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Routing a groove in the center of an edge question.

Routing a groove in the center of an edge question. (post #169530)

RoyTurning on Fri, 12/30/2011 - 18:26

Jigs, Fixtures, Tips & Tricks

I'm in the process of making cabinet doors with raised panels. I want to route a 5/16" groove along the inside edges of the rails and stiles and I want this groove to be centered from side to side. The "how-to" book says to make two passes rotating the stock end for end which sounds simple enough. However, when I do this the second pass chatters and I end up with a rough inside edge. I guess this is due to the rotation of the cutter head (1/4" spiral bit) grabbing the stock . Should I be feeding the stock in the opposite direction on the second pass or what?

Thanks,

Roy Turning

Not much of a router person am I but (post #169530, reply #1 of 7)

by roc in reply to RoyTurning [original] on Fri, 12/30/2011 - 20:38

Are you using some "feather" boards ( on the in feed side and on the out feed as well ) or other devices to hold the work firmly against the fence ?

Is the bit sharp ?

Has the stock changed a bit from the first pass ? Bowed a little ? Probably not but I had to ask.

Is there something loose ? The bit in the chuck or the fence ?

Those things occurred to me.

PS: you may have to make more than one pass depth wise ( vertical protrusion of bit above the router table ) with such a skinny little bit ( 1/4" ).

Is the most amount of the bit in the chuck as is possible. Meaning the closer the chuck is to the cut the less flexing in the bit.

What kind of wood ?

roc

Give me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )

Routing a groove in the center of an edge (post #169530, reply #3 of 7)

by RoyTurning in reply to roc [original] on Sun, 01/01/2012 - 08:02

Your commnts are well taken, I've covered most of them. I think Hammer 1 nailed it (there's a pun in here somewhere) in the next reply.

Thanks,

Roy

You are using the wrong type (post #169530, reply #2 of 7)

by hammer1 in reply to RoyTurning [original] on Fri, 12/30/2011 - 21:24

You are using the wrong type of bit. Use a slotting bit and run the work flat on the table, not up on edge. If you want to use the bit you have with the work on edge, you work opposite in measuring from the fence. The first pass would be set to the outside edge of the bit, the edge farthest from the fence, not from the fence to the inside edge of the bit, the way you would normally measure on a table saw.

Beat it to fit / Paint it to match

Routing a groove in the center of an edge (post #169530, reply #4 of 7)

by RoyTurning in reply to hammer1 [original] on Sun, 01/01/2012 - 08:24

Ah. . . I believe you solved my delima. I will get a slotted bit (that sounds a little easier than the second option) but both sound like good solutions.

Thanks again and Happy New Year.

Roy

the flip trick (post #169530, reply #5 of 7)

by RalphBarker in reply to RoyTurning [original] on Sun, 01/01/2012 - 10:01

The old flip the stock trick assures that you'll have equal amounts of remaining stock, and assures that the groove will be centered. It doesn't, however, guarantee a precise dimension for the groove without other set-up considerations being made.

Flipping the stock also ignores grain direction, which can contribute to one inside surface within the groove being rougher than the other.

Using a spiral or straight bit that is smaller than the desired size of the groove can also result in a "trapped" cut on the second pass, which can be dangerous. For that reason, using a bit that is the desired size in a single pass may be a better approach. To get it properly centered, you can simply do test cuts on waste stock to fine-tune the fence position.

I'd make the same recommendation if using a slotting cutter, so the single cut can be made with, rather than against the grain of the stock.

Routing a groove in the center of an edge (post #169530, reply #6 of 7)

by RoyTurning in reply to RalphBarker [original] on Mon, 01/02/2012 - 17:20

I used my 1/4" spiral bit to make a 5/16" groove as Hammer1 suggested - measuring from the fence to the outside of the bit and flipping the workpiece end for end. It worked pretty well, both groove walls were clean. However, since it was a blind groove, I did have some grabbing when I was completing the second pass as the bit came to the end of the previously routed stopped grove. In fact- it pulled out of my hands in a flash. Based on what I've learned at this point I'd say that if I wanted a centered groove that went all the way through both ends of the workpiece the flip method would be fine as long as I measured to the outside of the bit from the fence. Since I want both ends to be stopped I'll use a 5/16" bit as you suggested and forget the flip part.

Thanks to all,

Roy

You didn't mention doing a (post #169530, reply #7 of 7)

by hammer1 in reply to RoyTurning [original] on Tue, 01/03/2012 - 06:57

You didn't mention doing a stopped groove, Roy. Details are always important. Using a spiral bit the way you are isn't the ideal way to do the groove. When you do need to make a stop, you use an extra long fence and clamp stop blocks at both the start and finish, don't use a weak clamp like a quick grip and keep fingers a long distance away from the bit and your body out of the fly zone. Since you have to drop the work on the bit and then lift off, that's not an ideal situation either. You can drill a hole at the start and finish to make that easier but you don't want the bit to touch the end of the holes. Essentially, the info I have given is to help make a bad situation manageable but it's still an undesirable method.

Beat it to fit / Paint it to match