graphic eq enclosure

[BillyBoy]

Hi,

I finally got around to breadboarding a graphic eq I had been intending to build.  It has 7 bands and a master level.  Basically a GE-7 with regular bypass switching instead of all that Boss switching cruft, with upgraded parts, running at 15v (might be able to push 18, depending on final opamp selection).  I had scored some slider pots for it a long while ago.  I have one of those black 1590BB enclosures that is sort of textured on the outside, so there is plenty of room.  But I haven't come up with a good way to cut the 8 slots.  They have to be pretty accurate or the sliders won't work and look nice, of course.  Have any of you done that before?  How did you do it?  I've had a few ideas, but none that I think will be accurate enough to try.  Maybe I should be looking for a dead 8-slot EQ in nice cosmetic condition    When I had it on my breadboard, I used regular pots to get it going.  That's kinda clunky to use compared to the sliders, especially when I would have to put them in 2 rows to fit across an enclosure.  Also considered a single large rectangular hole, using epoxy or something to make a single assembly out of the sliders, but that's just plain ugly.

Probably the best idea I've had so far is to start each slot by drilling 3-4 holes in a line to create a long hole big enough to get a jigsaw blade into so I could finish the slot with a jigsaw and a metal cutting blade.  I think the blade width would be about right for the slot width.  I'm doubtful that I can control my jigsaw well enough to get nice slots, though.  There is a lot of vibration and tilt to control on a small surface and it will definitely mess up the finish on the enclosure.  Have seen a handle that accepts jigsaw blades (makes it like a keyhole saw) so I could cut them slowly/manually.  That's kinda where I'm at right now, but I'm doubtful it would actually work that well.

Also thought about using a nibbler, but I can't make a clean cut with one, even if it would cut the enclosure.  The one I have would make too wide a slot. 

Most rotary blade tools would probably leave non-vertical cuts at the ends of the slot.  I have to be careful there because I need tiny screw holes right at the ends of the slots to hold the sliders. 

I have some rotary blades that look like drill bits that you can use with a drill to cut sheetrock.  I could put them in my drill press, but I'm not sure they are up to cutting metal and they don't really work that well in softer materials - pretty rough cuts and difficult to control. 

Or maybe a small file - yuck.  Will probably need one anyway to smooth things up after whatever I do...

I know someone that worked in a lab that had a really cool 3D printer that printed titanium or some exotic metal.  Maybe I should sell my house and get one of those - no more drilling enclosures for me!

[GermanCdn]

All right, before I make any suggestions, let me start with this - whatever you do, be very, very careful, wear appropriate protective gear (i.e. at least safety glasses, maybe faceshield, hearing protection, and possibly hand protection).  Trying to machine aluminum without the proper machining setup can go bad really quick.

My first reaction would be to layout your lines, jig up a fence on a drill press base, drill out (slightly undersized) the entire slot length, and then finish with a Dremel mounted on a router base with a small diameter diamond coated grinding bit.  You're essentially using all of the tools as they are designed, and doing most of the work with the drill.

I would not try and mount any kind of cutting device into a drill press and trying to use it as a DIY milling machine.  Milling is a complicated correlation between speed, cutting tool diameter, lubricants, materials, etc, etc.  A drill press is not setup to be a milling machine (doesn't have enough speed control, bearings are not designed for lateral loads, etc, etc), and it could go really bad really quickly, and result is pretty serious injury if your cutting device blows apart.

Jig saw might work, but it might kick and buck a lot, which could result in damage to the enclosure.

[bcalla]

I agree that sliders would look better, but without a CNC machine I can't imagine pulling it off (at least for me - maybe you have amazing skills with power tools).  How about 9mm pots?

[selfdestroyer]

I suggest calling around in your city for any machine shops or even hackerspaces to see if they would help you out. You would be surprised how much support you could get from local businesses. On a proper CNC machine it would take minutes to make the needed cuts in aluminum.

Cody

[alanp]

I suggest calling around in your city for any machine shops or even hackerspaces to see if they would help you out. You would be surprised how much support you could get from local businesses. On a proper CNC machine it would take minutes to make the needed cuts in aluminum.

Cody

+1 on this.

http://www.madbeanpedals.com/forum/index.php?topic=18101.msg181499#msg181499

Or you could build a 14 band EQ, with a 24 volt swing (+/- 12V, I'm kidding with suggesting you do this project.)

