Focus ?

[Bert Kemp]

I often read to get a darker burn or contrast to take the laser out of focus a little. Does it make any difference which way you move the table. Do you get a better contrast moving closer to lens or further from lens. Or does it matter at all?

[Gary Hair]

As far as I know, the beam is hourglass shaped so it shouldn't matter. That said, I always move it up - for no reason other than consistency.

[Bert Kemp]

LOL you got me ;) You move the lens up further from the table or you move the table up closer to the lens ? LOL

As far as I know, the beam is hourglass shaped so it shouldn't matter. That said, I always move it up - for no reason other than consistency.

[Gary Hair]

you move the table up closer to the lens

This is what I do

[Robert Schmiede]

I have a ruler,part there of, glued to the frame of the machine between the up and down table so I can bring the table up closer to the lens to my prefered out of focus height. Ruler is vertical.

[Dan Hintz]

It generally doesn't matter, but I choose to move the table farther away from the lens. Darker lines = more smoke, so more distance between said smoke and my precious optics is always appreciated.

[Chuck Stone]

Personally, I never cared for the softer focus. Slowing it down a little gives me
the deeper color without sacrificing the sharpness.

[Bert Kemp]

Very neat Idea TY

I have a ruler,part there of, glued to the frame of the machine between the up and down table so I can bring the table up closer to the lens to my prefered out of focus height. Ruler is vertical.

[Bert Kemp]

That makes good sense too


It generally doesn't matter, but I choose to move the table farther away from the lens. Darker lines = more smoke, so more distance between said smoke and my precious optics is always appreciated.

[Bert Kemp]

Yes but doesn't that make the engraving deeper my material is 3mm so I don't want to go thru.

Personally, I never cared for the softer focus. Slowing it down a little gives me
the deeper color without sacrificing the sharpness.

[Chuck Stone]

Yes but doesn't that make the engraving deeper my material is 3mm so I don't want to go thru.

Sure .. a bit deeper. So I back off on the power a little
to compensate.

I'm not sure I'd do this if I did heavy engraving all the time, I'm
sure the extra time would add up. But as it is, on a full bed
engraving that might take 30-40 minutes or so, I don't notice it
taking longer. If I were a busy shop I might pay closer attention.

[Keith Colson]

When you engrave out of focus the engrave does not go as deep, it just gets a lot darker. I have a 22 hour job I am running which starts tomorrow. It would be 38 hours and unaffordable if I did it in focus but slower. The trick to doing it out of focus is to compensate for it in the artwork. I still get a sharp edge, its like colouring something in with a marker versus a pencil. No pencil lines and much faster. I will try and post a photo when this job is complete, the customer took the sample. Its almost black in colour. I got the job due to my quicker and lower price and he like the burnt look better too. I still billed the customer 3.5 hours @65 for the out of focus artwork and test sample.

Like Dan I put the bed further away to keep the optics clean. You also have more travel in this direction too.

[Bert Kemp]

Thanks to everyone I have a pretty good Idea nowof which way to go and how much and a ruler attached to keep track. I don't engrave a lot but I would like more contrast on what I do do thanks for all the good info.

[Keith Colson]

I completed my out of focus test run today, here is a comparison of the job done in focus by my competitor and the out of focus burn I did. These were both done in low resolution e.g. density 2 in the universal's 1 to 7 choice.Higher densities would have killed the job on hours. The focus was set 10mm out. The grain really pops out nicely.

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[Bert Kemp]

Yes really does stand out.:)

[Rich Harman]

I completed my out of focus test run today, here is a comparison of the job done in focus by my competitor and the out of focus burn I did. These were both done in low resolution e.g. density 2 in the universal's 1 to 7 choice.Higher densities would have killed the job on hours. The focus was set 10mm out. The grain really pops out nicely.

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Comparing two pieces done on the same material on the same machine would make a better example. This comparison against someone else's work has too many variables to be considered definitive. I'm not debating that out of focus wouldn't make for a darker engraving - just pointing out that the real difference made by changing the focus cannot be demonstrated when it was performed in different locations on different machines using different pieces of material.

[Richard Rumancik]

. . . Like Dan I put the bed further away to keep the optics clean. . . .

I also put the bed down but for a different reason. I want to know fairly accurately what the out-of-focus amount is. If I want to be .060" o.o.f. I can place a .060" shim on the workpiece and then focus off the shim. This ensures repeatibility.

Using the ruler idea, I wonder how one would be able to accurately read the table height off of the ruler graduations, if I understand it correctly.

[Keith Colson]

Rich, that is a good observation you have made. To get the job I engraved the "same" material and got very similar results. I engraved the back of the competitors sample and the customer took that away so I don't have photos.

Edit: Actually if you look to the very left of the picture you can see my engrave on the same material before I adjusted the artwork for the out of focus engrave.

Richard, you can focus your Z normally,then add 10mm in my case to the Z number. I do this automatically, so the Z axis goes back to the right position, before the cut out happens. I think its called "Auto Z" or something.

Cheers
Keith

[Bert Kemp]

You are using the shims sounds a lot easier then using a ruler off the side