Ok, I was trying .zip and .stp. I renamed the .stp to .step and it was accepted.
The attached STEP file is a model of the 1985 rev B cover. This is not the final version. This model was based on conventional measurements using scales, protractors, various calipers and radius gauges. I feel confident that most of the external dimensions are accurate within 1/64". The exception is the depth of the recess for the knob on the right side of the cover. I had no accurate means of measuring the depth of this vertical face from a face with a compound angle.
The interior details do not conform to the actual part. Being a slush casting the faces are irregular and each part would be unique. I did attempt to accurately represent the machined faces and to approximate the corner radii. I did not add the glued in pieces that receive the threaded inserts or the pin and surgical tubing for the interlock.
After I have the scan data I will make whatever adjustments are required, such as the depth of the knob recess.
The STEP file was created in Siemens NX 11.0. Let me know if it downloads and imports without issue.
model4.step (1.1 MB)
I found a few interesting features while measuring the part. Here is a summary:
This part was slush cast not injection molded. This allows for manufacture of plastic parts with accurate external features but not internal features. This is cost effective in that manufacture required only the female mold cavity with no male core.
There are some internal surfaces that have been machined to provide clearances or an accurate mating surface for internal components such as the threaded inserts and interlock pin.
The shape of the base of the unit is a trapezoid and not a rectangle. There is a side angle of 0.536124°. This angle is derived from the large top faced being angled at 15° and the sides having a draft angle of 2° and is intended to make the large top face rectangular rather than a trapezoid. I would never have known that from the screen caps.
I believe all of the openings thru the cover were machined and not cast. In some cases depressions were molded and then machined off. This includes:
• The round hole at the top of the cover is machined thru.
• The diagonal ventilation slots on top of the cover are machined thru.
• The openings in the horizontal ventilation slots in the rear of the cover. The slots and ribs were molded with a depression for the closed slots mounded at the bottom. then machined off.
• The vertical part of the opening for the sample in the vertical face was machined thru.
• The horizontal part of the opening for the sample in the horizontal face was molded as a depression and then machined off
• The rectangular opening for the control panel was molded as a depression and then machined off.
• The triangular opening for the transport knob was molded as a depression and then machined off.
With this understanding and looking at the two desktop medical devices, it's possible that these may have been factory rejects where the diagonal slots where never machined, or they might be from an earlier "rev A" version of the machine and the slots were added starting with "rev B".