Perma proto mounting holes?
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Perma proto mounting holes?

by wesg on Tue Sep 25, 2012 11:36 pm

I'm going to be using the quarter-sized perma-proto board for my next project, and as I'm designing it, I'm curious why the board only has 2 mounting holes. Assuming most applications need space beneath that require standoffs, why are there two in the middle? Would corner holes be considered for future versions?
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Re: Perma proto mounting holes?

by adafruit_support_bill on Wed Sep 26, 2012 5:02 am

Thanks for your suggestion. We will take it into consideration for future versions.

The basic concept of the PermaProto boards as they are today is to be hole-for-hole compatible with the same-size solderless breadboard. To add corner mounting holes, would mean eliminating some solder holes or making the board bigger.
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Re: Perma proto mounting holes?

by wesg on Thu Sep 27, 2012 2:35 pm

That makes sense. What's the typical, or recommended, mounting configuration? Balancing on the two holes?
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Re: Perma proto mounting holes?

by adafruit_support_bill on Thu Sep 27, 2012 3:04 pm

For most purposes a pair of standard 4-40 hex standoffs hold it rather securely. If it were to be getting regular stress (e.g. if you had off-center push-buttons mounted on it) I'd consider larger diameter standoffs or an edge mounted solution.

And if you are not using the corner holes, you can always drill out those out to accept standoffs too.
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Re: Perma proto mounting holes?

by MetPhoto on Sun Sep 30, 2012 6:35 am

Hi

I was going have a custom case 3D printed for a project. I was wondering how big the mounting holes are on the perma-proto quarter sized board? Also what is the distance between the centres? (Ideally in metric please.)

It would be great if you published the technical drawings for such items.

Many thanks
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Re: Perma proto mounting holes?

by adafruit_support_bill on Sun Sep 30, 2012 6:42 am

I'm at Maker Faire at the moment & don't have one to measure, but I'll see if someone at the factory can get that info for you...
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Re: Perma proto mounting holes?

by cstratton on Sun Sep 30, 2012 1:53 pm

Jumping in as this is a great opportunity to mention a useful technique: We know the board is fundamentally a grid of holes with .100" spacing, and there are good pictures of it taken fairly straight-on, so it should be easy to measure any feature of interest by proportion in a graphics program.

From dividing the spacing of 10 holes, it turns out that the back of board picture seems to be 300 dpi - could be a lucky accident or careful adjustment, but it raises the possibility the picture was made with a flatbed scanner rather than a camera.

From that, the diameter of the mounting holes appears to be .12" - not quite as accurate a measurement as you could get directly from the board (since there's some judging of edge shadow), but fairly close.

This is just under an eighth of an inch, and within measurement error over 3 mm. A 4-40 machine screw should pass through cleanly, and a 5-40 would thread in loosely.

Given the 300 dpi, you could probably print out the picture on thick paper and use it for mechanical fit testing - just measure the grid in both dimensions to verify the scaling came out right.
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Re: Perma proto mounting holes?

by MetPhoto on Sun Sep 30, 2012 1:57 pm

A nice bit of detective work. I guessed around 3mm myself. However the distance between the holes is equally important.

Certainly I am no hurry for the information.

Thanks
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Re: Perma proto mounting holes?

by cstratton on Sun Sep 30, 2012 2:24 pm

MetPhoto wrote:A nice bit of detective work. I guessed around 3mm myself. However the distance between the holes is equally important.


You should be able to find that yourself, or ballpark it by just counting rows.
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Re: Perma proto mounting holes?

by adafruit on Mon Oct 01, 2012 9:46 am

Drills are 0.12598425" and are precisely 1.4" apart
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Re: Perma proto mounting holes?

by MetPhoto on Mon Oct 01, 2012 9:54 am

Thank you for the prompt very reply.

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Re: Perma proto mounting holes?

by araugh on Wed Dec 05, 2012 9:23 am

Is there a datasheet or any CAD available for the mint tin mounting perma-proto board? I'm trying to find out what the overall dimensions of the board and specific dimensions of the mounting holes are.

Thanks!
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Re: Perma proto mounting holes?

by adafruit_support_rick on Wed Dec 05, 2012 9:30 am

This is from the product page. I'll see if I can get the spacing of the mounting holes.
30 rows of double 5-hole rows + 80 individual holes
4 power rails with positive/negative markings
3.6" x 2.24" (92mm x 57mm), 0.063" thick FR4
1.2mm / 0.047" drill holes
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Re: Perma proto mounting holes?

by araugh on Wed Dec 05, 2012 9:33 am

Spacing would be a huge help, Thanks!
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Re: Perma proto mounting holes?

by matt_adafruit on Wed Dec 05, 2012 10:10 am

Hello araugh!

Here is something that might be interesting to you. We have been sharing a Fritzing parts library for Adafruit here that I used the other day to make a mount for the Perma Proto units (you can export svg files etc from the free app Fritzing once you work out your circuit): https://github.com/adafruit/Fritzing-Library

This is one way to grab the details accurately for making a CAD model for enclosures etc!

Thanks,
Matt
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