Benefits Of 1.5" lenses ??

[Al Mutairi]

The lense that came with my laser is the standard 2" lense. When it comes to rastering or vectoring I can do pretty much everything with the 2" lense & get good results even with detailed rubber stamps (8 point fonts) .

What can a 1.5" lense do that a 2" lense can't do ?

Just an enquiry to help me & maybe others decide whether it's worth the investment .

Thanks,

Al

[Bruce Volden]

Al,


There is just a "finer" focal point (not that it is noticeable to you or I) with the 1.5" lens. Also it is much easier (1/2") to crash your optics when attempting to engrave bowls, dished cuts, etc...:D with the shorter focal length.


Bruce

[Mike Mackenzie]

Al,

The only difference is the spot size 2" lens=0.005 spot size 1.5" lens=0.003 spot size.

The 1.5" lens works great for small text engraving but does not work so well when it comes to cutting. You are also closer to the work pc. so they will tend to get dirty quicker.

[Rodne Gold]

A 1.5" lens will allow far quicker and better cutting of thin substrates with a finer cut width and less edge damage , it will allow better resolution engraving with less heat affected zones. Ours will allow us to engrave Stainless steel with a 30 w laser (very slow in vector mode)
It has to do with power density , cos the spot size is smaller , more power is concentrated and the lens will allow more vaporization and less adjacent burn. The depth of "field" of the lens is smaller , ie it diverges and converges more radically than a longer focal length lens and thus flatness of the substrate is vital for best results.

Its not worth it unless you have a specific application for it like processing thin stuff or veneer inlay work or kiss cutting etc.
You can get lenses a lot cheaper than the manufacturers from this place
http://www.reflexusa.com/co2lasprecop.html

[Dave Fifield]

All great answers. I use my 1.5" focal length lens specifically for cutting veneers for my laser marquetry work. You have to have dead-flat veneer though, or it doesn't cut properly. The usable focal length range is VERY short!

[David Fairfield]

Interesting. Are these available for the Epilog?

Dave

[Peck Sidara]

David,

Thank you to the members that responded, all excellent answers. Epilog offers a 1.5" lens. If you have a newer Epilog (Mini, Helix, EXT), please contact your local rep for pricing and ordering. If it's an older Epilog, please contact tech support at 303.215.9171 to order.

Regards,
Peck Sidara
Epilog Laser

[Bill Cunningham]

David,

Thank you to the members that responded, all excellent answers. Epilog offers a 1.5" lens. If you have a newer Epilog (Mini, Helix, EXT), please contact your local rep for pricing and ordering. If it's an older Epilog, please contact tech support at 303.215.9171 to order.

Regards,
Peck Sidara
Epilog Laser

Peck; Is there one available for the 24tt? Last I heard there was not, has anything changed?

[Peck Sidara]

Bill,

In the past we did not offer a 1.5" lens for the TT. We have since implemented a 1.5" lens for the Mini's and the TT shares the same optic block so yes, we are now offering a 1.5" lens for the TT. Please contact Epilog's Tech Support at 303.215.9171 for pricing.

Regards,

[Bill Cunningham]

Cool!!! What else does the TT have in common with any of the newer machines.. Sure wish the bottom up rastering was available.. There must be enough TT's in circulation to make a few changes in the software to allow some things like this.. Even if it was offered at a modest price, I would think most TT owners would part with a few bucks for new firmware

[Al Mutairi]

David,

Thank you to the members that responded, all excellent answers. Epilog offers a 1.5" lens. If you have a newer Epilog (Mini, Helix, EXT), please contact your local rep for pricing and ordering. If it's an older Epilog, please contact tech support at 303.215.9171 to order.

Regards,
Peck Sidara
Epilog Laser

Thank you for thanking the members on behalf of the thread starter !!

Do you have anything informative to add on the subject beside passing out telephone numbers !!!!

What can a 1.5" lense do that a 2" lense can't do ?

[Roy Brewer]

Al,

I'm not sure I can say it any better than others, but you can't do anything with a 1.5" lens that you can't do with a 2" lens. It just gives you a smaller dot size which means greater detail on very small fonts or highly detailed graphics. If cutting, it is normally more trouble than it is worth unless you have very flat material and you need to reduce your kerf (as in marquetry/inlay examples).

[Rob Bosworth]

Dear Al, you won't get any phone numbers in this post!!

