ruffrecords

How much gap between module front panels
« on: December 26, 2017, 06:56:43 PM »
In a modular mixer, how much of a gap should you allow between module front panels? For instance a standard Eurorack 7HP module pitch is 1.4 inches or  35.56mm. In front panel designer, when you specify a 7HP wide panel, what you actually get is one that is 35.22mm wide so there is a gap of 0.34mm or about 13 mil between adjacent modules. I guess the gap has to be small enough not to be obviously noticeable but wide enough to handle tolerances but 13 mil seems a bit on the low side to me.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


iturnknobs

Re: How much gap between module front panels
« Reply #1 on: December 26, 2017, 08:34:28 PM »
Finally, a topic I can contribute to :

0.34 mm = .0131" (very close, anyway)

CNC machines today are programmable within .0001".  Take "machine slop" and tool wear into account and machines today can consistently and accurately hold machining and placement tolerances of .001"-.002"(especially machining a thin aluminum front panel). I have operated a manually controlled precision grinding(and gauging) process(O.D. grinding wrist/piston pins) for Ford and Honda at 20,000 pcs /8hr shift, holding tolerances of +/- .000039 inches(including convex/concave profile taper). There appears to be plenty of play at the chassis bolt/screw position. Be happy that your modular rack/chassis is going to look really good without much effort. Double check your panel width to verify it is within tolerance with calipers should fitting issues occur. Paint and powder coat could obviously be an issue to take into consideration. Hope your project turns out well. Looks like most do. ;)

-Brian
« Last Edit: December 26, 2017, 09:21:57 PM by iturnknobs »

john12ax7

Re: How much gap between module front panels
« Reply #2 on: December 26, 2017, 08:46:00 PM »
Isn't tolerance usually a cost question?

For a standard (non-premium)  machining process what is the normal tolerance? 1 or 2 mill seems awfully low to me.


ruffrecords

Re: How much gap between module front panels
« Reply #3 on: December 27, 2017, 04:19:06 AM »
Thanks for the input. It seems 0.34mm is plenty and well within the capabilities of current production equipment. I must admit I have never measured the actual width of a front panel I have had made by Schaeffer or Frank Rollen. When it stops raining I might pop down to the workshop and check a few.

So given 13 mil is plenty, why is it this value? Why not 10mil or 7mil or 20 mil?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: How much gap between module front panels
« Reply #4 on: December 27, 2017, 04:42:42 AM »
So given 13 mil is plenty, why is it this value? Why not 10mil or 7mil or 20 mil?

Maybe because front panel designer is metric and 13 mil is more or less 1/3 mm ?

Best
Zam

ruffrecords

Re: How much gap between module front panels
« Reply #5 on: December 27, 2017, 04:50:00 AM »
Maybe because front panel designer is metric and 13 mil is more or less 1/3 mm ?

Best
Zam

I wondered that too. But is it a fixed value irrespective of the width of a panel? Or is it like about 1% of the panel width? I need to try in front panel designer with different panel widths.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: How much gap between module front panels
« Reply #6 on: December 27, 2017, 07:19:13 AM »
I wondered that too. But is it a fixed value irrespective of the width of a panel? Or is it like about 1% of the panel width? I need to try in front panel designer with different panel widths.

Cheers

Ian

I don't check this, but I suspect it is a fixed value, not a proportional value related to width.
With nHP - 0.3mm. Meaning 0.15mm at each side to allow little margin for alignment, as little room for insertion between others.

Best
Zam

Andy Peters

Re: How much gap between module front panels
« Reply #7 on: December 27, 2017, 10:46:37 AM »
I wondered that too. But is it a fixed value irrespective of the width of a panel? Or is it like about 1% of the panel width?

I don’t see why the tolerance should vary as a percentage of panel width. Or, put another way, should the gap between three-wide panels differ from that of a one-wide panels?
"On the Internet, nobody can hear you mix a band"

JohnRoberts

Re: How much gap between module front panels
« Reply #8 on: December 27, 2017, 11:59:04 AM »
The tolerance is whatever it needs to be.... 

Precision is required when stacking up tens of channels.  I recall the difficulty shoehorning modules into the first prototype big split console I did (last century). 36 input channels, 24 subs, 4 send-returns, and a master section... The original hand bent metal caused some real drama fitting them all into the prototype chassis. It doesn't take much error multiplied 60x to be a problem.  :o

For production metal we tooled up a forming tool, so the bent module metal width was reliably precise.  8)

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

ruffrecords

Re: How much gap between module front panels
« Reply #9 on: December 27, 2017, 04:20:12 PM »
I just ried a panel twice the width in front panel designer and the allowance is again exactly 0.34mm so I guess it is a constant.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


Gene Pink

Re: How much gap between module front panels
« Reply #10 on: December 27, 2017, 04:22:06 PM »
I don’t see why the tolerance should vary as a percentage of panel width. Or, put another way, should the gap between three-wide panels differ from that of a one-wide panels?
Heat expansion? ;D

ruffrecords

Re: How much gap between module front panels
« Reply #11 on: December 27, 2017, 05:09:59 PM »
Heat expansion? ;D
I wondered about that. The coefficient of fractional linear expansion of aluminium 2 x 10-6 per degree Celsius.

For a 1 inch wide panel to expand by 1 mil requires a temperature increase of 44 degrees Celsius.

So it is a factor but it's second order.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'