Dado troubles :( - Router Forums
 
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post #1 of 7 (permalink) Old 12-10-2007, 11:27 PM Thread Starter
 
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Default Dado troubles :(

I will start by saying I am quite new to woodworking and am learning as I go. I am making a small, very basic shelving unit for our front closet. I bought 3/4" mdf and figured I would use dados (made with my router) to strengthen the joints. I "measured twice and cut once" using my 3/4" straight bit and was excited to start assembly. The dado grooves are snug, actually too snug. It seems impossible to get the shelves 100% set in the grooves. Is this common? I know they should be a tight fit but this is rediculous! ha
HELP?
Thank you all in advance...

Last edited by worthia; 12-11-2007 at 12:21 AM.
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post #2 of 7 (permalink) Old 12-11-2007, 12:24 AM
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Hi worthia

It can be a buddy got some from HD and it was marked 3/4" but it was the same size as plywood 23/32 thick but the tag did say it was 3/4" , sounds like it going the way of the candy bar just getting smaller in all ways..looks like they found a way to make more money....

To get back to the MDF you got,, most of light brown ones are right on and some are darker brown are bit thicker, ,,,you may want to get your mike out and check it for sure..you can just make one more pass to clean it out just a bit more..or just put a very small rabbit on the ends to get it to fit in..this is a easy job on the router table...

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post #3 of 7 (permalink) Old 12-11-2007, 01:04 AM Thread Starter
 
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Thanks for the reply Bob. I measured the mdf and I think it's bang on. How deep should I go with my dado? Is there too deep? Would that affect the fit? With 3/4" mdf should I go with a depth of 1/4", 3/8"...? I did only make one pass with the router, maybe that has something to do with it, maybe another pass give the extra room I need...
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post #4 of 7 (permalink) Old 12-11-2007, 01:17 AM
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Hi worthia

I/4" to 1/2" should be just fine, not all router bits are made the same way,same size, you may want to mike the bit to make sure it's 3/4" , if so one more pass should do the trick..with just a little offset...( SMALL ) .010...make a small test pass about 1/2" long then put in a feeler gage to check it ,with the bit in the slot or a scrap block of the small stock that's going in the slot..

http://www.routerforums.com/attachme...ction-7976.jpg
http://www.routerforums.com/attachme...ction-7975.jpg
http://www.routerforums.com/attachme...ction-7974.jpg
a real quick jig for the dado slots ▼
http://www.routerforums.com/28689-post1.html


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Quote:
Originally Posted by worthia
Thanks for the reply Bob. I measured the mdf and I think it's bang on. How deep should I go with my dado? Is there too deep? Would that affect the fit? With 3/4" mdf should I go with a depth of 1/4", 3/8"...? I did only make one pass with the router, maybe that has something to do with it, maybe another pass give the extra room I need...



"It's fine to disagree with other members as long as you respect their opinions"

Marc Sommerfeld Tools ,Videos
http://www.youtube.com/channel/UCT-n...RWaEpMA/videos

Find all threads started by bobj3
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Last edited by bobj3; 12-11-2007 at 10:58 AM.
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post #5 of 7 (permalink) Old 12-11-2007, 01:29 AM Thread Starter
 
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Being new, I wonder about the tightness of the fit. Should I be able to push the shelf into the dado slot without any excess force? There was no way I was getting these shelves into the 3/8" deep dados without a fight... Is it common that one pass with the router wouldn't create a wide enough dado for the mdf to fit?
Sorry for all the questions, I just like to learn...
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post #6 of 7 (permalink) Old 12-11-2007, 08:07 AM
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Bob and Rick always use simple methods to ensure fewer mistakes. Their rule of thumb about dado's is to make them half the thickness of the material. If you use the same method every time you will never go wrong. As far as your fit problem, it is very possible that your 3/4" bit is not on size. There is a tolerance range for bits being acceptable, yours could be on the low end or slightly undersized. As long as you are aware of this you can adjust your routing guide and make a second pass for a perfect fit. You would mark your exact cut size, make a pass on one side and then reverse your set up to cut the other side to the mark.

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post #7 of 7 (permalink) Old 12-11-2007, 10:37 AM
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FWIW --
This may or may not help -- or it may be something you want to file away for other uses.

For cutting dadoes for shelves I use a double-sided guide rail.
The handy thing is -- it doesn't really matter if my bit is too small or not
When I first used it -- I needed a 3/4" dado and only had a 1/2" bit.
The left guide gives me one side of the dado - the right side gives me the other.

A couple of other things I like are
- I can clamp it across both sides of my cabinet case at the same time helping to insure they line up correctly.
- By cutting the dado first through each end of the jig -- I can see exactly where the cut is going to be on my boards.

Here it is being used to cut some dovetails a few months ago --

http://www.routerforums.com/attachme...-femalejig.jpg

Can't take credit for the idea -- can't give it either though -- cause I forget who I stole it from --

The one who says it can't be done --
Should avoid interrupting
the person doing it.

Last edited by Drugstore Cowboy; 12-11-2007 at 03:16 PM.
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