truss channel width

[Steve Malone]

I have a brief question which I am sure many people have or wanted to ask but I couldn't find one. My question is I am building a first 3 guitars, One is a test guitar which I have already learned many mistakes from, basically I made this from Poplar lamination, the other 2 are made from Cherry/Sapalee Lamination. The truss rod that I plan on using although I haven't purchased yet is a martin style for electrics 17.5". My question is that the rod is 7/16" and I have a 1/2" router bit, I also have a 1/4" bit but if I make a 1/2" channel, will that be too wide for the truss rod. I would think it would be ok being it would only be about 1/32" off from each side and I do plan on epoxing it down. I would just use my 1/4" bit and then do a second pass of 3/16" over, but I see the potential for a bigger mistake. Will it be ok if I am a little off or should I wait until I can find a 7/16" bit. I know I can get them via mail order, but I would rather get one locally and no one sells that size. Im sorry if this is a stupid question but I rather hear what some people experiences with this was.

Thanks in advance for your answer

[Dave Stewart]

I'm gonna' take a wild guess & say the trussrod is 7/16" DEEP, and only requires a slot (and bit)1/4" (or less) wide!
BTW Steve (?), this forum requires full names.

[David King]

Steve has stated that he is using a Martin style truss rod which is a different animal from the typical 2 way stacked rod most folks here are using. The Martin rod is an extruded aluminum "U" channel with a steel rod running down the center.

Steve NoName, Use your 1/4" router bit in an under-table with an adjustable fence. Adjust the fence so that your first pass is slightly off center, flip the neck around and equalize the slot's distance from each edge of the neck with your second pass. Measure the difference between the width of the rod and the current slot width and divide that distance by 2. Move the fence over by the same amount and take two more balanced passes. If you have two tight a fit you can slip a layer or two of paper between the neck and the fence until you have a nice easy fit. You need a little room for epoxy to work well. You also don't want the neck wood to shrink in wintertime and split the back of the neck open so make sure your wood is dry i.e your shop relative humidity is around 40%.

[Charlie Schultz]

Hi Steve and welcome to the forum. As David noted, we require the use of real first & last names here. If you will PM your correct name to me or one of the mods, we'll fix up your registration. Thanks!

[Warren May]

You can cut a truss rod pocket on a table saw, too, so that is an option if you have one. When I've used a tablesaw, I do the slot in 3 passes. First, a pass down the middle to establish center. Then, reset the fence outward to take just a bit more off and run both sides against the fence. Better to cut less and to creep up on it than cut the slot too wide, I think. You could use the same approach with your 1/4" router and a router table with fence. I used to try to cut the slots using a handheld router but always was a little disappointed with the quality of the cut. A handheld router would be a lot harder to get right, I think, with your 1/4" bit approach.

[Mario Proulx]

You want this truss rod system to fit very tightly into the neck; no slop, no gaps, and a press-fit! As the others have stated, a table works great(it's what I use), or your 1/4" bit, and move the fence over a wee bit at a time until, the rod -almost- fits. And stop there!

Do NOT begin the routing until your have the rods in hand; some are metric and are a bit wider or narrower than advertised. And you want a TIGHT fit.

Did I mention it needs to fit tightly??

[Warren May]

Agree with Mario that having the rod you are going to fit is best for most cases. I do find the exception with the StewMac 2-way rods that seem pretty consistent. I did finally break down and buy the StewMac router bit for their 2-way rods and having the correct size bit for the job is a definite plus. I just finished a mass run of 12 necks (8 quartersawn mahogany, 1 sapele and 3 maple) and the truss rods all fit very nicely into their slots. Setting up once is a definite advantage so that you get consistent depths and centers. Having the router table and bit takes a lot of the frustration out of getting the slot correct.

[Mario Proulx]

Don't muddy the waters, Warren. He didn't ask about StewMac HotRods, but about Martin style rods.

Stay on topic, please.

[Warren May]

Apologies to the group for rambling off topic...I'm an old man, you know, and we do that from time to time

[Mario Proulx]

Gettin' older and crankier here, too... My apologies for being a bit terse...