레이저 로터리 부착물로 안경을 레이저 조각하는 방법
Dec 21 , 2022
We have all seen beautiful glass laser engravings on sale in stores. Although these commercially available items have normally been mass-produced using sandblasting or chemical etching processes, you can learn glass engraving — how to engrave glasses with your OMTech laser engraver. With a bit of practice, you’ll create stunning laser etched pieces that not only rival the store-bought products but are fully customizable for you and your customers.
In this article, we will discuss how to choose the best types of glass for laser engraving, how to create and set up the glass laser engraving design, how to use a laser rotary attachment, and finally learn how to laser engrave glasses, producing and finishing the final laser engraved glass.
Glass is available in literally dozens of types and all with different formulas, although they almost all contain mostly Silicon Dioxide (Silicate), they can have different additives that change the way they behave. You may have heard of Soda Glass, Pyrex, Lead Crystal, etc and each of these has
different properties that determine just how successful laser engraving glass cups will be.
To understand this better, we need to understand how glass laser engraving works. If you are laser engraving wood, the laser beam hits the wood and vaporises it - that’s what creates the smoke. However, glass behaves differently. Instead of vaporising the glass, the laser beam hits the glass and causes it to rapidly expand at the point where the laser beam (which is only 0.1mm wide) hits. The surrounding glass does not expand as quickly and so the area under the beam fractures. This micro fracturing is what creates the engraving on the surface of the glass.
Depending upon the additives in the glass, this process behaves slightly differently and so having a couple of spares available for testing before committing is essential.
For example, adding lead to the glass to create Lead Crystal creates a glass that is softer than standard glass and is significantly harder to engrave successfully as the glass absorbs heat faster and so needs a higher power laser but that can then lead to the glass overheating and shattering.
The best glass to laser engrave is actually the cheapest — dollar store drink glassware will laser engrave extremely well and is a great choice to start learning how to laser engrave glasses and to get the best from your laser engraver with rotary attachment.
Your OMTech laser engraver comes from the factory with fixed X and Y rails and a laser workbed area that is fixed during the engraving or cutting process. As the laser beam exits the focal lens and reaches the workpiece, it has a very small depth of focus (or focus tolerance). This means the machine itself is ideal for laser engraving on flat surfaces.
To overcome these mechanical limitations and engrave on curved surfaces like tumblers and cups, you can use a laser rotary attachment to rotate the object in a pre-calculated sequence as the laser fires. This rotation allows the cylindrical workpiece to remain within the laser’s focal point while counteracting the workpiece’s curvature.
There are three main types of laser rotary attachments that you can add to your laser engraver. For my instructions and demonstration, I will be using a Jaw Chuck-style rotary axis attachment.
The Roller Rotary Attachment comprises two long rollers which rotate the workpiece and hold it in place throughout the engraving process. As the stepper motor turns the rollers, the object rotates in the opposite direction. These laser rotary attachments work with cylindrical objects such as water bottles, but anything with a handle can be very difficult to position correctly. For simple cylinders, they are quick and easy to set up. They do, however, rely on friction between the rollers and the workpiece and if they slip, the entire engraving design can be misaligned. They is also why performing a second pass of the laser is not recommended with roller rotary attachments.
The other type is called a Jaw Chuck Rotary Attachment which has a set of jaws mounted in a chuck and which are tightened and loosened with a key. Normally they are supplied with 2 sets of jaws — internal and external. The internal ones are designed to expand outwards to grip the inside of a hollow item such as a cup or glass. The external jaws grip the outside of the object. These rotary attachments hold the object securely and are therefore more accurate and less prone to slippage.
Four Wheel laser rotary attahchments are similar to the roller-style rotaries, except they have four individual wheels (one in each corner) on which the bottle or glass will rest. This style of rotary axis attachment allows you to raise and the lower the height of each pair of wheels so that you can counteract the slope of tapered or "conical" bottles and tumblers.
Pro Tip: Most jaws are made of steel, so put heat shrink tubing over the ends of the jaws to prevent scratching the object being engraved.
