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Hi all,

I'm at the point in my first build using the OLF medium jumbo where I have to install the end blocks. This design calls for an 3/8" thick extension that sits atop the neck block toward the upper transverse brace instead of just using a popsicle brace. My question is regarding the truss rod access point. I don't want to have an access point on the headstock so will I have to cut a 3/8" wide channel in the neck block's extension (or just cut the extension in 2 pieces with a 3/8" gap) in order to make the truss rod accessible from inside the sound hole?

Hi,

Without knowing which truss-rod you are using I would suggest you take a look at Robbie's video at LMI. Some great information here.

http://www.lmii.com/CartTwo/DisplayVideo.asp

I like to have the truss rod access via the head stock. I'm sure those that perfer the soundbox access will chime in.

_________________
Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

Thanks. I just don't like having a removable plate on the headstock. The plans I'm using seem to indicate that Michael Payne intended for a headstock access point though. All I've ever owned were Martin-inspired guitars and like the "cleaner" look, that's all.

FWIW I'm planning on purchasing a double-action Martin-style truss rod. I'm already using a pre-mortised neck block for a Martin dread. It's solid mahogany and I've also cut a 3/8" thick piece of Baltic birch plywood to size. I just haven't glued the two pieces together yet.

BTW, the link didn't work but I'm familiar with the video. It has no mention of the additional portion to the neck block though.

I route a slot in the top piece for truss rod access. I prefer the adjustment inside the body also.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Thanks for the picture, woody. That really helps.

Well, I went and bought some birch plywood from Rockler - though the local Michael's carries it too - and fashioned a block which I then cut into two pieces and glued up on my friend's treacherous go-bar deck. There was even a catastrophic malfunction and my top took a couple of hits as I'd also glued in the UTB but luckily nobody was hurt and the top's still i one piece!

That being said, that and the lateness of the hour left me a little flustered and things didn't go as planned...



I was hoping to kerf the second set of sides that I bent for this build but it looks like I've got another date with a chisel.

Not wanting to hijack this thread but I've seen reference multiple times to somebody building an "OLF ________" in this case jumbo; what constitutes an OLF Jumbo? Are there plans available somewhere or a website you can get them from?

Forgive my naivety...

_________________
"Never give in. Never give in. Never, never, never, never--in nothing, great or small, large or petty--never give in, except to convictions of honor and good sense. Never yield to force. Never yield to the apparently overwhelming might of the enemy." - Winston Churchill

Thanks for the info, Todd. You've given me lots to digest and I'll probably have to use a jig like that at some point but my extension simply isn't thick enough to route a channel; it's only 3/8". So I believe that I'm going to have to do a headstock access point which I'm coming to terms with.

BTW, I'm still confused about this neck block. The plans I'm using are actually the medium jumbo which IIRC is actually deeper than the SJ. The height of the sides at the neck block is supposed to be 3-15/16" but the block assembly inside is only 3.75" and I'm wondering why the difference? I thought there was supposed to be some excess on the block so that it came in full contact with the back?

So here's where I am for the second time in this build.


My sides are actually .4" higher than the block, but the plans call for 1/8" excess so I think I'm OK. It will be tricky for me on where to draw the line to glue in the kerfing but that's next. I need to get the blocks in first. After I took the picture I glued another piece of scrap mahogany to the base of the neck block. I'm hoping that gives me some more wiggle room, even if it means I'll have to trim away some excess.

There should be no "excess" side above or below the neck block. I don't have the MJ plans, but based on your info, it is telling you the neck block should be 3.75" tall and the final depth should be 3.9375". The 0.1875" difference factors in the body height added by the addition of the back and top. Also, know that those heights are flexible to a large degree (your top and back could be thicker or thinner than Mr. Payne's and slight variations in body depth will not have much perceived affect on tone (well, it might, but how would you ever know, right)).

So, trim your neck block close to 3.75". If you are using a 15' radius on the back, you will need to bevel the bottom of the neck block slightly so that it slants from the headstock side upward towards the tail. Install the neck block so it is flush and square to the top. Then trim the sides down until they are flush with the back of the neck block. Sand or plane the sides and blocks close to your desired top and back radius, install linings, and then sand or plane your radius in the neck and tail blocks, sides, and linings.

