MOTM

I just KNOW somebody here has already dealt with this problem, so here 
it goes...

Here I am, doing the math for a 24U cabinet. I just got my order for 
300 zinc hex drive inserts from McMaster.com (they're cheap AND fast 
too!) and I'm ready to go. 24U = 42 inches internal, check. With 3/4 
in. wood (of a type yet to be determined) we get an external length of 
42 + 1 and 1/2 in. = 43 1/2 inches, check. And two 1/2 in. thick pine 
strips on the inside horizontal,  to hold the inserts (huh...huh...I 
said inserts ;-)

Now comes the tricky part; figuring the *slop factor* (MOTM-spec is 
0.015 in. or, 1/64 in.). If we assume 24 *slop gaps*, then 24 times 1/
64 in. = 24/64 in. = 3/8 inch! Yikes! Can this be right? That's a lot 
of slop. So, should I add 3/8 in. to the overall length? I was planning 
to set the inserts by setting a '800 in the completed box, mark the 
holes, drill and set the inserts, bolt the '800 down, insert 1/64 in. 
spacer between it and a blank 1U panel, mark the holes, ect. so I'll 
need to know the correct length beforehand. I see there's enough play 
in the mounting holes on the panels to give me some wiggle room, so I 
guess my question is, am I being too anal about this *slop factor* 
stuff?

Somebody mentioned something about plastic strips for use as visual 
separators between modules (plastistruct?), ala Moog. I need to look 
into that and I'm too lazy to look it up in the archive ;-)

Chuck
being anal AND lazy

There should be no added slop in your cabinet design. The panels are 
mounted on exact 1U increments. 1U is exactly 1.75". The gaps between 
2 panels happens because the panels are cut about 0.025" narrower 
than the full width.

Now if you want to add separators, all bets are off. You'll have to 
add the thickness of the separators in and spread the holes out. But 
it will still be a problem between 1U and 2U modules, because there 
will be twice the thickness of separators to fit 2 1U panels into a 
width that formerly held a single 2U panel.

For this reason, I don't think separators that fit over the ends and 
spread the modules are practical. You can't spread the holes that 
hold a 2U panel, and those holes won't be wide enough to deal with 
the extra thickness of 2 1U modules. So you would end up with a cab 
that couldn't freely interchange the positions of 1U and 2U modules, 
and what's modular about that?

Moe

--- In motm@y..., drq48423@y... wrote:
> I just KNOW somebody here has already dealt with this problem, so 
here 
> it goes...
> 
> Here I am, doing the math for a 24U cabinet. I just got my order 
for 
> 300 zinc hex drive inserts from McMaster.com (they're cheap AND 
fast 
> too!) and I'm ready to go. 24U = 42 inches internal, check. With 
3/4 
> in. wood (of a type yet to be determined) we get an external length 
of 
> 42 + 1 and 1/2 in. = 43 1/2 inches, check. And two 1/2 in. thick 
pine 
> strips on the inside horizontal,  to hold the inserts 
(huh...huh...I 
> said inserts ;-)
> 
> Now comes the tricky part; figuring the *slop factor* (MOTM-spec is 
> 0.015 in. or, 1/64 in.). If we assume 24 *slop gaps*, then 24 times 
1/
> 64 in. = 24/64 in. = 3/8 inch! Yikes! Can this be right? That's a 
lot 
> of slop. So, should I add 3/8 in. to the overall length? I was 
planning 
> to set the inserts by setting a '800 in the completed box, mark the 
> holes, drill and set the inserts, bolt the '800 down, insert 1/64 
in. 
> spacer between it and a blank 1U panel, mark the holes, ect. so 
I'll 
> need to know the correct length beforehand. I see there's enough 
play 
> in the mounting holes on the panels to give me some wiggle room, so 
I 
> guess my question is, am I being too anal about this *slop factor* 
> stuff?
> 
> Somebody mentioned something about plastic strips for use as visual 
> separators between modules (plastistruct?), ala Moog. I need to 
look 

> into that and I'm too lazy to look it up in the archive ;-)
> 
> Chuck
> being anal AND lazy

----- Original Message ----- 

From: <drq48423@...>
Now comes the tricky part; figuring the *slop factor* (MOTM-spec is 
0.015 in. or, 1/64 in.). If we assume 24 *slop gaps*, then 24 times 1/
64 in. = 24/64 in. = 3/8 inch! Yikes! Can this be right?
-----------

As I see it,

The slop is subtracted from and not added to the full 1U / 2U panel width.

1U = 1.75 = .015 = 1.735   2U = 3.50 - 0.15 = 3.485

So, if you figure your cabinets on full 24 U spaces (42 inches inside) you
have already included the slop.

Larry H

--- In motm@y..., "J. Larry Hendry" <jlarryh@i...> wrote:
Thanx, Stooges. Yoda-like, backward thinking is me.

Chuck
wiring his brain to a reversing attenuator

> 
> ----- Original Message ----- 
> From: <drq48423@y...>
> Now comes the tricky part; figuring the *slop factor* (MOTM-spec is 
> 0.015 in. or, 1/64 in.). If we assume 24 *slop gaps*, then 24 times 1/
> 64 in. = 24/64 in. = 3/8 inch! Yikes! Can this be right?
> -----------
> 
> As I see it,
> 
> The slop is subtracted from and not added to the full 1U / 2U panel width.
> 
> 1U = 1.75 = .015 = 1.735   2U = 3.50 - 0.15 = 3.485
> 
> So, if you figure your cabinets on full 24 U spaces (42 inches inside) you
> have already included the slop.
> 
> Larry H