! warning: do not use a dado blade …..
Nails
| Posted in Tools for Home Building on
I just picked up a new 10″ table saw that has says the following in the instruction manual: !WARNING DO NOT USE A DADO BLADE LARGER THAN 6″ DIAMETER.
I’ve got an 8″ Freud stacked dado blade. Does that mean I can’t use it? I’m not sure why I wouldn’t be able to; they don’t say why not.
Only thing I can think of, is the smaller the diameter blade means it can’t be raised as high….for saftey reasons??
any ideas?
Replies
What kind of TS.
A lot of the contractors TS have warnings on them, because of the possilbe load of that size of blade hogging out material.
But everyone uses them "appropriately".
The label says: "!WARNING DO NOT USE A DADO BLADE LARGER THAN 6" DIAMETER."
And you asked: "I've got an 8" Freud stacked dado blade. Does that mean I can't use it?"
I must admit, your question made me laugh out loud!
Anyhow, to answer your "why" question; the reason for using a smaller diameter set is because the power required to turn an 8" is MUCH higher than the power required to turn the 6". If it's a direct drive saw, (upside down skil saw) than you will either burn out the motor, or the RPM's will be so low it will be dangerous to use.
Well...glad you got a good laugh....serves me right for asking.
I always thought there were no dumb questions ...only dumb answers...
but anyways...thnks for the info
The humor was in you asking if you can use an 8" after reading us a WARNING sticker that says use ONLY a 6 inch.Your question about WHY was a good question.
I guess I didn't convey my frustration at owning a $120 dado blade that I can't use, very well. It was meant as a rhetorical question. If something says "warning, do not use, do or otherwise". I won't. My point of the post was to learn why I can't. as I am a person that the likes to know the reason behind things. As opposed to go thru life just doing things, and when someone asks me "why" or "why not" only to have me say " I don't know." How many times I've had people say "that's just the way it is."
Nevertheless, you did provide me with an intelligent answer and I appreciate that.
You never indicated what kind of saw that you have.As I said those kind of warning are common for contractors TS and I many people, including me, use 8" dado's in them.
Sorry Bill...got focussed on molten laughing at me. lol.
In post #8 to Armin. I mentioned that is is a porter cable (with electric brake). To be specific it is the PC 3812 bench saw
What kind of saw do you have?
I would be wary against going against the warning label.
I'm going to try and find a 6" blade.....anyone have any recommendations?
I have a Jet, but I know people with the Delta contractors saw also use the 8".I did see the your mention of the PC, but I it went past me. AFAIK all of the PC are bench top/job site types and could probably not handle the mass.I think the Freud and several of the other major dado makers have the 6". But they are less common so you need to ask for them or go to the mail order suppleirs.
Yes..the 6" does seem to be less common. I've seen some cheaper ones, but they don't interest me. I did stop at the tool store today and saw they had some 6" freud blades but they were more expensive than the 8" that I have.
I phoned porter cable and they confirmed what yall have established about the power issue with the larger blade. But I couldn't get a specific answer regarding the wobble blade. They simple said it doesn't perform very well with the saw.
I also phoned Bosch, and they said their saw is actually rated for the 8" blade. But they said the same thing about the wobble blade.
I'm actually thinking of swapping my saw for the bosch model. I hate to give up that miter gauge on the porter cable though. But really...I guess most of those cuts I'm probably gonna make on the sliding miter anyways.
Yep, that Frued 6" set is pricy but IMHO it's worth it. I'm very happy with the results I get. With the 6" set on my Unisaw I can only go about 1-1/4" deep, but so far that's been plenty.
Back in the late 70's I had a Delta contractors saw and the wobbel dado worked just OK not great but OK. On my current General saw it works much better on my Dewalt jobsite saw it doesn't work worth a darn. My guess is the lighter saws have less mass and the arbor to saw body connections are not heavy enough to dampen any vibrations.
