper ) that shows
how the sheet tend to be liftet a bit from the table so you don´t get
the same debth trugh the cut thats why I thought of the old router :-)

if its chiping out from the dado and into the sheet ….. I wuold use a scoringblades
infront of the sawblades if the Ts can be updated with them
or score the dado with a knife before I cut them

Dennis

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BinghamtonEd

1593 posts in 1117 days


#7 posted 09-12-2012 07:38 PM

Dennis, you’re very right about the piece lifting with the dado set. When I first got my set, I had sloppy looking tenons because I did not maintain pressure over the cut. With just a little downward pressure though, they turn out well. Featherboards work well when cutting rabbets with the dado set. Good tip with scoring the dado, too, that works well also when using a router (electric, never used a hand router).

From my experience (however brief), chip-out has not been an issue on the TS except at the trailing end of the dado as it exits the workpiece, and a sacrificial fence helps that a lot.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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Dennisgrosen

10850 posts in 1863 days


#8 posted 09-12-2012 07:56 PM

I think it was when making Dado´s in plywood he talk about scoring the dado

Dennis

View teejk's profile

teejk

1215 posts in 1432 days


#9 posted 09-12-2012 08:39 PM

I’ve had a Delta 8” set for 8 years (on a Delta saw)...never had a problem unless I used a spacer (that stands to reason and I expect it…quick clean-out with a chisel).

I read here quite often about sloppy arbors where the inside blade can run high. That is one issue that I don’t have.

If you are stacking the chippers properly and you know you have a good perp from table to blade, the fact that you have run through a few sets tells me that you have a poorly machined arbor on your saw.

View Alexandre's profile

Alexandre

1417 posts in 939 days


#10 posted 09-12-2012 08:48 PM

I have a freud dado set. It is a good set.
You probably have a bad arbor.

-- My terrible signature...

View muleskinner's profile

muleskinner

740 posts in 1184 days


#11 posted 09-12-2012 09:07 PM

Grumpy, I know exactly what you’re talking about. It’s not you. It’s not the dado set. It’s your saw arbor. I wouldn’t say you have a bad arbor, it might be just the way it is. I had the same discussion a few weeks back. http://lumberjocks.com/topics/39853

-- Visualize whirled peas

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teejk

1215 posts in 1432 days


#12 posted 09-12-2012 09:58 PM

binghampton…I forgot to mention…due to a stupid thing I did with the TS a few years ago (where I got a new found respect that I think will stay with me until I die), I borrow the jointer push pads when I do dado work now. They allow me to apply some downward pressure on the cut and they are cheaper than band aids and blood cleaning solutions. I guess when you think about it, the concept of running a jointer is the same as running a dado on the TS.

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Grumpymike

1180 posts in 1063 days


#13 posted 09-13-2012 01:05 AM

Wow what a response!! First lets see if I can insert some photos, first is the arbor, I have laid a streight edge on it to see if it was indeed streight … appears to be OK. Well been at this for some time now, can’t seem to figger out how to get photos inserted here.
Let me answer some questions:
It is not chipping out the sides, the bottom is uneven like each chipper blade is a different size.
This is a new set never sharpened or resharpened I should say.
The TS is a Rigid 2424. The stock is not lifting off the table, I use a fingerboard on the fence to hold down.
If I could get dados like Knotscott shows I would be happy as a pig in mud!! And if I could get photos to show up here I’d show what I mean … I’m just not much of a computer guy, the G-Grandkids will be here in a few weeks maybe they can show me how.
I will contact Rigid to see if they can send a new arbor, this thing has a lifetime gaurentee. Lets see if they stand behind it??
Thanks to everyone for their help.

-- Grumpy old guy, and lookin' good Doin' it. ... Surprise Az.

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Grumpymike

1180 posts in 1063 days


#14 posted 09-13-2012 01:10 AM

Oh wow the photo showed up, now I will post the rest … By god this is a great day we have killed another giant … I got the computer to post a photo … Wheeeha!

-- Grumpy old guy, and lookin' good Doin' it. ... Surprise Az.

View knotscott's profile

knotscott

5601 posts in 2123 days


#15 posted 09-13-2012 02:12 AM

LOL…congrats on your pics!

It does indeed look like you have a miscut arbor. Getting a properly cut arbor is a solid fix if they’ll send you one, and if you’re up to it. I have heard of folks filling that miscut thread with JB Weld, and claiming good results….it’s not as elogant, but for $3, and 5 minutes of effort, it might do the trick. You can search the Ridgid forum for more info.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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