What size router bit for 1/8 dado?

[TheHinge]

I am building a box and it calls for a 1/8" dado. I have the router straigh bit for 1/8 and 3/16. My insert into the dado is 1/8" hardyboard (sp?) from HD. It was the only "plywood" I could find at 1/8". I did a little test with the 1/8" cut out dado, and since it is the same width as the board it does not allow the board to fit. If I really cram the hardyboard into the dado it will fit, but I didn't think that was right either. The 3/16" leaves a gap.

Any help you can offer is appreciated. Is there a 1/8" plywood anywhere? Should I use plywood less than 1/8"? Do I cram the wood in the slot, etc.? Thanks.

[drumpriest]

I'd just use a saw blade. Any 10" blade that ISN'T thin kerf is 1/8" thick.

[Tequila]

Another option is to rout the dado with the 1/8" bit, them move the fence as little as possible and widen the dado a tiny bit. That should give you the just over 1/8" that you need.

[monte]

You can sand the insert as well to give you a bitter fit.

[LCHIEN]

the problem with most sheet goods is that the nominal thickness they give is not the actual thickness.

It may vary +/- 1/32nd or more.

you can sand the edge of the sheet thinner or enlarge the slot.

[9johnny5]

Another option: Cover the edge with 2 layers of masking tape. Set your fence and leave it. Rout your dado, then peel the tape off and rout again. It should give you the extra width. You can use anything as a shim, I'd just suspect that tape would be the easiest.

Johnny

[JimD]

I like door skin plywood. My HD caries it with the other plywood. It is just a little under 1/8 inch thick and is just thin luan plywood. I think it is about $8 for a 3 foot by 7 foot sheet. I typically cut the dado with the saw blade as has already been mentioned.

Jim