Hey Nails,I will venture a guess on the prohibition of the wobble dado sets on smaller saws. The wobble dados are essentially a sawblade set akimbo so it wobbles as it spins, cutting a kerf wider than its thickness. As the blade moves left to right at about 4400 times a minute, it imparts lateral stresses to tne arbor, the bearing, and the entire mechanism that connects the blade to the frame/table of the saw.On benchtop saws, all these parts are lightly built, and are only engineered to react normal, symmetrical cutting loads. A wobble dado could cause the arbor to rise or fall, the bearings to overheat, a support to bend, etc, etc. A Unisaw (for example) has so much more mass and is so much more heavily built that there is less likelihood of a problem developing. However, a stack dado is still better, safer, and easier on the machine.I would use the 8" before I'd use the wobbler on a small saw, but the brake issue is a valid one, too. Hope this helps.Bill
Thanks Bill. I never was considering a wobble blade - I don't like em. You've got some good thoughts on the wobble blade, probably something to it. I ended up trading in the PC for the Bosch, because the Bosch is rated for an 8" dado. I'm happy with my descision, FHB gave Bosch the best rating. the one thing I miss about the PC is the slick miter gauge. But the other thing I didn't like on the PC was the extension support is kinda mickey mouse - the Bosch has a very nice extension support system.
Nails
Systematic(don't know if I'm spelling that right)makes a 6", we have one at work.
Every time I see an add for blades it seams like there is a 6" and 8" available, I don't think there all that uncommon.
You might not find one at the local hardware store though.
Doug
In post #8 to Armin. I mentioned that is is a porter cable (with electric brake). To be specific it is the PC 3812 bench saw"
Nails,
If the brake it automatic that's why. The starting load on an 8" isn't going to kill your saw, stopping it on a dime will.
WSJ
Thanks John...I don't think the starting load was ever the issue. It's once you starting making the blade work that is going to put a load on the motor.
Armin pointed out in his 1st post regarding the electric brake, affecting the arbor nuts. The brake slows the blade down, it no where near stops it on a dime. (not like those emergency brakes that seize the blade when skin contact is made with a running blade)So I really don't see how stopping will affect the motor. If the motor is off...how can there be a load on it? maybe hard on the brake. And even the issue with the arbor nuts, I'm not sure how big a deal it would be. The brakes on the PC slow it down not even as fast as circ saws with electric brakes. Like i said it doesn't stop the blade it merely slows it down.
Nails,
Just an FYI, I use that same dado (8" freud) on my 3HP Delta Unisaw. I also usually run a thin kerf rip blade 90% of the time. It spools up in a spilt second. Slows down pretty quick too.
The dado takes two to three seconds the reach RPM, and what seems like an eternity to slow down with a full stack of blades. It does make very clean dados....way better than any others I've used.
I think the larger diameter minimizes tearout. ie. you get a higher blade tip speed. IMO You don't run a larger one to get a deeper cut, you run it to get a cleaner cut.. Really, how deep does a dado need to go?
Based on your description of how the electric brake functions, I run the 8", but that's me. Probably harder on the saw, but so what? I
t's all a trade-off.
WSJ
I've got a small shop and have been using 8" Freud dado blades for 12 yrs. on a Delta 10" contractors saw. They work great. I've had them sharpened at least once or more. I have no need to change or alter the setup.
So I really don't see how stopping will affect the motor. It does not effect the motor life or function at all. With a heavy spinning mass the braking action does not have to be severe to loosen the arbor nut. Once that happens the stacked dado's spin on the arbor and chew up the treads or in my case totaled the threads and distroyed the teeth on the blades. I have seen this happen on several jobsite saws as well.
I'm with ya. I got that from your 1st post.
"So I really don't see how stopping will affect the motor." was directed at john whom I got the impression he was refering to the motor, as he'd made reference to the start up load, and no mention on arbors or nuts like you did.
As for the porter cable I've got. It's hard to imagine that there would be enough braking force for that to happen on this saw. Though there very well may be. I don't know about the braking power on other saws. anyhow, I'm not one to mess around with taking chances.
Bosch, says their saw is rated for an 8" dado, I'm thinking about swapping saws.
can you tell me what saws you've seen that happen on?
Delta contractors saw, the dewalt little yellow box saw and a Ryobe although I don't recall which model. A friend of mine has the Bosch saw and loves it, works well with a dado, I'm thinking of picking one up myself.
In re: your question about who makes a 6" dado set, you might want to look at Lee Valley. http://www.leevalley.com/wood/page.aspx?c=1&p=30061&cat=1,41080,41165 is a carbide-tipped model with chip-limiting; a 6"/18-tooth version is listed.
