Routing through 8/4 wood.

[NCGrimbo]

I'm getting ready to work on a new project and I'll be doing something that I've never done before and need some advice. I'm going to be routing wavy lines on some different species of wood and then glueing them together to form a single piece of wood. I found this image as an example of what I'm looking to do:

I have a template made up for the wavey lines and will be using a collet on the router to follow the template.

I have two questions about the procedure.
1) How deep of a cut with the router should I make for each pass?
2) Should I plane each board to the final thickness before routing/glueing or should I just route and glue up the 8/4 unplaned stock?

As a note, I'm using a router & template instead of the bandsaw due to my lack of ability to follow the lines accurately enough on the bandsaw to form a nice joint between the different pieces of wood.

Thanks.
-NCGrimbo

 

[bluedawg76]

why not rough cut on the bandsaw to save time leaving a 1/16" or so that you can clean up w/ the router/guide so that it's more like flush trimming rather plunging straight through 8/4 wood. just a thought. I don't like routing any deeper than ~3/16" at a time and even then 1/8" allows much more control (w/ a 2 1/4hp router) depending on the wood and router bit size. i'd plane close to thickness (w/in a 1/16-1/32) so that it's nice and square but wait til after the glue-up to plane to final.

Sam

 

[Joe Scharle]

I would plane the rough stock to 1/8" - 3/16" over-sized, to allow finish planning on both sides of the glued up pieces. And as Sam suggest, bandsaw the parts wide of the line and trim with a router to your template. If you are reeaallllyy bad at following a line, cut 1/4" wide of the line and make a few passes with your router. Don't forget that you can use the template guides and keep stepping closer to the actual bearing on your trim bit.

 

[Mike Mendelsohn]

If you have a bandsaw, try stacking the two pieces and cutting the curve. Since you are cutting both sides of the joint at the same time, you don't have to be accurate in following the line, they will match. The only hints are to make sure the blade is square to the table and to try to cut in one continuous pass. Hesitating might widen the cut.

As a bonus, you get to use the cutoffs to make a mirror image glueup.

I'll post some pictures of a project I just completed using this technique along with a couple of test boards.

Mike

 

[Mike Mendelsohn]

I added a couple of pictures of my wavy line glueups in the gallery. I also included descriptions of the process with the pictures.

In all honesty, I did a poor job of following the lines on the bandsaw. I was trying to manage a large hunk of wood around curves and varied off the line by as much as 1/8" at times. The results don't show the errors and the joints are gap free and clean. It's just that the sine waves aren't perfect.

As far as using a router and template, it is not as easy as it seems. If you use a single template to make both sides of the joint, you will need to attach it on the good side of one board and on the waste side of the other. You won't be able to do the rough cut on the bandsaw and cleanup with the router.

You will need two guide bushings to make the joint. The outer diameter of the bushings need to differ by twice the diameter of the bit. When cutting the board with the template on the good side, use the larger bushing. When cutting with the template on the waste side, use the smaller bushing. This provides the offset needed to compensate for the diameter of the bit. Think in terms of cutting a circle inlay using a template consisting of a round hole. If you didn't account for the offset, the inlay would be too small.

You could make a pair of templates using the two bushings to compensate for the offset. You could then rough cut and use a bearing guided bit to clean up the curves.

BTW - There are dual diameter bushings that are made for this type of cut. I have one for 1/8" and 1/4" bits. See - http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/router_inlay.html

From my experience, the bandsaw is a whole lot faster and easier.

 

[NCGrimbo]

Thanks for the info guys. I'm going to try practicing on the bandsaw and see if I can get good enough for the joints to match up. If not, I guess I'll be working with some templates instead.

-NCGrimbo

 

[CDPeters]

Using the band saw, I would recommend that you stack two adjacent (in the final product) workpieces together, staggered so one "keeper" piece is on either side of the blade. That way when you make the cut the two pieces wind up fitting together perfectly.

C.