Cutting and Engraving question

engraving
newbie
cutting
learning
qa

#1

Trying to learn the right/best way to engrave and cut things on a laser. I know that ideally every single material that we put into the GF should have already gone through a “template” that shows what different power and speed does to that material.

But what do you do if you don’t have any spare material? What do you do if someone gives you an item and asks you to engrave something on it?

In my situation, I have several friends who have the Jenga Game, and for parties they wanted each block to be engraved with an instruction on what you now have to do (think Truth or Dare where each block will either ask you a question or tells you to do something). How would I approach engraving each piece since I don’t have any “extra” blocks to “experiment” with?

Also interested in the approach in general and with other types of material.


#2

Well, you have to start somewhere.

I would try and find “similar” material, and try out a few power/speed settings on that first. For Jenga blocks, I would find scrap wood that feels similar. You won’t get the exact same result, but it should be close.

I would do one block, and then adjust it as I go along (i.e. if it’s too light, bring up the power.).

I would start with lower-power settings, and not move the block before determining if it’s acceptable. If it’s too light, you can always do a second pass to darken the engraving. And on the next block, do a higher power engraving. If you start with too high a power, you can’t undo that.

Also, I would probably create a template in which to place the blocks. So you know that your blocks are in the right place to be engraved. The GF camera might make this step unnecessary, but I would probably still do it. You can test that template position with something the same size as your Jenga blocks. Perhaps you could cut some cardboard or MDF to the same size as the Jenga pieces first.

See https://www.epiloglaser.com/resources/sample-club/jenga-block-engraving.htm for an example of what I’m talking about.

The other option is to look at what others have done before.

If you look at the link above, on it is says that for engraving Jenga blocks:

We used a 60-watt Helix with the following settings: 60% speed, 100% power, but you should use the     recommended settings in your user's manual for your wattage machines. Also, don't be afraid to experiment with different settings for a deeper or lighter look.

The GF is only 40 Watts, so perhaps bring that speed down to 50% instead. You might find others who have engraved Jenga blocks with a 40 Watts and ask them what settings they have used.


#3

Also this link: http://support.epiloglaser.com/article/8205/29904/how-to-create-a-jig-for-the-laser


#4

Fix the item in place so it’s not going to go anywhere because you’re going to make multiple passes until you get the results you want and you don’t want the subsequent passes to be “off” in terms of registration of the cut or engrave.

If I’m doing a cut, I take a look at my history (I keep a little book of projects with power & speed info) and would start with a similar material’s settings. To be safe, for wood, I’ll bump the speed down by about 10% from what my closest similar prior experience is. I always cut at 95% power so I’m only playing with speed. (Unless my “cut” is being used for an engrave outline but that’s another topic altogether.)

For engraves, I start with the same historical perspective. But for engraves, I tend to go for speed and adjust power in increments of about 10% until I get what I want. I’ll set it, send the job and then adjust before sending the next job with the power bumped up (or if I’ve run out of power, start decrementing the speed). However, I do tend to keep the power for most engraves under 75% and play with speed instead but that’s just my own personal quirk. A buddy of mine almost never engraves over 50% so his speeds are slower than mine.

If I’m going to do multiple iterations of something then I’ll bump the final power or speed by an additional 10% to account for the cumulative effect of the multiple iterations. For instance if I engrave at 600mm/s & 75% power and that’s not enough, I’ll step it down to 500-550mm/s & 75%. If that still wasn’t good, I’d bump it down to say 400mm/s & 75%. If that’s good, I’ll do subsequent pieces at 350mm/s & 75% because part of what made the 400mm/s one work was that it had already engraved at 500 and 600 so I need to account for that when I do one where I’m hoping to do a single pass.

If I have no experience with a similar material then I start out conservatively on power & speed so I don’t wreck the material out of the gate. So I might start cuts at 500/95 and drop in 100 or 200mm/s increments based on what I see the material doing. Similarly on engraves I’ll start at 30% power and 750mm/s and start to zero in on the two settings with multiple passes.

On my 60W I can adjust power & speed from the machine during a job up to 100% of whatever I sent from the software (so if the software spec’ed 90% power & 500mm/s I could reset that to 45% power and 250mm/s by setting the speed and power parameters on the console to 50% each - but I can’t set the machine to a higher amount than 100% of the sent parameter so I couldn’t for instance bump the speed up to 600mm/s because the software told the machine 500 was the max for the job). If I’m doing something large and I don’t want to wait for multiple passes I’ll send the job with high power/low speed to the laser and then do all my adjustments on the console starting & stopping & restarting the job while adjusting the power & speed percentages on the fly. That way I don’t get variable depth cuts/engraves or extra wide kerfs because I cut the thing in 3 or 4 tries except in a very small part of it as I was making an adjustment and then stopping it to re-adjust and restart.

It’s an art not a science :slight_smile:


#5

The thought of trying something that is similar first to create the power/speed template is a good tidbit. I’m just worried about being able to identify the material to be able to get a close match.

For example, Balsa, Baltic, and Pine all look VERY similar to the untrained eye, and unless you know the density of each wood, you might not be able to tell them apart, but they would all cut/engrave differently. Same with cut vs extruded acrylic and other materials. I was planning on a stepping approach, but I’m not sure if it is best to increment speed or power first, and do I increment by 1, 5 or 10% each time?

All, What is your step-by-step approach to cutting/engraving a piece if you aren’t sure what it is and don’t have much/enough to do a template on?


#6

James, this is fantastic! It’s this guidance that I was looking for. So many good pointers here, even the “I generally use this power and this speed for this application” is so very helpful.

And keeping a history on what you cut. Do you have a notebook to log all of this? Do you save the templates from materials that you’ve cut before?


#7

Since 40W is only 2/3 of the Helix’s 60W, I’d drop the speed by 1/3rd as well and not just 1/6th. So I’d take speed down to 40% (conveniently since they started with 60%).

BUT the problem with that is speed in this case isn’t defined as an ordinal. It’s a % of something. I don’t know if the max (100%) speed of a Helix is 500mm/s, 750mm/s or 1,000mms/s. What you need to do is find that out and figure out what their recommended 60% speed equates to in mm/s and then make the similar adjustment on the GF (or whatever machine you use).


#8

I keep a little notebook and I take a picture of the settings screen on the computer (Corel) when I send it to the laser. I also take a picture of everything I do so I know what it looked like when I was done so I have a visual reference too.


#9

I’m sure there will be a lot of “sneaking up on” an unknown material with settings until I nail the effect I’m looking for.