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Let me try to explain: I was NOT laughing at your question about why you can't use a 8" dado set. I was laughing because the warning label says to not use a dado bigger than a 6" diameter, but you asked if you could use your 8" set...do you get the humor now? Sorry if I made you upset or hurt your feelings.
no worries molten. In the end I appreciated your insight way more than your laughing at me bothered me.
You did explain yourself clearly in your previous post. I understand that you found it humorous that you thought I would consider using the 8" blade when it clearly states not to. perhaps you did not read my following post to you. I explained that it was a rhetorical question based on the fact that I had an expensive blade that I could not use. I also stated that it was I who had not made that clear enough in my orginal post.
once again no worries, and thanks again for the good info that you provided
Edited 5/29/2005 9:43 am ET by nails2
I second your comment. It depends on the saw. Both my powermatic and general 10 inch saws take an 8 inch dado. The arbors on light duty contractor saws or table top models are not heavy enough to take the load, especially if the dado head is out of balance. Another thing to consider is some light duty saws have a built in electric breaking. When you turn the saw off and the break kicks in the heavy spinning mass of the dado head has the tendency to loosen the arbor nut, once that happens all hell breaks loose as both the arbor treads and the dado teeth are trashed as the parts bang around inside the saw body. I speak from experience, first time ever I beat the dog to the door.
Armin, ty for your response, I appreciate the info. And also for not laughing at a guy seeking knowledge. In my mind I thought also about a smaller diameter spinning faster but never thought long enough about it to relate it to the power needed to turn the blade. But that makes alot of sense. Thought I'd just log on and throw it out there, to see if I could get some insights. Also, my saw ( Porter cable) does have an electric brake, so very good point.
Nails, if your question saved some guy from trashing his saw, I'll bet he will really be glad you asked. I had never thought about the electronic brake issue before. My old 78 model Uni doesn't have a power issue for sure but still, I might have hooked my 8" dado set up to someone else's contractor type saw w/o thinking so an excellent question IMHO. Thanks for asking it.
You might switch to a wobble blade. It would have less mass, especially in the wider settings.
I'm sorry, I thought you wanted it done the right way.
Good thought. But I didn't write the full warning. Here it is...!warning do not use a wobble dado blade or dado blade larger than 6" diameter.
As for why no wobble blade, you got me on that one. I know what they look like and how they work, but I have never used a wobble blade before so I'm not familiar with the dynamics of them.
Now that you've added woblers, you just have to suspect that there're clearance problems inside the saw that restrict the size - I've used an 8" dado on a Sears table saw and Sears RAS without problems, and they're about as under-powered as they come..
Phill Giles
The Unionville Woodwright
Unionville, Ontario
With some saws the issue is arbor length. Some of the wobble types are pretty wide because of the adjustment ring. I would guess that some of the cheap ones might be a little prone to inducing some vibration also.
One of the most awesome operations was using a low tooth number wobble on a radial arm. It will put the respect for shop safety in perspective. Prefer to not do that again.
Man. Your second paragraph is SO dead on. BTDT. Spheramid Enterprises Architectural Woodworks
The Morphine s eems to do no good at all..I'd run all the way if I would not fall...
I'm gonna agree with Molten on this one. To be honest it will probably work just fine but why take a chance on burning up your new saw?
More than likely, the opening for the Dado is not large enough to use an 8" blade at full height. If you have the blade spinning and crank up the height - the blade will jam into the insert. If this is a metal insert, stuff is going to fly all over the place - very dangerous.
I still have to buy the dado insert. If the opening is only large enough for a 6" blade I'm guessing it's because it's designed that way for the others reasons metioned in this thread.
Good point about the danger. Personally, I never raise my blade on anything with the motor running.
went to Amazon ...
typed in "6" dado blade" ... got 13 hits.
they're not that hard to find ...
this looks like the one I use in my portable DeWalt table saw ... I also have a wobble.
Both work fine ... both are 6" ... both "safe" for the saw.
I use the wobble for rough work ... the stacked for fine finish stuff.
View Image
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
yea the 6" should do all you need. After all I basically the largest dia I use mine for is 3/4 wide and 3/8 deep. If you need wider move the fence......
personally Ive started to use a router more for dadoing then amy dado blade. If ya figure set up time ect the router can be quicker and it does a cleaner job...
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