Purple Crayon

There have been several inquires about specs for Cassius when used as a mill – so a general posting seemed in order.

In anticipation for Beta testing the mill just underwent a lot of changes. Each axis was grown by a few inches and a bunch of little things identified in early testing were fixed. We switched vendors for the laser cut parts and are currently waiting to get a quote from a laser cutting vendor to make sure there are no problems producing the new larger design. Should be soon. We are committed to no vaporware – so we wont post specs from our SolidWorks models alone. Instead, we are waiting until we have one of the new designs running will post specs measured off a running mill.

Also, all the pictures on the web site are of our current run of prototypes. We deliberately kept the number of shots of the new design to a minimum. Our plan is to post a number of detailed photos of the new design with the specifications. To be honest though, we only spray painted our current prototypes to easily color-code them with revisions (black box, blue box, red box, etc,). So another part of the reason we have been waiting on getting the new mills to go nuts with photos is we want to take pictures of one with a decent paint job.

Once we get some of the new version built there are also plans for destructive testing of a few mills testing rigidity, wear, glue strength, drop testing, and just generally trying to measure what it takes to break them. Up until now we have not had any real problems – but then we have been working with the units as prototypes and not doing things like intentionally dropping them on the floor. After destructive testing we plan on updating the specs again to reflect the results the tests, and add suggestions of worst-case usage.

Mounting the flex shaft of a rotary tool, or the tool itself, to the mill provides a surprisingly high quality high-speed cutting spindle for cutting PCB boards, wood, and plastics. However we will be advising our customers to not cut metals with Cassius.

For soft materials like wood or plastic mills can cut the part out in two types of cutting passes; roughing passes and then smoothing passes. The roughing passes remove most of the raw material down to within some close distance to the final finished part. The smoothing passes are slower removing much less material and cutting the part to the final desired shape and smooth surface finish.

To be able to cut even “soft” metals like brass, aluminum, or softer steels – smaller mills need to break the cutting up into a much higher number of smaller passes. Essentially there is no roughing pass – just a really long smoothing passes. So if the user wants to cut out a one inch thick piece from a block of aluminum, with an aggressive (for a small mill) cut depth of 2/1000th of an inch – it still takes 500 passes to cut out the part. Even if the overall part size is fairly small and it only takes an average of thirty seconds per pass – the part will still take over four hours to cut out! It is not uncommon for parts cut from metal on a small mill to take many hours to cut out. Cutting the same part out of even the densest plastics or woods can usually be accomplished in a tiny fraction of that time.

Now imagine running a Dremel or other rotary tool in an apartment or dorm for over four hours straight. Chances are if your neighbors did not kill you your roommates or spouse would! In light of that the whole angry mob scenario – cutting metal seemed a lot less important and we focused on other features instead.