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Truss rod fit
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=40937		 Page 1 of 1
Author:  Mike Baker [ Sun Jul 21, 2013 2:28 pm ]
Post subject:  Truss rod fit
I'm using LMI's one way rod, which I have used on all but my very first build. Have had no problems with it, but I have a couple of questions.
LMI recommends and I use a 3/16" router bit(Bosch) to install. I just measured that bit. It is .159". After measuring the width of the rod, I get .185". Should be too big for the slot, yet the rod fits snuggly in the routed slot. Do router bits have a kerf?
The adjustment end of this rod requires a 1/4"(.250") notch. Since this rod is not wrapped, I would like to wrap it with electrical tape. As stated, the adjustment end measures .250". The rod itself, once wrapped with tape, measures .218".
If I rout a 1/4" slot (.250") the length of the neck, will the .032" play in the slot present a danger of truss rod rattle, or otherwise be too wide for the rod?
Thanks in advance for any assistance.
Author:  Joe Beaver [ Sun Jul 21, 2013 3:59 pm ]
Post subject:  Re: Truss rod fit
A 3/16 router bit should measure .1875". I would test it on a piece of scrap wood and try the fit. If it is indeed to snug I would send it back and buy a different 3/16 bit. A .1875 slot should be snug but perfect.
Author:  ZekeM [ Sun Jul 21, 2013 4:07 pm ]
Post subject:  Re: Truss rod fit
Yes 3/16 should be .1875, could be an out if tolerance bit that slipped thru. How are you measuring it? Measuring cutting tools can be a little tricky at times. Also if you have any run out in the router or collet the slot will be cut oversize.
Author:  Mike Baker [ Sun Jul 21, 2013 4:19 pm ]
Post subject:  Re: Truss rod fit
Thanks, guys. Perhaps I'm measuring wrong, but this is the same bit and same truss rod I've used over and over. The fit is good. The measurements I got just didn't seem right. I'm measuring the bit at the tip, across the "v" notch in the bit itself, which is the widest portion of that bit.
My actual question was if I wrap the rod, will it's wrapped width of .218" be to loose of a fit for a .250" slot? It's actually a moot point, since I realized that any width I gain from the wrap will also translate to an increase in depth for the truss rod slot as well. I'll assure a tight fit and cushion with silicon as per my usual. Thanks for the replies.
Author:  ZekeM [ Sun Jul 21, 2013 4:47 pm ]
Post subject:  Re: Truss rod fit
That'll work mike. I've never wrapped with electrical tape. How does that work? The only rod I wrapped was with metal tape.
Author:  Tim L [ Sun Jul 21, 2013 6:42 pm ]
Post subject:  Re: Truss rod fit
A router bit could cut big if one flute is longer than the other. or something else in the geometry is making it walk off. My first questions would be is it a 2 flute bit and what are you using to measure it with?
Another thing that I can't figure out is why wrap a one way rod? If it fits snugly into the channel, and you back fill the channel properly why add tape or shrink wrap? Aren't you just adding mush? I am using a single rod dropped into a 3/16" slot and then backfilled tightly with a 3/16" Mahogany strip. Rod's not going anywhere with the anchoring system that I use, which also makes it a 2 way rod, and the tight fitting backfill makes it so there is no chance of a rattle. The system has been used on 1000's of guitars and no rattles attributed to the truss rod.

Tim
Author:  Mike Baker [ Sun Jul 21, 2013 6:54 pm ]
Post subject:  Re: Truss rod fit
Actually, it's not the standard one way rod as used in a Gibson, et al.. It's a modern one.
https://www.lmii.com/products/mostly-not-wood/truss-rods/neck-parts/truss-rod-standard-welded-end
Similar to a modern two way. I like it because it requires a shallower slot than most, the flat top of the rod can rest against the back of the fretboard with no filler strip, and I can use a straight channel.
The only reason I wanted to wrap it was to allow me to rout a 1/4" channel, which matches the metal piece at the end where the rod adjusts instead of a 3/16" channel for the rod and a small 1/4" notch for the adjustment. But doing this will make the rod bigger all around, which will take away one of the reasons I prefer it, which is the shallower slot. I will install as usual, and I appreciate everyone's responses.
Author:  Tim L [ Mon Jul 22, 2013 11:53 am ]
Post subject:  Re: Truss rod fit
Hey Mike,

That makes more sense. Those can and do rattle. That is a bending rod a one way would be a compression rod. Thanks for clarifying.

Tim
Author:  Mike Baker [ Mon Jul 22, 2013 2:08 pm ]
Post subject:  Re: Truss rod fit
Tim, they're both one way. A one way rod will only adjust one way, no matter how it's constructed. But thanks for letting me know to call it a one way bending rod, as opposed to a one way compression rod. Now I can be more clear .
Author:  Colin North [ Sun Jul 28, 2013 5:45 am ]
Post subject:  Re: Truss rod fit
3 spots of silicone sealant seem to stave off rattles pretty well, and don't take up much clearance.
I just do 1 each end area and 1 in the middle
Just saying.
Author:  Mike Baker [ Sun Jul 28, 2013 7:50 am ]
Post subject:  Re: Truss rod fit
Todd Stock wrote:
A one-way rod bends the neck back (reduces relief), while a two way rod would allow the neck to be bent backward or forward. Not certain why the nature of the rod would matter - both bend the neck.

Agreed.
Author:  Clay S. [ Sun Jul 28, 2013 8:03 am ]
Post subject:  Re: Truss rod fit
For wrapping truss rods I like to use teflon tape that plumbers use for pipe threads. It doesn't add much to the thickness and helps keep rods from being glued in place.
Author:  SteveSmith [ Sun Jul 28, 2013 9:05 am ]
Post subject:  Re: Truss rod fit
Clay, that's a good idea - I'm stealing it :)
Author:  Colin North [ Sun Jul 28, 2013 12:31 pm ]
Post subject:  Re: Truss rod fit
Clay S. wrote:
For wrapping truss rods I like to use teflon tape that plumbers use for pipe threads. It doesn't add much to the thickness and helps keep rods from being glued in place.

Smart thinking Batman! I will try that too.
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