Thread: Acoustic build no 1

Ebony binding is a PITA to bend. I went through 5 bits to do a Mandola. I got a lot of advice but the best was "sand it to 1mm and laminate together after bending" Ive got some Pac Blackwood / Sollies Ebony for the next crack at it. I'll let you know how it goes. I think blackening some myrtle may also be the go but Im yet to do that experiment.

Soundboard radiusing is a fascinating subject.The trebles and mids get more accentuated as you increase the radius because the timber gets "tighter". My last couple of builds have all been bent tops so they are tighter again. They have also all been Mando family instruments so it is time for me to go back to Guitars for a while. I have a couple of little projects to knock off and then I want to do a few Selmer inspired instruments without the Gallic styling, I think its pretentious... As for the sound and the % changes I havent been able to quantify the effect. It also depends on bracing and soundboard thickness. As a kitchen bench luthier I havent been able to set up the rigs David Hurd proposes. I do spent a lot of time feeling the flex of the soundboard of different planes though.

There is a Yahoo group for Left Brained Lutherie BTW. There are some brilliant people who post there.

Mike the side laminator looks like it works well,is that the same type of press used with those electric heating blankets that I have seen being used ? I was looking closely at it to see how those arms worked to pull the timber around,then I noticed the slots and thread to pull down what must be stainless steel ? whats the foil on the inside of the arms for?

I asked a question back a bit about kinkead and siminoff bracing looking more radical than pictures I had seen so far, this page on frets.com answered my question Scalloped Braces? Frank Ford has put together a huge amount of info on his site,so thanks Frank.

Sebastiaan I agree with the ebony being a PITA ,I got my package of purfling today and the flexible black looks exactly the same as the ebony ,have you seen this guys guitar ? Stradivari Guitar on Exhibit at the National Music Museum
looks like he would have used ebony and ivory, you can see where he has joined the ivory around the lower right bout ,I cant see any joins in the ebony but maybe he did the same with the ebony? I will have to look up Selmer instruments.

I had a good chair maker walk into my workshop the other day, he makes windsor chairs by the dozen and has done heaps of steam bending, when I showed him my bending experiment he frowned and said Ebony ! no no ,as a rule temperate forest timbers ,generally the tropical stuff don't bend.
All that being said I think it is best to experiment any way and see what we learn,I now have a bending set up ready for the next binding or purfling try at what ever.
While I had the ebony in there I threw in a length of oak about 10mm x 20mm and made a flimsy walking stick or back scratcher

I took a picture with my sides laid on top of a Yamaha FG 200 for comparison and the finished bits so far.

cheers Rob

Originally Posted by auscab

Mike the side laminator looks like it works well,is that the same type of press used with those electric heating blankets that I have seen being used ? I was looking closely at it to see how those arms worked to pull the timber around,then I noticed the slots and thread to pull down what must be stainless steel ? whats the foil on the inside of the arms for?

I asked a question back a bit about kinkead and siminoff bracing looking more radical than pictures I had seen so far, this page on frets.com answered my question Scalloped Braces? Frank Ford has put together a huge amount of info on his site,so thanks Frank.

Sebastiaan I agree with the ebony being a PITA ,I got my package of purfling today and the flexible black looks exactly the same as the ebony ,have you seen this guys guitar ? Stradivari Guitar on Exhibit at the National Music Museum
looks like he would have used ebony and ivory, you can see where he has joined the ivory around the lower right bout ,I cant see any joins in the ebony but maybe he did the same with the ebony? I will have to look up Selmer instruments.

I had a good chair maker walk into my workshop the other day, he makes windsor chairs by the dozen and has done heaps of steam bending, when I showed him my bending experiment he frowned and said Ebony ! no no ,as a rule temperate forest timbers ,generally the tropical stuff don't bend.
All that being said I think it is best to experiment any way and see what we learn,I now have a bending set up ready for the next binding or purfling try at what ever.
While I had the ebony in there I threw in a length of oak about 10mm x 20mm and made a flimsy walking stick or back scratcher

I took a picture with my sides laid on top of a Yamaha FG 200 for comparison and the finished bits so far.

cheers Rob

Rob, My press is similar to those that use the heating blankets except that it's solid MDF, not just 2 sides with dowel spacers. The foil tape is just to keep the glue from sticking to the wooden parts and that is a piece of stainless steel. I wrapped the ends around some steel dowels that I had drilled and tapped for all thread. Once I tighten the top clamp I bring the ends down and tighten them. The arms serve to guide the laminations into place as I'm bending it around the form and then I use a wedge at the flatter portions of the ends to help compress them. I guess with enough practice I could get the hang of bending the sides, but would have to go through a lot of material to get the results you and others on the Forum have gotten. Again, great looking work you've done there, hope mine looks as good. Thanks for the info about frets.com, I'll check it out.Mike

Coming along nicely Rob, look forward to seeing that soundboard braced and the body closed up!

