Drag-knife for the Nomad/SO3?

I was surfing the inter-webs for a project and came across http://donektools.com/, seems like it could be useful, but for the Nomad would definitely require some fancy mounting business to decouple it from the spindle since you can’t really easily run jobs with the spindle off… although poking the g-code to see if this could be done would be a possibility.

For the So3 though this would chuck-up and cut like a champ I would think.

In fact, this guy made his own and made the files available.

Any enterprising people want to try it?

Seems like something I would put on my 3D printer, mainly because both my nozzle and my bed have springs. How do you make sure your work surface is that flat? My reasoning right now is that the spring will allow for some error in the flatness of the work surface. Is there a spring inside the drag-knife holder?

Also, what happens if I just disconnect the spindle wires? The connectors are pretty accessible, but would the brushless ESC freak out?

Collection of links here: http://www.shapeoko.com/wiki/index.php/Spindle_Overview#Drag_Knives

I worked up a design which I need to find the time to test out: http://www.shapeoko.com/forum/viewtopic.php?f=24&t=6335

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I have purchased some bearings, but I planned on doing this over my Christmas holiday.

I am very interested in the Donek drag knife, but was under the impression that using a 1/8 to 1/4" collet adaptor would make it possible to attach the 1/4" drag knife to the Nomad spindle. I was unaware that it would be necessary to decouple the spindle altogether. I have no real understanding of the process, but was about to get really excited. Please could you explain to me why that can’t be done?

I think the idea is to keep the spindle from coming on automatically. A drag knife doesn’t want to spin, although it does want to be able to swivel freely. The Donek has its own bearings, so it doesn’t rely on the bearings in your spindle, but a homemade design could use them instead, and maybe save some Z axis headroom, which might be an issue with the Nomad.

Andrew Werby

I watched a Donek video that showed how to change the code to disable the spindle rotation, but didn’t think about the z-axis constraint. I would imagine that the adaptor plus the height of the knife would likely preclude its use. Need to do sums.