Guild D40 Restore

[TEETERFAN]

I have used it about an inch thick, no problem. That’s covering an object. Casting larger objects, like a human face requires an outer layer of plaster to eliminate the alginate’s flexibility. Casting an internal shape should not require this. You may have to experiment with leaving a bit of a hollow area at the center so you can move the sides of the cast away from the wood, during removal. Overall, should work great.

[Diane Kauffmds]

Thanks Kevin.

[Diane Kauffmds]

I know what I'm going to do to make the casting.

I'm going to use resin, with a black pigment added. I'll explain that in a bit.

After leaving and straightening the cut, I'll line the cavity with tape, spray the cavity with cooking spray, then line it with cling wrap. I'll spray the cling wrap too. I'll heat the resin to kick start the exothermic reaction. When this starts, resin sets up fast. I'll pour it when it's thickening and can be molded. I'll stick 2 roofing nails in it, head first, so I have a way to pull it put.

I'll photograph it against a white background. That will make it easy to convert in the CNC program to a useful shape that I can cut on the CNC.

[TEETERFAN]

Ah ha! I was wondering if you were going to leverage your CNC abilities. The black resin sounds like the best choice. Alginate is pretty light, kinda flesh colored. Good luck!

[Diane Kauffmds]

Starting the Guild D-40 restoration.

The guitar is in the bench vise. I've lined the cavity with several layers of tape, and I've made a dam to keep the resin in place. You'll see a couple of pieces of wood cutoffs, which are there to strengthen the tape dam. I've sprayed the cavity with "dry" lube. But, WF40 Dry lube is very wet until it evaporates. I'll use baking spray, which is a combo of oil/flour. Between the tape and the sprays, the resin casting should come out fairly easily.

I had initially wanted to level the cuts, but upon inspection again, I think doing so will further weaken the sides. So, I'm going with what is already cut.

The 2 Part resin is mixed in a 1:1 ratio, by volume. I don't know how much I'll need, so I'm mixing 80mL. I've colored it opaque black. You'll see it sitting on a mat.

I found this mat on Amazon. Its a mat used to warm reptile enclosures. It's a nonstick 14w mat, this particular one is marketed for resin. It's temp adjustable, and came with a silicone protection mat, timer for 2, 4, or 12 hours, and a thermal lined cover to retain heat.

I made an adjustable table out of 3/8" plywood, inserts, and finger adjustable screws, so it's easily leveled. I taped the mat to the table with aluminum tape, used in HVAC, which can take heat.

The resin sets up by chemical exothermic reaction. It gets very hot as it sets up. The mat Kickstarts the reaction, and if I leave a mold on the table, will have it fully hardened in 2 hours, instead of 24+ hours. I'm using it to Kickstart the reaction. Once the reaction starts, the resin will harden very quickly. I'm stirring often. As soon as I feel it heating, I'll get it into the cavity quickly.

If anyone is interested in which mat I bought, I've put a link to it on below. I've had it for more than a year, and it's fantastic for resin. It's $25.

Epoxy Resin Heating Mat, Resin Curing Machine with Cover Timer, Quick Dry Tool Set Heater Coaster for Silicone Molds

https://a.co/d/6zWmpqC

[TEETERFAN]

Well, the patient seems well prepped for the procedure. This is really interesting, thanks for taking the time to document your process.

[Diane Kauffmds]

I've taking the casting out. It came out pretty easily, and with nothing on the guitar wood.

I realized that it has to go into a CAD program to be either converted or redrawn into a 3D format for Vectric. I have no idea how to do this, so for Today, I'm going to just get that dovetail shape to cut into a piece of mahogany, on the CNC, then shape it to the model by hand.

[Diane Kauffmds]

I've digitalized the deck mI"ⁿ and saved it as a .dxl file. I'll use a CAD program to make a 3D model, so VCarve can cut it out on the CNC

[Diane Kauffmds]

By George, I did it! I managed to make a 3D model of the dovetail mood, and get it into VCarve Desktop. As you can see, it's got the shape of the dovetail precisely. I will have to chisel the dovetail angles by hand. I thought it more important to get the shape of the dovetail itself than the angle. This took me a couple of days, after restarting more than I can count.

I could have made the top rectangle then the dovetail separately, then used epoxy to glue them, but I really want an integrated component. I'll machine it and see what happens. I can always cut them separately, capturing the dovetail angle if needed.

[TEETERFAN]

Mighty clever!