ABS Mold

[jdacal]

Made this for one of my first customers. He provided the link to the STL file. Came out pretty good!

http://www.sciencebuddies.org/science-f ... #materials

ABS Mold

2014-10-24 17.30.08_1.jpg (176.63 KiB) Viewed 12409 times

2014-10-24 17.59.58_1.jpg (148.56 KiB) Viewed 12409 times

[kentd]

Very Impressive!!!

Can you share a little bit more on what this piece will be used for? ( Just curious about the title " ABS Mold " )

What CAD software are you using?

Thanks,

Kent

[jsc]

Nice... but... if you're going to use it as a mold, you're going to want to fill in some of those internal gaps, which will trap whatever you're molding with and either make it hard to demold, or require finishing afterwards. Running a few quick tests, it looks like an extrusion width of .48 or .49 would do it, although I'm not sure how well it would work with a .35mm nozzle.

It looks the instructions call for a soft silicone, so it should work as is, but you may have a good deal of flashing to remove.

[jdacal]

Very Impressive!!!

Can you share a little bit more on what this piece will be used for? ( Just curious about the title " ABS Mold " )

What CAD software are you using?

Thanks,

Kent

Hi Kent, the link in the original post explains the entire process (there are several tabs on that page that you can click on for more detailed info.) All I know is that its for a school project.

[jdacal]

Nice... but... if you're going to use it as a mold, you're going to want to fill in some of those internal gaps, which will trap whatever you're molding with and either make it hard to demold, or require finishing afterwards. Running a few quick tests, it looks like an extrusion width of .48 or .49 would do it, although I'm not sure how well it would work with a .35mm nozzle.

It looks the instructions call for a soft silicone, so it should work as is, but you may have a good deal of flashing to remove.

Wow! Thanks jsc for pointing that out. I've never done a mold before I didn't realize those gaps were not part of the design, but you are correct. Would I need to go to a .40 or .50 nozzle?

[jsc]

I would just run a test print at .48mm and see what happens. You can set up a test print to just print off a few layers out of the middle to see how well the gap in the ribs closes with various extrusion widths: double click the model and move it by -z so that just the ribs are above the bed. And stop the print whenever you've seen enough to satisfy you.

[jdacal]

Thanks! Will give that a try tonight.

EDIT: Cool trick by the way, I didn't know you could do that.

[jdacal]

I would just run a test print at .48mm and see what happens. You can set up a test print to just print off a few layers out of the middle to see how well the gap in the ribs closes with various extrusion widths: double click the model and move it by -z so that just the ribs are above the bed. And stop the print whenever you've seen enough to satisfy you.

I think that did the trick. I tried .48 and it closed up completely along the X axis but still had a very tiny slit on the Y axis lines. I turned it up to .52 and everything closed up nicely with no apparent overlaps. As the print progresses that might change but will post a picture when done.

Thanks jsc I didn't know that setting could make such a radical difference.

[Dale Reed]

I'm pretty sure you just have the .STL file. If you had the original CAD, you could of course tweak the dimensions... Other alternatives might be to scale the part so that the thickness of the rib is a multiple of your normal extrusion width, or to make the extrusion width SMALLER with a goal of fitting exactly three threads there where there's a gap with two now. But you can't really take the extrusion width much smaller -- you probably can't successfully print with the width as small as or smaller than your nozzle diameter.

So Jin gave you the best option first --- his advice is good that way!

I've had to tweak designs to get dimensions to be multiples of the layer height or multiples of the extrusion width, as well as tweak the back end of the process. Most of my stuff is done in OpenSCAD, and the dimensions just naturally show up as parameters that you can make variables and change at the top, or search and replace if you just use numbers as parameters.

Sometimes, you just need to think and design in integer multiples of the layer height or extrusion width -- and you get used to it.

Can't wait to see a video of your silicone grabber in action!
Dale

[jdacal]

Thanks Dale. I'm glad that I ran into this problem as I have learned a lot from this thread. Its not an issue I had in the past so it really opens up my mind to all the options that we have, hearing you guys talk about it. Its one of those learn-by-doing experiences that really opens up your eyes and really starts to get you into the finer details of tweaking here and there to get the results you need.

Thank you both for the great feedback.

I'm not the one doing the mold though so I won't have a video. I think there is a video on the page of the original link I posted. I think they pump compressed air into it or something that makes it grip.