I keep saying that I should have a blog, or keep better build logs of things; so why not do it here?
I’ve been learning to play the Ukulele. I’m not good but I enjoy it. I wanted to learn a bit more about the instrument and just kept going until I committed to making my own.
I drew it up in Fusion 360
http://imgur.com/iux9Ieo
Then cut one on the laser cutter and made sure my measurements were right (they weren’t, so I fixed it and cut again)
http://imgur.com/pPxc6N8
http://imgur.com/UsSO7FJ
Gluing the jig parts together
http://imgur.com/rdDDl1L
http://imgur.com/w89R0Rd
http://imgur.com/TjidAeM
http://imgur.com/fyDpA5Z
http://imgur.com/rQ33XU6
http://imgur.com/rk5nwhU
Yessssss
Are there guidelines on shapes that are good, or are you just aiming for aesthetically pleasing?
This is a good reference for the frequency discussion.
Though there are a lot of free-form ukuleles; the most important length is the Scale Length
Was wondering if you knew if ukuleles could also be made from acrylic, but I figured I should Google first…
The answer is yes!
Today I bought a nice board of White Oak from Windsor Plywood.
I knew I needed to make some cuts that would require a fair bit of stability. When I was a kid, my dad would use lots of feather boards and other jigs he would make to make good cuts.
So I started off the day by making a couple feather boards.
The first one I made was from a cross cut piece, so it ended up not having much strength before a piece cracked off; but it was still useful, the second was from a more suitable piece of scrap. This proved to be quite valuable to the cuts I was about to make.
I made successive cuts, one cross-cut to get a piece down to working length, one to get a nice clean edge to go against the guard (the small offcut piece from that will later be used for structural ribs).
The remaining piece I ripped down into the depth of the ukulele ( 2 5/8").
I then set up another vertical rip half-way through that piece at a width of ~4mm, flipped the board and did the other half. I didn’t get a great cut, but it was passable. I cleaned it up on the benchtop belt sander and got the saw marks out of the board. It is now approximately 2.5-3mm thick after sanding.
The consistency isn’t great, but I’m going to use this as a bending prototype. If this goes well I’ll make the 5mm rough cuts (or even 6mm) and rent a thickness planer from the VTL and clean them all up in one go.
Here you can see the piece I’ve cleaned up on the sander and will be my first steaming test. I’ll probably either hand-plane it a bit to thin it out, or sand it some more; as it is slightly too thick/
http://imgur.com/GZUpTBq
http://imgur.com/7nuzaya
I also sanded some high spots out of the jig caused by some slight misalignment in the layers:
And finally, today I picked up a tea kettle that should prove to be a good steam source for the ammo box (ammo box not pictured).
I need to figure out a way to attach a hose attachment to the top of the kettle, and one on the other side of the hose to attach to the ammo box.
Next Step… a test bend.
Forgot to document my failures, so I’m writing them down here.
I think it is important to also write down what didn’t work.
(if there’s someone out there that knows how to do this properly, I’d welcome advice). I had done a fair bit of research online to see how to do this specific cut on the bandsaw but clearly, I’m missing something.You might be running into physics if you’re trying to do a very deep cut on a bandsaw.
I’m excited to see how this comes out!
This is called resawing. Aside from needing a powerful enough motor on the bandsaw, you need a wide blade with a small tooth count. A 1/2" wide blade or wider with 3 TPI (teeth per inch) would be best. Larger tooth counts cannot clear out the sawdust fast enough and will cause the blade to bind. Narrow blades don’t have deep enough gullets between the teeth. Also, do not use a fence. The blade tends to wander a bit during resawing so it is best to scribe a line along the top edge of the board and steer the board through the blade along the line.
If you put a dent in a board, don’t try to smooth it out by removing the wood around it. Instead, put a damp cloth over the dent and then apply a hot iron until the dent lifts. Denting the wood compresses the fibres. Steaming the compressed fibres will ‘reinflate’ them.[quote=“mike, post:8, topic:5052”]
I didn’t cut through the wood nearly fast enough; I got some burnt edges. It might be worth looking into purchasing a new sharp blade for the table saw for a cleaner cut and I should have smoother more consistent pressure when doing my cuts.
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Burning along the cut is likely a result of a couple of different things: dull blade and too many teeth per inch. Cheap blades from home centres are dull out of the blister pack. Get a good blade from Lee Valley or KMS Tools or have one made up at Quality Saw and Knife. If you have sharp blade with a low tooth count then a slow feed rate won’t likely burn the cut. A faster feed rate may cause the blade to bow and/or or wander in the cut.
