Anyway I managed to do some more things:
- Bend the side back to shape to eliminate any spring back
- Shaving of braces to 7mm wide and 3mm tall (Torres fan)
- Plane the topboard to between 2 to 3 mm thick
Side Bending
I use the Aluminium pipe coupled with the heat gun to bend the sides.
To bend the side the heat gun have to set to about 75% full power which is quite hot.
Without a thermometer I can't really tell how hot it is, but I guess its quite hot but not as hot as stove. (Because I bend w/o wearing any glove)
Now as a safety precaution, you should always use a glove to bend.
The hardest part of the bend, was the waist.
I let the gun blow hot air onto the waist to heat it up.
Then I slowly press onto the heat pipe and rock the sides around the heat pipe.
No spraying of water was used as I found it to be unnecessary.
Well I nearly crack the piece, but luckily stop in time to prevent the cracking.
After a few rounds, the waist conforms to the acrylic template which I take as reference.
Then I bend the lower bout to reduce the spring back and then the upper bout.
It was fun; I have never felt more satisfied with myself.
Here is the side after the bend.
There is virtually no spring back, only slightly open at the both ends.
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Compare with the previous picture, the spring back was pretty bad.
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Bracing
For the bracing, after so many rounds of consideration, I decided on the Torres fan bracing pattern.
The braces are 7mm wide by 3mm and so I began to shave down the braces to size.
I never regretted acquiring the Stanley block planes.
It really makes the whole planing process a joy.
Top
Finally, I manage to thin down the top.
When it came it was abt 3.x mm thick.
I dont have a thickness dial gauge so I cant tell you the exact thickness.
The only measurement was at the edge using a veneer caliper.
After planing I measured the edge was about 2mm. The center which I leave it slight thicker should be between 2 to 3 mm.
Adjusting the stanley block plane was fairly easy.
Using the block plane, I managed to thin out the top board and smoothen it using a scraper.
Here is the braces and the top after the work.
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What's next
I think the whole thing is ready for some bracing action.
All I need next, is either one of the 3:
- Get some weights
- Building cam clamp
- Building a screw system
- Building a go-bar deck
Weights
The easiest of them all and requires no building.
However to get dense weight w/o occupying a large area is quite hard to find.
I tried several stationary shops around they don't seem to carry any paper weights...
Cam Clamp
Previously, I had bought some Aluminium bar from the Kelantan Lane.
They were meant for building cam clamps.
However, building cam clamps is a tedious process and I need to source for the wood.
I think I will leave at it for the moment.
Screw System
I was thinking of getting a metal bar across the top board and use a screw and bolt to press down on the brace while gluing.
This is a pretty fast method of building but involves some careful design consideration
I need to acquire alot of screws which may add up quite a bit of cost.
Also it need some making for the screw to attach to the bar and press against the braces.
Go-bar Deck
Finally, the proven go-bar deck system.
I will be acquiring some plywood from a local supplier Chiang Leng Hup Plywood
for about SGD20 a piece for a 2m x 1m x 1cm plywood.
If you are interested you can contact them for the quotes.
The staff are very friendly to deal with.
For the go-bar deck, I just need to do the following:
- Saw the plywood into 2 2 foot square (60cm).
- For the rest of the wood, it will be used as "braces" to support the plywood.
The stress on the plywood is quite great, enough to bend the whole board.
- Drill 4 holes at the edge for the metal support.
- Saw 2 screw rods into halves (which I have acquired previously) (1m each)
I need four of them; 1 for each corner
- Reinforce the board with the struts (glue or nail or screw)
- Assemble the deck accordingly.
For the go-bar itself, I will be sawing some bamboo pole in length excess of the deck height.
Once the deck is up it's easy to add new go-bars, which is the main reason why I will opting for this method of clamping.
Now to acquire the plywood 1st.
Bridge blank
I bought some padauk bridge turning wood for making the bridge, which is an African hardwood.
The turning square is enough to make 3 bridges.
(See the LMI bridge blank compare to the turning square)
According to many makers, paduak is a lighter material compare to rosewood.
The famous Australian maker Greg Smallman is also using paduak bridges to reduce the weight on the top.
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1 comment:
hallo
I'm Indonesian luthier
http://kayyuguitar.blogspot.com
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