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I printed a clamp the other day. It has a hole that I tapped for a screw thread (1/4-20, but that doesn't really matter). I noticed as it was printing that the hole in the part was printed with just a layer or two of ABS around it, and then it went to the crosshatch filler pattern.

Is there a way to make holes in parts have more plastic around them (make them more solid) so that when I tap them there is more plastic for the screw to bite into? I want to leave the infill as it is (I don't want to make the whole part solid).

Thanks,
Darren

Adjust the slicing settings. In MatterSlice or Slic3r and some others, it's specified as number of perimeters. In Cura, it's called out as shell thickness, I believe. When defined as a dimension (Cura) the value should be an integer multiple of the extrusion width.

Seems relevant.

http://formlabs.com/en/company/blog/201 ... ted-parts/

What I do if I need to have more shells in a certain area is make a super thin wall cut(.0001") concentric with a screw hole as deep as I need it, it treats this as another wall and creates more borders in that area, and since the cut is so thin it actually bonds up nicely and makes a thick spot.

You can see it in this picture - this is the bottom of a part printed on a raft so the first layer doesn't look super nice but I wanted the part on the other side of the flange to be super strong, and it is.

[img]http://i.imgur.com/UqTL3qP.jpg[/img]

Very interesting trick. You basically put your 0.0001" cut once every nozzle-width out from the wall for as many perimeters as you need, right? Clever...

So that would actually be 2 parts in my modeling program? The inner sleeve and the outer flange, separated by .0001"?

On a semi-related note, what is the smallest screw thread you've been able to print out? I created a 1/4-20 bolt in solidworks and tried to print it out just for kicks, and it did not work very well. The threads are a mess.

Darren

It does not need to be 2 distinct parts. Just a cut that goes down until the last mm. (ideally where you have your solid layers and the infill has not yet started.

Very nice trick btw. This will make drilling out the holes a much simpler process. Thanks.

The cut spacing would be 2x wall thickness - so if you do 2x .55mm layers, every 2.2mm you'd want a cut if that is what you wanted. And no you don't have to go all the way through the part unless you want to. If you run 4x .25mm layers - you'd have 1mm top and bottom, you could start the cut 1mm in and end it 1mm before the end of the part - when you do a cut extrude in SW, the first option is to set the cut plane/surface, etc. You can offset it in there, then end it offset from the opposite surface.

Solidworks will save a multi-body part as a single STL file - I know S3D will treat it as such, not sure how other slicers do it.

I'll go to McMaster Carrs website, and download the solidworks file of a bolt or screw that has the thread pitch I want. I then insert it into the part and do a subtract, leaving the threads behind. After printing, I'll run a tap through them to clean them up. Sure beats doing an extrude cut along a helical path.

This is great and I had never thought of it before. Now how does one unlock the downloaded .STEP File?

nitewatchman wrote:This is great and I had never thought of it before. Now how does one unlock the downloaded .STEP File?

I have had no problems using the solidwork files with solidworks.

Using Design Spark and the .STEP files come in Locked with no Unlock Icon. Don't have Solidworks at home.

strange, does design spark use iges files?

Unfortunately not.

Just downloaded a step file, and opened it with solidworks. Must be design spark is being finicky?

I know there's a trick to do it, but it is possible to unlock the STEP file in DSM. I forgot what it is off the top of my head - let me noodle on it for a bit.

EDIT: Got it! Here's the process:

1. Open the STEP file in DSM.
2. Copy the components you want into another design that you can edit.
3. Move the copied components into their own New Component, and activate that component.
4. Insert a new dummy solid into the component. Doesn't matter what it is.
5. Right click on the component that contains your copied objects and your dummy solid, and untick Lock option.
6. Everything underneath should become unlocked, including your copied STEP components.

Not sure all those steps are absolutely necessary, but that's what worked for me. Also, I use an old version of DSM (2012.1.2.02111), so I don't know if that same method works in the most recent release.