Finaly got the soundboard done,two Saturdays of
watching football took it's toll on the build,but it
was worth it.

1. is the sound board marked 55 mm in from the
edge where it will taper from 2.92 down to the
edge at 2.5 mm

2 . took it down with the spoke shave then sanded

3. soundboard braces marked off the plan , next
to it is a Ibanez laminated sound board that has
failed at the bridge ,the tension of the strings has
broken the bridge plate and snapped the sound
board,it's another project to replace with a solid
top,just there to compare

4. The two lights to the left I got from bunnings
they clamp where ever I need them, I have been
using them to get those warm pictures, I used
them here to see the light between the brace
and the top

5 and 6 shows the gap

7 to shape the x braces to fitt was a real challenge ,
I couldn't do it with a plane on the shooting
board because because the brace has a 2mm
dip in the middle but at the ends drops back
down .5mm for the edge taper, I roughed it with
a plane then took to it with the scraper fitted to
an oak block which had a band saw cut which
was curved, I could then hammer the scraper
down in to it and tap it to scrape square and
use on the shooting board, it left it a bit rough,
but got the general shape

8 and 9 is a block with 120 grit ironed on with
white glue ,this on the shooting board saved
the day, I used it to fine tune the shape then
held the brace on the sound board with 120 in
between [ I have some pics of that coming ]
after that the brace had a bit of a curve, the
edge not being square ,it was rolling left to right
but was a good fit down the length, this block
squared it up.

cheers Rob

1 and 2 shows the brace coming down to the sound board shape,the go bar held the sound board down ,my left hand held the brace at the far peak where it tapers off at 55 mm in , my right hand held it at the close peak and I jiggled it back and forth about 20 mm, I was getting it wrong at first holding the brace in the middle but found it flexed and was wrong, then it was back to the shooting board with the 120 on the block. I ended doing this to all the braces, the two X braces were the hardest though . I think I am learning here why there is such a thing as a flat top guitar

3 4 and 5 glueing in place with the hide glue

6 the end of the day, to pick up and tap it rings more than the back does,sort of like knocking a dinner plate without as much sustain

one interesting thing is when I got home and looked at the pictures, the upper transverse graft or the thin brace furthest to the right in pic 6 looked longer on one end, the upper end in pic 6 ,I had transfered the plan direct to my sounboard with pin pricks through the plan,I checked the plan and it's longer to that side by 5mm ,I thought this must be wrong so trimmed it back. shaped and finished the braces, will post later, am going to glue in the bridge patch tomorrow

cheers Rob

1 shaping the braces

2 and 3 left them at that ,basicly did them same looking as plan plus old Martin tops seen at frets .com , tapped as I was going,did I hear any changes ? well the sound seemed to get lighter and a little higher I think it's interesting comparing visually to that old Ibanez top ,the braces in that top are about the same height as the low point on my x braces so this top seems to look a lot stronger, any one got any theory's on this please throw them in

4 london plane tree bridge plate sitting on some maple, it seemed same hardness when I did a dent test on both ,they both seem to ring the same when tapped and I had perfect quarter sawn plane tree

5 this could be a mistake ,I glued the bridge plate down to the curve of the top across the span of the plate ,it was probably pressed down .5 mm so will mean my bridge will need same curve,should it have been a flat caul ? the book says the bridge should be shaped to match a curve that should be there but did not say wether cauls should be flat or not ,unless i missed it.
the masonite caul had 2 minutes in the micro wave and came out smoking

6 and 7 sides sitting loose on top and I did the halving joint with cloth like in the old pictures I have been looking at.

That's some really nice work, really enjoying watching your progress. Keep the pics coming.Mike

Originally Posted by auscab

5 this could be a mistake ,I glued the bridge plate down to the curve of the top across the span of the plate ,it was probably pressed down .5 mm so will mean my bridge will need same curve,should it have been a flat caul ? the book says the bridge should be shaped to match a curve that should be there but did not say wether cauls should be flat or not ,unless i missed it.
the masonite caul had 2 minutes in the micro wave and came out smoking

I make my cauls out of MDF and face the working side with cork. The cork moulds to the slight curve of the top.

