ruffrecords

Aluminium Front Panel Thickness
« on: June 23, 2016, 07:27:03 AM »
Inspired by Humners mixer build  I have been looking at how to recess  switch/pot nuts in a front panel so they can be covered by another, purely cosmetic,  front panel that also has the legend for the controls. I have measured the thickness of the nuts of all the switches/pots I can get hold of and none of them is thicker than 2.3mm. So I thought a 2.5mm recess would be about right.  The question is, what thickness of aluminium is the minimum acceptable for actually fixing the switch/pots? If I allow 1.5mm for this it makes the panel 4mm thick. If I make the cosmetic panel the same thickness we now have an overall thickness of 5.5mm. Are these numbers OK. Could I reduce them to 1mm or would that lead to structural weakness? Should I make them thicker?

Cheers

ian


Rocinante

Re: Aluminium Front Panel Thickness
« Reply #1 on: June 23, 2016, 10:49:24 AM »
I had Frank Rollen  make a 2mm cosmetic panel for a dual channel compressor  that looked similar to how the UA LA-610 or 2-1176 looks. I drilled the holes on the 'bottom' thicker 4mm panel wider while the 'top' thinner 1.5 mm panel holes were just long enough to fit the shafts.  So in a sense the pots sat 'inside' the thicker 4mm panel and latched onto the 'thinner' 1.5mm panel.  I have no idea if this is how it is done and i also used knobs that had deep shaft holes. Had the knobs been a collet like sifam or elma or similar shallow shafted knob i might have made the bottom panel holes just  wide enough. So i guess i would say knob shaft hole size is integral.
If there's a harder way to do this, I haven't found it yet.

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #2 on: June 23, 2016, 11:09:30 AM »
I had Frank Rollen  make a 2mm cosmetic panel for a dual channel compressor  that looked similar to how the UA LA-610 or 2-1176 looks. I drilled the holes on the 'bottom' thicker 4mm panel wider while the 'top' thinner 1.5 mm panel holes were just long enough to fit the shafts.  So in a sense the pots sat 'inside' the thicker 4mm panel and latched onto the 'thinner' 1.5mm panel.  I have no idea if this is how it is done and i also used knobs that had deep shaft holes. Had the knobs been a collet like sifam or elma or similar shallow shafted knob i might have made the bottom panel holes just  wide enough. So i guess i would say knob shaft hole size is integral.

I have read this post five or more times and each time I think I have understood it I find something that contradicts what I thought it was.  I am not clear if there are two or three panels in this scheme - you mention a 2mm one, a 1.5mm one and a 4mm one. Am I right in thinking the pots are attached to the bottom 1.5mm panel, on top  of that goes the 4mm panel with big holes for the nuts and on top of that goes the 2mm cosmetic one. Is that right?

Cheers

Ian

audiomixer

Re: Aluminium Front Panel Thickness
« Reply #3 on: June 23, 2016, 11:48:52 AM »
if you are reliing on the lower panel to support the mechanics it should be thicker then 1.5mm aluminum. how about milling  around the but in a thicker panel and having a 1mm thin panel fot the  lettering? a 90 deg bend helps a lot also

- Michael

JohnRoberts

Re: Aluminium Front Panel Thickness
« Reply #4 on: June 23, 2016, 03:00:26 PM »
I count three...

thin rear panel the pot nut attaches to
a thick(?) spacer-panel with clearance hole for the nut (you can get thin nuts too)
a thin top escutcheon or cosmetic panel. 

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #5 on: June 23, 2016, 05:30:28 PM »
if you are reliing on the lower panel to support the mechanics it should be thicker then 1.5mm aluminum. how about milling  around the but in a thicker panel and having a 1mm thin panel fot the  lettering? a 90 deg bend helps a lot also

- Michael

That was pretty much what I described in the original post. A 4mm panel with 2.5mm deep recess for the nuts. The panel is 1.5mm thick where the controls are actually attached but 4mm everywhere else. I think the overall panel stiffness/strength would be fine - I was concerned about the 1.5mm thick section where the controls are attached.

