Jam's Gone Mad.

[Akula]

Hey all,

 

Starting a new build. Quite a departure from anything I've done before, and sanity to boot. It'll mix up some techniques and add some new materials to the mix.

 

I've ordered a big sheet of clear acrylic, enough maple for a one-piece neck-through, some mirrored plastic, and some Barbie dolls.

 

My wife dared me to do it. I swear.

 

 - Jam

[henrim]

14 minutes ago, Akula said:

some Barbie dolls

Yeah, can’t go wrong!

[Bizman62]

Yikes! That's going to be something amazingly insane!

[Akula]

It's going to be different, that's for sure! 

 

Picked up my slab of Maple today. Its over 100mm wide - it has to be, so that the "wings" have something to bite into. 

 

Anyone used Weldon glue before? My experiments with gluing bits of acrylic together with epoxy were quite underwhelming, and my joins are really structural. Looks like acrylic cement properly melts the two parts together. Reminds me of making Airfix models when I was a kid.

 

School's out for summer. Hoping to spend the vast majority of next week out in the shop making sawdust... And acrylic chips.

And dead barbies.

 

 - Jam

[henrim]

I’m not familiar with Weldon. The stuff I use is called Acrifix. Melts acrylic and creates a seamless joint.

https://www.plexiglas.de/en/products/acrifix

[henrim]

45 minutes ago, Akula said:

Reminds me of making Airfix models when I was a kid.

Seems like Weldon has a similar product as Acrifix. Same principle as with gluing scale models. Although scale models are polystyrene and the solvent is different.

[Akula]

Sweet. I just ordered some Weldon - every google search from Australia for Acrifix turned out results for Weldon. 

Does it stick to MDF? I'm hoping not... I'll be gluing my pieces and clamping them inside a mould. Almost like an acoustic guitar mould, but that comparison to my project is utterly blasphemous!

 - Jam

[henrim]

19 minutes ago, Akula said:

Sweet. I just ordered some Weldon - every google search from Australia for Acrifix turned out results for Weldon. 

Likewise, if I search Weldon the results show Acrifix

21 minutes ago, Akula said:

Does it stick to MDF?

Good question. I don’t think it’s a good glue for MDF, but as the acrylic cures it will stick to anything it can hook into. Probably a protective layer of something would help. I say “something” because I don’t really know what would be the best option. Bees wax or some other wax maybe? You have to test. Or quite likely that information exists already somewhere.

[Bizman62]

2 hours ago, Akula said:

Does it stick to MDF? I'm hoping not...

MDF is porous so most likely it will.

My first thought was to suggest using tape to prevent sticking but then I realized that tape is made of plastic film and the glue is intended to melt plastic. No wonder it's sold in metal packages! I wonder what sort of plastic the caps are made of, though. Finding that as tape might work. Then again, metal tapes are widely available in various widths and aluminium tape isn't too expensive.

Wax might work as well but it depends on the solvents used and the time of exposure i.e. will the solvent penetrate the wax layer before evaporating. Waxes can be dissolved at least into alcohol and turpentine, never thought about stronger stuff with them but a quick search reveals that many other solvents can be used to remove wax.

[henrim]

Ok. Couldn’t resist. Have to wait till they are cured, but here’s a couple of test pieces with Acrifix.

1. mdf glued to mdf.

2. acrylic glued to mdf, factory surface 

3. acrylic glued to mdf, sawn edge

4. acrylic to paraffin 

5. acrylic to beeswax 

I’ll report back.

[henrim]

Ok, I cured them with the help of an UV light source. 

Mdf to mdf joints obviously doesn’t get the needed UV light so they may not have been fully cured. But they were dry. No real bond there, as expected.

Mdf to acrylic sticks to some degree. The joints still come loose without much force but the surface of mdf may stick to acrylic.

Beeswax seem to stick to acrylic to some degree. Still easily removable but affects the surface.

Paraffin. Lifts easily from paraffin treated mdf. And paraffin doesn’t stick to acrylic. 

So, based on this highly unscientific test, I would do a test piece resembling the real mold and treat it with paraffin.

[Akula]

Dude! Thank you so much, that's really helpful. Yep, I'll hit the mold with paraffin and do a few test runs first. The experimental nature of this one keeps my brain on it's toes, that's for sure.

