I bought a Stingray last week but am uncertain just how to deal with it in a workflow. My only remotely-related experience was with a Roland engraving machine I used to own.
It had a depth-setting collar and a spring-loaded carriage (i.e. vertical compliance). Z was either “up” or “down”. The adjustable collar controlled the depth of cut, and the spring ensured that the collar was always in contact with the work surface.
Sounds a lot like the Stingray to me. There is a Z adjustment which sets the protrusion of the cutting tip from the surrounding collar. There is a spring above the collar which, I assume, keeps the collar down on the surface, ensuring that the protrusion of the tip is the true depth of cut regardless of workpiece undulations.
I don’t have the slightest idea of how to set up the cut. With an endmill I touch down onto the workpiece with a sheet of cigarette paper pinched between. Then CM goes and measures the Z value of the cutter in the spindle. For the Stingray do I touch down the cutting tip or the surrounding collar? And when it is touched, do I call that some value, say Z .020", to ensure that the backup spring is always under compression during the cut?
The couple of YouTube videos I’ve seen (Kevin Barnett’s and John Clark’s) talk about cutting “passes” as if it were an endmill. This I don’t understand at all. Say the material is .005" thick, cut in 3 passes. Each cut is then .0017" deep, probably shallower than the workpiece waviness. Is that actually realistic?
I have a couple of days in which to learn–my machine is being held hostage right now by a fixture for modifying some PC boards for work, before I can get to trying the Stingray.
Anyway, I’d really appreciate an explanation of the actual workflow. Thanks!
Roger that, Cullen!! I’m imagining that I can disable the spindle using the unlabeled button on the side of the controller enclosure, like the standalone 65mm VFD…
Thank you, Will. The shop page video is Kevin’s YouTube video I mentioned above. And I have read that thread (several times–the latest this lunch hour…) Lots of information in all the posts here about workholding, but the part I’m wondering about is setting tool Z vs. the workpiece during the job setup. The Stingray has a compliant element (spring) between the collet and the tip, and that is what my sticking point is…
Disable the BitSetter (on a Shapeoko — for a Nomad ensure spring tension is greater than the BitSetter)
Set zero by hand, then make a test cut — if it doesn’t cut deeply enough, increase the spring tension a bit and try again — after a while one gets a feel for it.
OK, thanks, Will. So I control spring tension by “depth of cut” below the actual work surface. I can visualize that.
I will need to do some experimenting to see if I can do a BitSetter-less N4 run… On my 883 “Classic+”, if I remember right, the only way to go BitSetter-less was to use an alternate gcode sender, but that was a long time ago in a state far, far away…
I believe having the speed set to 0 keeps the spindle from turning on — can’t you just unplug the spindle? Or disable it from a button on the front panel?
I did an experiment this morning. I started a spindle warmup cycle in Motion, and then pressed the “Spindle Enable” button on the controller housing (which is unlabeled on the housing itself, but called out in the proto-manual). I discovered that when the button surround is red-lit, the spindle is armed/enabled, and when the surround is unlit, the spindle is disabled. I was able to turn the spindle on and off during the warmup cycle using that button, so it seems pretty reliable.
I could unplug the spindle cable from the controller, but I would prefer not to. Needing to physically disconnect equipment seems to me like an unplanned-for workflow… Likewise, the control box reminds me of the 1960’s Star Trek Enterprise’s bridge, full of controls and readouts which were totally unlabeled. I can appreciate that silkscreening the control box would add cost, but I think it would be proper to have everything labeled…
Likewise, I will experiment with SheetCam to see if I can set a zero spindle speed, or I could just edit the resultant gcode to eliminate any M3 commands. It looks like I’ll be running my decal gcode through DXF to G-code Converter to add the little overcut arcs at the corners and maybe there will be a setting there to strip spindle commands… I have downloaded but not installed it yet.
I program all my drag knife operations at zero depth (0.0001, since it won’t calculate at 0.0000)
then adjust Z to add depth/tension.
I’ll touch off the material, type in 0.005 in the Z field instead of clicking “Set Z zero”
Then if I need it a bit deeper after the first cut, I add a few thou to the value in Z & rerun.
i.e. if Z has retracted to 3.284 & I want to go 0.003 deeper, I change it to 3.287
I also try to make sure the surface I’m putting the material on is really flat, surfaced, beforehand to avoid the ‘waviness’ you mention. But either way, make sure your retract is enough to clear your max cut depth plus any surface variation.
Thank you, @Tod1d . For the work surface I plan to use the float glass I used to tram the spindle, with a sheet of green (medium) Cricut mat on top of it. The glass itself is trammed to about .002" across its width, and hopefully the Cricut mat is not too uneven.
But you are confirming that “depth of cut” is really “loading up the spring tension” and that I can understand. when I’m done modifying the PCB’s for work and can clear the N4’s table for the glass&mat I’ll do some experimenting. I have a sheet of Oracal 651 silver-gray and also a small roll of Cricut silver “permanent” vinyl (I’m at work now and forget their model name…)
I did install DXF to G-Code converter and put in my decal DXF, and it does look like it puts in the appropriate arcs at the square corners.
I was thinking about putting the corners of the mat under my glass clamps in case the backside wasn’t tacky, and it’s sounding like you are saying only the front side of the mat is tacky…
I don’t think the back on the one I bought was tacky.
I also bought some sort of tacky glue that I apply to the surface of the mat anyway. It is sort of like a thin rubber cement.
But, my point was to not underestimate the forces that will be applied to the material even though the spindle isn’t turning.
Thank you, Cullen. I’ll keep that in mind. And Estop is front and center (well, front and over to the side a little–I kept bumping it with my belly when I was leaning in to watch the machine… )
