PSU bracket remake ?

STF clone project.
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exxos
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PSU bracket remake ?

Post by exxos » Fri Aug 10, 2018 7:41 pm

Was actually thinking about the metal power supply plate, mostly in terms of the remake project, also maybe use with normal Atari's as well..

If anyone is up for the challenge of creating and printing out the power supply bases, could probably be used for my new power supplies, and indeed intention for the new motherboard as well. Not really any need for metal and I'm sure with a little tweaking it can be made out of plastic instead (3-D printed).

Of course the back part where the mains connector and main switch go without be made out of thick plastic but I don't think that would be a problem anyway. The fixings where the bracket screws into the motherboard would have to be made out of plastic pillars and a longer screw used, but there is space to do that and would solve that problem as well..

In terms of my latest power supply it does not need any metalwork for cooling. But of course other power supplies could be used as well, in terms of remake project, a general 5V brick PSU could be mounted internally on a special bracket for example.

It is probably one of them silly things which may well be cheap enough to get injection moulding done.. Main problem I have is my power supplies do not include the metal framework for obvious reasons, I think people would rather buy complete unit to simply swap out.. I do have some metal frameworks some power supplies probably next year, but with no sustainable source of these, I think a 3D printed one would likely be the way to go..

So if any 3D designers are up for doing this...
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sandord
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Re: PSU bracket remake ?

Post by sandord » Mon Aug 20, 2018 11:22 pm

I just measured the plate itself being 12cm x 12cm which is EXACTLY the same as the printing limits of my 3D printer. That is, excluding the legs, which extend a little outwards.

So, I could draw the thing and print a prototype, no problem. But, it will not be in one piece, the legs will have to be mounted separately.

I definitely don't want to draw something that I cannot hold in my hands to check it for flaws. So, you'll have to agree to separate legs for me to continue.

I don't think separate legs much of a problem, it's easy to print a connection that locks them in, the weight of the plate and the psu further securing the locks.

Concerning the screw holes where the psu goes, I would embed a nut instead of leaving a simple hole. This provides a much more reliable fit as the plastic will wear off quickly. This might require the use of different screws though but that should not be much of a problem in my opinion.

After sanding and treating the whole thing with
ethyl acetate (I'm printing PLA only, melting point at around 180C), it can give a rather smooth result that could be used to make a mold if you'd want to do that.

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Re: PSU bracket remake ?

Post by exxos » Tue Aug 21, 2018 1:07 pm

sandord wrote:
Mon Aug 20, 2018 11:22 pm
So, I could draw the thing and print a prototype, no problem. But, it will not be in one piece, the legs will have to be mounted separately.
Ahh yep good point.

sandord wrote:
Mon Aug 20, 2018 11:22 pm
I don't think separate legs much of a problem, it's easy to print a connection that locks them in, the weight of the plate and the psu further securing the locks.
If the base plate had a small recess of just 1mm, then a post could slot into it, will hold the thing all stable once screwed (bit like the floppy posts)
sandord wrote:
Mon Aug 20, 2018 11:22 pm
Concerning the screw holes where the psu goes, I would embed a nut instead of leaving a simple hole. This provides a much more reliable fit as the plastic will wear off quickly. This might require the use of different screws though but that should not be much of a problem in my opinion.
Go with how the floppy posts are done.. a simple "tube" which slots into the base plate, even just 1mm will work fine. It will need a longer screw, but thats not really a problem, the floppy screws are long and work fine that way. Case bottom has the "nut", so all it needs is a long bolt, maybe a small washer on top.
sandord wrote:
Mon Aug 20, 2018 11:22 pm
After sanding and treating the whole thing with
ethyl acetate (I'm printing PLA only, melting point at around 180C), it can give a rather smooth result that could be used to make a mold if you'd want to do that.
I might look into a proper mold, I guess it depends on cost of it all.. companies can make molds with 3D files anyway.
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Re: PSU bracket remake ?

Post by sandord » Tue Aug 21, 2018 8:28 pm

I've started do draw the existing bracket, as a starting point for the modifications. I also think it's easier to discuss with detailed pictures at hand.

The only thing missing in the current drawing is the four standing pieces to which the power connector and switch are connected. I'll add those soon.
1.png
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2.png
2.png (35.14 KiB) Viewed 504 times
3.png
3.png (47.71 KiB) Viewed 504 times
Actually, if someone has a 3D printer that supports printing 14.5cm x 12cm models, this model could be printed complete already. I just have to add the four missing pieces as described before.

