How to route an offset?

[Dan West02]

I am making a clamping fixture to clamp pieces in a laminated curve. The parts to be clamped are 9 of pieces that are 1/16” thick. The overall laminated thickness is 1 1/16”

There are a number of small gradual curves and I know the gap between the male section of the clamp and the female section needs to be the 1 1/16”.

I can make one half of the clamp OK, but have not been able to figure out how to route the 1 1/16” gap over to the other half. I don’t want to scribe it and saw and sand to the line because I don’t feel it will be accurate enough.

Maybe I am missing something, so if anyone has a method that works for them I would sure like to see it.

[johnny means]

:confused:How do nine ⅟₁₆ pieces add up to 1 ⅟₁₆?

[Cliff Rohrabacher]

I am making a clamping fixture to clamp pieces in a laminated curve. The parts to be clamped are 9 of pieces that are 1/16” thick. The overall laminated thickness is 1 1/16”

You mean like for Rocking chair rockers?


I can make one half of the clamp OK, but have not been able to figure out how to route the 1 1/16” gap over to the other half. I don’t want to scribe it and saw and sand to the line because I don’t feel it will be accurate enough.

There are a couple ways. Easiest is to band saw (or jig saw) the curves using a compass to get the complimentary curve. you'll cut two lines.

Other way involves a bit of math. you need to know your arc dimensions and where on the arcs your tangents are and lay it all out.

[Dan West02]

I must have been half asleep when I posted. What I should have said was 15 pieces 1/16" thick with room for 1/16" thick cork on both faces.

I can do the layouts very accurately (CAD program), but don't think I can do the saw and sand process accurate enough - thus, am looking for some way to pattern route with an offset to get it just right.

[Warren E. Johnson]

I can do the layouts very accurately (CAD program), but don't think I can do the saw and sand process accurate enough - thus, am looking for some way to pattern route with an offset to get it just right.

When building jigs to laminate strips into a curve "ya anin't building pianas." The cork you are planning on using will take up a lot of irregularities. Also note that the finished piece will not onform exactly to your jig so exact is not of a lot of value (although with 1/16th in. strips the spring back will not be very much).

I say lay our your curves and cut as close as you can. Sand to your liines and go for it.

Warren

[Floyd Mah]

Here's a way to do this. You want to create the complementary part of the clamp but can't figure out how to match it to the primary face of the clamp, especially because it is separated by a 1 1/16" gap. First establish the primary face of the clamp using whatever method you choose. Having done that, fasten it with screws to another board. Take strips of cardboard, or whatever you have that is 1/16" (or less) and layer it onto the primary face until you have the 1 1/16" thickness. You can now do several things, since the outside of the layers outline the face of the complementary side. You can trace the outline to another board and use that to form the face of the clamp. You can glue up by layers the second face of the clamp, using thin strips of wood. You can glue blocks to the board that would make up the complementary face and use that as the clamp face (the complementary face doesn't have to be continuous since your work material will bridge the gaps smoothly). You could also build up the complementary face vertically, using 1/8" or 1/4" material cut along the layout line and duplicated with a pattern bit and a router. You could also build up the clamp face using the pattern and a pattern router bit on thicker material. Anyway, sounds like a lot of fun.

[Bill ThompsonNM]

It really doesn't to be as exact as you think... so cut and sanding to match will work fine. If for some reason you do want a more precise match...
temporarily laminate a 1/16 inch ply to the original curve then thin plastic then add a thick bead of epoxy putty and finally add a "close" curve for the compliment and clamp together. You can then either use the epoxy faced curve as your mold or use it as a template to create a mold with your router

[Joe Chritz]

It doesn't have to be that exact but if you can run a cad program it is a simple and cheap option to find someone with a CNC and have them knock out the master parts for you.

I suppose you could fab up some kind of jig that rides off the initial face but I really don't think it is worth the extra effort.

Joe