Search found 465 matches

by johnparchem
Tue Oct 20, 2020 3:26 am
Forum: Instrument Builders Forum
Topic: Fretting, Michael Bashkin
Replies: 1
Views: 112

Re: Fretting, Michael Bashkin

I have it and I agree with your assessment. Well worth it.
by johnparchem
Tue Oct 20, 2020 12:06 am
Forum: Instrument Builders Forum
Topic: Wood bending fail - looking for advice
Replies: 10
Views: 237

Re: Wood bending fail - looking for advice

I also bend as hot as my iron goes. I have found as you mentioned the wood becomes plastic relatively quickly with a very hot iron. I have also found it possible to cook the the wood such that it takes a rather brittle set. There is a lot of gluing service so you may be able to use CA. A fix might n...
by johnparchem
Sat Sep 12, 2020 11:52 pm
Forum: Instrument Builders Forum
Topic: Guitar bridge as a brace
Replies: 4
Views: 992

Re: Guitar bridge as a brace

Adding the bridge to my falcate braced classical guitars without a lower transverse brace raises the top frequency (T(1,1)2) nearly 10 Hz. My bridges are generally around 18 grams. So the bridge in this case has added enough stiffness to the top to more than make up for the added mass. I haven't use...
by johnparchem
Sun Aug 30, 2020 11:15 am
Forum: Instrument Builders Forum
Topic: french polishing courses/tutorials?
Replies: 7
Views: 811

Re: french polishing courses/tutorials?

Robbie has a French Polish online course; it is much like the Milburn method but optimised. The best FP finishes I have seen are not really French Polished. It is the slow application of shellac with a FP like pad (no oil) over some weeks. The surface is leveled every day or couple of days. When the...
by johnparchem
Fri Aug 07, 2020 3:49 am
Forum: Instrument Builders Forum
Topic: Removing Lacquer
Replies: 8
Views: 929

Re: Removing Lacquer

A respirator, good ventilation and lacquer thinner or stripper?
by johnparchem
Sat May 23, 2020 12:46 pm
Forum: Instrument Builders Forum
Topic: Test post
Replies: 9
Views: 2161

Re: Test post

kiwigeo wrote:
Sat May 23, 2020 11:33 am
[youtube]https://www.youtube.com/watch?v=JBM5r5WnPOs[/youtube]

You still need to to it like this

Code: Select all

[youtube]JBM5r5WnPOs[/youtube]




youtu.be/JBM5r5WnPOs
by johnparchem
Sat May 23, 2020 6:29 am
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 94
Views: 27187

Re: Classical Build (s) - Hopefully falcate!

Hello folks. I'm probably going to be shot down for this long and complicated post, but that's OK, if perhaps even a small part of what follows might be useful to someone. Perhaps I should post it elsewhere. I'll preface what follows with the statement that I have spent my previous long working lif...
by johnparchem
Fri May 22, 2020 1:54 pm
Forum: Instrument Builders Forum
Topic: Advice on removing HHGed binding
Replies: 3
Views: 1319

Re: Advice on removing HHGed binding

If I am not saving the bindings I just pretend they are not there and recut the binding channels with my binding jig. If I want to save the bindings I start at one end and use a heat gun and a spatula to gently work the bind off. I just work along the binding heating and removing.
by johnparchem
Thu May 21, 2020 10:46 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 94
Views: 27187

Re: Classical Build (s) - Hopefully falcate!

Careful with the methanol it is very toxic, even the fumes. In the US cheap denatured alcohol is about half methanol. I avoid it for pure ethanol as I do not want to wear a mask through all the time it takes to French Polish. Methanol is highly flammable and toxic. Direct ingestion of more than 10mL...
by johnparchem
Wed May 20, 2020 11:15 pm
Forum: Instrument Builders Forum
Topic: Classical Build (s) - Hopefully falcate!
Replies: 94
Views: 27187

Re: Classical Build (s) - Hopefully falcate!

The guitar looks good. I also wonder about the consistent lack of T(1,1)1 on your plots. I just wonder in you setup something is filtering out the lower frequencies. It should be showing up very clear. You can hum into the box around the frequency you think it is an hear where it resonates. I have f...
by johnparchem
Mon May 18, 2020 5:59 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Establishing the target plate thickness for Flamenco guitars
Replies: 1
Views: 769

Re: Establishing the target plate thickness for Flamenco guitars

I had a very good Flamenco guitar in my shop with the back having a lower resonance than the top; a very thin back. I used Spanish cypress and use the same back vibrational stiffness that I use for classicals and pitched the back for semitones from the top. That might not be typical for a flamenco. ...
by johnparchem
Sun May 10, 2020 3:01 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Reducing BOBO neck weight
Replies: 12
Views: 2330

Re: Reducing BOBO neck weight

Just a thought, not my idea as it was posted on this site awhile back. Set things up so that you can install the bolt on neck sans fret board before gluing on the back but after gluing on the top. Then while gluing on the back you can set the forward angle by tilting the bolt on neck to the correct ...
by johnparchem
Fri May 08, 2020 11:58 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Reducing BOBO neck weight
Replies: 12
Views: 2330

Re: Reducing BOBO neck weight

Am I right in thinking that the 'wedge' for the BOBO classical neck might not be required for a flamenco, where the desirable saddle height is 7-8mm, rather than 10-11mm for a classical? I think you still need the wedge. Just imagine flat, no neck angle, with a 6 mm fretboard 2.5 mm of action will ...
by johnparchem
Mon May 04, 2020 4:40 am
Forum: Instrument Builders Forum
Topic: Best way to repair bent sides?
Replies: 10
Views: 2733

Re: Best way to repair bent sides?

