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Clam Shells

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Posted (edited)
2 hours ago, Ksarul said:

Look at the places where studs intersect with the holes in the 32K card (the ones near the card edge, not the ones in the corners). These are your problem studs, as third-party cards almost never have holes at these points, and some will even have components in one or more of those areas.

 

Definitely a good start on a printable file though! Be careful how much you beef up the bottom two corner studs as well--those screw holes often go through voltage regulators/heat sinks.

 

 

The diameters (top and bottom, since it is drafted) are 8mm and 6mm, bottom and top (on the original).  the 6mm diameter is sufficient to install an M3 standoff already.  The beefing is around the bottom, to prevent the post from being sheared off/popped off. It is significantly thicker at the bottom now, and has both a 3mm fillet, AND a 45deg x 3mm chamfer, all the way around.  That should push the extreme bottom diameter closer to 15mm.  Plenty of beef to keep it from being popped off.  Top of the screw post is still 6mm dia.

 

The bottom two posts are slightly shorter (about .5mm? Hard to tell with just calipers) than the top two, and that has been incorporated. 

 

I will investigate the tab situation.  If I can knock those puppies off, the more the merrier. Printing will go faster without all that travel anyway.

Edited by wierd_w

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4 hours ago, wierd_w said:

I dunno?

 

I only have metal TI shells inside my PEB.  The card I grabbed at random was the 32k card.  I am about 45% done with the initial modelling of the clamshell. (90% done with one side.)

 

I have taken the liberty to .... beef up... the studs and screw posts, so that a 3D print would actually be serviceable.  I still need to cut the vent holes, and make the recesses into which the wire pull tabs go. (also needs the M3 standoff holes put into the studs)

 

 

 

 

 

to keep it easy to print, I have made the sticker area not be recessed. I just made a groove in the outer surface of the case to indicate its location. It is recessed in the original PEB card shell.

 

I will continue working on it.  I am unsure if my printer can make this though. If so, it will take up the entire allowed Y axis.

 

 

The metal ones I have come to suspect, were cast.  There is a 2 degree draft angle all over everything.  Incidentally, this means it should be possible to make resin shells. (use silicone mold builder to make a negative of the shell using an original, then pour some resin.)

great start.  maybe for the screw post you can use something like I have done on some of my cases.  Maybe use a knurled brass threaded insert.  something like this:

 

https://www.amazon.com/uxcell-Knurled-Threaded-Insert-Embedment/dp/B07LBQXWZJ

 

It's fairly easy to get the post setup with a small hole to take the insert.  I use my soldering iron to press the brass insert into the post and the plastic melts around the knurling and secures it very well.  

 

 

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For the hinged speech synth enclosure I did, I used M3 brass stand offs.

 

Those have a nice, standard size profile that I can use to model a recess to put them into (Slightly undersize, so I can insert with soldering iron, as suggested-- It's exactly what I did. Used a cheap walmart iron that is no loss if it gets gooed up with melted plastic)

 

The benefit of using the M3 stand off, is that standard computer case screws can then be used, and those are very cheap in bulk.

 

 

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Hi Wierd_w, did you get any test clam shells made up? I'd like to try one.

Thanks,

Dan

 

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I have been working on at least 3 projects at the same time.

 

My coworker has tasked me with getting invitation cards for her daughter's quinceanera in Sept made.. (and thats a lot of cards).
I have been working on getting my printer to like the PVC filament (and printing some much needed replacement components; The originals were PLA, and suffered heat related deformation)

I have embarked down an ambitious project to make some 3D printed cabinetry for my kitchen with the PVC. (It can make use of plumbing grade PVC glue, which I have tested, and yes-- it totally works!)

and of course, working on this clamshell project.

 

I *CAN* however, state with conviction that I think the PVC filament would make EXCELLENT shells. The natural color of the filament is this ugly greenish beige, that seems to suit old electronics fine. More importantly, it is everything ABS wishes it could be.

 

The only downside is that you *HAVE* to print fast with it. (MINIMUM 40mm/sec!)  If it stays in the extruder for any length of time, it scorches and blocks the extruder.  Playing with it without properly configuring flow rates and print speeds, ended up with me inadvertently widening my nozzle from .4mm to .6mm from all the repeated clear-outs.  (I have new brass nozzles arriving sometime tomorrow, according to amazon, but I think I will leave the larger nozzle for this material for the time being.)

