no shrinkage resin!?

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IrgendwerAusIrgendwo
Posts: 18
Joined: Wed Mar 05, 2014 3:48 am

no shrinkage resin!?

Postby IrgendwerAusIrgendwo » Sat Apr 12, 2014 4:18 pm

Hey,

I've designed a SLA Printer with a build plate of 240*135mm (1920 resolution *1,25):
If I would use a resin with even 1% shrinkage a part with e.g. 200mm dimension would shrink around 2mm! :shock:

...so: is there a resin with nearly zero shrinkage rate?

Finhead
Posts: 276
Joined: Fri Jan 31, 2014 12:56 pm

Re: no shrinkage resin!?

Postby Finhead » Sat Apr 12, 2014 5:28 pm

That's not quit how you figure shrinkage I don't think. Here Darren posted this up thought it was pretty good to have on hand. :)
"A quick way to get your part scale for resin volume shrink is to take the cube root of the shrink percentage + 1. I hope I'm saying this correctly.

For example: MakerJuice SubG+ shrinks at 3.5%

1+3.5% = 1.035
1.035^1/3 = 1.011533...

So now you can scale your part by 1.011533 in x, y, and z. This should get you close and you can tweak from there"

And as far as low shrink resins Fun To Do is the lowest I found but it is not a very hard resin even after curing it is very soft. If you printing mostly small pieces or fairly thick walled you might be fine. My last large print at 2mm thick walls was so soft during the print it moved around so much on the Z it had very nasty banding. Small stuff or solid pieces print very very nice though.

Clinton

IrgendwerAusIrgendwo
Posts: 18
Joined: Wed Mar 05, 2014 3:48 am

Re: no shrinkage resin!?

Postby IrgendwerAusIrgendwo » Sat Apr 12, 2014 5:38 pm

Finhead wrote:1.035^1/3 = 1.011533...



Ok that means that 3,5% is VOLUME shrinkage not dimensional shrinkage! :D

However: when printing e.g. a part with 200mm I think I will still not be able to print the first layer on the build platform directly as the shrinkage is too high: having the support material between platform and first layer of my object will hopefiully solve the issue!

Finhead
Posts: 276
Joined: Fri Jan 31, 2014 12:56 pm

Re: no shrinkage resin!?

Postby Finhead » Sat Apr 12, 2014 8:01 pm

IrgendwerAusIrgendwo wrote:
Finhead wrote:1.035^1/3 = 1.011533...



Ok that means that 3,5% is VOLUME shrinkage not dimensional shrinkage! :D

However: when printing e.g. a part with 200mm I think I will still not be able to print the first layer on the build platform directly as the shrinkage is too high: having the support material between platform and first layer of my object will hopefiully solve the issue!


You pretty much always want to use support and angle your prints on a DLP printer so you don't destroy your VAT coating by repeated exposure. Nice little tip form Jon Watson works great to prolong your Vat coating. You'll figure it out after a few prints.

Clinton


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