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| Genuine Martin 2-way truss rod slot http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=50922 |
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| Author: | Robbie_McD [ Thu Aug 23, 2018 3:01 pm ] |
| Post subject: | Genuine Martin 2-way truss rod slot |
Hi fellas, I am fitting the Martin G13NR009 2 way rods for the first time. These differ a little from the LMI/Allied rods I have used in the past. The rod is completely coated in plastic wrap, and is rounded on the bottom. It appears the rod is nominally 1/4" wide and 3/8" wide for 2 inches at the at the adjustment end. Question for those that have used these: Should the slot be rounded at the bottom? Are these glued into place or installed dry? Also, I assume the slot needs to be a bit wider than 1/4" to allow for the plastic wrap. Thanks! Rob |
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| Author: | Freeman [ Thu Aug 23, 2018 3:05 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
Ping John Hall at Bluescreek |
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| Author: | jfmckenna [ Thu Aug 23, 2018 3:09 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
I just use a 1/4in bit and it fits right in. A rounded bit would be nice but I use a straight one. This kind of goes over to my 'removable truss rod' thread but I always glued those in dry by using a piece of masking tape over it as I apply the glue then remove the tape and clamp the fret bard down. After it's glued up you can pull the rod right out. The adjustment end is a bit wider. ON my guitars that extension is in the head block so I just use a round rasp and make it a bit wider. |
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| Author: | Robbie_McD [ Thu Aug 23, 2018 8:10 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
I went out and bought 1/4" and 3/8" core box bits to rout the slot with a round bottom. For you repair guys, how does Martin route these slots? Any glue at the ends? I don't want any rattles. Rob |
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| Author: | Bri [ Thu Aug 23, 2018 8:23 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
I use those rods, and that bit. The rod will push in with medium thumb pressure, just sneak up on the depth. Not much room for a rattle, but a drop or three of any glue to take up any movement. B |
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| Author: | Woodie G [ Thu Aug 23, 2018 8:43 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
We mill a round-bottomed slot to 0.365"-0.370" based on actual rod measurement (they vary a few thousandths). We used to mill a flat-bottomed slot at about 0.300 and use a 1/4" piece of drill rod to scrap the bottom to a round shape, but the router is faster and more consistent. We mill the adjuster area out with a standard two flute end mill or spiral router bit - far enough into the neck that a stress riser is not a factor. The rod is not glued in, but we also don't do anything to keep glue from the slot, and some will penetrate, but the heat-shrink sheath will not permit rattles in any case. If sloppy with glue, it's a good idea to tape over the operating end of the rod such that the tape can be pulled after the glue dries. FWIW, there are big differences between the Martin-style rod and the sort-of-look-alikes sold by StewMac and on Ebay...we use only the Martin rods, after dissecting a Martin and a few look-alike rod side-by-side. |
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| Author: | Robbie_McD [ Thu Aug 23, 2018 8:49 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
Excellent, thanks Woodie and Bri! Exactly the info I was looking for. And yes, these rods came directly from the Martin 1833 shop. Nice folks there, BTW... Cheers! Rob |
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| Author: | klooker [ Fri Aug 24, 2018 7:18 am ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
Robbie_McD wrote: I went out and bought 1/4" and 3/8" core box bits to rout the slot with a round bottom. ... Rob That's what I've been using with good results. In the instructions that came with my first build, a Martin factory kit, they said to fill the slot with white glue or Titebond before inserting the rod. I don't do that but I also epoxy my fingerboards to the neck to avoid introducing any moisture which can cause back-bow. I know some of the excess epoxy goes into the slot to reduce the potential for rattles. Kevin Looker |
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| Author: | Brad Goodman [ Fri Aug 24, 2018 9:00 am ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
These are the best rods in my opinion. I buy them from Martin. I use a 1/4" round bottom bit and bed the rod in with yellow glue as I am gluing the fretboard on. |
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| Author: | Glen H [ Fri Aug 24, 2018 7:11 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
Doesn’t gluing it in cause it to be limited in the length of the adjustment? I’m sure Martin knows what they are doing but it seems kind of unintuitive to me. |
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| Author: | doncaparker [ Fri Aug 24, 2018 11:58 pm ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
My own personal view: Like a few other 2 way truss rods, the Martin rods have a flat bar on top and a round bar on the bottom. It is often said that, with a flat bar on top, you don’t need a filler strip on top; you can just have the flat bar against the bottom of the fingerboard. However, I prefer to make the slot just a smidge deeper than needed and use a filler strip on top of the flat bar anyway. Why? Because that makes sure the bar is as snug as possible inside the neck, thereby helping reduce the chances of a rattle. I just put the rod in, glue the strip in, clamp it down, and plane it level with the neck after it dries. |
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| Author: | bluescreek [ Sun Aug 26, 2018 9:41 am ] |
| Post subject: | Re: Genuine Martin 2-way truss rod slot |
only use these and I use tite bond just to fill the voids . |
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