Originally Posted by kiwigeo

The cork moulds to the slight curve of the top.

Thanks Mike , and thanks Martin , so the slight curve is ok, when I pressed mine in, the top was in the dish in the go bar press so the bridge plate has taken the same shape as the top,I started to wonder if it was supposed to be pressed flat while the plate was being glued in to hold the bridge area slightly more straight.

Decided to get rid of the bolt on neck idea and go the dove tail neck join , problem was one the wood I needed had been sitting in the outside timber rack so I machined it down close and let it sit in the humidity cabinet for three weeks,when I went to take out the old one the good old trick of glueing the job down with newspaper in between for easy separation failed, so I cleaned it up and added a bit of chipboard in between,with no paper , that worked.

picture 3 is the jig I am going to use to glue down the top and back on , I didn't like the Idea of fixing blocks all around the inside of the mould, I kept the off cuts from making the mould, which I have been using inside the mould to hold the sides up to work on, they are now glued to a board and the mould will be clamped down to that board,the ply cut out will be screwed down and wedges will help out, basicly Kinkade method exept his does not have the middle cut out, he routs 8mm down to three exept for the rim, I hate routing ply or chip board unless I have to , will give this a test run to see if it works, I cut it three times from wide to smaller till the flex felt right to conform to the back curve

Thought I'd show a bit of wood , We got the job to build a round 1550 diameter walnut table ,the top will come out of three 7 foot slabs I bought three years back,and they have been sitting in the workshop waiting for the right person to want them,three weeks back it happened ,the design settled on ,the boards went to the machine room, they are approximately 60mm thick and from the yellow to yellow on the middle slab is about 620mm . the great bit was that circled in red was a curly bit not needed in the top,and I just had a new blade on the big band saw and had given it a bit of a service,I got eight of these backs and eough for eight sides out of off cuts they will be put away for later builds when I know a bit more about what I'm doing ,but I'm dreaming of a pair of 00 size ,slotted head maybe 12 fret to the body ,one with a red spruce top and the other ? sweet little things ,

last pic is the new twin drum sander, just been lifted off the trolley

cheers Rob

That lumber is going to make some beatiful guitars. Let me know how the drum sander works, I'd sure like to get one eventually. Don't know where I'd put it if I ever get the funds to purchase one, cross that bridge when I come to it. I'm going to start a new thread and show the results of the acoustic I designed. I was going to patent it but decided not to. Building the guitar was very time consuming and expensive, getting a patent is even more so. I'm just going to put it out there and let anybody that wants to, use it. Mike

Originally Posted by auscab

picture 3 is the jig I am going to use to glue down the top and back on , I didn't like the Idea of fixing blocks all around the inside of the mould, I kept the off cuts from making the mould, which I have been using inside the mould to hold the sides up to work on, they are now glued to a board and the mould will be clamped down to that board,the ply cut out will be screwed down and wedges will help out, basicly Kinkade method exept his does not have the middle cut out, he routs 8mm down to three exept for the rim, I hate routing ply or chip board unless I have to , will give this a test run to see if it works, I cut it three times from wide to smaller till the flex felt right to conform to the back curve

Hi Rob,

I tried the Kincaid method for clamping down the top but didn't like it and ended up doing what you've done for clamping up the back.

You're making good progress there...most impressive.

Cheers Martin

Yeah Mike nice wood ,I went in Today and counted again , 8 bits = 4 backs and 4 sides, not 8 and 8 . I have used the sander on some Oak test bits and parts for two side tables in walnut, and a Kauri pine guitar top ,the front drum has 80 grit and the back 120 , it works well but you have to take it a little at a time , it got a bit hot with the Oak , loved the Walnut and Pine and cherry as well , I have it on wheels and it gets tucked away under some shelves when not in use.
Saw you post , I bet it was a lot of work, good on you for what you have made though, wish I could strum it.

Its getting close to the glue up Martin,got the clamp sorted Today for both sides , I wanted to have the top glued on Today but had to many interuptions and then I had to leave early.
It seems to work well ,follows the curve of the back ,and with the right pressure from the screws the whole thing pulls down and twists a bit to the right angle