Routing Flutes Across a Board: CNC Versus Jig Rig

This thread has some practical suggestions for routing flutes across the width of a board, and some good arguments for farming the job out to a shop with a CNC. August 5, 2010

I need suggestions for a technique to route a series of ~48 flutes vertically along a ~74" horizontal board such as this:

I know how to easily route vertical flutes in a vertical board, but I am puzzling over an easy way to do this. The best idea that I have is to use the 52" fence and rail on my table saw to increment the flutes with some type of captive jig/carriage at the router bit to keep the cuts aligned across the board.

Forum Responses
(Architectural Woodworking Forum)
From contributor K:
I would make a template for a router jig which uses a guide bushing in the base of the router. I would use a dado set to cut the size of the bushing with a TS sled. I would make it like a comb. Glue on a strip to close the open teeth of the comb. You may have to make it leaving every other gap in place to leave enough to be sturdy, then shift it when half are done. Plunge router.

From contributor W:
I would use a small jig that indexes itself by a short boss that fits into the first cove, and spaces the router over for the next cove cut. You would have to register off the edge of the board, because the boss wouldn't necessarily fit into the rounded end of the cove cut. A plunge router would be ideal for this, to avoid burning in the entry and exit.

From contributor D:

I would call someone with CNC.

From contributor K:
Yep, easy work for a CNC. Post your location and you may find someone in your area. I have some friends in the 100k garages thing and people want their work done for nothing, so I'm just going to keep building kitchens with mine.

From the original questioner:
I like K.I.S.S. principle solutions. Last night I thought about the pegboard top on my workbench with downdraft dust collection. I have blocks with pegs that I stick in the peg holes to hold objects still on the bench top when I am sanding. I plan to build a jig that will sit on the board with pegs that extend into the pegboard and index each flute. Hopefully, the spacing will work out perfectly. If not, I should be able to easily adjust the spacing within the jig setup.

I checked out the CNC jobbers. Nothing within my area. Thanks for the suggestions.

From contributor J:
I've done these before and a simple jig will get you there. Probably take as long to program the CNC to do it as it would to build the jig, and for only 10'? All you need is a board with a slot routed out for your guide bushing. This board has a bottom rail perpendicular to the slot that rides along the bottom edge of the board. As mentioned previously, a secondary hole next to the slot has your guide pin which registers the jig to the previous slot. In the hour it would take you to drive to a shop with a CNC, you'll be done.

From contributor D:
I have done these numerous times, and once you see it, the rest is easy.

Remove the saw blade from your radial arm saw, and fasten a 1/4" aluminum plate to the saw motor bottom and hang the plate out to the right of the motor. Prep the outboard plate to receive a router and fasten the router to the plate. Chuck up a bit and set the height and you are ready to roll. Index by eye, by layout or by something like a ballcatch fixed over the already fluted part.

You can leave the setup in place if you just make square cuts with the arm saw. It is great for dentil molds, half lapping, any repetitive cross actions. It is a bit dicey to tap into the motor housing, but if you are careful, you won't do any damage to the motor. All this is done before the guy with the CNC gives you a price, and it is entirely within your control. KISS indeed - know-how reigns.

From contributor G:
Yeah, who needs the CNC guy? Expensive, 2 hr drive, etc. I can do it faster with a jig/router, tablesaw, pin router, etc.

I used to make exterior/interior louver doors with the jig/router setup, plus one-offs as you need, until we contracted a 70 louver door project. Got a CNC and have not looked back. So besides louvers, we are able to make a whole new realm of things, with speed and precision beyond the jig/router setup.

CNC is the way to go. Invest some research time and see where you can increase your bottom line.

From contributor R:
LRH Magic Moulder head on a table saw or a plain old moulding head. Just did something similar and made an incremental spacer using 1-3/8" blocks hinged together and clamped it to the Bies fence on the saw. Easily repeatable spacing, virtually foolproof. Some of the ideas are more complicated than they need to be. Sounds like an easy, quick job - just do it.

From contributor B:
To program that on a CNC might take 3 minutes. The run time might be 6 minutes. What you don't have and have never used would make it difficult to see the benefit. You might lose on your drive time, however you also might learn something. CNC is the most efficient way to do this. Developing a relationship with a CNC owner would benefit you over time.

From contributor L:
I second the trip to a CNC - fast, easy and dead on!

From contributor N:
I'm with the CNC on this one. After one or two mistakes, the drive time probably won't seem that bad. Plus like the gentleman said, making friends with the CNC guy is always a good thing.