MY alignment issue, as a separate thread

alignment
#1

I have been trying to get my etchings to land consistently in about the same place, on several different denim jean legs. I have a crumb tray replacement that measures exactly at 1.5" on my new calipers. I use the same calipers to find the depth of the material I’m using (fyi, that’s the thickness of the metal sheet I place inside the jeans leg, plus 2 layers of denim).

Here are the screen shots I’ve been taking of the app after the etch run is complete, showing both where the artwork is placed on-screen, plus where the etch actually lands. As you can see, the on-screen placement is up to 1" from finished placement.

I realize that I’ve had to learn Inkscape pretty much from the ground up, and may well have done something wrong in creating the artwork. If anyone else wants to test the files, I’d be more than happy to supply.

I’ve refined my process down to the point where I can get a relative good run on each of the 4 sides of the pant legs.

  1. Position metal sheet inside pant leg, and using magnets, try to get seam edge lined up correctly and rest of material flat, with extra behind the metal sheet.
  2. Place material into Glowforge, with rest of jeans folded under jig/down under laser head, and use ruler to position seam horizontally straight and equi-distance from inner front wall. Note: jig is created so there is a gap where the excess material/waistband can go out of the way.
  3. Make sure gantry arm can move back and forth, and side to side freely. Refold/scrunch until it does.
  4. Place thin cardboard on top of jeans, aligned with hem and seam edge, and hold with magnets.
  5. Open, RESIZE, and position artwork with best guess as to where it will end up.
  6. Run job.
  7. Stand at Glowforge to ensure test star (in each artwork, I positioned a star at the bottom/edge so that it is always the first thing that gets etched) is in correct place.
    7a. If test star is not correctly placed, lift lid to stop job. On app, move artwork to correct placement (best guess again). Run job again. Repeat until test star lands correctly.
    7b. When test star is correctly placed, great! Lift lid to stop job, and remove the cardboard. Run job again and allow to complete.

This process can include two or three attempts at correct placement until things are lined up well enough. So I can get it to a comfortable degree of placement, but it involved many more steps than I think it should. Also, I use Inkscape, and create the artwork to a specific height/width. When it uploads to the app, it appears much larger than the original, and has to be resized, which bothers me. It’s really going to be a pain when I move to cutting things out.

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#2

My guess is that in spite of your hard work to the contrary, the math on the material thickness isn’t coming out correctly. It looks like you’re off by maybe an eight of an inch. You can experiment by typing different material thicknesses in when you’re looking at one of those screens you’ve got shots of and see which direction gets you closer. This is similar to the experimentation you’ve been doing, but if you can get a repeatable distance from the laser head then the material thickness you’ve discovered should also be mostly repeatable.

Material thickness == 0, means that the surface of the material is precisely at the height of the top of the crumb tray. Material thickness == 0.5 means that the surface of material is precisely 0.5" above the height of the top of the crumb tray when it is installed as it was when it left the factory.

It looks like what you’ve attempted is to make a crumb tray replacement that holds your material above the bottom of the unit by the same amount as the crumb tray. Note that this is not the same as the thickness of the crumb tray because it has feet and divots for the feet.

The kicker is that very small differences in material surface height will translate into significantly larger horizontal differences in bed image rendering, particularly as you move away from the center because of the ratio of the distance to the camera of the image to the distance of the camera to the center of the material.

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#3

Your depth is off most likely. The crumb trays are actually 1.3xx-1.4xxx not 1.5". So you are telling the gf camera that you material is lower than it actually is.

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#4

Thanks @markwal!

With regards to printing on materials provided by other vendors, unfortunately, I don’t have any guidance. It’s very common for materials to perform inconsistently in a laser. However, Proofgrade materials should print perfectly every time. Should you find a problem when printing on them, please let us know right away.

I was about to move this to Beyond the Manual so the discussion can continue there when I saw your post here: Shifting image?. That made me want to double check - have you had other prints in which shapes haven’t lined up with themselves the way you expect - like the lines in the star in that image? If so, would you please:

  • Turn off your Glowforge (this is important to avoid damage to your unit)
  • Open the lid and, using both hands, gently move the laser arm to the center of the bed
  • Gently move the head under the lid camera
  • Put in the crumb tray that we provided
  • Turn your Glowforge back on
  • We included an extra piece of Proofgrade Draftboard with your materials shipment for troubleshooting. Please print the Gift of Good Measure on Proofgrade Draftboard in the lower right hand corner of the bed
  • Let us know the result. If the print looks incorrect, please include a photo.
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#5

Tomorrow I shall measure both the height of the original crumb tray, and the jig.

