Routing an Irregular Outline

Woodworkers compare a pin router to a CNC as the device for cutting the outline of a map or other irregular object. February 19, 2013

If you had to cut a mass quantity of an irregular shape of, let's say, the USA map out of solid maple, but had to cut out the center as well, leaving just the outlined frame of the USA map, how would you do it without a CNC machine?

I have used scroll saws before to cut small parts and center pieces, but this requires a pre-drilled hole to then disconnect the blade from the scroll saw and stick it through the hole and re-attach blade and cut out the center. Any ideas?

Forum Responses
(Cabinetmaking Forum)
From contributor J:
Pin router and two templates.

From contributor M:
Ditto on the pin router. Cakewalk. If you don't own one, there are many inverted Onsruds out there for reasonable prices as shops move to CNC. In some cases these machines are better suited for some projects (especially smaller runs) than a CNC. See ours if you are unfamiliar with these type of machines.

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From the original questioner:

Thanks. I was looking at the Daisy pin router assembly. I'm sure it could work on a shaper as well to get more HP.

From contributor O:
Hire a CNC shop to do 1 as a pattern, the use a flush bit to copy.

From contributor B:
Ditto on the flush trim bit. If you can make the pattern yourself you may save a few bucks.

From contributor M:
Flush trim cutters are fine for just a few pieces - but in this case, the questioner is looking for mass quantities. That coupled with the shape (a thin perimeter) would need to have clamps applied to use the flush router bit, including relocating the clamps to enable routing the entire perimeter. And probably two templates since the work piece may be too narrow to balance a router on correctly (yeah, you could always hot melt a standing block on the base of the router). This all is time consuming, plus the chance of the piece moving slightly while relocating the clamps.

Can be done - don't get me wrong, but depending on exactly how many pieces, this is perhaps more suited to using a template on an inverted router. Only one template is needed for this application, one path groove for the inside diameter and one groove for the outside diameter. A vacuum clamp is best, but we've found that sandpaper applied to the template can work to keep the work piece from moving at the very end of the cut - this is usually where you can get a slight indentation as the finished piece is freed from the waste.

Now, if this is a one time contract - perhaps the cost of acquiring a pin router is not viable. Unless you can foresee the myriad of uses this machine potentially adds to your machinery arsenal in a shop… ;) We picked up ours for only $1,200.00 in excellent shape. I was fortunate to not need shipping - a shop about 10 miles away had put it out for sale and I drove over and loaded (his forklift). Shipping could be a no-deal since these machines do weigh up to 2,000 pounds. The newer ones are much lighter, though more costly.

I guess it all comes down to how much time the questioner can afford to spend on this job. Time is valuable - but if you are slow and no work down the road - take your time and do it the flush trim route by all means. But if time is of essence, and you are looking to maximize your costs - a pin router beats the flush router bit. Or, farm it out to a CNC shop close by. Get a quote - maybe you can turn a better profit paying them to do the job!

From contributor L:
We've got both a CNC and a pin router. For some things the pin router is actually cheaper. If you are trying to use a minimal bit diameter the pin router is easy to step into the work a bit at a time. Depending on size a vacuum fixture works great because you can cut all the way around and change out parts quickly. I bought a used SCM R8 a long time ago, cheap, very solid machine. It doesn't get used all that often but is hard to beat for some things. The tilt table has been very useful.