Tooling Up for Production of Grooves

For high-volume production of stock with a 1/2-inch-deep groove, it's hard to beat a shaper.April 29, 2012

I have to make 6mm wide by 1/2" deep grooves in solid ash pieces, about 1000-5000 lineal feet monthly. My dado blade only goes down to 1/4" width, and I am currently using a 6mm spiral bit in a router table, and have to make two passes to sneak up on the depth without chatter and tear out. Is there a faster way? I tried straight bits, about the same as the spiral, a little slower. Would a shaper with lots of power work better? A 6mm 6" diameter dado would be perfect, but 6 mm is just under 1/4".

Forum Responses
(Solid Wood Machining Forum)
From contributor C:
Amana makes a dado set that goes from 1/8 to 13/16 x 6" diameter for under $150, and I'm sure there are some other manufacturers with them too. Get some shims and you ought to be all set.

From contributor J:
How far from the edge of the workpiece is the slot? 6mm slot cutters are easy to find, and this cut is small enough to be handled by a router table if the slot is close enough to the edge. Failing that, modify a dado cutter with shims or by having a blade custom-ground.

From contributor G:
For almost no investment a slot cutter fits the bill, but if youíre doing 1000/1500 lineal feet a month a shaper with a power feeder is a good choice. If you donít have a shaper already you can get a used one and it could help you with other processes as well.

From contributor H:
I would agree. A 6mm groover on a shaper with a power feed would be the way to go on this.

From contributor F:
As said a slot cutter on the shaper is a good way to go. If however you don't have a shaper, you can also get a grooving blade for your tablesaw to do the same thing. Also with the quantity youíre doing I'd recommend using the power feeder also. It will save a lot of wear and tear on your most valuable tool - your body.

From the original questioner:
I am always amazed at the great responses from those who have done it before. I am looking at the Amana adjustable slot cutter router bit, (it has a dial on it you adjust for the width) - has anyone used this one? My stock is 1-1/2" wide, groove is centered. Will the router be able to plow this out in one pass clean and fast? I use a 2hp porter cable and Bosch routers in the table. I would like to leave my shaper set up for another operation on the same workpiece, and the tablesaw set up for ripping the same workpiece.

From contributor G:
Routers are great for short runs and stopped cuts but if you think in the long term I really would recommend a shaper. Tooling is an investment which you will use for other applications as well. 6mm sounds like light duty drawer bottoms and grooves splines and such. Think about the savings in time and productivity! I am a one man shop and between the business aspects, client calls, and installations building is what I spend the least time on. A feeder really helps with cut quality.

From contributor F:
A router could do the job, at least for a while, but it's not going to cut anywhere near as fast or clean as a shaper or tablesaw.

Youíre comparing a really small diameter cutting radius to a 4" or even 6" diameter cutter. The cut quality is going to be better on the larger diameter cutter. Not to mention a router is a universal motor really made for short runs, not thousands of feet. Trying to push that cut through too fast will burn it out, or at the very least kill the bearings.

I agree with Contributor C, a used second shaper and feeder will get your stock through much cleaner, more accurately, and in far less time. For that sized groove with a decent shaper youíre probably talking about feeding 20 fpm or more. Youíre not going to get near that on the router table. The time you save will pay for the equipment pretty fast.