About the Add-ons & Modifications category


Show off the ideas and implementations you’ve had for how to modify, improve, or accessorize your CNC!


I’ll toss a question out there. The 3.5"x3.5" touch plate that I discussed in my post here: XYZ Zeroing plate and tool diameter finally got some use yesterday at my local Makerspace. It immediately occured to me that I need about 7" clear of the hard stop end of each axis before I position my workpiece. Otherwise the travel of the router won’t be far enough to clear the plate and run the calibration routine (assuming worst case distances). But this bummed me out because I was hoping to mostly use full 4’ wide sheets.

So does the Sienci touchplate (which is, smartly, smaller than mine) constrain the work area at all or is there a bit of extra travel outside the published 30"x30" number and it can use that bit of extra area so a full 30x30 workpiece can be used with the plate?



…and I’ll throw another idea out there. The plates can help find the corner repeatably but they won’t help you identify if there is skew. Or at least the code I have for the Shopbot one doesn’t.

It has been hypothesized that once the exact corner is found, going back and checking the one axis in three different locations along the plate and comparing the related value from the opposing axis (which should be identical, as you’re moving in a line along the test axis) would help identify if there is any noticeable skew in the work piece on the bed. Any idea if this is included in the UGS code for the block?



No skew finding techniques that I know of. The assumption normally is that the stock material has been properly aligned. The LongMill 30x30 does have a slightly larger cutting area than 30"x30" (although the dust shoe add-on normally eliminates some of the X travel to being slightly under 30") so there should be some additional room for corner finding with our smaller touch plate. That being said, if you’re using the touch plate for homing in the Z axis only then you won’t require the additional X and Y space :+1:


Hmm ok. Perhaps it’s a good idea to cut a shallow outline of the main cutting area in to the wasteboard to aid in skew alignment? Or would you just aline to the feet of the rail?



Yeah either of those options would work. If you’ve got a level on-hand or a track piece from a track saw or any other piece of straight material you could run it across the feet and bump your material up to it for easy alignment. I usually just cut an ‘L’-shaped outline into the wasteboard for alignment by eye :+1:


Ah you reminded me, I intend to put 20mm or 3/4" dog holes in an L and pop some dogs in to square it.

I am seriously considering going vertical from the outset with my unit, I have an almost ideal space between two windows in my shop and not a lot of other places to put the Longmill. I was wondering what happens if you send gcode that overshoots the valid work area of the machine?

If I accidentally tell it to do a 33" long cut, are there some kind of emergency end stops that stop it from driving itself off the lead screw or hitting the end of the lead screw range and working the motor hard to advance and go nowhere?



If the LongMill is told to move somewhere it’ll go there. If you want to install limit hard stops then that’s supported by the controller and in that case it would stop/ throw an error, but the machine has been designed such that it can’t ever destroy itself; so moving it past its limits won’t ever do any damage.


So is it possible to send the gantry supporting the router right off the end of the side gantries?



No, every gantry is constrained by the machine geometry at their ends, the motors torque out at these limits.