Aaron Craig

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Aaron Craig

I might still be missing something like a fish misses water but I think I see what you're saying: I'll have to trim excess away from the top rim before I put in the neck block. I'm thinking I should use a block plane for that job.

There's a lot of ways to build a guitar, but I think if you try to rim excess side material "away from the top rim," trim the sides from the top down to the neck block, you will create a host of problems.

Prior to bending the sides, it is general practice to joint the sides along the edge that will be glued to the top. This way you have a nice, straight reference when you put them in your mold and glue the blocks. There is generally no taper from back to front built into the top. Builders generally use only a slight radius on the top (28 or 30'), so the amount of material one needs to remove from top of the sides, neck block, and tail block is rather minimal. The back, however, normally is built with a much larger dome (smaller radi like 15') and almost always tapers from tail to neck block. So, you need to lose the extra height from the sides from the back of the sides above the neck block. Your sides on the back will taper from the tail block down to the height of your neck block. However, if you use say a 15' radius on the make, the taper will not be a straight line from the tail to the neck block. Rather, you should see a hump in the waist area.

To try and summarize: Glue your neck block so that the top block is flush with the top of the sides. This should leave side material above the back of the block. Use a block plane or chisel to bring the sides down till flush to the back of the neck block, but don't take too much off the sides in the waist area. Sand the back and top of sides in the appropriate hollow form to establish your radius. Glue in linings, and then sand again to perfect your radius on top and back. Then you should think of how to deal with neck angle in the upper bout on the top. Some, me included, sand the upper bout above the waist flat.

I doubt very much that my explanation makes the process crystal clear. It is a simple process that would be rather easy to teach by doing, but is somewhat more difficult to explain in words. There are probably some videos available in the tutorials section or youtube that will help you out. I would think your friend with the go-bar deck could also help you if he or shee has build a guitar or two. I would also highly recommend construction videos from OLF member John Mayes. You can buy the whole set or sections relating to specific parts of the build that will help with problem areas. I found his advanced bracing video was very, very useful. John Hall of Blues Creek Guitars has some good videos on youtube you should also check out. Just type in "Blues Creek" and you will see a bunch of them.

Aaron

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Aaron Craig

Looks like you glued the extension pieces to the wrong side of your neck block.

The clamping pressure you are getting from three go-bars is totally inadequate for this neck block glue-up; not even close. Use real clamps.

I actually am of the opinion that extending the neck block to the UTB is a mistake. It will hasten the collapse of the top above the soundhole. IMO, which nobody asked for, of course.

Kerf the sides? Ho ho ho. This is where bad English usage will lead. Not your fault, OP. Somebody else will explain it.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

[quote="nkwak"]... glued up on my friend's treacherous go-bar deck. There was even a catastrophic malfunction and my top took a couple of hits as I'd also glued in the UTB but luckily nobody was hurt and the top's still i one piece!

That being said, that and the lateness of the hour left me a little flustered and things didn't go as planned...



Those go-bars are WAY overbent. They will develop their maximum clamping force when they are bent only 1" to 2" from perfectly straight. Additional bending only stores energy that can cause mayhem - as you have already experienced. I hope you were using safety glasses.

_________________
Steve Smith
"Music is what feelings sound like"

That actually does help. Thanks, Aaron.

FWIW the top radius is 28', the back is going to be 20' only because I don't have access to a 15' radius dish. My sides are pre-profiled so that the top is already flat so I'll focus on the back rim.

BTW, Steve,

I agree. Those go-bars are too long for his 24" go-bar deck. He's got some spool clamps but I don't think they'd work on my home made mold.

Also, Howard, this time around I just used 3 cam clamps.

Put the 3rd attempt at a neck block in last night.



My mold has many imperfections and limitations so I needed to put some shims in to get a tighter glue joint:



If this doesn't work then I'll probably have to take it out of the mold to get even pressure all around and do it over. The mold seemed to get in the way of the clamps. There wasn't much in the way of squeeze out at all which leads me to believe that I may indeed have to do it over.