Cheers

ian

Re: Aluminium Front Panel Thickness
« Reply #6 on: June 23, 2016, 06:09:37 PM »
The trouble you have with alloy is its propensity to warp. Even at thicknesses like 3mm it's rarely dead flat after machining. If you couple this to its inherent malleability, after a while the controls could drift and start to look a little skew whiff. Using an inter-panel to hold pots etc is something that I do all the time - but made out of steel. For your own gear alloy might be fine, but if you're selling it I'd opt for steel.
Prepare yourself. You are about to become the voice of Interplanetary Parliament.

john12ax7

Re: Aluminium Front Panel Thickness
« Reply #7 on: June 23, 2016, 09:12:28 PM »
I think the answer would depend on how big the panel is and how much structural support you need aside from just the pots. It's pretty common to fix pots onto .050" (1.25mm) aluminum on 500 series modules. Whereas 19" rack mount tends to be thicker steel.

Timothytitus88

Re: Aluminium Front Panel Thickness
« Reply #8 on: June 23, 2016, 09:24:52 PM »
Hey Guys,

Perhaps we need some cross sectional sketches so we are all on the same page.....

Doing a 2.5mm counterbore (recess) in a 4mm panel (so the pot grips onto the remaining 1.5mm) should be fine. even 1mm will be fine. The strength comes from the whole panel around the counterbore. Of course if you are lining up counterbores across the whole width of a panel, leaving not much meat in between, that's another matter.

For material selection, I disagree about the warping after machining. Of course the correct alloy needs to be used... the softer bendy ones that are good for folding and welding are no good for machining, so you would not use them anyway. Anodized engraving sheet comes dead flat, and i have not had a problem with any warping during machining. Most issues with the finished product not being flat is because of guillotining before it goes on the machine. Also if you are laser cutting the panel, it will probably not end up flat.

The limiting factor here is the availability of different thicknesses in the correct alloy (something like 6061T6) - and in an array of colors. I am currently working out my supply chain for this....particularly nice colors in thicker 6061, for 19" panels.  I am seriously considering getting set up to do anodizing myself.

I am not 100% sure why the pot nut and washer needs to be covered by a cosmetic plate... are they not covered by the knob anyway? given we are talking about machining anyway, what does the cosmetic plate achieve that a 2mm counterbore in a 3mm plate will not achieve? Perhaps I am missing something.

Anyway, now I am rambling.

On a side note, almost bang on 4 years ago I documented the build of my second CNC machine here, but then work took over and I did not to get to do much with it since. Well that has now changed and I have finally been able to start spending some time in the workshop building. I really should revive that old thread and get some pics up.

Cheers,

Tim



Rocinante

Re: Aluminium Front Panel Thickness
« Reply #9 on: June 23, 2016, 11:20:29 PM »
Sorry work stole me for the day. I originally thought it was 2mm but while typing the post I checked my invoice from Frank and saw it was actually 1.5mm. While proofreading the post I somehow skipped the first sentence. 
My apologies for the confusion.
It was 1.5mm on top of 4mm.
If there's a harder way to do this, I haven't found it yet.


Rocinante

Re: Aluminium Front Panel Thickness
« Reply #10 on: June 24, 2016, 05:00:46 AM »
One of the benefits of doing a plate over panel is cost. I think it looks nice too.  A 19" 2u panel engraved by schaffer isnt cheap. And this is where trophy shops and the like come in as well. Many of the metal and trophy shops use thinner aluminum (1.5-2 mm) and work with 1- 3" by 5 - 7" plates often.  The 3" look great in a 2u having a .25" reveal on top and bottom of the panel.  In my inquiries the various metal shops can usually work with an inkscape or pdf or autodesk file.
« Last Edit: June 24, 2016, 05:08:30 AM by Rocinante »
If there's a harder way to do this, I haven't found it yet.

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #11 on: June 24, 2016, 05:58:21 AM »
I think the answer would depend on how big the panel is and how much structural support you need aside from just the pots. It's pretty common to fix pots onto .050" (1.25mm) aluminum on 500 series modules. Whereas 19" rack mount tends to be thicker steel.

