Re: StlWork beta progress & 3D inexpensive modelers

> Date: Thu, 31 May 2001 21:57:10 -0600
> From: Doug Fortune <pentam@...>
>Subject: Re: StlWork beta progress & 3D inexpensive modelers
>
>A question about the waterline toolpathing and its efficiency:
>
>- Lets presume I have "lots of islands" separated by big distances
>(such as Pacific Islands in the Pacific Ocean), and I want to use waterline
>tool paths.

Hard to program is always relative. ;-) One of the hardest things to program appears to be constant climb milling. It's fairly easy for mountains and valleys, but when you allow designers or NC programmers to select or design models with disrupted sections, it becomes important (even if difficult) to determine which direction is Climb & which is Conventional.

With the present beta we have not yet optimized the toolpath between isolated mountains or valleys. We have controlled the rapid height between rings so that the cutter can rapid from one side of a canyon to the other without having to retract all the way to stock clearance height.

In the present StlWork beta, it is possible to individually select each island and develop an independent cutting strategy for each. The selection criteria include X-Y-Z physical boundaries, geometry of the model within the X-Y-Z area, and male or female surface. Each of these is controlled separately, and the model geometry overrides the X-Y-Z criteria, within the defined zone.

The efficiency from waterline or constant Z level finishing, is from elimination of the weak Z axis, and improved surface finishes around vertical and near vertical sidewalls. Most home/hobby CNC machines and many industrial strength machines have slower feed rates for the Z axis. On machines like Sherlines, routers, and even Z-quill driven Bridgeports, the Z axis is like a limb recovering from Polio. It's weak, has more inertia, and if not counterbalanced, also gravity to fight. The waterline cutting strategy lets you mill in flat planar patterns at the fastest speed your cutter and material can take and still hold dimensional accuracy. In many cases with materials like plastics, wood, or even aluminum, this speed is closer to the X-Y rapid rates and nearly always faster than the Z max rate. I have been able to cut complex 3D models in wood on the Shopbot here in 6-30 minutes that others have claimed MUST take at least 3-4 hours to cut. and... we are still debating if we will add arc fitting to the rings, that will be another immense improvement for machines that handle continuous contouring poorly, but do a good job on arc interpolation, not to mention massive reduction in program size.

Also I forgot to mention these two with usable/low cost solid modelers:

DesignCad $395 V-3000
Turbocad $399, IMSI, V 7,ACIS based, WOW!

Url is product name.


Best Regards, Fred Smith- IMService
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