Can anyone explain why a Ukulele should be tapered? Is there any Acoustical reasoning behind this, or is it just traditional? . They do not need to be and many traditional ukulele's are not. I think the tapered sides on a tenor looks better. It matters less to me with a soprano or true ukulele. I m...
by johnparchem
Sun May 03, 2020 11:46 am
Forum: Instrument Builders Forum
Topic: Best way to repair bent sides?
Replies: 10
Views: 2733

Re: Best way to repair bent sides?

This all looks normal to me. Agree with taper the sides, the block and the heel cap until all is in plane.
by johnparchem
Sat May 02, 2020 11:57 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Trevor’s video by Robbie
Replies: 10
Views: 3085

Re: Trevor’s video by Robbie

I have just gone through the video published by Robbie O’Brien of Trevor going through the whole process of analysing a guitar’s responses. It is incredibly useful. It is not a criticism of the book to say that a video of many of the processes involved is very powerful. Words can only take you so f...
by johnparchem
Thu Apr 09, 2020 5:40 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 3991

Re: 1. falcate braced classical

Thanks John. My bracing is going to be more or less the same as the steel string layout. I drafted my own but will amend it slightly. Im intending to put the lower TB in. 20200403_133723.jpg ... The lower transverse brace even an open will make a big difference when determining the height of the fa...
by johnparchem
Thu Apr 09, 2020 1:16 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 3991

Re: 1. falcate braced classical

After my actually quite nice results with a steel string falcate braced 000 style guitar I thought I can easily adapt a classical guitar to falcate bracing. Little did I know :) I should have believed John Parchem build description and stayed with the bracing height for steel strings. What I did wa...
by johnparchem
Mon Apr 06, 2020 8:04 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: having a go at spectrums
Replies: 11
Views: 2740

Re: having a go at spectrums

They look sort of noisy to me, like maybe your mic is clipping. You might turn down the gain. Because of the extra peaks I can not tell what the back might be.
by johnparchem
Fri Apr 03, 2020 7:48 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Closed box T(1,1)2 less than 200 Hz - Edge thinning
Replies: 3
Views: 1220

Re: Closed box T(1,1)2 less than 200 Hz - Edge thinning

I think both of your guitars that came in around 195 Hz had a good chance of hitting 180 Hz once finished. It would have depended on the mass of the bridge and how much the bridge lowers the top's resonance. On the steel strings I have been seeing <-10 Hz adding the bridge and another <-5 adding the...
by johnparchem
Thu Apr 02, 2020 6:28 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Closed box T(1,1)2 less than 200 Hz - Edge thinning
Replies: 3
Views: 1220

Re: Closed box T(1,1)2 less than 200 Hz - Edge thinning

Thinning the edges is a good way to Lower T(1,1)2 Lowering the braces is a real good way to Lower T(1,1)2 Having A thinner top is a good way to Lower T(1,1)2 The tops resonance is based on both stiffness and mass. In all the above three cases you are lowering the stiffness more than you are lowering...
by johnparchem
Wed Apr 01, 2020 2:57 am
Forum: Instrument Builders Forum
Topic: Bellied up top
Replies: 28
Views: 7703

Re: Bellied up top

I do not think changing the tone bars will do anything for you. The belly is from the nut side of the bridge rotating in. One fix I might try if I did not want to remove the top would be to sister taller braces on the over carved x-braces from the X to the finger braces on each side. Having said tha...
by johnparchem
Sat Mar 28, 2020 9:55 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: 1. falcate braced classical
Replies: 10
Views: 3991

Re: 1. falcate braced classical

Ok, old top off, new top on. Actually easier than I thought. Thanks the advice Jim. New values after binding and sanding: T(1,1)1= 90Hz T(1,1)2=195Hz T(1,1)3= 244Hz I had been wondering why the T(1,1)1 is so low until I checked the diameter of the soundhole... Great! Instead of 85mm I have just 79m...
by johnparchem
Fri Mar 27, 2020 2:04 am
Forum: Instrument Builders Forum
Topic: Bellied up top
Replies: 28
Views: 7703

Re: Bellied up top

I was taught not to start the scallop before the bridge plate for structural reasons. When I shift the braces toward the sound hole I am thinking about just the X not the entire scallop pattern. The low part of the braces are right where you need structural support.
by johnparchem
Wed Mar 18, 2020 8:24 am
Forum: Instrument Builders Forum
Topic: Carbon Graphite neck bracing, too much?
Replies: 6
Views: 4758

Re: Carbon Graphite neck bracing, too much?

Richard thanks for your reply, I had not thought about the creep factor over time. On many of my guitars I use a 2 way truss rod so I can dial it out. But for many of my classical guitars without a truss rod it is worth a thought.