Everything is too tight.

I was just taking another look at the calibration wiki page. There's a model there for checking one object will go in another object, so if you create a plug and a socket, the plug should fit in the socket.

This is important for me as I'm consistently printing things which are the right size, except the holes are too tight. I've just printed something which is supposed to hold a linear bearing and I can't get the thing in the hole, it's a good mm too tight. The calibration page talks about settings which don't exist outside of skeinforge, I'm using Slic3r. Are there any settings in Slic3r I should be looking at?

Thanks

This is a well known attribute of FDM printing. It has to do with 2 main things 1. plastic shrinking inward and that circles are made from straight lines so they "cut corners",

The only cure right now is to print a size chart and calculate hole size based on that or estimate about 1mm extra on holes. Here is the hole chart I developed, it's thin so does not take up much material yet the holes are 1mm increments unlike others that can be 5mm increments [www.thingiverse.com]

I typically print objects at 101% to allow for shrinkage.

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Waitaki 3D Printer

Interesting, I can imagine that working for some prints, but anything with screw holes would end up with them offset by a bit. I'll give it a go though and see what comes out.

Quote
tmorris9
This is a well known attribute of FDM printing. It has to do with 2 main things 1. plastic shrinking inward and that circles are made from straight lines so they "cut corners",

The only cure right now is to print a size chart and calculate hole size based on that or estimate about 1mm extra on holes. Here is the hole chart I developed, it's thin so does not take up much material yet the holes are 1mm increments unlike others that can be 5mm increments [www.thingiverse.com]

Funnily enough I made exactly the same thing up at the weekend. I've had some other issues so haven't printed it yet, but I think yours is nicer, so I'll steal that

The problem is with bits where I've just got the stls. When I'm designing my own bits I can scale bits happily, but it's harder when I download an x-carriage (the item that prompted this post) :/ It does make me wonder whether people are either a) using the parts they are uploading, b) filing bits off like demons, c) using a different slicer.

The slicer option is interesting, an option which does th equivilent of filing a layer off all external surfaces would be pretty damn cool. That would retain the position of holes, but make them larger.

There has been a lot of talk of this and a lengthy thread in the Sli3r section of this forum. The creator of Slic3r has chimed in and he really does not know how to implement this.

While I don't have first hand knowledge I think the program for Replicator gets closer. You can also drill out holes but most things I have printed from Thingiverse were already set up with the holes to print the right size for most printers. All of the items I upload have holes that print proper size.

It's an interesting problem for sure, I think it might be easier to do it at the stl, separate from slicing, as another option. The problems I've had recently are with carriages that take a linear bearing. It's a nightmare edit: drilling out the channels.

Edited 1 time(s). Last edit at 09/30/2014 05:51AM by UkIan.

This won't help for pre made items but when I am designing and I want to test fit, I will print the outside part then print the part with the hole only a few layers and then see if it fits and adjust if necessary. That way I only waste a small amount of plastic if it's wrong.