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Well, it was bound to happen. I think I now know why folks like the dove tail necks. Way more adaptive. On my harp, it looks like the sound board has to bend too far down to make contact with the neck block. I am really uncomfortable with this. I thought about scabbing in a thin layer (less than typical binding width). But then realized the neck would not be flush with top once mounted. So what to do? Can one "elongate " the holes for the bolts? The heel comes plenty far south.

There is a good reason for this problem. The width of the boards at the neck joint are a bit off from what is needed. Also, I did put a 25' radius in the top. OK, live and learn. Thats why I am here.

So, thoughts?

Mike

I'm not sure I understand the exact nature of the problem so I can't say if this is the best solution, but in answer to the question, there is no harm in elongating the holes in the heel block a bit as long as there is still enough bearing for the nut and enough solid wood in the heel block to hold it all together. The main function of the bolts is to pull the heel firmly into the body. The bolts do not need to fit the holes tightly. In fact, I don't know anyone that doesn't leave some wiggle room there (although I may after writing this ).

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http://www.chassonguitars.com

Weeeeeell, its a complicated story. I have studied the geometry problem over and over. Being a harp guitar does not help things. However, it does appear that one way that this could arise is if the butt ends of the sides at the neck joint were not square. Problem is, thats not how harp guitars (Dyers) work. Anyways, at the center seam of the top above the neck block, there is a 1/8" gap that tapers off to zero right and left of the neck block. I can press the top down, but it deforms to the soundhole. So thats no good. I can fill in the gap, but then the neck will sit below the top a bit (1/8", no FB installed yet). However, if I can elongate the holes by 1/8" then I can bring the neck up flush with the top (and put some kind of filler below the tenon)

Reasonable?

Mike

One more thing I just thought about. Since this is the first radiused top I have done, I just realized another source of error. I should have left the neck and end blocks proud of the top. I did not do that. The end block is easily remedied, but not so with the neck block. But if I can elongate the neck bolt holes, all should work out.

I dont see how the type of neck joint would make anything here any easier .... either the neck heel and FB ext fit or they dont.

What I think I am hearing is that the rim is not properly shaped to accept the top, as you need to push the top down to meet the neck block ... now that said , there are plenty of builders that force a radiused top onto a flat rim. I am thinking you need to take some rim wood off on either side of the neck block, and possibly down the arm in order to get the top to fit better without the gap at the neck. But I could be "seeing" the problem all wrong too !!!!

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Mike bro I am not sure that I understand the problem either - pics would greatly help please?

Anyway since you mentioned elongating the neck block holes on a bolt on this might help: Prior to shimming the neck and tail blocks on glue-up I was having to elongate the bolt holes more that I was comfortable with. So I started shimming the blocks when I glued the sides to them. This made it much easier to sand the dome into the top without creating a mismatch for the bolt holes. It also was much faster to profile the rim in a dish because the blocks don't contact the paper in the dish until you are very nearly done sanding.

Here is how I do it: http://luthiersforum.3element.com/forum/forum_posts.asp?TID=9528&%20amp;KW=(pics)#forumTop%22

I'm guessing he means a dovetail can be shaved or shimmed to get the neck level with the top.

Yes, the blocks need to be a bit proud of the sides with radiused rims unless you want to sand all that meat off the sides.

Elongating the holes should be fine. I always drill mine after the body is together to avoid that problem.

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http://www.chassonguitars.com

Now, I had not thought about this! It does appear you are onto something. Sanding down the arm AND other side would do exactly what you are saying.

Thank you Tony!!

Mike

I think Tony has solved my problem... How do you locate the holes?

here is how I do my bolt holes .. they are predrilled into the block with counterswinks, prior to being glued to the sides. Then once in, I drill thru the sides - now the holes inthe body are complete. When making my neck, I use a butt heel, and get the neck pretty mcuh set into place, both for pitch and side to side/centreline. Then if you simply mark the edges of the holes parallel to the biding, extend those lines to outside of where the neck heel will sit, you can trasfer the holes to the neck heel. You could also use a centre punch thru the hole if you have one. I then transfer the marks to the inside of the heel, and drill/sink the threaded inserts. Works for me.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Here is a method that I use to locate the holes:

After the sound box is glued up (glue dry of course), I cut the mortise. I then screw two pins that have been ground to a point on one end into the neck inserts and press the neck tenon into the mortise. The points on the pins mark where the holes should be drilled.
The pins can be made from cut off 1/4 bolts or threaded rod. I simply used my grinder to grind a point on one end of the pins. This has completely eliminated the alignment problems that I had in the past.

Alan

ummm, I use 3/8" holes and regular knockdown bolts. plenty of wiggle room to account for neck angle changes, top thickness variation, etc...

incidently, i drill the holes in the neck block first, then clamp the neck block to the neck and use it as a drill guide. my threaded inserts require a 3/8" hole (which is how I arrived at that number..)

Justin

Tony and Hesh win the prize.

I FORGOT to profile the top of the sides on the the 25' radius dish.

Man, you ought try this with a big protusion hanging off the upper bout. All I can say is WOW! (that's MOM upside down). Those Dyer & Knutsen fellows had to really know what they were doing to pull this design off. I am also guessing at this point that they did not use a radiused top (plans say nothing about that). However, had they done so, more may have survived the enormous stress that those sub-bases put on the top.



Mike

I am figuring that the sub bass only make it about the same as a 12 string, maybe a bit more ... if the gauges are chosen properly .. Stephen Bennett uses gauges anywhere from 70 to about 45 for them (I will get the goods when I see him Monday), so with the lowest string only a 70, and tuned to F/G, with a scale length somewhere around 32-33 inches ... thats not all that much compared to a true bass string at .100/.105 tuned to E .... same goes for the highest - usually tuned to G, with a scale around 30 inches ...

BTW.. his std tuning for the subs is G A B C D G .....

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Tony,

Thanks! Yes, find out about the gauges. Oh, and please tell him to come to Huntsville AL for a show.

Mike

Meh. it's still only 11 strings total.

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http://www.birkonium.com CNC Products for Luthiers
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Mike, how big is your radius dish for that harp-top? Where does it peak?

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

It is a 24" diameter, 25' radius dish (talking about the top).

Man, if I had a dollar for every error I made on this one, I could buy a good reproduction.

I want to finish this one and start on my "lessons learned" model.

I have the box closed and the neck fitted. NOw, I am attempting to figure out the harp peghead. There is nothing easy about this part. I think I am close though.

Mike