There are two steps involved in working with your laser rotary attachment:
The first thing you will need to do is to lower the laser engraver bed to its lowest point so that the rotary attachment will fit and clear the engraving nozzle. Place the laser rotary attachment onto the workbed with the chuck on the right and square it to the edge of the bed — this ensures that you are laser engraving at the correct angle.
Now take the round plug from the rotary attachment and locate the similar socket on the right hand inside of the cabinet and connect the two. Tighten the collar to prevent the plug from falling out. Note that it only fits in one way so do not force it.
Now, making sure that the laser is switched off, open the electronics cabinet on the right-hand side of the laser engraver and locate the loose green connector. You now remove the same connector
from the Y-axis stepper motor controller and replace it with the loose connector. Now close the cabinet.
Now that the controller is connected to the rotary attachment, we need to inform the software that a rotary attachment is being used. In LightBurn, open Rotary Setup under the Tools menu. In the dialog, you can now enable the rotary. For this article, we are using a Chuck rotary, so we select “Chuck” and then click to Enable Rotary. If you are using a Roller Rotary Attachment today, please make that selection instead. There is one final step needed.
The chuck of the rotary attachment is driven by a stepper motor. As the name implies, this motor rotates in a number of ‘steps’ and we need to set this number correctly in the software so that it knows how many pulses to send to the motor to rotate it correctly. A typical rotary attachment will need 10,000 or 15,000 pulses or steps to achieve a full rotation and so if you cannot find this number in the rotary attachment documentation you will need to guess and test. Start with 10,000 and then place a piece of tape on the top of the chuck and press the TEST button in the LightBurn dialog. LightBurn will then instruct the Ruida controller to send 10,000 pulses to the rotary. If the number is correct, the tape should end up at exactly the same position as it started - if not then you will need to change the number accordingly.
It’s now time to think about the design that you want to laser engrave on the glass. The first consideration is how much of the glass object can be engraved. Even though the object will be rotated, it is turned on only one axis. Therefore it cannot make any allowance for changes in height — so we need to consider any curves or ridges in the object and design the engraving with these in mind.
If the laser beam encounters a ridge in the glass, the beam will go out of focus as it travels over the ridge and will distort on the sides of the ridge - so that is not an area to engrave. If the glass object has a curve then we need to consider between what distances the laser beam remains sufficiently in focus to achieve a clean engraving. We can do this by performing a ramp test on the laser engraver and examining the resulting hourglass shape. There will be a point that the lens starts to appear sharp and where it starts to widen — for a short focal length lens this will be quite small and for a longer focal length it will be larger. The nozzle to workpiece distance from these start to finish points on the ramp test will tell us how much curvature of the glass we can successfully engrave.
When you have created your design in LightBurn, you will need to rotate it by 90 degrees so that the top of the design is on the right. This is because we are using the Y-axis to move the rotary.
You will need at least one spare glass object to use for testing. As with any work we undertake on the laser engraver, we always need to test the material with various settings to see which works best. With a wine glass, for example, we can actually use several areas of the glass for testing.
On my 60W OMTech laser engraver, I start with 100mm/s speed and 25% max power and 20% min power in the CUTS/LAYERS dialog for any Line layers and 100mm/s speed and 20% max and min power for any Fill layers.
Pro Tip: Be aware that some glassware has a moulding line — a thin “seam” where the two pieces of glass were moulded together. Always avoid the moulding line when laser engraving glass.
일반적으로 레이저 조각을 할 때 공작물은 완벽하게 평평하므로 재료 표면에 레이저 초점을 맞춥니다. 그러나 많은 유리 음료 용기가 휘어져 있으므로 조각의 많은 부분이 가능한 한 초점에 맞춰 위치를 찾아야 합니다. 아주 약간의 곡선을 다루는 경우 이를 무시하고 노즐에 가장 가까운 지점에 초점을 맞출 수 있습니다. 그러나 곡률이 더 큰 경우 이상적인 초점 지점을 찾기 위해 더 많은 실험을 해야 할 수 있습니다.