 

I really do need to finish measuring and digitally mocking up the clamshell.

 

 

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Posted (edited)

OK. I am test printing the "Side A" of the shell...  It will take 14.5 Hr to complete...

 

I have determined that the claims of the material supplier concerning adhesion are lies. (it does not want to stick to PVA)  However, my initial plan of PVA -> PVC glue seems to work FANTASTICALLY.  The PVC glue releases easily (gentle pry) from the PVA, and the melted PVC sticks to the dried glue like concrete.  Works great, just as expected.

 

The part is really too large to fit "Properly" in my printer's build volume, so I have to angle it funny. (It is positioned diagonally in the print bed to get the maximum reach, and has to make use of quite a bit of Z axis to fit in the volume... I hesitate to use my Z axis, as it is.... Not steady.)  As such, I had to turn on all kinds of wacky supports.

 

Cross your fingers.

 

I will consider it a "Success" if PVC print side A, mates with metal cast side B, with the screws going in.

I almost never get this right on the first try, so...

Edited by wierd_w
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Well.. THe part came out with layer adhesion issues, and split apart while printing. (yay tall prints. YAY.)

 

Part of the problem is that the PVC apparently creeps on the nozzle like PETG does.  I may need to implement a nozzle cleaning brush on the printer.

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I am tired of having models that are too large to be printed in a SANE orientation.  This model is really intended to be printed FLAT, not up in the air in some goofy angle.  Printing it up in the air in a goofy angle is resulting in TERRIBLE prints.

 

As such, I have ordered a printer.

 

15" x 15" build area.  it is more than 2x the size of my current printer, in both X and Y.  It also has an autoleveling bed.  (and the price is acceptable.)

 

I will have no problems printing the shell with it laying flat on that.  I wont feel so afraid of modifying the old printer now either. (STILL want to give it that extend Y axis.)

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On 3/25/2021 at 4:17 PM, wierd_w said:

I am tired of having models that are too large to be printed in a SANE orientation.  This model is really intended to be printed FLAT, not up in the air in some goofy angle.  Printing it up in the air in a goofy angle is resulting in TERRIBLE prints.

 

As such, I have ordered a printer.

 

15" x 15" build area.  it is more than 2x the size of my current printer, in both X and Y.  It also has an autoleveling bed.  (and the price is acceptable.)

 

I will have no problems printing the shell with it laying flat on that.  I wont feel so afraid of modifying the old printer now either. (STILL want to give it that extend Y axis.)

are you planning on sharing your design?

 

 

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Posted (edited)

After testing and fitting, of course!

 

I am presumably supposed to get the printer late in the evening tomorrow.

Edited by wierd_w

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got the new printer put together..

 

It is HUGE.  This is it sitting on my deep freeze.

 

It dominates the space.

 

20210401_071547.thumb.jpg.76a277d17406e59dbaf232cd8dc72d42.jpg

 

 

I am doing calibration now... then will do some benchies.

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I am printing a "Side A" test sample out of the (conveniently provided) White PLA that came with the printer.  IN A SANE ORIENTATION.

 

If I like what I see, I will try the PVC.

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Posted (edited)

UWEEE HEHEHE!

 

The white PLA print looks great!  Screw holes line up, LED lines up with the slot-- all that jazz!  Even got the plastic side to mate with the corresponding metal side! (Using the original screws!!)

 

My cellphone battery is flat at the moment, so it will be a bit-- but once it is up enough to do the needful, I will make some photos.

 

I need to do some minor revisions (I never added the recess for the pull tab, and there is an issue with the LED cutout (it cuts through both sides of the shell... Just an issue with the type of cutout in my cad software. Easy fix.)  and with one of the screw posts trying to 'ever so slightly' collide with a voltage regulator on the 32k card by about half a millimeter, indicating the post needs to be shaved a bit there.) but this bodes **VERY** well for making 3D printed clamshells.

 

 

20210401_235241.thumb.jpg.00f16c988d1bc1b7f9572b9ea67638e6.jpg

20210401_235148.thumb.jpg.05ec333ae42bc2ee700f7fd3a0ddf3e6.jpg

20210401_235102.thumb.jpg.6e1cde74f7941c0f651c2768883c3dc4.jpg

 

and YES-- it DOES fit inside the PEB!