[davent]

Maybe make a front panel from acrylic to replace the aluminum top face of the enclosure. Has to be easier to machine then aluminum.

For aluminum this would be my approach as well with needle files for tidying up.

My first reaction would be to layout your lines, jig up a fence on a drill press base, drill out (slightly undersized) the entire slot length, and then finish with a Dremel mounted on a router base with a small diameter diamond coated grinding bit.  You're essentially using all of the tools as they are designed, and doing most of the work with the drill.

[BillyBoy]

That's a wicked Yusynth project!  If you can drive that beast with all those pots, I'll quit whining about my little 8-pot problem now!!!

Thanks for the ideas.

I think the best option for slots is to get a proper machine shop to do it for me.  The more I think about it, even marking the enclosure is going to have to be done differently from how I normally do it.  It's one thing to be off by half the width of your mark when you are drilling a footswitch hole, but quite another thing when you have all those slots side by side with only a few mm between them.  Assuming I mark and cut nicely, then I have to hit 16 screw holes perfectly.  Those margins of error could easily add up to a disappointing result. 

If I do talk myself into a DIY job, I think the "drill lots of holes" approach is probably the right starting point for me.  I have a pretty good drill press for metal working, but I don't have a fence and my vise isn't the kind that allows for lateral positioning adjustment.  I might do a reasonable job of it with a good fence or vice, a small file for cleanup, and some patience.  Once I see the price of a good fence/vise setup, I have a hunch that 8 rotary pots may seem like a pretty good solution for a one-off project.

[davent]

For a fence all you need is a 2 clamps and a straight piece of wood.

Used a piece of aluminum for a fence and working with wood, used a router table and fence to connect the end holes- instead of needing to drill a line of holes but same idea with using a fence to ensure a true line of holes.

[BillyBoy]

Very nice work!

I've rigged a fence like that for woodworking a number of times and it has always worked great.  When I first started drilling enclosures, I had one that somehow snagged on a bit, got away, and went all high-speed projectile on me, leaving a trail of minor damage and destruction as it ricocheted around.  That will *never* happen again!  I bought my drill press vise before I drilled another one, and am pretty sold on that approach.  But my vise is just a plain one and it is not easy to use.  What I need to get is a 6" cross slide vise.  That will let me drill a row of aligned holes while still holding the enclosure securely.  I looked at them quickly last night.  There's a wide range of prices and quality, so I'll have to do my homework. 

[davent]

Could you not use the press vise in conjunction with the fence to get your cross slide?

I confess i've only ever handheld enclosures while drilling but start at 1/16" and take 1/32' steps up to the finished size, with very sharp bits you pretty much don't need to even hang on.

[BillyBoy]

Kinda hard to describe, but the mounts on my vise and table, crank on the vise, cranks on my drill press, table size, locations for clamps, etc just don't work well together.  It's a cheap vise, so it's not a big deal to get rid of it.  After using it for a while, I have a better idea of what I should look for in a replacement.

I haven't been using step bits, although I've considered it.  Will probably get one and try it next time I need bits.  I think they would be less likely to launch something the way a regular bit can.

[davent]

Know what you mean, so many variables, no standardization...

Step bits are great but even they start at 1/8". I find i get much more accurate results with a good center punch dimple then a 1/16" bit for the pilot hole, nestles nicely in the dimple and is small and fragile enough to never grab and launch an enclosure. Then i redrill with a 3/32" and then a 1/8" then the step bit which also has 1/32" steps. (And i do all the holes before moving on to the next size of bit.)

[BillyBoy]

I'm impatient - I just mark 'em and drill 'em. 

I like that punch idea - I'll try that.  I have another idea that I've been hesitating to try.  I have a set of nice brad point bits.  I got them for finish work in wood.  I guess they should work OK in aluminum, but I just didn't want to risk messing them up.  They have a very sharp point that allows very accurate placement.  They cut the circumference of the hole just a tiny bit before they remove the material inside the hole.  You would probably end up with a thin disk of aluminum with a hole in the center.  In wood, it all just turns into sawdust.  Other than maybe messing up some pricey bits, I wonder if when drilling metal there would just be too much going on - drilling the pilot hole, cutting the circumference, and removing the material between the edge and the pilot.  Maybe I'll buy one cheaper one and give it a try one of these days. 

[blearyeyes]

Sharks with "Lasers" on their heads. That's what I would use.