What you accomplish by using a 1.5" fl lens is a smaller spot size, which gives you greater energy density. The greater the energy density you have when laser processing, the greater control you have on the heat going into the material. You can also operate faster with greater energy density.

The drawback to using a shorter focal length lens is the shorter your focal length lens, the smaller your depth of focus. So to achieve a consistent cut quality across the range of motion of your machine, the part has to lay flatter the shorter the focal length optic used.

Using a 1.5" fl. lens to cut 1/16" thick veneer, you will get very fast vector cutting speeds to cut the part. The edge of the cut will look fairly perpendicular to the surface.

Using a 1.5" fl lens to cut 1/4" thk. material, you will either see a small kerf on the topside, or bottom side, with the other side having a fairly wide kerf. Let's say you focused your beam to the top of the material, you might only have a .004" wide kerf on the topside of a cut part. Flip the material over, and you will probably see a .012" wide kerf on the underside. And you will probably notice that the exit side of the material is much more burned or charred and probably not as smooth as the entry side. If you focus the beam with a 1.5" fl. lens into the middle of the 1/4" thk. part, you will see that the edges of the cut looks more like an hour glass rather than a perpendicular cut edge. The thicker the material you are cutting, the more pronounced this hour glass edge becomes.

Oh sorry. I miswrote above. You will see a phone number in this post. It is part of my automatic signature, and I do not know how to disable it.:eek:

[Peck Sidara]

Cool!!! What else does the TT have in common with any of the newer machines.. Sure wish the bottom up rastering was available.. There must be enough TT's in circulation to make a few changes in the software to allow some things like this.. Even if it was offered at a modest price, I would think most TT owners would part with a few bucks for new firmware

Bill,

The TT shares a few mechanical and electrical components with the Mini/Helix. Parts such as the mirrors, lens, lens block and a few of the smaller PCB boards are shared. The driver, firmware and controller board are different and is primarily the reason why bottom up engraving and some of the newer driver features aren't available on the TT.

Thanks,

[Richard Rumancik]

I see that there are mixed opinions on the usefulness of the 1.5" lens. It all depends on one's perspective, the types of parts they are making, what level of accuracy they are trying to achieve, the cost objectives of the customer, and their own objectives as to quality. It may also depend a bit on visual acuity. Not intended to be a slight to anyone - I wear glasses too. I make the assumption that my customers can see better than me. But I use magnification to help determine what the laser is doing. I am making some precise parts and need good accuracy so I look for ways of improving my results. Also I try to make my bitmap images as good as I can. I would not likely use a 2" lens for a photo, picture or plaque. If I am doing text or a small logo at 600 or 1000 dpi (wood or stainless) it would seem counterproductive to use a 2" lens for this.

I fabricate a lot of thinner materials. Unless the material is warped like some veneer - which I don't use - I do not have a big problem with flatness (and thus short focal length) using the 1.5" lens. I use weights, vacuum, whatever works to hold thin materials down. I also have my own 3" thick table clamped above my factory table. This table has adjustments, so I can quickly level the cutting surface in 4 corners with a screwdriver. The factory table can't be leveled easily. Plus my method levels the material, not the table.

If you are trying to use the entire table area with a 1.5" lens then focal length may come in to play. For fine work I try to stay in the top left corner as much as possible (0,0). My laser does not do a great job in the lower right with any lens. There is too much drop-off in laser power as well, so I would not try to do fine engraving in the lower right. Some of this is just the result of the use of flying optics. The beam travels the longest distance through air in the lower right, so beam diameter and beam quality is affected, thereby affecting focus.

You won't get my 1.5" lens out of my hands without a struggle.

On the other hand, I have not found a good use for a 4" lens. It could be useful if I had more power but with only 30 watt I don't find many applications for it.

[Rodne Gold]

4" lens is great for a few applications like large surface engraving where the larger spot size allows you to use low dpi's , like 150. It radically cuts down time on large signage or the like. You can also cut 8-12mm pex with your 30 w with a 4" lens and maintain stright cuts and good edges.
Often useful on my machine with a rotary attachment or with other items you want the head to be far away from.
We have 6 lasers and only 1x 1.5" and only 1x 4" lens and we could easily live without them if needs be.