I should have mentioned this is mainly for EZTubeMIxer modules which are 2.8 inches wide and either 5.25 or 10.5 inches tall. Unlike many module designs, the edges of the panel are supported all the way around the periphery by an extrusion that forms the sides of the module.

Cheers

Ian

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #12 on: June 24, 2016, 06:20:54 AM »

I am not 100% sure why the pot nut and washer needs to be covered by a cosmetic plate... are they not covered by the knob anyway? given we are talking about machining anyway, what does the cosmetic plate achieve that a 2mm counterbore in a 3mm plate will not achieve? Perhaps I am missing something.

On many of these panels there are switches on 1 inch centres. The switches have 1/4 inch shafts and 3/8 inch bushes. The maximum width across the nut, point to point is 0.62 inches. To cover the nut the knob need to be about  0.7 inches diameter.  However, this leaves only 0.3 inches for the legends between adjacent switches which is a severe restriction. With a cosmetic panel, the hole only needs to be slightly greater than the 1/4 inc shaft diameter. This means you can use a  smaller diameter knob, say 0.5 inch, which leaves a lot more room for legend between switches.

Cheers

Ian

Timothytitus88

Re: Aluminium Front Panel Thickness
« Reply #13 on: June 25, 2016, 12:37:56 AM »

Ahhhh, well if your knob is smaller than your nut, I see your problem....

T

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #14 on: June 25, 2016, 02:39:18 AM »

Ahhhh, well if your knob is smaller than your nut, I see your problem....

T

No, its just my nuts are too close together  :o

Cheers

Ian

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #15 on: June 30, 2016, 03:54:53 AM »
I just came across a completely different solution for modules. This is what Soundskulptor does for is 500 series modules. The attached pic is taken from one of their assembly manuals. Basically it looks like a steel plate with some tapped stand offs, to which the PCB is attached,  and a couple of bent ears with tapped stand offs to which the front panel is attached. In another pic in the manual you can see the pot and switch nuts are NOT used to attach the controls to the front panel; their shafts just poke through. Pretty neat; strong, provides inter-module screening and the front panel is just cosmetic.

Cheers

Ian

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #16 on: June 30, 2016, 03:57:53 AM »
Here is a pic of the completed module.

Now where do I get my own steel panels like this made?

Cheers

Ian

john12ax7

Re: Aluminium Front Panel Thickness
« Reply #17 on: June 30, 2016, 04:05:09 AM »
Is there any mechanical support for the pots, or is it just the solder then?

I have been looking at emachineshop for getting plates made, might be a similar option in your neighborhood.

ruffrecords

Re: Aluminium Front Panel Thickness
« Reply #18 on: June 30, 2016, 04:08:47 AM »
Is there any mechanical support for the pots, or is it just the solder then?

I have been looking at emachineshop for getting plates made, might be a similar option in your neighborhood.

There is mechanical support for the pots. There is a bracket that is supplied with them. The manual I was looking at you can fine here:

http://www.soundskulptor.com/docs/mp599-assembly-guide-01.pdf

Paragraph 15 shows the pot bracket. The ALPS pots I have in mind to use have a built in bracket.

Cheers

Ian

audiomixer

Re: Aluminium Front Panel Thickness
« Reply #19 on: June 30, 2016, 04:19:08 AM »
two things to add:

I personally really dislike gear that has the pots not attached to the frontpanel. the feel has always been sloppy and they are prone to pot / pcb failures due to mechanical stress. even the ones with additional tabs on the pot. this model might be different, I don't know.

I bought some nuts (inserts) I can mount into a panel (mostly for aluminium, but steel works to) similar to the one shown. drill a slightly larger diameter, and pull the nut with its teethed part into the hole. works great if you can maintain pressure in the final assembly - when you have the nut on the rear side of  the panel. the other option is to look into threaded stand offs that you can rivet in. not quite as nice but doable. for me the way to do it in the past has been using stand offs and to screw them in from the back (counter sunk and flush) but this has always been a PITA - precision, counterboooring, loose fit on the mount when unscrewing.... so I changed to using inserts. Now I have a welding machine, I might try spot welding.... hehe....



- Michael