What kind of aluminum are Hammonds, etc. made of?

[Taylor]

I'm thinking about ordering some sheet aluminum for faceplates in a modular synth I want to build.

I found these guys who cut to size:

https://metalbytheinch.com/

They have 3 types of sheet aluminum:

3003-H14
5052-H32
6061-T6

Based on the vague descriptions, it sounds to me like the 3003-H14 is the softest, which I want for easy drilling. I won't be stomping on these panels so I don't need extreme strength.

Any pointers on which of these would be closest to the alloy used in the die cast boxes we normally use, in terms of drilling?

[Earthscum]

Not sure about the H rating, but the T ratings are T1=soft, annealed, while T6 is tempered for precision machining and strength. Once you heat T6 alloys you have to re-temper them... though, that is not crucial to your situation. If you WERE to use a stomp switch, I would avoid excessive heat, and stick with about 3/32" or 1/8" thickness. I don't really find 6061 to be all that bad when you machine it. Aluminum is soft, tempered or not. The only time it REALLY gets hard is when you anodize the surface... even then, you're only anodizing the outer surface to maybe a mil or 2 deep. Once you get through that, it's butter as long as you have decent bits.

6061 is an alloy that is corrosion resistant. It's one of the alloys that are referred to as "Aircraft Grade" alloy It's easy to polish, and the T6 is harder to really gouge a good one. IMHO, 6061 is one of the best alloys for longevity. It won't wear and 'crush' like the softer alloys will. Fairly easy to machine.

[defaced]

You won't notice a difference with drilling.  You're still in the "very soft" range when it comes to metals.  6061-T6 is probably the most common of the three.  

T is tempering through heat treating
H is strengthening through strain hardening
You can read more on Wiki under aluminum alloys and their temper designations.  

Cast alloys like what are used for the Hammond boxes will be different, if even only slightly, from the sheet alloys you can get.  This is because the casting alloy has to flow more than the material that is being rolled into a sheet. 

[newperson]

Go for the 6000 series.  I have tried a 5000 and 7000 for the same thing you are doing.  The softer AL leaves strings when drilling.  The part where is curls up the drill bit when drilling out the hole.  This becomes a big deal when you are drilling out something that is painted.  It can spin around with the bit when coming out of the hole and scratch your paint job.  So you end up with a little circle scratch around the hole.  Very annoying.  The 7000 series I just drilled did it a lot less than the 5000.  Plus I had to do debur the back of the holes much less.  Only two holes needed it out of about 40 drilled.  The softer AL needed all of the holes deburred.


Just so you know the two I have tried so far:

5052-H32 .063
7475-T76 .063 (7075)

[newperson]

This is what I am talking about.  It happened on the last hole.

[frank_p]

If you are concerned about scratches:

The T6 have a hardness of 90 Brinell compared to 40 for H14 and  60 for H32. So if you are concerned about scratches (no painting ?) I would go with the T6.  The elasticity of the three are about the same so you have to design with thickness for rigidity.

[Mark Hammer]

For faceplates for a modular system, my immediate concern would be that I could use mini phone jacks for patching.  The concommitant of that would be that the material could not be too thick (threaded collets on those jacks aren't particularly long/deep), nor could it be too thin (you don't want there to be any give or buckling as you insert or unplug things to and from jacks).

Part of the structural rigidity thing is addressed by the size and orientation of the panels.  If the panels are relatively small in surface area, rigidity is easier to maintain in the face of thinner panels.  Alternatively, if any jacks are situated near those edges where the panel is secured/supported, there will be much less risk of buckling.

Insomuch as something mounted in an above-the-floor chassis is not subject to as much physical abuse, I'm not sure what the relevant difference would be among aluminums of different composition/hardness.  For me, once the rigidity/jack-requirments are addressed, the key thing would be whether it contributes appreciably to weight, since they are all going to be equally easy to machine....or at least not as different as aluminum vs steel.

[Taylor]

Hey Mark, yep I plan to use 1/8" jacks in a Eurorack-ish format (panels 5.25" tall, variable width). The collet depth is a good point, which I hadn't thought about yet. I was mostly just making sure that the hardened forms of aluminum are not nearly as hard as steel, because drilling steel enclosures is huge drag and really dulled all of my Unibits when I built this:

http://www.diystompboxes.com/smfforum/index.php?topic=86729.0

[newperson]

None of the AL I have drilled was hard at all, but I have never used a step bit.  I have been using a cheap set of bits from harbor freight for about 4 years now.