Resawing is tricky and requires a well tuned bandsaw, sharp blade, and proper blade tensioning.
Oops! Didn’t read your part about burning on the cut well enough. Thought you were talking about the resaw cut on the bandsaw. My bad.
You’re right - burning on a tablesaw cut is the direct result of a dull blade and/or slow feed rate. A sharp blade will make all the difference in the world. Burning can also be caused by the fence not being perfectly parallel to the saw blade, not to mention increasing the danger of a kickback.
Thanks all for the suggestions and encouragement.
Today’s effort was on the first steps of the steamer box. I discussed with @TyIsI what the best locations to put my ingress and egress steam points (ideal including storage of the box). We decided that the output valve for escaping air should be on the lid, while the ingress should be high on the back of the side.
I made marker points and drilled them out for both sections with a small bit then went full sized.
I’m using a hose spigot so I can adjust how open I want the valve to be:
http://imgur.com/eAriuJ6
Here is the full temp setup (with VERY temporary connections on the kettle)
One problem I have is there seems to be a leak in the kettle that triggers a short; it appears to be moisture dripping down to the base, we think it might be the level indicator, so my next attempt will be to block it up tight and try again.
Note that some electric kettles seem to use air pressure to judge when the water is boiling, in order to automatically turn the heating element off. Unless the short you mentioned is actually tripping a breaker, this might be the problem you’re having.
Also, your current setup is giving the hot air a long distance to cool off and condense. I’d try to keep the kettle on as short a hose as possible.
The tea kettle has a steam temperature sensor to detect the boiling water and shut off the element. It’s also probably not designed to operate for extended periods of time.
I have a water heater element from a dishwasher, 1200W at 120VAC. It also has an integrated temperature probe. It’s similar to this one:
It requires a rectangular opening with rounded corners. You could make a steam source from a baking pan and the heater.
I’m also thinking that the metal of the ammo box may dissipate the heat too quickly and condense your steam. At the very least you may need to add insulation to the outside of the metal box.
I helped my friend build a boat, he built a steam box out of wood for that reason ( less heat conduction ). both ends were open with a plastic flap. We pushed the pieces in from the cold side, and took them out the other end which was the hot side (steam inlet). For a steam source he used a large kettle and an electric hot plate.
I ‘bypassed’ the shutoff switch with gravity (read, I put a thing on the lever to prevent it from popping up).
I was indeed tripping the breaker on the surge bar. This is exactly the sort of position I didn’t want to be in.
On the plus side, I found a garment steamer on craigslist for $20!
I tried it out; it produces steam well enough (at least as well as the tea kettle) and it has a water intake spot so it’ll be easier to fill up as it goes.
I opened up the head and this is what I found:
A nice rubber hose that I can make use of with one of those crimper rings… Yay! This should be easy to attach!
Yes, I think you are right; I’ll need to find some insulation. I’m already over-budget on this build so if I can find something that would insulate nicely on the cheap/free I’ll try to incorporate it.
You might be able to get away with cheap yoga mats, which you could even double up depending on how much you’d want to spend. I’d check CL and dollar stores for this. The other option is to make sure that your “throughput” is high enough to warm the entire ammo box.
This stuff is about $9 for a large sheet. Not sure if that fits in your budget.
That looks pretty good; I can probably spend that; but I’ll steam it up first and see if it is genuinely required; no reason to prematurely optimize.
I tried the steamer out last night and it actually did quite well at producing steam; I get about 2-3 minutes of constant steam, then about 30 seconds of off-time and then another 2-3 minutes. (the element seems to cycle).
It is a 1500W unit; so that’s a fair bit of energy going into the system at a decent duty cycle. I should get a chance to try it out this week; I’ll post results.
PS Anyone (space included) have a logging thermometer that I could drop in there for real metrics?
I had a quick look around for data logging multimeters… The name brand ones are >$500 but AliExpress to the rescue!
Cheapest ‘off the shelf’ way to do this (assuming you have a spare PC/Pi/etc.) that I am aware of is the Digitek DT-4000ZC multimeter. Comes with the USB cable and TC for about $50. The only problem for long-term datalogging is battery life, but easy enough to run it off a 5V power supply (for temperature monitoring, even the USB port) if you need to. It’s supported by sigrok and I think UltraDMM.