선을 조각하는 경우 걱정해야 할 유일한 설정은 속도와 힘입니다. 레이저 조각기와 유리에 가장 적합한 설정을 찾을 때까지 다양한 설정을 실험해 보십시오. 두꺼운 글자나 모양을 만드는 경우 채우기 모드를 사용하고 있을 수 있습니다. 이 경우 각 조각 패스에 대해 레이저 빔이 이동하는 거리인 라인 간격 또는 LPI(Lines Per Inch)도 고려해야 합니다. 낮은 LPI는 눈에 보이는 선을 만들 수 있는 반면, 높은 LPI는 유리에 너무 많은 열을 가하여 균열을 일으킬 수 있습니다. 다시 말하지만, 여기에서 어떤 것이 최상의 결과를 제공하는지 확인하기 위해 실험해야 합니다. 저는 0.1mm(254 LPI)로 시작하지만 0.08mm(318 LPI)에서도 좋은 결과를 얻었습니다.
유리를 레이저 조각할 때 노즐에 많은 공기가 필요하지 않으므로 조정 가능한 공기 보조 장치가 있는 경우 렌즈를 깨끗하게 유지하기 위해 노즐에 양압을 생성하기에 충분한 공기로 공기를 최소한으로 유지하십시오.
이제 유리를 척에 단단히 장착해야 합니다. 머리는 개체의 중심선 위에 앉아 유리에 초점을 맞춰야 합니다. 이제 환기 팬을 가동하고 냉각수 온도를 68°F(20°C) 미만으로 유지하고 뚜껑을 닫은 상태에서 조각을 시작할 수 있습니다.
레이저 기계를 작동하는 동안 무인 상태로 두지 마십시오. 화재 징후가 있는지 레이저를 관찰하고 필요한 경우 비상 정지 버튼을 사용하십시오.
각인이 끝나면 결과를 검토하고(돋보기 사용을 권장합니다) 원하는 대로 고르게 각인되었는지 확인할 수 있습니다. 어느 정도 정의된 이미지를 생성하기 위해 필요에 따라 속도와 전력을 조정할 수 있습니다.
다음 단계는 매우 중요합니다. 앞서 설명한 바와 같이 레이저 조각 유리는 표면을 미세하게 파쇄하는 작업을 포함하며 이는 매우 날카로운 유리의 매우 작은 입자를 생성합니다. 따라서 새겨진 유리를 다룰 때 손과 눈 보호 장치가 필요합니다. 조각을 넘기려면 와이어 브러시 또는 전기 드릴에 와이어 휠이 필요합니다(Dremel 유형 드릴을 사용할 수도 있음). 이렇게 하면 유리 입자가 제거되고 완성된 각인이 만졌을 때 매끄러워집니다. 와이어 브러시는 유리를 손상시키지 않습니다.
레이저 조각 유리는 레이저 조각기와 회전식 부착물을 설정하는 방법을 배우면 매우 간단한 기술입니다. 또한 조각 작업을 완료하는 데 시간이 거의 걸리지 않습니다. 독특한 레이저 각인 선물을 만들 수 있는 기회는 당신의 상상력에 의해서만 제한되며 완벽한 결혼 선물과 기념일을 만듭니다. 벌크 유리 제품은 매우 저렴하게 구입할 수 있으며 각인은 상당한 가치를 더할 수 있습니다.
내 레이저 조각 사업에서 한 고객이 결혼식을 위해 조각된 샴페인 피리 한 쌍을 요청했지만 예를 보고 플루트의 저렴한 비용을 이해한 후 모든 하객에게 기념품으로 주기 위해 120개를 주문했습니다. 이렇게 많은 수에도 불구하고 빠른 조각 시간으로 인해 상대적으로 짧은(그리고 수익성 있는) 생산 시간이었습니다. 다른 레이저 각인 컵과 안경은 은퇴 선물용이었습니다. 일치하는 증류주 병을 각인할 수도 있습니다!
이제 유리를 레이저 조각하는 방법을 배우기 시작했으므로 다른 유형으로 시야를 넓힐 수 있습니다. 다양한 유형의 유리를 실험하고 테스트하고 모든 재료와 마찬가지로 LightBurn 재료 라이브러리에 결과를 기록하는 것을 잊지 마십시오.