Here are a couple pictures of the jack size in the thinner AL and the thicker "standard" thickness that most pre made panels seem to be.







As you can see neither of the thickness comes close to filling up the shaft length.  I would however pay the bit extra and get the thicker AL.

[Taylor]

I was thinking something like .08", just a little thinner than the walls of a Hammond or 4 site box. Is that about the thickness you'd recommend?

[Mark Hammer]

What panel size are you planning on?  Something like MOTM size?

[defaced]

Thickness should be dependent on the maximum unsupported span.  Translation: thin stuff flexes if there's nothing to support it like a wide open sheet but is fine if you're working with a small panel of only a couple of inches. 

[Taylor]

As above, Eurorack - 5.25" (3U) tall, variable width, probably up to 7.5" wide for bigger modules.

[Mark Hammer]

That's why I ask about size and orientation.   For example, consider the old PAiA modular synths.  Here, the modules are not always very large, but if they need to be larger, they are oriented such that they are secured along the long side, rather than the narrow side.  That lets you use thinner panels and still maintain rigidity.

[newperson]

.08 is plenty thick.  That will provide a really nice solid feel to it.  The .063 I used before is thick enough but 'feels' a little thin.  But this is spanning across 15 inches by about 10 inches tall.  So the 5.25 size would feel much better.  I recently got that thicker panel (which is the 5.25 size) and it feels thick enough to use as a weapon.  The next sheet I buy will be the .08 size. 

[JRM]

Aluminium was part of my life for 6 years a couple of years ago... Go for the 60XX series: easy to machine, you can anodize it, paint it (powder or liquid paint) and is quite corrosive resistant. The 70XX series is better if you need havy machining that will not happen if you're just going to drill some holes for pots, leds, switches and jacks. 70XX is used to build bikes. 60XX is used everywhere from windows and doors to cars. The Hammonds are cast aluminium, which have a different alloy.
For the thickness you'd have to calculate, depending on what size you'r looking for and the internal arrangement (suports). I believe 2mm (0.08") is enough for the majority of the cases.

[Beo]

I'm doing something similar. I have an old studiomaster mixer that I'm going to use tilted as a floor multieffect box. It's 17" wide by 14" long and 2" deep. The original top panel needs to be replace as it's a mess of slider, knob and jack holes. I do intend to have one or two rows of stomp switches on the bottom half, so I need to consider strength. Any recommendations on width for a panel this big, using 6061-T6? Thanks.

Thickness:
.063
.080
.090
.125
.190

[defaced]

That's a pretty good sized open span.  0.125 would be the minimum I'd consider, and I'd probably add some mid span supports as needed.  Really it depends on how close the stomp switches will be to the edge of the box - assuming the box is providing support for the top along that side.  Do you have a picture?

[Beo]

Here's a google image of the same one I have. I've taken the mixer apart and unmounted all the hardware from the top panel (lots of good pots and jacks taken from the guts). The panel that I've taken off is really stiff, even with the holes, while only 1/16th or less thick. My guess is that it is steel, or something anodized. I could use it as a backing plate with a slim aluminum panel over it.

(Sorry, I couldn't figure out how to embed the image. Please follow the link to see the pic.)

http://www.google.com/imgres?imgurl=http://img715.imageshack.us/img715/5193/img3765d.jpg&imgrefurl=http://www.gutefrage.net/frage/mischpult-aufnehmen&usg=__YmzTMBX8kS9DNugeSKMY6DlY9h8=&h=2304&w=3072&sz=3369&hl=en&start=184&zoom=1&tbnid=N-oqeHgw7ZqJOM:&tbnh=162&tbnw=223&prev=/images%3Fq%3Dstudiomaster%2Bdiamond%2B8-2%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26sa%3DX%26rls%3Dorg.mozilla:en-US:official%26biw%3D1372%26bih%3D842%26tbs%3Disch:10%2C5700&um=1&itbs=1&iact=hc&vpx=855&vpy=474&dur=57&hovh=194&hovw=259&tx=124&ty=96&ei=hci3TM_tLJS2sAPJupWBCQ&oei=Xsi3TNjbCoyosAPP0o3mCA&esq=9&page=9&ndsp=21&ved=1t:429,r:13,s:184&biw=1372&bih=842