 

But while I'm waiting for the less traditional materials to arrive, I have the standard jobs to perform on this maple neck. Here's marking out.

 

 - Jam

[avengers63]

You sound a lot like me. 

A random, likely bad , certainly bizarre ides wandered into your head.

It's so "out there" that you are now you are obligated to make it into reality.

[Akula]

13 hours ago, avengers63 said:

It's so "out there" that you are now you are obligated to make it into reality.

Haha! Yep. This build is like an inappropriate joke that pops into your head during a sincere moment, the kind of line that you shouldn't say out loud, but you just gotta do it!

 

I turned the maple into something more resembling the core of a guitar. I won't elaborate too much, as the processes here aren't much new. One thing that was a little sketchy - because of the width of the "body", I had to cut the profile of the neck right through about 100mm of hard maple, on a 10" bandsaw! That was slow.

 

Managed to get one more slice of Ironbark off my billet, so that became the fretboard. 

 

 - Jam

[Crusader]

If its worth mentioning, to me Weldon is just like SuperGlue but thicker and not quite as strong

I had some but it got punctured somehow and I was left with a hollow blue tube

[Akula]

On 12/21/2023 at 12:02 PM, Crusader said:

If its worth mentioning, to me Weldon is just like SuperGlue but thicker and not quite as strong

I had some but it got punctured somehow and I was left with a hollow blue tube

Copy that! I'll take care of the tube. Yeah I'm interested to see just how strong it is - allegedly it softens the two plastics and "welds" them together, hence the name, but the surface area is something of concern.

It's a hard one, because essentially the glue joint will be akin to gluing the sides and top of an acoustic guitar but without the kerfing, and with acrylic sheet instead of wood. I'd love to reinforce the butt joint with some mechanical aid such as tiny machine screws, but that'll clash with the aesthetic of the design. 

It's all one big experiment.

 

Fretboard radiused, frets installed and dressed, neck carved, volute and heel carved, nut installed, bridge recessed and string through holes drilled. I could put strings on it right now and play it. I've made a very pointy stick!

 

I forgot to order string ferrules, and in this season it'll take ages to get them delivered. So I improvised - aluminium tubing hammered through the depth of the body then routed at a recess on the back. The tubes sit against the underside of the bridge, so they're not moving under tension. If anyone asks, I'll tell them it's the latest in groundbreaking tone-transfer technology.... or something like that.

 

 - Jam

[Bizman62]

2 hours ago, Akula said:

I'd love to reinforce the butt joint

How about a full length dovetail groove, guess rather in the wood as a wooden slat inside the plastic might swell and crack the plastic.

[Akula]

4 minutes ago, Bizman62 said:

How about a full length dovetail groove, guess rather in the wood as a wooden slat inside the plastic might swell and crack the plastic.

Oh yes, to join the acrylic to the timber core I'm using a dado - the wings will extend into a groove in the neck. That will be glued with epoxy, and I think it will come out rather strong.

What concerns me is the joint between the all-acrylic sides, top, and back of the wings. That is a 90' butt joint with a surface area of 4mm in cross section. On the plus side, that cross section measures 700mm long in the length of the "sides", and the wings are a triangular shape which should add some geometric strength and resist twisting and popping open the glue joints 

 

Again, all an experiment. I'll let ya know how I go!

 

 - Jam

[Akula]

Had a right proper day in the shed.

 

Proper planning is key, especially when embarking into the unknown. These plans might even throw a little light upon the bigger picture here. 

 

Transferred the desired shape onto MDF and started making my mould. 

 

I cut one shape and transferred it onto six layers with the router. I banned MDF from my workshop some time ago, and will only bring it in when plywood just won't do. The mask will help my lungs, but this fluffy dust makes me all itchy. Horrible stuff. And the bandsaw hates it.

 

Next up, I cut the four pieces of acrylic for the tops and backs of the wings. Being that the mould will dictate the shape of the sides, I used it as a negative template. I cut all this acrylic on the bandsaw - poor machine has had the worst materials today. I'm going to have to buy my bandsaw a drink.

 

Used a fence on the bandsaw (poor machine) to cut strips of acrylic at exactly 32mm wide for the sides. I clamped them together and sanded the blade marks out, and measured them to be straight and true at the right width. Any deviations could introduce gaps when gluing up.

