Category: Instruments

Bender ender – how to listen up and quit breaking sh#t

Like a drunk tiptoeing into his AA meeting with actual quitting on his mind, I’m finally ready to quit breaking taps – and pay attention to all the solid advice I’ve been getting along the way.

Tonight, I took it all in hand and put it to work on my one surviving 6mm tapping tool – and the dozen-plus very serious holes I had left to tap:

  • The machinist recommended I countersink the holes and use cutting fluid … But I had a long way to go – the last 8 holes in the stringers for Keyboard 3, plus the remaining three very deep holes in Keyboard 1’s crosspiece – each of them through a thick, 3-layer sandwich of aluminum.



    I started with the drill …

    Straight down, through three layers of aluminum, half an inch thick each. Nice, clean, smooth holes. Thanks to the guys at Baller Hardware for assuring me that “any light oil ought to do it” after I realized the only actual tapping fluid they had comes in a huge industrial jug.

    I chose 2-stroke engine oil.Then, many thanks to Jeremy and others over at CrashSpace for the invaluable reminder of something I forgot since tapping engine heads more than 20 years ago: For every three or four turns of the tap as you cut the threads, you have to back the tap out a turn or three, to clear out the cuttings that might bind up its tip …


    I also followed my own instincts after comparing notes with Vinny, my oldest friend in the world and an inveterate shade-tree mechanic: “You know that point where you *know* you’re turning too hard, but you keep going, and then it snaps” – I tried to stop myself every time I felt the tap binding up to the ppoint where it might snap … and I backed the thing all the way out, cleaned off the metal cuttings, and resumed tapping …

    And lo and behold, every single hole was tapped cleanly and safely … and the tap survived.


    This let me proceed to building Keyboard 2 …

    … and Keyboard 3. We’ll be capping off the mounting screws with locknuts – and god knows what all else – very, very soon.

Go back, Jack. Do it again.

Keyboard 1 is more than 7 and 2 1/2 octaves long – running from A to high D#.

All that metal is pretty heavy, pharmacy and the weight actually bows the stringers that carry the keys across it, so I’m building in a crosspiece for support. It will run vertically between the top rail and bottom rail, and all four stringers will screw down to it for support.

I lay out the keys then I tighten the frame at the corners along the bottom …

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Wherein we get a little professional help, and joy is restored

All the geek opinion and doomsaying in the world can’t beat a crusty old Chicano machinist in a crusty old machine shop.

After Googling and dialing all over Hollywood, Los Feliz and Glendale in search of an EDM-equipped shop, I phoned a local machine shop and described my two mistakes.

“Ehhh, bring it in, we’ll see what we can do,” says the crusty old voice at S&K Precision Engineering Co.

So I bring it in. Within an hour and a half, I get a call saying “It’s all set.” They drilled in with a carbide bit (probably a better one than I used, and used an extractor on one broken tap, and a punch on the other – and now the holes are cleared.

The guy even took pity on me and told me the secret: countersink the holes from now on before tapping them – and use some cutting oil.

Done. I’ll be attacking that just as soon as the best little hardware store in Silver Lake restocks their 6mm Irwin thread taps. The ones that I seem to keep steadily depleting.

Low-rent metal-work in three easy steps

My plans for a productive evening of xylophone-building thus foiled, I turned to slapping together the rest of the frame-mounting hardware.

Unfortunately, the Hollaender company turned out a couple of SpeedRail parts with nasty burrs inside that kept them from sliding onto the 2-inch aluminum tubing that we’re using for xylophone frames.

I tried grinding out the lip on both sides of the mount …

But no luck. The collar still wouldn’t slide on over the tubing …

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Damn it. Again.

In machining – as in lovemaking and war – if it hurts, you’re not doing it right.


I seem to keep making the same damn mistake. alienrobot did a great job of tapping most of the mounting holes in Keyboard 1 using just the little 4-inch tap handle that came with the set.

Then I got all clever, applied excessive leverage and snapped a tap off in a hole by using too much leverage. It came out with a pair of pliers … but then I did it again.

And I just did it again tonight. Here’s what it looks like from the back.

Opinions on the CrashSpace forum ranged from “A high-end machine shop will need to use EDM to burn the tap out of there” to “Yep, you’re fully fucked.”

Guess I’ll go look up a machinist. And hope I’m not fully fucked.

Machinist’s woe: How the hell do I fix THIS?

So I was tapping a stringer on Keyboard 1 and the tap snapped off in the hole.

Below the surface. That’s hardened steel. Drilling it out so I could use a reverse-extractor was fruitless: I blunted, and finally snapped a cobalt bit, which the hardware store said was the hardest thing they sell.

Now WTF do I do? Anyone have any brilliant solutions? Please forward this to all the metalworkers you know.

Machining the superstructure for Keyboard 2

I’d like to think we’ve known how to build XyloVan from day one, but the truth is – we’re dumb. We’re like sack-of-hammers, short-bus, don’t-get-the-knock-knock-jokes dumb.

We’re like chimps who have seen television, digging around in the back of the live set with screwdrivers. We make dumb mistakes, do dumb things, suffer from dumb ideas. And along the way, stuff gets built.

So this 3-foot-long chunk of 1.5-inch by .5-inch aluminum is one of the four stringers for Keyboard 2. These serve as the airframe for the instrument …

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Keyboard 2 of 3 laid out (well, okay, it’s half a full keyboard, but …)

By now, it should be plain that there’s absolutely no linear flow to the XyloVan construction plan.

With Maker Faire bearing down on us in 7 weeks, we’re tackling tasks willy-nilly, like a crew of chimps with A.D.D. and a pound of meth – frenziedly, for long stretches, whether in teams or alone, whenever we’re able.

