Modelling for 3d printing

[mashton-2]

I have been asked if we can have something on models for 3d printing that we can use as a reference to measure the the printed part to confirm it's accuracy without having to fully dimension a drawing or measure every feature. Of course the easy answer would be CMM but that is not available. 

So some kind of fiducial would seem to be the next thing to look at.

Does anybody do this? If so How?

[StephenW]

Make a critical dimension drawing with only the dimensions that you need checked.

Or a drawing with just a horizontal/vertical dimension, basically verifies print scale in both directions.

If you don't want a drawing at all, make a model of a 1" scale (or your favorite size/units equivalent) and use that as a cutout on each of your models.

My preference would be a critical dimension drawing, if you are really concerned about the quality of your part, then likely you are really only concerned with a small number of critical dimensions, just check those.

[mashton-2]

Stephen

We call it a Key point drawing but that is exactly what we do to go with the STEP file for machined parts and have done for 3d prints to date. 

I personally think it is a good method.

The idea of a model of a scale is interesting I have passed it on to my colleague so we will see what he makes of it.

I will give it a bit longer before I accept the solution.

[tbraxton]

I would ask what the impetus is behind adding a fiducial to a 3D print? Most professional grade printers have calibration protocols and when operating within nominal conditions would specify tolerances on any printed feature and layer build thickness. I have never seen the need to add a reference to the printed part. I will just measure the part if I suspect it is not within spec. I do not use 3D printing for production parts so maybe you have a different scenario.

You could print a scale reference on the build platform next to the parts that is easily measured. This would be analogous to the scale reference on a 2D drawing. I would use a round hollow boss as this would give you x,y,z features to easily measure.

[mashton-2]

Thanks for the response. I admit I was a bit nonplussed when the question came up. I need to get a chat with the 3D Printing guy as it came to me from a production engineer so a bit second hand. 

Though I have modelled for 3d printing for about 30 years (when we used to call it stereo lithography and rapid prototyping) I do not consider myself an expert in the field. 

We do make production parts using 3d printing and it can get you out of a hole sometimes but sometimes people use it in inappropriate situations.

I like the round boss idea.

[Catalina]

Hi @mashton-2,

I wanted to see if you got the help you needed.

If so, please mark the appropriate reply as the Accepted Solution or please feel free to detail in a reply what has helped you and mark it as the Accepted Solution. It will help other members who may have the same question.
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Thanks,

[mashton-2 · Accepted solution]

After having a conversation with the guy driving the issue, it seems it certain parts with more free form shapes curved ducts and the like that are the problem for inspection. So a CMM system is the best answer, it is likely that we will have to get one (crazy that we don't have one - best not get started on that). Another possibility is the use of a 3d scanner - we have one of those.