Engraving circles on cups

[Bob WrightNC]

I'm trying to engrave a true circular logo onto a cup and having a heck of a time getting a good looking circle. Is there a formula for engraving a circle onto a round object that takes into account radius and give you something that looks good. I'm engraving blue tape like there's no tomorrow but can't seem to hit a sweet spot. Thanks.

[Brian Leavitt]

I just print the logo out on a sheet of paper, in several different widths, and wrap it around the cup to find which one looks right.

[Mark Sipes]

circumference of cup / 3.1416 = D This formula?




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[Mike Troncalli]

I like Brian's idea.. print out several ovals in different widths and see which one looks best for your cup..

[Mark Sipes]

Gee, I thought he was getting ovals now and wanted circles.... I must have read the thread all wrong..

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[Scott Shepherd]

Mark, I think he's got a circle, but once on the cup, looks visually like an oval and he wants to fix that. It's not a math issue, per se, it's a visual thing. Math wise, it's a circle, visually, it's an oval.

I think Brian's method is going to be the easiest.

[Bob WrightNC]

I think you're right, print it and stick it and see which one looks best.

[Michael Kowalczyk]

you will probably need a 4" lens also

[Mark Sipes]

I like Brian's idea.. print out several ovals in different widths and see which one looks best for your cup..

Scott thanks for the clarification...... Maybe Mike T. is the one who got it wrong??


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[Mark Sipes]

It's not a math issue, per se, it's a visual thing. Math wise, it's a circle, visually, it's an oval.

I think Brian's method is going to be the easiest.

So you are sure the Diameter of the cup was correctly input into the software?? or I guess that makes no difference

[Bob WrightNC]

So you are sure the Diameter of the cup was correctly input into the software?? or I guess that makes no difference

Let say you take a circle 2.25 inches wide and engrave it on a cup 3.2 inches in diameter. After you burn it, you can take calipers, measure the width of the logo, and it's 2.1 inches wide, even though it is 2.25 inches around the outside of the cup. Hence the problem. Now if you stretch it a little wider (2.31 inches), it looks better head on, but if you get about 10 or 2 and slightly out front, you got one ugly looking oval. Depth of field and point of view can really give you a distorted look.

Take home message for me is stay away from circular logos.

[Scott Shepherd]

Bob, give Trotec a call and ask them. Seems like there is a correction value for that sort of stuff on the Universal, but I honestly use the rotary attachment so rarely, I can't help, not to mention the fact, I don't even own one for the Trotec and I've only used it on a Trotec a couple of times while helping other people that had them. I'll look in the settings, maybe the ability to scale it is there.

[Bob WrightNC]

Bob, give Trotec a call and ask them. Seems like there is a correction value for that sort of stuff on the Universal, but I honestly use the rotary attachment so rarely, I can't help, not to mention the fact, I don't even own one for the Trotec and I've only used it on a Trotec a couple of times while helping other people that had them. I'll look in the settings, maybe the ability to scale it is there.

They're just gonna turn around and call you! LOL!

[Mark Sipes]

Any Pictures of your dilemma?

[Scott Shepherd]

They're just gonna turn around and call you! LOL!

Call the main number, not the one in NC ;)

Do you have this setup right? I'm not sure if that needs to be set or not. I know when you send the job over, it asks you the diameter of the job, but I'm not sure if this number has to match that number or not. I'd write the number that's in there down, and then I'd change it to make both numbers match, then I'd give it a try.

We have the same issue when we sandblast glasses, so it's not a laser related issue, it's just a visual thing (or should be).

Check this setting, try what I said and report back!

304708

[Bob WrightNC]

Scott, I've got those settings, in particular because I wanted the laser to return to the point of origin. I'm guessing two things - I may not have had the cup/glass seated well but more likely, it is what it is and it's just a matter of visual perspective. Part of my frustration though as a newbie, is that there is nothing in concrete for settings, so every different substrate requires testing - even glass engraves different depending on the quality, etc. Eighth inch of this acrylic cuts different than another color or brand. And, even though we have the same machine, your settings may not be good for mine. Frustrating and time consuming but it's slowly coming together.

[Matt Turner (physics)]

The first-order formula you're asking for would be: [horiz. rescale factor] = [object diameter]/[logo width] * arcsin([logo width]/[object diameter]). This is only going to get the width of the outermost circle correct for a straight-on view from far away, though. If there are smaller concentric circles, then they'll look distorted, and even the outermost circle won't look like a perfect circle.

[Scott Shepherd]

Part of my frustration though as a newbie, is that there is nothing in concrete for settings, so every different substrate requires testing - even glass engraves different depending on the quality, etc. Eighth inch of this acrylic cuts different than another color or brand. And, even though we have the same machine, your settings may not be good for mine. Frustrating and time consuming but it's slowly coming together.

That is 100% true! That's what makes us money, not the engraving so much, but the knowledge to run jobs efficiently and make decent judgement calls on the fly. Honestly, if it were "so easy a caveman could do it", then I'd be deeply concerned for our business.

Some time last year, a customer of mine decided it was all so easy. Armed with the knowledge of watching me make his parts, and seeing who the customers were laying on the tables every time he came in, he thought it would be a breeze to do his own parts and steal our customers.

He was all around town, talking himself up to my customers, put photos online all the time that were swiped from other engraving companies, built an impressive website that had 4-5 people working there with all different titles. I don't think it worked out for him. My customers told me he was calling, stuck with us, he stopped updating photos all over the place and took his website down a couple months ago.

If you pay attention, keep good records and understand why thing do what they do, you will do well. All the guys I know on this forum that I consider very successful, all paid the same dues you are paying. It's not always fun in the early stages, but it'll get a LOT better.

Hang in there!

I'll catch up with you on a Saturday or Sunday and we will see if we can fast track you through some things.

[Dan Hintz]

They're just gonna turn around and call you! LOL!

I got a really good chuckle out of this one... ;)

[Scott Shepherd]

Scott, I've got those settings, in particular because I wanted the laser to return to the point of origin.

Are you saying your diameter is the same when you enter it in the print driver dialogue box as it is in the settings I posted? That's what I'm talking about. I'm not talking about any "home" positioning.

[Scott Shepherd]

I got a really good chuckle out of this one... ;)

Don't laugh too much, you're in my speed dial when I don't know how to do something :p Without you, Dave, Mike, Gary, and a couple of other people, I'd have no one to ask!

[Keith Colson]

If you want to see how it will look with out messing around with the laser engraver, you could try loading up 3d cad e.g. sketchup and put your artwork on a virtual cup. You can then view it in perspective mode and see what works.

Cheers
Keith

[Greg Holt]

I know this problem. :)

Usually I start by encouraging the customer to make the logo smaller. Thereby reducing the visual distortion.

[Dan Hintz]

Well, there IS a mathematical way to distort the image so that it looks normal, but it only works when viewed straight on... if people really care I could go into it, but I think your best (and fastest) bet is to eyeball it, as suggested.