 

Bending! Okay, this is kind of like bending sides for an acoustic guitar, except that it's a damned sight easier. Acrylic is a homogenous material and doesn't crack or split, but it can warp and distort in planes other than the desired ones. I used a hot-air gun, affectionately known as "The Hag".

 

This here is just a test piece. See how the curve pulls the plastic into a concave shape? The mould helps with this, but doesn't alleviate it completely. More of note is the corresponding "bump" in the top and bottom faces, which will create gaps when gluing up with the top and back. Easily solved with sanding on a flat surface, though.

Pr

 

I did a few tests, then got down to bending the actual sides. Seen here is my clamping system - one pulls the interior of the mould towards the tip of the wing, and another holds it true against the long edge. To avoid any spring-back on the workpiece, I left it in there for long enough to cool down to room temperature.

 

Here we go - I've successfully made two triangular boxes. 

 

Quick mock-up. The rear end of the maple isn't shaped to it's final dimensions yet - I realised I would have to do that after installing the wings so as to get the correct angle following through from the acrylic wings into the maple.

 

One last job for the day was cutting a chamfer into the sides so that they marry neatly to the core.

 

Anyways, my shed is covered in acrylic shavings and MDF-fluff. Can I just move house and start another workshop?

 

 - Jam

[Bizman62]

Ahh, didn't realize until now that it's going to be hollow! Now I guess I understand the gluing problem better.

Is there going to be a straight piece of acrylic against the wooden body?

 

[Akula]

2 hours ago, Bizman62 said:

Ahh, didn't realize until now that it's going to be hollow! Now I guess I understand the gluing problem better.

Is there going to be a straight piece of acrylic against the wooden body?

 

There's two problems with solid acrylic guitars - they sound like crap, because acrylic doesn't resonate very well, and they're heavy as hell! Making a hollow one with a timber core cancels both of those issues.... I hope!

 

Nope, no acrylic against the jointed face of the body, I'm relying entirely on a routed groove to hold the wings into the body. 

 

 - Jam

[Bizman62]

1 hour ago, Akula said:

Nope, no acrylic against the jointed face of the body, I'm relying entirely on a routed groove to hold the wings into the body. 

Oh yes, I found the drawing that explains. Seems solid,

[avengers63]

 

I'd not have considered the clamping notch on the inside piece of the mold. Rather obvious in hindsight.

[Akula]

The whole expanse of maple will be stained black eventually, so I did the sides of the core now, so I wouldn't have to much around with masking off the insides of the hollow wings at a later time.

 

Then I glued the backs and sides of the wings to the core. 

 

So there's three kinds of glue going on here. There's epoxy resin, which glues the back acrylic into the dado grooves in the maple core. I roughed up the acrylic with sandpaper so the epoxy would have something to grab onto. Then there's the Weldon glue which attaches the sides to the back. Apparently this glue has a working time of 5-6 minutes, which is total bullshit - it sets within a few minutes, but for a good bond you really want the pieces in the right spots right away. Then I'm using CA glue to hold these locating pins in place.

All of these photos look really messy. It's a combination of glue squeeze-out, the black stain bleeding, and hideous end grain scratches. All of these points will be nullified or rectified.

 

A little more about those locating pins. Getting the wings in the right places for the sides to line up properly... nightmare. Half a mil at the front of the "wing" could result in miles apart at the tip of the "wing". So I drilled some holes through the maple and acrylic clamped in the right spot and put some little black screws to hold them in place. However, this looked a bit unclean, so for the final glue-up I removed the screws and replaced them with 2mm aluminium tube. A drop of CA over the top and they're solid, providing a good mechanical joint as well as a clean aesthetic. They'll look great when it's all stained black.

 

There's a bit of overhang where the back acrylic overshoots the sides, and especially noticeable at the heel end. Once the glue has cured I'll route to profile with a bearing. I'm anticipating a fair bit of sanding drum action as well.

 

Tomorrow I need to fill the empty wings with their secret material - and no I am not flooding it with epoxy - and then glue the tops to the wings to close the box. I can foresee issues with glue squeeze out and messiness, as I need to slide the wings into place in their grooves. Wiring is also a problem. After filling the wings with their secret objects, how will I get pickup wires to the electronics cavity underneath the pickguard, or output wiring to the output jack? I have an idea, but we'll see how it goes.

[Bizman62]

Ooh, secret objects! Can't wait!