box joints

[kmcleod]

HELP !!!

ok,,now that I've got that out of my system, can anyone help / advise me...

In a bid to tidy up my tools and get rid of some cardboard and plastic cases I thought I would make up some boxes from ply, and thought, why not use a box joint to do it....

So purchases the ply - 9mm, cuts to size for for boxes, (so far so good), the starts to setup the dovetail jig with the box template, and disaster,,,so far every attempt has resulted in the same - the ply splinters and end up with mangled teeth,,

Any ideas, I've tried varying the router speed, same result, I've switched joint size - same thing....

 

[Philly]

Try sandwiching the ply between some waste ply - prevents the tearout (although it uses more ply!)
Hope this helps
Philly

 

[kmcleod]

Sorry Philly,,,

But tried that and still getting it chewed up badly,,,this has got me scratching head and completely baffled,,,

 

[Chris Knight]

All ply has this tendency, some worse than others. What kind of ply did you buy?

Are you sure your cutter is sharp? It might also be that the cutter is poor quality with unsuitable cutting angles etc.

 

[kmcleod]

ply is 9mm thick pine faced ply,,,used it on lots of other projects with no problems - cuts fine on table and mitre saw usually nice clean cuts.

Router bits are both brand new,,,,Trend double fluted straight bits, one is 12.7mm, the other is 6.3 mm,,,and I'm using a dewalt dovetail jig,,,,

This may sound dumb - but what the hell - am I using the router in the correct direction ?

 

[GCR]

I have managed to cut finger joints in ply, but I used a woodrat rather than a dovetail jig. I found that I had to sandwich the ply between inner and outer scrap ply and really clamp it hard with a G clamp (the woodrat clamp holding the work also presses the scrap to the work piece)and the G clamp had to be very close to the router bit. I have several g clamps with shallow grooves in them now! Even then I experienced some tearout which necessitated a little filler.

Bob

 

[compo]

Why not cut your finger joints on the table saw?

 

[Oryxdesign]

Have you tried precutting the bottoms with a stanley knife?

 

[Guy Forks]

All

I use this.

To make these.

From this.

But with the board being so wide tear out is a thing. I can't get enough pressure on the board to prevent it and I have a replaceable insert directly behind the cutters to prevent precisely this problem. I've found double sided tape and MDF stuck to the work as a backer helps a lot. But you need pressure any gap = tear out.

Glynn

 

[Chris Knight]

Glynn,
That's a great recycling effort! Nice results too.

 

[kmcleod]

Glynn,

Looks lovely, nice big jig, and produces and nice work....

As a sanity check I ran some scrap wood through the process using the jig and router - and great results pretty much first time....so aint the jig...

so have come to the conclusion that router and jig and 9mm pin dont mix and gone for a different method of making up the boxes....(thank god for glue and pins !!!!)