3D Toolpaths

[geoff_harman]

I am currently getting quite a few orders for female moulds.
I import the 3D object into Aspire and use it to determine the toolpaths.
The moulds are usually machined in MDF with a rough pass and a coarse finish pass. I then soak the MDF in epoxy and do a final finish pass the next day.
The end result is generally excellent but Aspire being bitmap based will leave jagged edges especially if the edge is slightly off axis.
Previously I would sand them out but now after epoxying the finished product is very hard and it is difficult to sand out the jags without damaging the rest of the mould.
Does anyone have experience of reasonably priced toolpath generators on the market that have ShopBot post processors and are capable of 3D contouring.
I don't need a CAD/CAM system - just the CAM side
Regards
Geoff Harman

[adrianm]

You shouldn't be getting jagged sides like that.

Do you have the resolution set to an appropriate value for the parts? Is there a lot of empty space on the material? Have you created a modelling block for the mould within Aspire first?

It may well be worth posting on the Vectric forum as well as I'm sure it's something that can be resolved by setup.

[geoff_harman]

Thanks Adrian
I have contacted Vectric and they have said the following.
"First of all, bitmap machining packages such as ours are not the ideal
tool for machining model of this type, as angled straight lines in 3D models
will always produce stepped edges of the kind that you have seen."
They have suggested Powermill or Mastercam so I am wondering about other peoples experiences with these and similar packages - particularly where ShopBot post processers are concerned.

[bleeth]

I would imagine that you shared the models with Brian or someone at Vectric to elicit that response. Considering their long previous relationship with Delcam if they suggest Powermill I would believe it.
Something to remember also is the limits that you will hit in machining with a rack and pinion driven machine. At some point you will hit resolution limits that could only be overcome by a different mill.

[bob_s]

Geoff;
I use Aspire and I have been cutting a lot of "impossible" molding shapes lately. They are molding profile wrapped around a curve or sometimes wrapped around a curve and arching at the same time. It sounds similar shape wise as I need to maintain the crisp original profile as it travels in 3d space. I have had better luck by raising the model resolution to "high" it isn't really much slower on a modern computer.
The problem occurs when I need to create a shape, export it as an STL and then import that to wrap another 2 rail sweep over it. Then I found I was getting steps of about .007 to .012. By holding the shift key when you open "set job dimensions" you can choose the model resolution and you can get 2 more choices - extreme and Maximum. If I use Max for the first shape and then tesselate the STL to 100,000 triangles I reduce the steps in the final model to .003 to .005 which seems to be ok in wood.
some shapes do produce steps that are noticeable because of how they catch the light, even if they are only .002 or .003 - I guess that's why they make sandpaper.
Bob