Thread: Precision routing

I haven't done this, so I may be way off. Having said that, this is how I would attempt that. You could use a similar method on a table, or by attaching a jig to the router base and using it freehand. Essentially, I would set it up so that there was a flat board with the router bit protruding through it. At the correct distance from the bit, I would have a piece of timber set up so that it fit precisely in the groove you are routing. Then you rout one groove, place that groove over the wooden guide rail, and do the next one. What I am thinking of is similar in principle to a finger joint jig, but for a through groove.

Peter

How wide, long, deep are these dados and how many are there? If they are wide enough, deep enough and far enough apart, I would make up a step and repeat type template out of MDF or hardboard.

Basicly, a base sheet wide enough to support the router for the full length of the cut, with a guide fence on top to run the router against, and a reference fence on one side to hold square to the edge of the timber. Then on the bottom, a section (preferably adjustable) that is a neat fit into the last dado made to establish and maintain spacing. Then, once the first dado is formed, the section fits into that and positions the jig for the next one etc.

If you take this appoach, mark the router baseplate and make all cuts with the marked point running against the guide fence. Rotating the router and base can affect accuracy.

Originally Posted by Wongdai

I want to route lots of tracks across the grain of a length of timber two metres long with precision, i.e. each exactly the same distance apart.

How do I do this? I'm guessing make a template. But to make the template is the only way to measure each bit and route it out? I'm not sure that would be accurate enough.

Is there A Better Way(tm)?

Sort of, but not by much. It depends mostly upon how many pieces are to be produced, and how well they need to mate with one another. If spacing is critical only within one piece, reference to the neighboring slot should be satisfactory. If many (two or more) pieces must mate with each other, "True Positioning" is superior, because it eliminates buildup of tolerances. Such measuring systems also allow variation of spacing within the piece, as long as the pieces must mate only with respect to their origins.

A template according to this theory could consist of a board long enough to reach the most distant slot, with a ledger below to engage the origin of the workpiece. For shorter distances, place fillers of incremental lengths between the ledger and the origin. The accuracy of the spacings will be no better than the precision of the incremental lengths, but they will at least be consistent. Essentially, this is how gage blocks and story boards work. The business end of the template should be clamped to the workpiece to avoid wobbling, and the router would ride across the template to make the cut.

Joe

Originally Posted by Wongdai

I want to route lots of tracks across the grain of a length of timber two metres long with precision, i.e. each exactly the same distance apart.

How do I do this? I'm guessing make a template. But to make the template is the only way to measure each bit and route it out? I'm not sure that would be accurate enough.

Is there A Better Way(tm)?

More details are required before I will attempt to answer your query, for example the width of the board to be cut. The size of each groove and the distance you would require them to be apart. How deep the grooves have to be
Tom

Make a jig like this like a fixed cross cut sled that the router slides in .
The boards to be trenched slides between the front and rear fences (left to right)
Make a square base from ply to and fit it to your router base so that it fits in to the rebated cross pieces .
You make an indexing peg to fit the dado or trench so you can use it as a stop to set the distance between dados .You can build stops in for the router so you can limit the cross distance if you want stopped dadoes.
Clamp the whole arrangement to the bench
Cut the first trench slide the board the correct distance ,set the peg in place ,and cut the next and so forth .
I may have simplified the process a bit but you should get the idea .
Just learning myself Solid Edge so its a crappy drawing.
Kev

Sorry Woodlee, I don't really understand your description at all. It shounds like you are on the right track but I can't quite figure out what you mean.

Joe, at first I thought your idea would be ideal, but then I realised that the incremental error would be a problem, as it is for two pieces that will fit together.

Tom, the length of the pieces are about 30 inches and they are 2x4, so in other words lots of 4 inch long trenches until the entire 30 inch long board is done. There are four boards. The trenches are V shaped, and it must be accurate enough so two boards will mate up with each others V's.

I don't think the other methods mentioned would be accurate enough.

Your problem statements seem to be ill-defined. Are the boards two metres long or 30 inches? Do the four boards mate in pairs, two at a time, or some other combination(s)? And what variation(s) are required in the combinations? There may, in fact, be a better way to accomplish your objective with less angst.

Also note that precision and accuracy are not the same thing. Two watches that are exactly wrong are nonetheless precisely wrong; one watch that is exactly right is accurate.

Joe

Hi there

The four boards make up two ends to a bench, so two boards will mate with each other. They are approximately 30 inches in length.

The idea is not structural, it is design (form). The only other way I can think to achieve the design is by using a table saw with an angled blade, but I still can't think how to index it appropriately.

If it all turns out too hard I will just mate the boards up together with no special teepee design.

regards

Wongdai

Is it important to do it yourself, or to just get it done?

There should be a couple or three signwriters in Perth with CNC routers who could rout that for you easily & accurately. If you were closer to SE Qld, I could do it for you!

Originally Posted by Wongdai

Sorry Woodlee, I don't really understand your description at all. It shounds like you are on the right track but I can't quite figure out what you mean.

Joe, at first I thought your idea would be ideal, but then I realised that the incremental error would be a problem, as it is for two pieces that will fit together.

Tom, the length of the pieces are about 30 inches and they are 2x4, so in other words lots of 4 inch long trenches until the entire 30 inch long board is done. There are four boards. The trenches are V shaped, and it must be accurate enough so two boards will mate up with each others V's.

I don't think the other methods mentioned would be accurate enough.

You have me confused when you start talking in inches. How long have You been in Australia? I was brought up in the imperial measurement back in the old country but I have been using metric since 1967. Sorry the details you have supplied are not sufficient for me to make any comment.
Tom

I can handle feet, inches, metric, furlongs, yards, cubits, and any combinations thereof, but unable to proceed further without pictures. Photo(s) of crayon sketches would be an improvement.

Joe

Originally Posted by Woodlee

Make a jig like this like a fixed cross cut sled that the router slides in .
The boards to be trenched slides between the front and rear fences (left to right)
Make a square base from ply to and fit it to your router base so that it fits in to the rebated cross pieces .
You make an indexing peg to fit the dado or trench so you can use it as a stop to set the distance between dados .You can build stops in for the router so you can limit the cross distance if you want stopped dadoes.
Clamp the whole arrangement to the bench
Cut the first trench slide the board the correct distance ,set the peg in place ,and cut the next and so forth .
I may have simplified the process a bit but you should get the idea .
Just learning myself Solid Edge so its a crappy drawing.
Kev

Ok revised drawing ,

Router fits between the rebated rails make a square ply base or other material for the router that sits on the rebates set the distance between the rebated rails to match the width of the temporary router base "B" The router can slide back and forth along the rebates as in "Y "

The dimension between the fences "B" is the same as the board width ,the board should be able to be moved perpendicular to "Y " .You could fit a couple of toggle clamps on the rear fence to clamp the board while routing.


Hope this helps
Kev

Kev, your sketches are satisfactory, I think.

Wongdai's sketches are absent.

Joe

Thanks Woodlee

Thats perfect. I can see exactly what you mean now. I can also make an indexing thing but using a long board with holes set the right distance apart and a dowel.

I think I will try on a practice piece first.

regards

Wongdai