Thread: Bit for Aussie (18mm) ply

Originally Posted by Robo1

Hi
I have to make some more bookshelves for the school I work at, now I have a 1/2" Triton router I want to use daddo's and rabbets instead of just using butt joints. I see that Carbatec have a 18.2mm straight cutting bit, is this the one I need for our 18mm ply or should I get an 19mm bit? Would bunnings have one or dose anyone know another place that sells them, I live on the Tweed and Carbatec is a bit of a drive.
Thanks....Rob

Rob, two things: First, plywood is hard to dado without serious tearout problems. The best way to avoid it is to cut along the edge of what will be the dado with a knife. Score the fibres down to the first glue line if you can and that should mitigate an impending problem.

Secondly, I always cut my dados just a tad large. 18.2 sounds good to me. But I would recommend using a dado jig and a smaller bit. I've made one with a sliding jaw. I fit the shelf material in it before closing to the width of the dado, and I stick a business card in it as a spacer (there's your .2mm!).
Pull it out and away we go. For an 18mm dado, I would typically use a 10mm spiral downcut bit to give a nice top edge. 10mm? I hear you ask. Yes. I cut across against one reference edge and then back along the other, removing the remaining material. If you want to see the jig, I can take a few snaps of it and post them here.

Michael

This is off your point Robo1, I know, but do you paint or stain the finished bookcase and, if so, with what, please?

Originally Posted by cellist

If you want to see the jig, I can take a few snaps of it and post them here.

Michael

I wouldn't mind seeing some pics of the jig.

Thanks

Hi Michael
Yes a picture would be good, thanks. I might be able to make one for myself!
Old Farmer
I just sand and clear coat it with Wattle satin estapol. the school bought some off a commercial supplier they cost about $200 from them I make them out of a single sheet of 18mm hoop ply and a length of 3x2 ($120) mine are exactly the same, the finish has stood up well after a full year of abuse and the teachers are happy with them and now they want a couple more, I just want to have a go at daddoing.
I have a good workshop (table saw, jointer, bandsaw ect) I just buy stuff as I can afford it, and I teach myself and ask a lot of people questions, the best way to learn is to have a go.
Thanks Rob.....

Thanks very much, Rob.