Edited by wierd_w
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Since I dont think any of us really wants to go sourcing suitable wire to make the pull tabs with anyway...

 

I have elected to try something different.  I am going to model on some "pull nubs" at the top of the shell, like this.

 

1623785178_nubside.png.0b00dd8a255ab5940a4c3edd935a0304.png2074635211_nubtop.png.bb883f5f8c699ad822f112e2c7070242.png

 

This should be well within the allowed area inside the PEB, and should not collide with anything-- and still provide a mechanical spot to hold on to when yanking an assembled shell.

 

Any thoughts?

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If I understand the tabs correctly, make sure the back tab doesn't stick out so far it prevents the PEBox cover from seating properly.  I don't have a system in front of me at the moment, so I am not certain if there is an inner lip on the underneath side of the PEBox lid that may limit card length.

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Posted (edited)

The tab is very short. ~3mm extension.  Just enough to get a finger tip under to get some leverage.  The vertical guide flange on side B of the shell extends further.

 

I am about to start printing a side A with the nubs (and with more aggressive print settings. Cura estimates 10 hours)--- I will see how well it lives inside a PEB.

Edited by wierd_w
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OK.

 

New print time was 10hr 45min actual.  That still 3hr 15min faster than last time.

 

Plastic half of shell mounted neatly to metal half. Installed fine.  Lid closes fine.

 

I am about 90% done modelling side B.  I will mess with it later. I work tonight so I have to sleep.  All it needs are the cutout for the LED, some cleanup on the card-out provision, and the screw holes poked, then it should be ready for export and printing.

 

The finger grip nubs seem to work.

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Progress!

 

20210403_160552.thumb.jpg.c7afb57dde40eea8df9769cd4cc4189e.jpg

20210403_160604.thumb.jpg.a43f640fa959efb0424f5806c58ad608.jpg

20210403_160625.thumb.jpg.2219108d12747390aacc2741a135cb47.jpg

20210403_160638.thumb.jpg.b968c4d534213fc39a6a58028765bda6.jpg

 

There DOES seem to be a design error though:

 

The bottom of the shell aparrently needs to be flat and not draft angled (as currently modeled), since i note the assembled module "wiggles" in the PEB.

 

I will have to switch to either surplus desert tan to to blue nylon for subsequent prototypes, since the freebie mini roll of white PLA I got with the printer is getting skimpy on the reel.

 

Still, the shell look quite good, and is fanrastically lighter than the diecast metal one.  

 

I need to unshell a card with a back porch to make sure it properly fits cards with outputs. I have an RS232 card that will suffice for that task.

 

But that 32k look pretty hawt in the new clothes.

 

:)

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2 minutes ago, ti99iuc said:

Wow! it seems to be very nice! :) thanks for your effort in creating this!

I am either getting better at reverse engineering or got fantastically lucky when working with just this pair of harbor freight calipers.

 

:)

 

once I get the "wiggle" problem sorted, i will upload 3D data.

 

I suspect arcade shopper could sell these easily.

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2 hours ago, wierd_w said:

I am either getting better at reverse engineering or got fantastically lucky when working with just this pair of harbor freight calipers.

 

:)

 

once I get the "wiggle" problem sorted, i will upload 3D data.

 

I suspect arcade shopper could sell these easily.

if I can print them.. which I probably will need a bigger printer.. got creality 5 and 3 and a prusa that's currently down 

 

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Posted (edited)

Your creality 5 might be able to do it, but it would be a tight fit.

 

Long direction end-to-end measurement of the model is 206mm.  (my printer has a 200mm max area).  Your Creality 5 has a 220mm x 220mm bed, so it should be able to do it.

Barely.

 

The huge Chiron I ordered is a bit overkill, but damnit, I am TIRED of dealing with the issue of "printer too small" :)

Edited by wierd_w

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I am going to print a set out of the blue nylon.  I have set the new machine up with the material profile, spooled up an empty spool, and resliced with the new material def loaded. (nylon is actually 1.65mm dia, not 1.75mm, so needs to be prodded. Also has a lower melt than the generic nylon preset in cura.)

 

This will have the flat bottom.  See you in a day.

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