dcal
Sore Fingers
Posts: 7 
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Post by dcal on Oct 23, 2018 23:44:24 GMT
Thanks for the tips Colin and Francis.
My sides were cut to a template before they were bent and fitted reasonably well in the mold.
I thought they were fairly close but they still seemed to take an age to sand, the sandpaper was probably past it's best but even so! Should there be a individual template for the sides of each guitar shape? Should I make a former and bending jig for the next build?
Colin,
How do you make a true template? And how / when do you mark it out on to the sides? Before or after bending?
Also how do you sand the end blocks to the "correct profile"? Do you sand them on their own on the radius dish? Is that not difficult to get right (especially for a novice) and easy to sand them too thin or at an angle?
Francis, I think I understand how you are marking out the side, but why have you such a big off set from the radius dish?
Are you making a thin bodied guitar and have plenty of material to remove? or is this just to explain the process?
On marking the line with the pencil as shown in the photo, can you please clarify (to help me get my head around it) should the line be offset from the radius dish exactly at the point where the side and the dish touch?
Can you get an error by running the pencil and block further in towards the center of the radius dish (minor I'm sure and taken out by the sanding, but I'm sure I could substantially increase the error) or have I completely misunderstood?
Apologies for the (very possibly) stupid questions, but I am really keen to learn
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 24, 2018 9:03:31 GMT
Here's a tutorial on template making I posted on another forum back in 2006. You'll need to do this for each body shape you make. www.luthiersforum.com/forum/viewtopic.php?f=10102&t=8117%22I profile the back edge of the sides before bending, remember that the back tapers from tail to head, this is where it's important to have the ends of the template square to the top edge. I leave the top square as this aids me in getting the side properly positioned in the bending jig. After bending I tape the paper template to the side and mark the top profile then with the sides in the mould plane to the mark. I know the height of the blocks, I use 'C' head block, so when putting the three pieces together I build the angle needed onto the block and refine it by sanding in the radius dishes, holding the face that will be glued onto the sides against the face of the mould, this guarantees the correct angle. The first sanding of the sides in the dish takes place after the head and tail blocks are glued on, and yes the sides are in the mould. For each guitar shape you make you'll need to make a new bending jig, outside mould and yes a new laminated linings jig I'm afraid all of this stuff takes time. Have a look at these build threads: acousticsoundboard.co.uk/thread/9234/hb9-prize-guitar-build-threadacousticsoundboard.co.uk/thread/5966/euro-spruce-madagasgan-rosewood-twistColin |
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francis
C.O.G. 
Posts: 2,483
My main instrument is: Whatever I'm building...
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Post by francis on Oct 24, 2018 9:58:14 GMT
dcal  What I do  Having bent the sides (I do not pre shape my sides  ) and placed them in the mould/former. I place them (sides/former assembly) on my radius dish. I use 20 foot radius for fronts and 15 foot for backs. For the top/soundboard: I set a pencil gauge height to match the largest gap between the sides and the radius dish, place a few thin wedges between the sides and the radius dish to prevent rocking and draw a line around the inside of the sides with my pencil gauge. I then either plane down to that line or leave till later. For the back: I first mark the heights of the neck and tail blocks on the inside of the sides from the earlier pencil mark for the top/soundboard or the edge if I've planed to profile at their respective positions. Then I use two pairs of opposing wedges at the neck and tail positions to raise/lower the tail/neck block marks until they are equal heights above the radius dish. I set my pencil gauge to this height and draw around the sides off the radius dish. In this way you trace the side profiles from the radius dish to the sides. Plane down to the pencil line(s) before a final sanding on the radius dish... In the earlier photo the side timbers were much wider than the required design depth needed so it just appears heavily offset. Remember I mark the top edge first and usually profile that before profiling the back edge. Hope that helps
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dcal
Sore Fingers
Posts: 7
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Post by dcal on Oct 25, 2018 0:11:36 GMT
Thanks Colin and Francis,
Really appreciate the time you have given to help me and others, not to mention sharing your ideas and IP. The explanations and links have really helped me to understand some of your processes.
Brilliant work on your builds, I can but dream I will ever get to that standard.
It would have made sense for me to have asked these questions while I was doing my build but there is always the next one and I will certainly be using your ideas (and hopefully lots of others ideas from here) when I do start it.
For my next build I intend to do as much as I can at home, but I also need to try and get a grip on the amount of tools I will need to buy / make / borrow and need to decide if it's worth it for maybe one build.
I have already go a fair few wood working tools but will be sure to require others. I, like most on here I'm sure, have a real problem with tools and have more than any sensible person should (or so my wife says)
Few more pics of my build. I cut and installed the stiffeners for the sides and installed them between the linings. Sorry for never using the right terminology.
Also marked up and cut the slots in the sides to let in the ends of the bracing.
I tried to keep these slots shallow because, for better or worse, I wanted to keep the bindings very simple and small.
I decided to keep the routed slot for the purflings to 5mm so needed to be sure the slots were less the that.
Getting ready to close the box.
You might notice the slots I had to "repair" in the back of the neck block (I had cut them for the soundboard bracing!) The sooner I get the front and back glued on the sooner I'll stop mixing up the front and the back.
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) and placed them in the mould/former. I place them (sides/former assembly) on my radius dish. I use 20 foot radius for fronts and 15 foot for backs.
Jo whoever he is.
