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Re: 2nd scratch build - Carpathian over EIR

Posted: Sat Oct 13, 2018 3:22 pm
by nkwak
LOL, yeah there's something to be said about a well-sharpened chisel or block plane. Sawing, OTOH - well, my elbow doesn't like that so much!

FWIW, I'm finding that for rough cuts I like power tools but for fine work nothing beats a drawn line to whittle away with a fine blade toward. I'm really not a big fan of Dremels or sanding bone saddles. I guess I'm not cut out to be a dentist! XD

Re: 2nd scratch build - Carpathian over EIR

Posted: Thu Oct 25, 2018 8:53 am
by nkwak
I feel like I'm continually making excuses for not making progress but I still enjoy working on this - even if I fail to meet even my own expectations.

Today I'm just going to vent about notching the rims. Just when I'm about to glue the plates on the temperature takes a nose dive and the furnace kicks on. I need to shift my focus to installing that humidifier because after a week my plates are acting like they want to become potato chips and are resisting the pressure of the gobar deck.

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Jan 30, 2019 1:37 am
by nkwak
From my other thread about spool clamps...

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The bigger one will come in handy to ensure that the upper bout and the neck block extension make 100% contact.

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Once the RH gets above 35% I'll put the sides back in the mold and glue the back to the rims. That way I'll also get to clean up the excess glue that would be visible through the sound hole. Once it's a "boat" the waist should be stabilized enough to glue the top on with the sides outside of the mold.

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Jan 30, 2019 9:06 am
by Diane Kauffmds
I thought you got that humidifier in and running.

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Jan 30, 2019 10:36 am
by nkwak
Diane Kauffmds wrote:I thought you got that humidifier in and running.
I did, but because of the space considerations I had to mount it on the return duct. It's made a notable improvement in the humidity but it's not working to its full potential and during times of excessive cold it can't keep up - though I also need to find a more reliable means of tracking actual humidity. The portable hygrometer I put atop the thermostat is reading 36% at present but because of my wife's wine collection (which is stored beneath the work bench) I've shut the duct in the basement and it reads 27%.

Really though, I'm going by what my hands are telling me and they've gotten pretty dry and cracked from my efforts two days ago. Better safe than sorry, so I've turned my efforts toward working with treated lumber, plywood and MDF. I fact, I've been "jigging up" in anticipation of a future build, an OM:

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Re: 2nd scratch build - Carpathian over EIR

Posted: Fri Feb 01, 2019 8:09 am
by Diane Kauffmds
I was just joking. Besides, the humidifier can only work when the furnace runs. At our house, the furnace doesn't run enough to maintain the humidity. Tightening up a house and installing high efficiency furnaces is a double edged sword.

I like your mold. I need to make another mold too.

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Mar 20, 2019 11:18 am
by nkwak
Can somebody explain to me why we radius the rims? It seems like having a lateral arc (across the width of the body) is counterproductive to assembly somehow. Looking at my factory guitars I see a straight line across the neck block and tail areas. It was troublesome when trying to set up the initial geometry for the fingerboard slope on the top and with the back being tapered it's downright frustrating.

The issue is painfully apparent at the inlets of the first ladder brace from the neck. In trying to inlet the end of the brace into the rims I discovered that I have to practically deform the brace in the opposite direction where I painstakingly sanded a 15' radius.

*grumble*

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Mar 20, 2019 1:40 pm
by Danl8
The back is typically made with a lateral/radial curve (for example, 15') for a variety of reasons, most popular of which is to mitigate cracking in humidity changes. The sides also taper longitudinally where the upper bout is usually more shallow than the lower bout. The sides at the waist are higher because they are closer to the guitar's longitudinal center line. The 15' dish in theory conforms the shape of the sides to the shape of the back, where, in an ideal world, the mating is perfect without any forcing needed. That's worked a few times for me and occasionally isn't a perfect fit, but forcing never needed. Be glad you're not building a baroque guitar -- 15' radius is comparatively child's play. Any way you can post a pic of your situation?

BTW, completely flat can work and is simpler with assembly. My $19 Sears & Roebuck Silvertone guitar was definitely done that way.

Re: 2nd scratch build - Carpathian over EIR

Posted: Wed Mar 20, 2019 2:16 pm
by ruby@magpage.com
For a while, Gibson made the curvature of the back a cylinder along a curve. To sand it you would need a radius beam (like a curved 2X4) and you would move it up and down the length of the back without spinning it.

Also, it is not uncommon to see a ladder braced guitar with a truly flat top- no radius. I built one, and the geometry is very easy to visualize and create. Just like a ukulele.

Ed

Re: 2nd scratch build - Carpathian over EIR

Posted: Thu Mar 21, 2019 10:30 am
by nkwak
Danl8 wrote:The back is typically made with a lateral/radial curve (for example, 15') for a variety of reasons, most popular of which is to mitigate cracking in humidity changes. The sides also taper longitudinally where the upper bout is usually more shallow than the lower bout. The sides at the waist are higher because they are closer to the guitar's longitudinal center line. The 15' dish in theory conforms the shape of the sides to the shape of the back, where, in an ideal world, the mating is perfect without any forcing needed. That's worked a few times for me and occasionally isn't a perfect fit, but forcing never needed. Be glad you're not building a baroque guitar -- 15' radius is comparatively child's play. Any way you can post a pic of your situation?

BTW, completely flat can work and is simpler with assembly. My $19 Sears & Roebuck Silvertone guitar was definitely done that way.
What I'm seeing is a "hump" at the base of the neck block:

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I've since gone at it with a block plane to level it out and feel better about it now.