confirming edge measurements on 500 series units

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imo

Well-known member
Joined
Jan 19, 2006
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397
Location
vashon, wa
Hello,
According to the meta, there is a .438" gap to the left edge of the card. I was hoping to confim this and also see what size standoffs people were using to get "close enough"
I got one of Igor's 500 TG1 kits. He has dropped off of the face of the earth, and the mechanical parts in the kit are not right. I want to make sure that i am able to go straight into the card slot without any flex.
Total width per unti is 1.188, so for a double i would need a total standoff length, all in, or 2.376(minus the width of the aluminum)
Any info on this would be great
Thanks
Ian
 
Not really sure what you are asking, does this help?
 

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Bruce,
Yes, i am referencing that. I am trying to figure out how far from the left edge does the actual pcb need to be to fit into the 18 pin holder. I see that the gap is .438"according to the unofficial doc, but i just wanted to confirm that measurement and see how people got close to it with a standoff. For instance, would it be better to use a 3/8", knowing you have a slight addition with the aluminum width of the case, or are people using 1/2" standoff's and find that the boards can take a slight flex?
Ian
 
(Edited) If you are referring to the left to right position of the card as it meets the front panel, that is not particularly important.  There is no card slot in a 500 Case, the only attachments are the card fingers, and the 2 screws on the front panel.

Typically there is an L bracket behind the front panel. Typically there are standoff's from the long part of that L bracket.  Measurements for standoff from L bracket later in the thread.
 
I think your measurements sound about right. I wasn't taking into account the thickness of the PCB.
I am actually looking at the card-slot(terminology?) where the PCB plugs into the back. I know there is some give, but don't want it to be too far off. The outer case of the TG1-500 is an aluminum frame(l-bracket), so i would be mounting the pcb to it with a short standoff. It sounds like the 1/4" standoff is the way to go. I have just had some 500 series units, including commercial ones, that were kind of tough to fit without wiggling around a bit.
Thanks for the help Bruce!
Ian
 
Gemini is right, I am wrong.  Edited my post.

Why?

First, gemini86 made a fantastic 51X module that fits PERFECTLY.

Second... I look at the drawing again and I (we) misread it. The face plate is about 1.5" wide, then the center line is at .75" then the 0.438 dimension is apparently to the top surface of the PCB.  There is no dimension for UNDER the PCB given, and the drawing doesnt provide an L Bracket carrier, but:

1.5" - 0.75" -0.438" = 0.312" from bottom (left) side to front of PCB then continue... -0.063" (typical PCB thickness) -.06 (L bracket thickness)  =0.189" standoff between Lbracket and PCB ( and as Rodney said, 5mm is closest size).

My previous incorrect post edited
 
I tried .25 inch standoff first, thinking it would be close enough, and it is, mostly. The problem is that everything will be slightly bent and shifted out of it's designated little space. If you have a bunch of DIY open frame modules, that's fine. But, try to fit a fully enclosed commercial module to the slot on the left, and it will bump with the bracket next to it and won't plug in.
 
Keep in mind that 500 series is an American design, metric measurements will always be a little off.  In 60s and 70s America, I don't think it was as easy to get metric parts as it is today. 

That said, when we did the first run of the EQP-1S5 we used something close to 5mm standoffs (with a washer underneath), and the module passed VPR spec. But it depends on the thickness of the sled as well, and how much you want to have it protruding from the left of the faceplate.

Also, the 0.438" is to the CENTER of the PCB, not the edge.
 
mitsos said:
Keep in mind that 500 series is an American design, metric measurements will always be a little off.

Say what? Last I checked metric measurements converted to their stateside medieval equivalents absolutely perfectly. There is no fudge factor involved.
 
You can't seriously believe there is no fudge factor:  0.25" = 6.35mm.  0.35mm? Not counting CNC, how many people can measure that accuracy on their drill press? Maybe you can, but I'd bet the average person can't.  But a quarter inch is a quarter inch, everyone can measure that.

When you stay within one system or the other, these issues are non-existent (no one in their right mind would ever design something in the metric system 6.35mm wide/high/long/whatever, they'd probably do 5mm.  But 5mm becomes 0.19" which might get rounded to 0.2" or whatever. So you'd get errors going that way too. 
 
mitsos said:
But a quarter inch is a quarter inch, everyone can measure that.

If you could please enlighten us how one can achieve more accuracy using metric system vs. inches.  :eek:

When an inch is an inch, where does 6.35mm change to anything other than 6.35mm? Don't people stateside know what division is? That would certainly explain a thing or two.  :eek: Ever heard of Mars Rover?
 
when did you become a troll?
 
Do you really not understand what I wrote? Your post about there not being fudge factor is uninformed. I don't understand why, but all europeans get bent out of shape when talking about imperial vs metric.  I've lived in the US, EU, and south America, and speak from experience with fabrication in both units of measurement.  If you read my post, I said there is no problem if you stick to one or the other system, but when you go from one to the other, there definitely IS a "fudge factor."

 
Look at gun ammunition. Lot's of people thing that .308 inch = 7.62mm... well it's not so. .308 inch is 7.82mm. a straight .300 inches is 7.62mm, but nobody get's that specific.

The fudge factor only applies to certain things: guns, low precision hand tools, automotive.

That being said, I don't think it's impossible that api was using metric in the 60s and 70s. There was a lot of german equipment, cars, motorcycles, etc. being sold in the US, metric was making it's way around. They didn't have mouser or digikey around with thousands of parts in stock to choose from, so I would imagine most of their parts were manufactured for them to their specs.

Just be clear, I'm not claiming to know anything for sure... forgive me for speculating. I just know that with a typical L bracket being used, a metric standoff gives you more pie slices to chose from. 5mm, was what I found to fit according to VPR spec.
 
I use 5mm. That being said, it depends how you design the L-Bracket.
I could design one using 4mm or 3mm stand offs ...
 

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mitsos said:
I said there is no problem if you stick to one or the other system, but when you go from one to the other, there definitely IS a "fudge factor."

I'm not trolling. I'm trying to point out we are not in secondary school or kindergarten making paper airplanes. When you say half an inch, that is a perfect 12.7mm with nothing left to imagination. And we certainly should not be using low precision hand tools, or even talking about them in these contexts. Or get better tools. Even the ancient (50 years a go) mechanical engineers had them.
 
This is a bit different then me making a CAD design from scratch where i can control the paramaters. I am building a kit from Igor, who lives in Israel. The kit came incomplete(missing some of the standoffs and mechanical parts) and there are no physical measurements to go by, so i am trying to get as standardized dimensions as i can, and then reverse engineer so that there is no warp as the PCB goes into the card edge. I am going to try the 5mm standoffs and see if that gets me close enough
 

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