# putting dado in plywood



## autoBrad (May 21, 2008)

Hey guys,

On a recent project, i am working with 3/4 inch poplar plywood. I needed to put a 3/4 wide by 3/8 dado in a piece for a t slot track.. I started doing it on a piece of scrap with a 3/4 inch router bit in my router in the table.. I started doing it and I realized the bit was getting very hot and smoke was coming out with the saw dust.. It was buring the plywood.. 

Now the end of the bit looks burnt. Maybe some resin/pitch remover will get it off.. I stopped doing the test piece when I seen the smoke.. Now I know when doing round overs if I get smoke I turn the speed of the router down and feed the stock quicker to cut down on temperature .. and that works, in this case I tried that.. The router was only set to 16500 and I even turned it down to 10500 but it was still burning it.. I hope my bit isn't shot..

With this problem I just stopped and used a stack dado and did the job on the table saw.. like a charm.. I can't believe that the router/bit would have a problem with doing that on this plywood.. Is there something you can think I am doing wrong??

THanks

Brad


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## Gene Howe (Feb 28, 2009)

I'm sure you considered it but, sounds like a dull bit. 
Another (less likely) cause; I've heard that some BORG plywood from China has metal in it????


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## autoBrad (May 21, 2008)

Here's some pics


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## autoBrad (May 21, 2008)

Yeah, i'm hoping it's not the bit.. I'm trying to remember what else I routed with it.. I may have routed some melamine with it.. maybe that dulled the hell out of it..


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## knotscott (Nov 8, 2007)

It wouldn't hurt to clean the bit with any spray on degreaser (ie: 409 or Simple Green) and an old toothbrush.

It might help to make multiple partial cuts instead of all at once if you're not doing that already.


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## Garmar (Apr 7, 2009)

autoBrad said:


> Yeah, i'm hoping it's not the bit.. I'm trying to remember what else I routed with it.. I may have routed some melamine with it.. maybe that dulled the hell out of it..


Melamine is rough on bits. Lots of metal in the substrate. Don't ya just love those little ragged edges when you get it off of the truck? 

Anyway, that bit looks shot. It's a Grizzly. Those are dirt cheap so I would just buy a new one. 

gar

Edit: and like knotscott said. Cleaning the pitch off of it will reduce those burn marks a lot. If the bit is as dull as I suspect it is it will probably just pitch up again immediately.


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## autoBrad (May 21, 2008)

Yeah, i have some resin and pitch remover.. I'll clean it and try again.. It's actually a woodriver bit I got at woodcraft for 35 bucks.. It's not a grizzly.. If it is still crappy after cleaning then I'll either have to try to get it sharpened or buy a new bit..


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## johnv51 (Oct 27, 2008)

I vote dull bit as well. I use a dado jig with my hand held router and don't usually take more than 1/4" depth per pass. For a 3/4" wide slot I would take even less.


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## woodnthings (Jan 24, 2009)

*You can put a clean edge on it yourself*



autoBrad said:


> Yeah, i have some resin and pitch remover.. I'll clean it and try again.. It's actually a woodriver bit I got at woodcraft for 35 bucks.. It's not a grizzly.. If it is still crappy after cleaning then I'll either have to try to get it sharpened or buy a new bit..


Harbor Freight has a 4 sided diamond? hone with grits from 200 to 600 for $15. Since the cutters are flat and bevel, no curves, you should be able to bring it back to usable life....if it didn't get too hot. The hone is a useful tool to have for general sharpening of chisels, plane blades as well as router bits. Granted it's not a 1200 grit superfine but I find it works for most things I do. I just got my second one, in case I can't find the other one....heh...heh.:blink:
BTW I'm up in Oxford. MI. Dexter is on the way to Hell, I think?
Rode thru there a few times on my way to having fun. bill


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## cabinetman (Jul 5, 2007)

My guess is a dull bit. I run dadoes at full speed. Try a new bit, and try two passes. Your feed speed can be determined by the cutting ability of both the bit and the router. 

You can dress carbide edges with diamond embedded files, but you have no way of knowing if all the flutes are equal. If they aren't, that puts more load on one or more flutes (depending on the bit).


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## Gene Howe (Feb 28, 2009)

autoBrad said:


> Yeah, i have some resin and pitch remover.. I'll clean it and try again.. It's actually a woodriver bit I got at woodcraft for 35 bucks.. It's not a grizzly.. If it is still crappy after cleaning then I'll either have to try to get it sharpened or buy a new bit..


Please let us know how you come out re: cleaning...new bit, sharpening????


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## BloomingtonMike (Jan 3, 2008)

How many passes did you take? You could try doing it in a few passes.

Try cleaning the bit first but I agree with the poster above, get a new bit and try again. You can always try sharpening it latter but you will probably want to keep several of these around anyway. I would think the $5 Woodcraft/Woodriver bits (when on sale which is a LOT of teh time) would be just as good as your Grizzly bit. Maybe upgrade and get yourself a Whiteside. I have AWESOME luck with them. 

Brian Gumper runs www.holbren.com and he sells whiteside and gives a 10% or 15% discount (can't remember off hand) to woodnet and sawmillcreek members (other WW forums). Go there and search for him and holbren discounts if you are interested in those. Not that you care, but I got a couple Whiteside 1/2" upcut spiral two-flute Whiteside bits from him today in the mail - $27 each shiped was his sale on them last week (now over) - That is about 40% the going rate for those and free ship no tax! He is a great dude.


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## Ed'sGarage (Aug 16, 2007)

*dull bit?*

I'm with the dull bit folks on this. Just my .02, if I use a router bit for a dado, I make multiple passes and take out the waste a little at a time. Secondly if the size of the piece warrants(smaller, rather than larger), I use my TS. Shelf dados, if the piece size warrants, IMHO, are better on the TS, as you can set the fence and the are perfectly equal in height. Sorry to get off on a tangent here, but the pics show some real burnining; I never saw a router bit burn that bad. 
Ed
Just as an aside, with the price of bits these days, sometimes it is cheaper just to replace the bit with a new one.


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## The Mind Train (Nov 10, 2008)

It seems you are not alone Brad. This link is to a woodworking forum in the UK 
http://www.woodworkersinstitute.com/forum/forum_posts.asp?TID=903

Bob


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