Tonight, I was alone, so I spent it cutting aluminum stringers to fit the frames and laying out Keyboard 2, which with Keyboard 3 will cover the passenger side of the van.

The full keyboard (about 2.5 octaves) would be seven or eight feet long, but we have to somehow accommodate the van’s sliding door …

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There, I fixed it – Part 1

So here’s the solution to the problem I discovered yesterday.

The problem was that the xylophone – if bolted to the van with the upper hinge of the frame just below the windows – would have scraped the ground.

Solution: Get a few more Speed-Rail parts and create a sort of offset cantilever hinge. Built right, it should pivot out and away from the van to playing position (about a 20-degree angle from the ground) when deployed, then fold up flat against the van when stowed for travel.

First, I have to modify one of the parts, a sort of T-joint that is too wide to fit between the anchors for the key stringers.

A little circular saw abuse – followed by much cursing and futzing and hollowing out the apparently mis-forged piece so that it actually *fits* over 1.5-inch pipe – and the piece now fits snugly between the stringer ends …

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Roughing out the frame for keyboard 1

Now that the keys are all cut, price we have to lay out the frame.

As I said, I don’t have strict engineering plans for this thing, I’m going by the seat of my pants. But I know what the materials will be, so I’ve laid out the frame – it’s 1-1/2-inch aluminum scaffold tubing, held together with Hollaender Speed Rail and then the keys ride on custom-fabricated 1/2 x 1-1/2-inch aluminum stringers … More

Finding the nodes, drilling the keys


(video lost when we quit Facebook)
Once the keys are cut and rough-tuned, they must be mounted.

Step one is finding the “nodes,” or the dead spots at either end of the key where the metal doesn’t vibrate. This is where I’ll drill holes for mounting.

To do this, you park the key atop two pairs of balled-up socks so it vibrates when struck. Then sprinkle a little salt near either end of the key and whack it repeatedly. The resonating metal bounces the salt away from the most-vibrating part into the nodes, the deadest spot in each key …

I mark each key, then put it on the drillpress and drill a 3/8-inch-diameter hole through each key’s nodes.

Drilling one of the two keyboards (about 30 keys) took the better part of an hour and resulted in several pounds of this fantastic aluminum chaff.

Wonder what I should do with it all …

Tubular bells array – sound check

(video lost when we quit facebook)

Here’s the first set of tubular bells, untuned. Tuning them is a pain in the ass: Unlike the keys, these cannot be made flatter by hollowing out the middle, between the nodes.

Instead, you can only sharp them by carving slices off the ends. Luckily, I wound up creating a sort of Middle-Eastern koto-sounding thang, that kind of works. I hope these don’t dull down too much when I mount them.

Miking and amplifying will be a challenge – I’ll need to figure out a resonator or some sort of sound funnel feeding a mike at one end of the tubes. But they resonate deeply, and they’ll look pretty wikkid bolted to the side of the van.

Enjoy the sustain.

Xylophoned!

I took a little time tonight to lay out a near-full keyboard on some telephone wire just to see how the 2-½-octave range sounded:

(video lost when we quit Facebook)

The keys don’t ring yet because there are no insulators under them, no holes drilled, no resonators to catch the sound yet, and it still needs a final tuning. But everything sounds solid so far.

Looks like I need to finish it up with a D at the high end. I’ll probably cut some more for the low end just because they sound so rich and I think I can keep going down before the metal’s native harmonics overwhelm each key’s primary tone.

Amplification tests – how do we mike this thing?

This weekend’s work has been mostly about sound (with a little van tinkering here and there).

How do we amplify two full keyboards of two and a half octaves of keys each, order plus numerous gongs and chimes?

Full-court press – set up a testing environment, bring in some mikes and amps, and sort it out, right?

We picked up a little mixing board at Guitar Center on Saturday night and spent some time bullshitting with the staff about microphones.

The challenge of the project is getting a full, clean mix out of the instrument in the face of these facts:

  • the high keys are very faint compared with the low ones
  • ambient noise will be a challenge, particularly on the playa
  • We want to get enough sound out of the system to reach across the playa without causing feedback through the pickups
  • The instruments will be bolted to the van full-time, so the miking solution must be removable to avoid the worst of the weather …
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Busy night at the xylophone factory

I got into a real rhythm last night and blew through a good 27 linear feet of aluminum bar stock, cutting keys for the xylophones.

To the right here is what my shop floor looks like – thick with aluminum dust. I must have swept up 5 pounds of the stuff. (The logo on the floor reminds me not to crack my head on the face-height 6×10″ beam hovering just 5 feet off the floor – I’m always standing up under it suddenly. Not for nothing is the beam called The Widowmaker.) …

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Sound check

We’ve knocked out two octaves worth of keys so far, only a sample of which will fit on the bench for a demo. Obviously they’ll sound much fuller after we figure out how to set up resonators and amplification, but at least they’re correctly tuned.

(videos lost when we quit facebook, but read on)

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As for finish, the first three are polished, the rest are still raw, and none have been drilled yet for mounting)

I picked up a new, slimmer metal-cutting disc for the circular saw the other day, and cutting is dramatically easier than it was. Now it takes barely four minutes to slice through the half-inch by 3-inch aluminum bar stock we’re using for keys.

Meanwhile, I’ve also been tinkering with disk gongs – I want people to have a broad array of stuff to bang on beyond the tuned keyboards on either side of the van. Otherwise, they may take to hammering on the mirrors or the coachwork.

These quarter-inch-thick steel disks have a tinny, bell-like quality …

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