Need help with a case.

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theboz1419
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Need help with a case.

Post by theboz1419 » Tue Oct 04, 2016 6:31 am

http://www.thingiverse.com/thing:1700586

I have been having tons of issue printing this case for my customers. Everytime I print it it wants to pull away in the corners. I have tried hairspray, glue, ABS juice, heating my enclosure to between 120°f and 130°f can go hotter if needed.

Nothing seems to work. Tried different ABS rolls with same results. I have been talking to the designer of the case and he has made some changes, but the changes have not helped. The older version of a case we made prints great, but the walls are not has high(half the height). The newer case is for newer Raspberrypi's and a newer version of our BBQ controller.

My abs temps have generally been about 240° and my bed temps at 110° the material I'm using is from Fry's, I also tried makergeek and they both warp the same.

Any help would be very much appreciated.
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ednisley
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Re: Need help with a case.

Post by ednisley » Tue Oct 04, 2016 2:25 pm

theboz1419 wrote:it wants to pull away in the corners
Unfortunately, that design doesn't take into account how FDM 3D printing works, so it's always going to be difficult.

Those stylin' 45° chamfers around all the bottom edges mean that the (relative thick) walls are only half-attached to the platform. As the plastic cools and shrinks, the highest stress appears at the corners where only the inner 1/4 of the joint attaches to the platform: the stress easily pulls that tiny patch free.

Removing the chamfers would definitely help, although 3D printing large boxes always tends to have iffy results.

Adding large "mouse ears" extending from the corners would also help; make them two layers thick to get reasonable bonding, then remove them after printing and fix up the scars. If you're already finishing / painting the boxes, maybe nobody would notice the blemishes.
the walls are ... half the height
That helps by reducing the plastic area applying force to the bottom layers, but the real problem remains the lack of platform contact area under the walls.

Get rid of the chamfers and see how that changes the results...

theboz1419
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Re: Need help with a case.

Post by theboz1419 » Tue Oct 04, 2016 6:13 pm

Thanks, I will let him know. I didn't like how the chamfer looked anyways.
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insta
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Re: Need help with a case.

Post by insta » Wed Oct 05, 2016 1:16 am

You can also try chasing the print head around with a heat gun, to de-stress the part.
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Tim
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Re: Need help with a case.

Post by Tim » Wed Oct 05, 2016 1:19 am

insta wrote:You can also try chasing the print head around with a heat gun, to de-stress the part.
Interesting idea. How well does that work?

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insta
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Re: Need help with a case.

Post by insta » Wed Oct 05, 2016 4:37 am

Tim wrote:
insta wrote:You can also try chasing the print head around with a heat gun, to de-stress the part.
Interesting idea. How well does that work?
*shrug* no idea :)
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zemlin
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Re: Need help with a case.

Post by zemlin » Wed Oct 05, 2016 1:20 pm

i have had the best luck printing ABS on PEI over aluminum with a very light coat of ABS juice and a 105C bed temp. My printer is not enclosed. I've printed some pretty large, sturdy parts with no lifting or warping. I have settled on Hatchbox ABS, but I haven't used many others - just getting great results so why look elsewhere.

PEI will stick to ABS without the juice, but with it I find the 1st layer requirements are less critical and my success rate is much higher.

theboz1419
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Re: Need help with a case.

Post by theboz1419 » Wed Oct 05, 2016 8:31 pm

The ABS juice worked the best, and probably would work with the enclosure temperature of 130°, as it did not warp as much. But, the face that is attached to the build plate needs to be perfect as possible, and ABS juice leave a surface that I don'tlike.

Insta- LOL, would 1350° be enough, hehe.

While my wife and baby are in Malaysia, I'm going to build a new enclosure using the heat gun as the heat source, and to control the temperature, I build thermocouple wifi controllers for BBQs that will control a blower and servo(if needed). I will connect the controller to a SSR and I will be able to turn of and on the heat gun to control the heat and have a servo controlled a vent, if needed.
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zemlin
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Re: Need help with a case.

Post by zemlin » Wed Oct 05, 2016 8:37 pm

Does it need to be ABS? PETG builds nicely on Kapton over Glass.

theboz1419
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Re: Need help with a case.

Post by theboz1419 » Wed Oct 05, 2016 9:42 pm

zemlin wrote:Does it need to be ABS? PETG builds nicely on Kapton over Glass.
Nope, but I had some request Abs and some colors are only Abs. PLA also works, but tend to have warping in hot climates and being near hot grills.

I printed a case with makergeek yellow transparent PETG and it came out pretty good on a older style and less problematic case. I also print a servo controlled air inlet valve, and Petg is more sticky then Abs when the parts move over each other. But, PETg does work.
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