[Dave Jones]

Al, I'm not sure why you got so angry at Peck. You started the thread, but other members have questions too and Peck was answering one of those, namely is the lens available for an Epilog.

[Richard Rumancik]

Bruce said: There is just a "finer" focal point (not that it is noticeable to you or I) with the 1.5" lens. Also it is much easier (1/2") to crash your optics when attempting to engrave bowls, dished cuts, etc... with the shorter focal length.


Mike Mackenzie said: The only difference is the spot size 2" lens=0.005 spot size 1.5" lens=0.003 spot size. The 1.5" lens works great for small text engraving but does not work so well when it comes to cutting. You are also closer to the work pc. so they will tend to get dirty quicker.
_______________________________________

Bruce: there is more risk with a crash on some machines; the Mercury might be different than Epilog in that respect. With the LaserPro there are two places to insert the lens. The 1.5" lens goes in a slot .50" lower down than the 2" lens. As a result the nose cone of the laser is exactly the same distance from the material regardless of which lens is used. One focus probe is used as well for both lenses. (If using autofocus you don't have to tell the laser you are changing lenses.)

On the LaserPro you can also remove the nose cone and use a flat plate with a hole if you are engraving close to an object.

Mike: Since the lens is closer to the work regardless of model, you are correct that there is more risk of getting the lens dirty. When using air assist I have not seen a problem. But if a material tends to flame or spark it might put the lens at a higher risk for damage.

[Kim Vellore]

You can get lenses a lot cheaper than the manufacturers from this place
http://www.reflexusa.com/co2lasprecop.html I got all excited when I saw the cheap lenses and was trying to get a 1" lens from them but they quoted a price of $295 which was high for me and from what I saw at the website. Anyway I'll keep looking. Kim

[Richard Rumancik]

I got all excited when I saw the cheap lenses and was trying to get a 1" lens from them but they quoted a price of $295 which was high for me and from what I saw at the website. Anyway I'll keep looking. Kim

Do you mind me asking what you will be using a 1" focal length lens for? A lot of people in this thread have expressed that they don't find the 1.5" focal length lens to be absolutely necessary - you must have a unique application.

Richard

[Kim Vellore]

Do you mind me asking what you will be using a 1" focal length lens for? A lot of people in this thread have expressed that they don't find the 1.5" focal length lens to be absolutely necessary - you must have a unique application.

Richard Richard, I have been using my laser as a RP machine. It works great for the scale I am working in. I have been using a 1.5" lens and I get great result but I want even better results for my casting project. To give an idea, here is a picture of a steam engine boiler I made from Delrin with my own rotary fixture. http://kimsartshop.com/060/060Side2.JPG http://kimsartshop.com/060/060Top.JPG as you can see a clean etching great for investment casting. In the rotary axis I get 1 rotation for 2.3" and with 1200DPI it is just perfect. Now here is a picture of the front http://kimsartshop.com/060/060Front.JPG This is rastered with 1200DPI but the Y axis range 12" You can see the raster lines, you don't notice when you look at it with a naked eye but it shows up with macro photos, I get more visible lines with a 2" lens than 1.5" so I was hoping to get perfect results with a 1" lens like the rotary version. I have modified my laser quite a bit to do this, and this is not a normal operation for most folks, I was just trying to do some RP which can be cast in brass. It is the ultimate modelers dream just draw up a part in a computer and you have it in your hand in brass. The normal RP (Rapid Prototype) machines are too expensive and you cannot cast from them directly and they still show fine lines in the scale I am working in. This could be a poor man's RP machine. That is why I am looking for a cheap 1" lens. Kim

[Rodne Gold]

You might get WORSE surfaces with a 1" lens in your case
We do a ton of models for spin casting and surface finish is a huge problem with the laser.
We have tried various strategies like trying chemicals or solvents to smooth surfaces , sandblasting , using various patterns for surface finishing etc.
2 things work
First prize = hand finishing
2nd prize = polishing pass (low power high speed pass over already engraved surfaces )
A lot of the problem has to do with the motion system of the laser and the by products of vaporaization. Things you cant really control that well.
We do have a LOT of success in making masters for various moulding procedures tho.
Often an intermediate process works better , like using wax and other materials that respond with smoother surfaces and making a RTV mould with em for casting masters in resin that can be used in the high temp vulcanising rubber of spin cast moulds , however this means that the casting is off a casting and is not 1st generation.