No, this was done with v2.52. The before boolean model is in the file. The object named "insert heel." I also included the cube I used to do the boolean.

-Randy

Hi Randy, it may be something involving tolerances and the pretty small size of some of the individual features that you've got in the model.

I produced the attached version in the current v3 beta release by first scaling up your objects by 10 times in size and then doing the boolean, and it seems to be going ok now.

There's a tolerance involved when any intersection operations take place, and when that tolerance becomes close to the actual size of individual pieces of your model it tends to cause things to get collapsed or glued together in ways that you don't want to have happen, that's what can produce the kind of result you saw originally.

So you may want to increase the size of your model by about 10 times in scale before continuing to work on it to avoid running into this problem too much, to do that select your object, run Transform > Scale, type in 0 and push enter to specify 0,0,0 as the scale origin, and then type in 10 as the scale factor and push enter.

I do have some things in place that tries to adjust the tolerance to suit the overall size of the object but that doesn't work too well when you've got something that's somewhat larger in one direction like your shape here.

- Michael

Michael, thank you so much! You have an awesome program! Just some snags for me every once in a while. Great support!
-Randy

Hi Randy yeah so this kind of thing is a kind of difficult case to get an automatic tolerance mechanism to work very well with.

The overall object size is about 2.4 units across, so the relative tolerance mechanism looks at that bounding size and decides that a tolerance of 0.001 units would be a good tolerance for that.

But some of the individual cylinder fillets you've got in this piece have a radius of only 0.002 units - that's too close to the intersection tolerance and when the fitting tolerance is too close to the size of entire edges like you've got here it becomes easy for some things to glue entire edges to one side (since both sides of the whole edge are within tolerance of some other piece that it's intersecting or measuring against).

If you scale your object up by 10x in size, you'll have an object size of about 24 units across and the relative tolerance mechanism will still pick a fitting tolerance of 0.001 units for this (it uses that for anything between 1 and 100 units across), but now that fitting tolerance will be small enough in comparison to those individual features that accurate enough intersections will get generated.

Generally I'd recommend not creating things at too small of a scale like where individual edges or radius values are approaching very close to 0.001 units in size, instead try to scale such an object up by either 10 times or 100 times so that individual pieces are more like 0.01 units across or so instead of nearly 0.001 units across.

- Michael

Thanks for that explanation! I will make sure I scale models up.

I have an additional question about units. A client of mine provides models that they create using inches. How can I import their STEP file so that the model is an accurate size to begin with? They seem to import around four times too small.

Thanks, again!
-Randy

Hi Randy,

> How can I import their STEP file so that the model is an accurate size
> to begin with? They seem to import around four times too small.

You'll need to tell MoI what units your current file is in, then when you do an import of a file that has a different unit system it will know how to size it correctly when it's imported.

To set the current units go to Options > General, and use the "Unit system:" dropdown, it's the one at the top:




- Michael