I'm pretty sure the material thickness has to be increased because (like you already pointed out) the strength is much less than the metal original.

I'm going to respond to your feedback in a subsequent reply.

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Re: PSU bracket remake ?

Post by exxos » Tue Aug 21, 2018 9:07 pm

That looks awesome! My printer bed is 22cmx28cm.. but still trying to get it working right :roll: Hopefully have some time friday...
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Re: PSU bracket remake ?

Post by exxos » Tue Aug 21, 2018 9:38 pm

In fact those raised parts where the PCB screws go into, the whole base can be flat, and just have some raised circles for the PCB to rest on with a hole in middle.. Which then would make sense to using hex nuts in the underside for the screws to go into..
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Re: PSU bracket remake ?

Post by sandord » Tue Aug 21, 2018 9:55 pm

exxos wrote:
Tue Aug 21, 2018 9:07 pm
That looks awesome! My printer bed is 22cmx28cm.. but still trying to get it working right :roll: Hopefully have some time friday...
That's great, I could send you the STL file so you can try it out.

I might print it myself as well, just in parts which should be okay for testing. Don't know when I will have the time though, it will be a LONG print.
exxos wrote:
Tue Aug 21, 2018 9:38 pm
In fact those raised parts where the PCB screws go into, the whole base can be flat, and just have some raised circles for the PCB to rest on with a hole in middle.. Which then would make sense to using hex nuts in the underside for the screws to go into..
Exactly! That was the place where I figured the nuts would go, not so much on the main board.

I agree that a simple standing tube of some sorts will do (with an embedded nut), the original model was clearly designed for using a hydraulic press on a flat plate so we won't need those funny curvatures per se.

At least we know exactly where to put the modifications, now that there's a (nearly complete) model of the original.
exxos wrote:
Tue Aug 21, 2018 1:07 pm
Go with how the floppy posts are done.. a simple "tube" which slots into the base plate, even just 1mm will work fine. It will need a longer screw, but thats not really a problem, the floppy screws are long and work fine that way. Case bottom has the "nut", so all it needs is a long bolt, maybe a small washer on top.
So you're saying we should put 'floppy posts' on the outer holes, the ones that go on the main board? Those would sit upside down in comparison to the floppy posts, as the screw would go top-down instead of bottom-up. Okay, this would mean the base plate would have to be increased in size. I'll have to check against the parts and the shielding if that would work. Besides, I like to try to stay as close to the original as possible, I kind of like the aesthetics of the original :P


Okay, I'm going to draw a proposal as well as soon as I have time. Hopefully that will be this thursday.

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Re: PSU bracket remake ?

Post by exxos » Tue Aug 21, 2018 10:14 pm

sandord wrote:
Tue Aug 21, 2018 9:55 pm
So you're saying we should put 'floppy posts' on the outer holes, the ones that go on the main board? Those would sit upside down in comparison to the floppy posts, as the screw would go top-down instead of bottom-up. Okay, this would mean the base plate would have to be increased in size. I'll have to check against the parts and the shielding if that would work. Besides, I like to try to stay as close to the original as possible, I kind of like the aesthetics of the original :P
Yeah it would make it a fraction wider, or have more plastic on the post parts..

hard to explain.. but like this..

3.png
3.png (53.76 KiB) Viewed 485 times

It would have to be thicker plastic anyway, just make the whole "block" solid and have a long screw top to bottom..

Not sure that would work really... thinking about it, still would need to make the base larger for the "blocks" to be able to screw to something... Can only think making the base larger would do it.. at least around those fixing points...
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Re: PSU bracket remake ?

Post by exxos » Tue Aug 21, 2018 10:20 pm

Actually easier to see from top view... making the purple parts stick out from the base, so that can all be printed flat...

Then those "stick out bits" have a small recess for the posts (like the plastic floppy posts) then they would slot in place and be printed separately..

1.png
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Re: PSU bracket remake ?

Post by Forgottenmyname » Wed Aug 22, 2018 11:42 am

I can't help but think this would be better as a perspex sheet with floppy like spacers added where it would mount to the case and then to the power supply.

If you do 3d print it, I'd probably turn it upside down, will save on the amount of printed support needed.

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