Using a Router - Following lines

[Mr. Tickle]

Hello,

I am planning on building a set of three shelves to fit inside an alcove.

They are all different sizes, the top one being thin and getting wider on the middle one and wider still on the bottom shelf.

At one end, they curve so that the left hand side is, say 40cm wide and the right hand side is 20cm wide. This means there is an internal curve and external curve to go from thin (20cm) to the thicker end (40cm).

Now, i am going to round over the edges, which is easy as i will use a bearing bit to follow the edge - but i want to put in a supporting piece of wood along the length of the shelf - glued in perpendicular inside a rebated groove.

I would like to follow the edge here too. But the support wood will be about 10cm inside from the shelf edge.

How do i follow the edge of the shelf, and the curves, to give a rebated gulley that i can glue into? The extended fence that the router has will follow a straight edge, but when i get to the internal corner, in paticular, the edges of the fence/guide will obviously strike against the radius and stop the curve being followed accuratly.

Thanks for any input you can give me on this. I haven't used a router before and i'm looking forward to having a go!

 

[Jasonb]

If you mean a rebate then a bearing guided rebate bit will do the job, just fit the correct bearing to give the size of rebate you require.

The way you describe it sounds more like you want a groove set 10mm back from the edge. The only way to do this is to make a template and use a guide bush in the router. The template will need the correct offset to suit the bush/bit diameter.

This page shows how to calculate the offset, just imagine that your cutter is only going part depth of the wood and there is some timber left over on the right hand side

Jason

 

[Mr. Tickle]

Yes, that is what i meant; a groove 10mm from the edge. OK, will do it like that. Make a pattern first and follow that. I was thinking some sort of single-point fence or guide - like an extended bearing. But a pattern is dooable!

I suppose i can make that out of thin hardboard?

Mr. T.

 

[mother]

What you are looking for is a copy follower. It depends on what make of router that you have, so what patern of rails tht you hve to match to. I can giveyou the Elu/ Dewalt part no. but for other makes Trend is probably your best port of call.

 

[neilsumner]

Attach a piece of hardboard to your shelf then with a flush trimming router bit follow the edge of your shelf.
This will make the template for you. All you then need to do is set it back the right amount to follow and cut your trench.

-Neil

 

[Jasonb]

Mr T the only thing that would have a single point follower would be a laminate trimmer, the main problem will be keeping the bit/follower bearing at the right alignment, any slight deviation will alter the 10mm backset. Also very likely to get the bit snatch in that situation.

This is what Mother is talking about but they are really only for cutting the two surfaces flush.

Neil, if you just copy the curve and move it back the radius will not have been reduced so the cut will not be parallel to the shelf edge, you will just have moved the pivot point.

Jason