25/32 Straight router bit? Who has one?
alanplanesaw
| Posted in General Discussion on
I have some birch plywood, supposedly 3/4 inch. It is marked 18 mm.
The calipers say it is 23/32 of an inch. I need to cut a dado for this. Know anyone who makes a bit that size? 3/4 inch would be too big.
Thanks,
Alan – planesaw
Edited 6/25/2005 10:20 pm ET by Alan
Replies
CMT makes a router bit expressly for the undersized dimensions of plywood.
Make two passes with any smaller bit.
I jut bought one yesterday. If you have a woodworkers tool store nearby, give them a try. If not, Rocklers, MLCS, or others have them.
How about using a dado blade? In most applications it should work as well. Good luck.
It is a large piece of plywood that I need to cut the dado in and I was afraid of some variable depth if I used a dado blade on the tablesaw. Figured a router bit would be better.
But, I set up the table saw with a dado blade and will probably use it.
Thanks everyone for suggestions on the undersized bits. I'll be checking them out.
Thanks,
Alan - planesaw
Given the variable thickness of plywood these days, I am perplexed why anyone would attempt a full width dado. I cut a 3/8" dado on everything, and then cut a matching tongue to fit. As they say ---- easypeasy..................********************************************************
"I tend to live in the past because most of my life is there."
-- Herb Caen (1916-1997)
Alan,
Nikkiwood is correct. I bought one of those special sized router bits for 3/4" ply a few years ago...the problem is the variable thickness of the plywood...making it too tight in some areas and too loose in others.
I put a shoulder on an adjoining piece and use a 1/2" bit/dado.
Alan,
In addition to the sensible suggestions made by others to make two passes with a narrower bit, you can also do the job with a single pass; use a rabbet-dado joint, instead of milling a full-width dado.
-Jazzdogg-
Whether you think you can, or you think you can't, you're right.
There's a neat trick to cutting dados exactly the size of the plywood or board that will fit into the dado. It requires a pattern bit (bearing on top), a couple clamps and two scrap pieces of wood that are longer than the dado to cut, and 2-4" wide.
To make it easier to follow, call the board that will have the dado cut into it the "Side." The board that will fit into the "Side" we'll call the "Shelf."
1) Set the Side onto the Shelf at exactly the position you want the dado. That is, the edges of the Shelf are located where the shoulders of the dado will be.
2) Place the scrap pieces of wood on either side of the Shelf, flat side down (on the Side). Clamp them in place.
3) Remove the Shelf. You are now looking at a gap between the scrap pieces that is exactly the width of the dado to cut, and located exactly where it needs to go. Use the pattern bit adjusted to the right depth of cut to make the dado.
4) You now have a dado of the correct width, whether 23/32, 25/32, 3/4, 49/64, 127/359s, etc.
I've used this trick many times- I think it is the best way to get a matched fit. If the first pass is too tight (which sometimes happens if the bit and the bearing are not sized exactly the same), shim the shelf with a dollar bill when setting up the scraps of wood on either side to guide the bearing.Glaucon
If you don't think too good, then don't think too much...
http://hersaf.com/cutters.html
I use pauls method, and it is very easy and accurate. If you have several dados to make you can tack the two strips togather on the ends. That will lock the size in place.
If you really want that size bit you can get any size imaginable from a machine tooling suplier. You just have to fing them with 1/2" shanks.
Mike
http://www.holbren.com
If you do ALOT of cuts in ply.. A bit expensive BUT... Accurate Woodworking tools LLC make a router guide that WORKS! Well, if ya have the money to get it.. Worth every cent if you do ALOT of cuts with a router..
Just me though...
Whiteside makes under-size plywood bits.
Catalogue page (PDF format):
http://www.whitesiderouterbits.com/catalog/CTStraights2.pdf
Main page:
http://www.whitesiderouterbits.com/
I purchased mine from:
http://www.routerbits.com/
I've used the 23/32" bit with good results.
Regards,
Leon Jester
Edited 6/27/2005 11:50 pm ET by Leon Jester
A while back I built the shopnotes dado guide for routers. I use a 3/8" bit also. The thing is self adjusting for thickness and takes all of 60 seconds to setup. It doesn't care about variable size stock.
Joe
I have used the Whiteside bit with good results. I don't have a tablesaw that is large enough to do the dados needed for cabinets, so the router is the way I have to go. Birch ply and Apple Ply are pretty consistant with what I have seen, sizewise, so I haven't had the problem with inconsistancy that others have. HTH.
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