Threading help. screwing a steel sheet.

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Re: Threading help. screwing a steel sheet.

Postby gcb » December 19th, 2012, 12:41 am

the Nail idea totaly does not work :)

it either wrech the rim, or does nothing usefull.

k-ww wrote:FYI: This is a generic version of the tooling that made that shape:

http://pdf.directindustry.com/pdf/wilso ... 6-_11.html


ah, those trapezoids are driving me crazy, i hate all of them and have to find a way to lower them... i think i will just saw them away.
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Re: Threading help. screwing a steel sheet.

Postby semicolo » December 19th, 2012, 7:30 am

If you've got an M3 tap you must use M3 screws (or I misunderstood what you said).
Instead of a nail maybe one of these punch tools, don't know how it's called in english, a pointy metal thingy used to make a small bump where you want to drill, but I think you'd be better off with nuts or some wider tapped material on the back of your metal sheet.
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Re: Threading help. screwing a steel sheet.

Postby gcb » January 9th, 2013, 10:49 pm

semicolo wrote:If you've got an M3 tap you must use M3 screws (or I misunderstood what you said).
Instead of a nail maybe one of these punch tools, don't know how it's called in english, a pointy metal thingy used to make a small bump where you want to drill, but I think you'd be better off with nuts or some wider tapped material on the back of your metal sheet.


The nail was to simulate the press thing... didn't even get close to working, unfortunately. I thought a hammer could apply the same pressure as a press, but the mechanics are different... easy to see when you do it, but hard to explain. it lacks the support to form the metal.

The tap worked pretty well on 2 to 3mm sheets i tested. the screw go in stay firm until abused for a while, then it gain some play.

sadly on the 1.2mm sheet i will be using, they get some 20° of play right away... in fact, the tap already have play because it's only riding on one, maybe 1 1/2, threads.


well, this is the last pic here, i will be moving to documenting this joke of work i'm doing on the project thread viewtopic.php?f=3&t=3034

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This is the tapped hole on the 2mm steel. even though you can see 3 threads there, two of them are almost on the rim, so they are not 'usable' by the screw as the metal on that rim is firm as butter.

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here is something i didn't imagine would happen with the tap being inserted slowly... it deforms a lot the metal on the exit point. The two holes in front are my taps. the back one is the original, reinforced one. in this case, it's not only just pressed to have more steel area, but it seems there an extra sheet soldered there for more thickness. (this is a reinforcement plate that was holding the heavy transformer for the original receiver)

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And here is just me being dumb. tried to insert the screw directly into the 2mm of steel after having drilled a hole with the diameter of the inner threading... it did worked like a tap for a while, but while trying to remove the screw it went ...no idea the word to use... in Portuguese we say the screw went "blind" or "spanned". you can see the portion that i managed to move out as it's 'polished'... that screw has no play though

*edit: on the last pic, on the left side, you can see more pics of the simple pressed rim we were talking about doing with the screw.
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Re: Threading help. screwing a steel sheet.

Postby semicolo » January 10th, 2013, 9:54 am

What about self tapping screws? http://www.mcfeelys.com/self-tapping-screws
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Re: Threading help. screwing a steel sheet.

Postby gcb » January 10th, 2013, 1:10 pm

semicolo wrote:What about self tapping screws? http://www.mcfeelys.com/self-tapping-screws


hum, had never heard of them... but from that page i guess they would not work for me as the max thickness is 0.5mm (if i converted right... damn imperial units :)

but the goal of those holes is to host those Hexagonal Standoffs to hold the motherboard... i think it will be impossible to find those with self tapping capabilities. Specially since they are all made from brass, which would have a hard time doing anything to steel.

also, an update on this... i did all the holes, threaded them, and when i attached the hex standoffs (which finally arrived from china. impossible to buy local) they magically get stable! the base of the standoffs plus the single thread combine to make a perfect fit and there's no play and it does not get loose easily.

i will still use the nuts just because i may loose them with constant screwing in and out of the mother board. but otherwise, the one thread would suffice. i would use threading glue but i'm afraid it would impact the grounding, so i will just torque the hell out of the nuts, which is also cheaper :)

Edit: realized that the carefully measured mask of the motherboard i had to use while drilling the holes was used backwards :/ now i should learn to not trust my markings done from more than 2 weeks when doing something.
cursed for 2 hours straight yesterday. now i'm considering mounting the motherboard upside down

edit2: i'm tired is screwing holes in this case... Enough is enough.
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Re: Threading help. screwing a steel sheet.

Postby Dragonwim » January 30th, 2013, 1:11 pm

From a machinists point of view, I saw get a center punch, pop an indent ion in the spots that you need holes, then hand drill those spots with the recommended drill for your tap size.
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