Crumb tray height vs Glowforge floor height max values

Ok folks… I need to tap into the ‘cumulative wisdom’ for a bit of clarification…

New user, so as such I’m trying to wrap my head around facts, fantasy, procedures, and limits.

Here my question:

Maximum focus height of item being worked using crumb tray = 0.5”
Maximum focus height of item being worked from the Glowforge floor = 2.0”

Both of these values I believe are in the documentation as well as ‘general knowledge’.

Now in my case… the height of my crumb tray is 1.365”… and if I add the additional height of 0.5” that brings the hight (using the tray, measured from the floor) up to 1.865”… which is 0.135” shy of the 2.0” mark (also measure from the floor).

My question is: In my case, with my values… can is USE that extra 0.135” of height for items I’m printing using the tray and consider my “tray max” to be (crumb-tray-height) + (0.50 + 0.135)?.. instead of just 0.5” (tray max).

Logically, and 2.0” item sitting on the floor would be exactly the same focal distance away from the head as an 0.635” item sitting on the tray (using ‘my’ tray height numbers).

It would obviously be nice to be able to work with that bit of ‘extra’ space when using the tray.

What am I missing here?.. is there a problem I’m not seeing?

You can engrave without the tray. I tried it once on cutting boards. I recall advertising was 1.5 in max

You might want to read these 2 threads:

Thank you for your reply… I agree that is a good tutorial… but it doesn’t focus on what my question was.

The point I’m trying to clarify is… if the max focus height is 2.0" when the work item is on the floor and the measurement also starts at the floor… then it would be reasonable to assume that when the work item is on the tray… the max focus height would also be 2.0" when measured from the floor.

With my tray height at 1.365 (from the floor) and I add 0.5" I don’t get to use that extra 0.135" of potential ‘item thickness’.

I’m just looking for ‘confirmation’ that (in my case) I could put a work item of 0.635" (which is under the 2.0" max focus height) without some issue I’m not aware of.

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This is forcing me to think, and I haven’t had my coffee yet. :smile:

Let me go get some and I’ll get back to you.

Oh, no wait…I can tell you exactly how to figure out how tall of an item you can place on the crumb tray.

Get a new deck of cards. Place it on the center of the tray with the machine turned off. Move the head back and forth manually, over the deck of cards. The air assist diverter behind the head will knock a few of the cards off. Remove a card or two from the top of the remaining stack and then measure the cards still in the stack. That’s how tall of an item that you can place on top of the tray without hitting it with the air assist diverter, with exactly two card thicknesses worth of leeway in case you make a mistake, or your tray isn’t completely seated in the dimples.

You don’t want to hit any material with the air assist, it will bump the gantry off the rails. (So that is your fixed height limit for material, and you’d better be 100% accurate with your measurement and have no warp at all in the material.)

Since the focal point settings are set in the software, you will have a slight error introduced in the focus for anything over 0.5 inches, since that’s a hard coded limit. You can’t enter a thickness number for focal point higher than 0.5 inches.

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This is a brilliant way of figuring out the exact height you can use - Jules to the rescue again!!!
I’ll bookmark this!

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Can’t take credit for this one…I think I read about it somewhere on the forum. :slightly_smiling_face:

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But you remembered it without coffee… :coffee:

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It’s dangerous to be walking around and giving advice without your heart being started… Good for you Jules… you now have a Gold Star next to your name!

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Be sure to measure each corner of your tray, as well. I recently found out that mine was off by 6 hundredths in one corner which was causing me a little grief with kerf and cut through. Guess I’m just saying make sure you’re level across your tray, because as Jules mentioned, the air assist will definitely ruin a nice project if given the chance.

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The interface won’t allow a measurement larger than .5 - so even if you type in .635 it’ll revert to .5

So your math seems right, but runs into the programming…not sure how to solve for that!

Perhaps one day https://community.openglow.org/ will have that answer. :slight_smile:

Want to know the simplest answer? Stick it in there, make sure it clears properly, and run the job.

It will work fine. I’ve done it.

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Thanks for all the great suggestions, everyone! If you need help in the future, please open a new thread.