I think one of the points of confusion here has to do with the assumption that there is a fixed relationship between the drawing space and the bed space.
In other words that the drawing has an x,y zero point, and that once imported that point maps to some specific x,y point in the drawing interface (i.e. on the bed image), which then maps to a similar point in the physical machine.
Perhaps @dan (or @Tony) could explain how the drawing is imported (the first time) and a little bit about how the interface decides where to place it on the bed image.
Specific questions given an empty drawing with units in inches:
If I put a 1" diameter circle centered on the 0,0 point of my drawing, where will it show up on the bed image.
If I put a 1" diameter circle centered on the 6,6 (in inches) point of my drawing, where will it show up on the bed image.
The use case for this information is to understand how we can, for instance, engrave repeatedly on objects which have existing pre-printed text. I do understand there are ways to do this, I even described one already, but I think the thought experiment would answer the underlying question.
So I decided to draw up a visual guide. Something like this would be incredibly helpful. Basically its an L shaped ruler/square with 3 registration points. If the glowforge could read those points it would know exactly where it sits in the bed, and its orientation, and where the corner is that we can align objects against. Then if we can enter an offset against that corner location for our cut to be made, it would give us the desired accuracy.
For example in the drawing below I want to cut the 2 black holes in the template (pink box) ive made on my CNC machine. I know that they need to be 60mm from the top of the piece, and 4mm/30mm from the left. I know that the top corner of the material is now aligned with the homing ruler and glowforge now considers the top left inside corner of that 0,0.
I load a circle svg into the UI and tell it to move the top left corner of that svg down 60m and left 4mm from the 0,0 point glowforge has ‘generated’ based on the location of the homing ruler. then im good to go. Rinse and repeat for the next hole 30mm over.
This was what I was describing before. A moveable L shaped “tool” with the 3 registration points. Thanks for drawing it up so nicely. This should be mostly a software thing, but something would have to be done about how to make the precise hardware piece that the GF would recognize.
Thanks @takitus and @julybighouse !
That is very clever and probably solves most if not all of these issues!
Given that the Glowforge can cut the template and engrave the fiducial marks we could make templates of any shape and those three points would align them repeatably.
In the mean time (i.e. until that makes it out of the hopper) I would still love to hear how the default positioning works. If it is repeatable we could have the template in the drawing and use a jig that registers against the machine (as described way above).
In addition to the Registration of pre-printed sheets thread, here’s another thread about how useful being able to align to registration marks would be useful…
default positioning? I don’t think that would be needed. The intersection of the two arms make the initial 0,0 point, the arms would just tell the software the specific rotational orientation of the piece.
So you should be able to literally drop this piece on the tray, snug up your piece in between the arms, and go from there. If you are off by 1,2, or 85 degrees, it shouldn’t matter, the three registration points would tell the software the orientation of the piece and the software should be able to make the adjustments.
Yes, once they write the software to do that. Using the default drawing import 0,0 point is a work around until that (fairly complex) software is written/tested/deployed.
I think its going to be very similar to the flip-over cut functionality they planned on having anyways… so I dont think it would be too much trouble to implement.
It occurs to me that this whole requirement for a known origin is generally being demanded by people that have used CNC machines before.
I totally get the need for consistently placing objects and having your file consistently placed over them, but I honestly think we are selling the Glowforge team short by assuming they have irreversibly failed at delivering that, and need to implement a whole new alignment system, before the machine has even been shipped. Dan has stated repeatedly that they have gone out of their way to make sure that we will not need to interact with the Glowforge the same way we would have with other CNC machines, and that is in fact one of its biggest selling points, yet people are essentially demanding that they can use a workflow with the Glowforge that was required for those other more difficult to use CNC machines.
All the Glowforge really needs to do the same as the CNC machines that came before it is to be extremely accurate and consistent, and I’m pretty sure they’re not going out of their way to make it either inaccurate or inconsistent.
The way I see it, all that is needed to fulfill the use cases stated herein are for following two statements to be true:
We can consistently and repeatably place our material/guides/jig in exactly the same place within the physical bed,
Any file that we import into the user interface will be consistently placed relative to the physical bed every time that file is imported.
Item 1 it’s pretty much on us. The bed area is a physical space with some hard edges, so we should be able to figure out how to put our material or jig in the same place every time.
Item 2 is on the Glowforge team, and that requires two things:
that the laser head itself can be consistently aligned with the physical bed (which Dan demonstrated above as being very good already and stated they are working on improvements), and
that the software will consistently load a file in the same place relative to that bed every single time.
With this in mind it seems we have only one outstanding question; will the software consistently load the same file in the same place relative to the physical bed every time? We know the software is aware of the position of the physical bed, since we’ve seen that it can outline the non-printable area, so this seems completely doable too.
Glowforge has camera so you should just be able to drop your work in, align it once manually and then drop in another identical piece and have it automatically align to that, preserving the same offset from two edges. I don’t see why you need jigs with fiducials.
I do have a an L shaped jig on my CNC and it is screwed down into screw holes drilled by CNC, so I have run thousands of jobs from that. But my CNC doesn’t have cameras, it does have limit switches though.
If I cannot use a laser with the degree of accuracy it is capable of, its pretty much just a toy to me. I cant really justify spending that much money on a toy.
It IS capable of cutting things with incredible accuracy, they just need to find the best way to accomplish that. Weve dropped a few viable ideas on them that I dont think would be too hard to implement, especially considering the work will overlap with stuff already promised.
I have faith they can make something that will work for the not-so-picky crew, as well as the super picky crew that I was basically born into by way of two incredibly science-oriented parents hahaha
thats the one gotcha for a permanently attached L guide in the glowforge, is the passthrough. Its going to have to be removable so you can make full use of the bed. after removal youll want to know that you have got it back in place and perfectly aligned with the GFs 0,0 location. if it werent for the fact that all that stuff has to be removed sometimes I dont think we would have this predicament
Getting the hyper accurate alignment that people are asking for cannot physically be done manually, due to limitations both in our eyesight and the cameras eyesight. To get down to .001 inch accuracy absolutely requires a carefully placed jig or set of guides that can be used again and again to provide hard and repeatable physical stops for the objects to be engraved, and also depends on not moving the objects within the UI whatsoever after it’s loaded.
If we’re just going for visual accuracy, then fiducials would probably suffice, but once they get the cameras dialled in, fiducial marks wouldn’t really be necessary for that either.
That would also need the Glowforge to have limit switches accurate to 0.001" as well. I don’t think it even has them. It just uses the cameras for everything unless I am mistaken. The head camera has a laser line as well.
It would only need to use limit switches if it depended on aligning everything from the 0,0 point, which it doesn’t do because it doesn’t need to. It aligns the head using the lid camera above the centre of the bed. I think the disconnect is that people keep trying to equate this machine with machines that don’t have cameras.
