HELP: Dimensional Accuracy on Makerbot Rep2X

[SteinbrinkEng]

I know there are previous posts on this, but haven't found a solution to it yet.

I'm essentially trying to print a part that seems to be too small compared to my CAD model. It seems that the overall scaling is off, but i've checked this. One critical feature is a cylinder with an internal diameter of .65". When it's printed, it measures .61". I'm printing with Taulman Bridge, so I expect to see a shrinkage of 2%, but where is the other 6% coming from? For now, I've scaled the part by 8%, but I'd like to nail down where the issue is stemming from.

What do you all think what could be causing this? I want to point my finger at the machine configuration, but I'd rather not touch it, as i'm sure the S3D crew did a good job with the initial settings for the Makerbot Rep2X.

Any ideas?

Cheers,
Nevin

[wirlybird]

In my experience with making cylindrical parts like a bushing I have had to make the inner hole a bit larger than spec to accommodate for the plastic. For instance I have a 2mm hole and had to make it something like 2.2mm so the part would fit.

I think if you search the forums you will find a lot of talk on this subject.

[SteinbrinkEng]

The issue i'm having is that the hole is off by 1mm. This is not a difference in the thickness of the extruded plastic. We're talking about 2-3 thicknesses. The issue is larger than an extrusion multiplier.

[horst.w]

If possible attache your .factory-file here (>File>Save as ..)


H.

[dorsai3d]

Are you using an actual Replicator 2X? Because I the Replicator 1 Dual steps/mm numbers are about 6% different from the 2X (94.1 vs 88.5), and most dual extruder Makerbot clones are actually Rep 1 Dual clones, not 2X clones.

[dkightley]

One thing to bear in mind is that you make printer or setting changes to get an inside diameter slightly larger, you're going to affect the overall object dimensions as well.

Have you checked the overall dimensions compared with the design dimensions?? If they're within an acceptable range, then the best way of getting the hole size right is to adjust the size of the CAD design. I always have to adjust dimensions to get a good fit between two parts...both rectangular and round. By how much comes from experience......