Double sided cut



Just a guess:

indexing -

  1. vertical “stick” taped to bottom side of the pre-cut circle or medallion
  2. horizontal stick taped to the top side
  3. engraving and cut jig on the right

Cut the jig and remove the center.
Engrave the text on one side of circular medallion.
Flip medallion along vertical axis and remove the vertical stick on the top.
Engrave the text on the other side.

i think what @dan was referring to with the circles, was that if you try to engrave on both sides of a pre-cut circle without indexing it in some way, the text might be rotated away from where you want it placed on the medallion on the back side


Remember that the primary benefit of the double cut capability (as advertised) is that you can cut deep (1/4"+) into one side, flip, and finish all the way through (1/2"+) material, The two cuts will be perfectly aligned and appear as if you cut all the way through from one side. Thereby doubling the maximum cut depth. If all we want to do is engrave something on both sides on any material then you don’t really need the double sided cut capability because alignment is generally not critical.


I would say something like that, but Id cut a circle that fit around the thing youre cutting, with the spokes sticking out of it so there wont be any height variance. Then just tape to prevent rotation inside the jig.

Crude drawing:


Yep! That would be even better. :slight_smile:


have there been reports from beta testers or the pre-releases that allow you to set an absolute X/Y starting position? That way if you make a jig for your double sided cut/engrave, you can bypass any limitations of the unit by doing the alignment yourself


Want to be clear, since other lasers don’t allow you to automatically perform a double sided cut, it is not a Glowforge limitation. Apples and Oranges. Now there are of course limits in how the capabilty can be used.

Separate subject… Folks have argued here, at length, about the benefits and limitations with respect to a Glowforge home or set 0,0. There has been discussion with one of the operators about testing it on a pre-release unit. Suggest you start with these topics. Good luck because it is very long and all over the place. Sorry I can’t give you a direct answer that won’t devolve into the same back and forth.


Reason I asked was because I read all the forums, and I do not recall a decisive answer on this item.

I recall things like positioning using keyboard vs mouse, but nothing else.

Part of the problem with the forums is that there so much speculation on the questions that is hard to pick out any hard information


Yeah, sorry. I know it was discussed for testing by marmak3261. Honestly, I couldn’t tell you the answer. I have read every single post but that discussion made my eyes gloss over. Too many people with very specialized needs that didn’t interest me enough to burn brain cells.

An aside: marmak3261 already does way too much. The forum is relentless in it’s need for individual attention. I probably have dozens of questions left to be answered. But I’m going to let him enjoy the unit and eagerly await any new information as he discovers it.


The answer was something like, “No, you will not be able to enter where you want to place something numerically, but we’ll put it in the hopper.”

I am also having trouble wading through the 340 posts in that topic, so I can’t link it for you.

I think someone is supposed to report back a different way of making jigs reusable. Using the edges of the machine or adding some physical guides. I have a feeling that it’ll have to wait 'till some of the software accuracy issues are waded through.


As noted, the only challenge is if you’re trying to engrave or cut both sides of a circle. Engraving or cutting a circle from rectangular material is fine.


Presumably to do a double sided cut that meets perfectly in the middle the edges of the blank material would need to be absolutely vertical, so that when flipped the corners are exactly the same viewed from the other side. Since laser cutting leaves edges not quite square one might need to square up the blanks on a bench sander first if they have been precut.

Do the proofgrade sheets have perfect edges?


I don’t think you need “perfect edges”. I think you just need a defining characteristic. As long as the software can positively identify a part and able to determine placement and rotation off of that part, you should be fine.


It won’t matter how straight they are, they can be irregular and curved, but if they slant vertically then any features on the other side won’t be laterally aligned with those on the first side. They will be offset, so the cut from the other side will be offset by the same amount unless Glowforge can build a 3D model of the work piece, not just a 2D silhouette.


Maybe I’m misunderstanding what you’re saying, but I’m thinking… Sure they will. You’re just going to slant your backside image in relation to the medium’s slant (if any). As such, everything will be aligned.

  • Tom


We are talking about a double sided cut that meets in the middle to cut through material too thick to cut in one pass. It won’t meet if the edges slant. Yes a double sided engraving will work as you want that aligned with the edges of the surface it is on, rather than the edges underneath.


Yeah… Not seeing a difference. The optical alignment will mean that when you flip the item over the software will know how to cut appropriately with the flipped item.

But, hey, I’m probably missing the point entirely. I’ll bow out now.

  • Tom


It would if it could see in 3D but if it looks at the 2D outline of the top surface, and that doesn’t match the bottom surface due to slanted edges, then it will be offset relative to the cut it did from the bottom.


I see what you are saying, so the real question is whether the overhead camera will view the pieces as a 2D or a 3D structure.

I would suspect that the answer will be 3D given all the other features presented.


I don’t think the lid camera will be able to see the bottom edge because the top is closer, so in general hides all of it.

The head camera can move, so could get a view of the edge from several angles and build up a 3D representation. It is all looking very complicated though. I hope all this was taken into consideration when they advertised it. To double side cut without an ugly seam requires alignment to a precision less than the kerf.


What @palmercr has brought up is something I’ve been wondering/worrying about as well.

Here’s a bad drawing of the potential issue…