Router cut direction confusion

Hobo

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I'm going to use a Bosch Colt router and flush trim bit to trim the front and back sound boards on my Baritone. I'm confused about the direction of cut.

One instruction says to trim in a clockwise direction. Another instruction says to do clockwise 'climb cuts' at the tops of the bouts and finish off with a counter-clockwise direction around the whole body to avoid tear-outs.

My understanding is when using a router the recommended direction is to go counter-clockwise for best results. I'm confused.
 
I always start from the top of the bouts to the waist, and from the top of the bouts to the tail block or neck block. This is the same for both sides.
 
Blackbear is correct. You can do it differently than that but it depends on the material, how much you are removing in proportion to the diameter of the bit as well as what type of bit you're using. I am less diligent one hardwoods and more diligent on soft woods. Spruce can splinter pretty easily. I'd do as he says and you'll be fine.
 
Practice on non-critical pieces. Mock stuff up. You have to learn the difference between "climb cutting" and "conventional cutting". You have to develop a feel for this. You have to be ready to screw up...and move on. With climb cutting, you'll have to resist the tendency for the router to self feed. You won't learn any of this until you've destroyed some work a few times. Get used to it.
 
Climd cutting works when you are taking off small amounts as you do with binding and purflin ledges, After I have made the initial cuts as described above I sand the flat surfaces then buzz the router around against the rotation in a conventional cutting mode. This cleans up any 'fur' on the ledges.
 
For my students I always take a piece of chalk and mark the direction of the cuts on the top or back. It's very easy to get confused half way through the job.

I remember the first few instruments I did and the bum was puckered and the sweat was poring off of me. Now I don't even really think about it.
 
Clean the floor and bench top area you are about to rout in. At sometime a sliver will break off and you will want to find it to glue back. Ask me how I know.
 
Yes! I've ruined a few on this part of the build :(...searched the floor for splinters? yes done that as well :eek:..also had the cutter come loose and fly out and knocking a hole in the side of the upper bout :mad:....i just did a couple this morning with no problems so I must be getting better at it :D
 
Here's tutorial from Stew-Mac:
Avoiding wood tear-out
Running a router around the entire guitar body in one pass is not a good idea; at various points, the cutter bit will face end grain from a direction that's likely to tear out wood. Wood tear-out is always possible when routing, but it's especially likely with long-grain tonewoods such as spruce tops. The solution to this problem is to cut the channel in a planned series of passes. Referring to Diagram A, first cut the four areas marked with arrows, cutting in the direction of the arrows. These are the spots where tear-out is most likely, and cutting in the direction shown minimizes the possibility.

08_climbcuts_sm.gif



After making these four cuts, make one long cut around the entire guitar moving in the other direction, Diagram B. Because the first four areas are already cut, the router won't encounter likely tear-out spots on this long pass.
 
Ditto on the stew mac advice. Take a few shallow passes until its flush. Never remove more than 1/8th at a time.
I've had to "expand my purfling design" to hide a couple blowouts, especially in the upper bout.
 
The StewMac diagram is exactly what I do, as referred to in most of the replies about climb cutting. I don't do it that far simply because the more you do, the greater the chance of it running away; the you can just forget about looking for slivers.

When I first started, I thought a smaller bit would be better, but I realized its just cheaper. Now I use at least a 1/2" pattern bit in the table. Yes, the back gets tricky, but not as tricky as holding a router or lam trimmer IMO.

Aaron
 
I'll photograph my setup - I got a DeSoutter parallel arm on eBay for £25 and had Ken make a 'mushroom' for me - this is my back routing setup, as good as any costing 10x as much :) Never be without this dude and my laminate trimmers all set up for binding and purflin cuts. I'm serious tho - the direction of cut is as equally important on the sides as it is for the top.
 
Don't forget that if you're using a table router, all is backwards...

I use both a table router and overarm pin router for some operations so I can go "down hill" on the grain on small pieces at all times. I do some scary operations when I have to "hand make" my Renaissance guitar and bass bridges.
 
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