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#6

Damn. I just measured the original crumb tray…1.378.

Tomorrow, I get to make a new jig…and test…again.

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#7

I applaud your persistence!! You’ll get it dialed in.

Remember that you just need to get the top of the material within that 1/2” range and then set the material height to the difference between the height off the floor of the machine and the 1.378” you determined to be the top of your crumb tray.

So you may not need to change your jig, just recalculate the height to enter for the uncertified material.

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#8

Persistence is my middle name.

This is the 3rd jig I’ve made. The first one to get to what I thought was the proper height. I’ll make another that IS the correct height!

On another note, I had figured out how to get the jean leg almost perfectly flat…and tonight I used a pair of jean that were to skinny for the 6" wide sheet metal I use!

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#9

Seems like the height value might be the culprit here but have you ever tried making something with the provided Proofgrade materials?

If you did and placement was acceptable, then at least you know there isn’t something wrong with the machine.

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#10

I’ve lasered some denim clothing, and the material thickness was all over the place due to seams, clothing design, etc. Luckily engraving denim seems fairly forgiving.

I wrap the clothing around a wood board (PG draft board), on a ‘stand’ that holds up the board by the corners, so that it’s a quarter inch shorter than the crumb tray, with the parts of the clothing that aren’t being lasered wrapped under the board.

To measure the ‘height’ I use a ruler with a tape mark at the ‘zero’ height of the crumb tray, pressed to the bottom of the GlowForge (not the lowered slots for the crumb tray’s feet). So far the material usually works out to about the same as the quarter inch, so even though I measure, so far I end up engraving at “0.01” inches (since you can’t enter 0 height).

Denim is pretty low-res, so I engrave at 150 lpi and it looks fine - finer detail tends to be too fine to see on denim, at least on the clothes I tried.

For placement, I center the clothing under the camera, so any optical distortion will be ‘balanced’ on both sides, and that’s been close enough for putting names and logo’s on denim jackets and pants. For me, the error is mainly left-right, so (for example) if I’m engraving denim pants, I’ll run the pants the length of the GlowForge, so the centering on the leg is accurate, and if there’s a little error where on the length of the leg it’s placed nobody has complained. :slight_smile:

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#11

That’s pretty much what I am trying to do. But I’m looking at a full leg length design. It requires 2 different runs for a single leg, and although the design is split in two, they still have to line up to a good degree. I’m working on getting a better jig. But I’m curious if you’ve tried lining up like this?

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#12

I haven’t tried lining up two separate engraves after moving the material - there’s so much flex and stretch, I didn’t think it possible.

What I have done is a series of engraves on material, without moving it. That worked fine. That’s what I had to do when the image was too large for the GF to cut in a single job. So I split it into two bitmaps in Photoshop, lined them up in Illustrator, and sent as an SVG to the GlowForge. Then loaded it, turned one on and one off, sent it to the GF, then flipped the other one on and the first one off, and sent that. Perfectly aligned, since the GF is always consistent with itself.

Very happy that jobs auto-save now, which means that you don’t have to worry about anything happening between two jobs run from the same file. Before, accidentally closing a browser tab (or reloading it) meant you lost alignment between the first engrave and the second.

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#13

I’m going to go ahead and move this to Beyond the Manual so the discussion can continue there. If you see the shifting image issue again, please either start a new thread or email support@glowforge.com.

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#14

I forget who posted this idea, but you should try these steps to help you align where you want. 1. Put grid paper in your gf. 2. Make a print file with just a line cross, and line it up with a cross on the paper. 3. Print it once it is perfectly aligned, and after print is complete, line up your print file in the exact same spot as before. Then use your arrow keys to move it one click at a time ( making sure to keep track of how many clicks in each direction ) line the print up with the actual spot it cut. Any time you print you should then move the print that many clicks in the opposite direction and then print. Example: if I had to move my print 4 clicks down and 2 left to line it up with where it actually cut I would have to move it 4 up and 2 right to get it to cut where I want.

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#15

Here is that original idea’s post if I was confusing :slight_smile: A way to improve object placement

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#16

I think I’ve gotten the placement/alignment issue down pretty well for the things I’ve been trying to do.

I simplified it so that it’s a simple placement issue; right now I’m using registration marks to place the design where I want it. When I can get the design simplified so that it etches faster than 3+ hours to do a single pair of jeans, I’ll move back to a larger design that has to be split and aligned. But I think my current process for placement will make that alignment easier.

I wrote a little about my process for etching jeans here: https://community.glowforge.com/t/tips-for-holding-garments-flat/18298

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