Switching out to 4" lens

[Kimmy Armstrong]

Has anyone bought and switched out the standard lens to the 4" lens from laserbits? Have you had any problems? All I really need is the lens because I don't auto focus. Epilog requires you purchase one from your rep. and buy the whole assembly. I have a Epilog Mini 24.

[Gary Hair]

I would shop around, you might find the prices "interesting"...

http://www.laserresearch.net/laser_engravers.asp

[Kimmy Armstrong]

Cool thanks!

[Rodne Gold]

Why are you switching to the 4" lens? There are some downsides to going to a longer lens.

[Kimmy Armstrong]

Well we are cutting through 1/4" plywood and have a cone accelerator on it that extends down 2 inches. If we try to focus down on the wood so that the point of convergence is half way into the wood, the accelerator drags on top of the wood. I hear it is better for cutting thicker things than the standard lens also. What's the downsides before I go ahead and order it?

50 watt Epilog Mini 24

[Dan Hintz]

The biggest down side is spot size is larger, which means less power density. A typical 2"FL lens gives a spot size of 5mils, whereas a 4"FL lens is 7mils+. This translates to a power density reduction of roughly 30% (or more). You'll have to slow down your cuts by a similar amount, and possibly expect more charring of the edges.

[Kimmy Armstrong]

I guess that means a wider cut also?

[Kimmy Armstrong]

What about the 2.5" lens? I don't need a wider cut.

[Richard Rumancik]

Is the cone accelerator an Epilog product or is it the FACT Engineering gadget? If Epilog, then go to them for advice . . . in my opinion, I would go with the 2.5" lens if it will clear the work, or even a non-standard FL lens, so you don't increase your spot size any more than needed. Just make sure you have adequate nose clearance for it to work correctly.

Sounds like you want to convert to the single FL lens for everything. In my opinion, I would bite the bullet and buy the assembly as required to enable you to switch lenses back and forth if need be. I'm not really familiar with the Epilog lenses. Sooner or later it will be necessary to change lenses and you want to make it quick. Some people can get by with one FL lens, but I use 1.5", 2", and 4" for different jobs. Plus I have a few "oddballs" like a 2" FL lens that fits the lower lens slot of a Mercury, to give me increased nose clearance.

[Kimmy Armstrong]

It's a Fact Engineering Product. It was weird because our Epilog rep. didn't even suggest an Epilog one, just the one from Fact Engineering one. We didn't know Epilog made one. We only run one standard item (1/4" plywood) and were thinking of the lens from laserresearch.net.

[Rodne Gold]

Well you do lose power density but only at the point of focus , with a longer lens you have less convergence and divergence from the focal point so you have more power density further from the focal point than with a shorter lens , a short lerns beam shape is like X , a longer one more like)(.
The issue as has been pointed out is wider kerf , bigger spot size and the fact that the power density due to the larger spot size might not be enough to get a good vaporisation - if your laser is lowish powered. A 2.5" lens would be your best bet , a 4" engraves badly and a 2.5 will give the clearance and maintain fair detail. Is it not possible to make the cone a little shorter? That would be your easiest solution....

[kyle bonnell]

I bought a 3" lens from laser research for $115. You dont need the whole assembly if you will use it all the time. I did ask my ULS dealer do send me a mount for the lens. He sent me one with a cracked lens in it for $10. I had to remove the old lens and epoxy the new but that too all of 10 minutes to do. Now I can switch between 2" and 3" lenses.

[Richard Rumancik]

I didn't mean to imply that Epilog made an equivalent to the Fact Engineering device. Probably they don't. Just wanted to make sure I understood what it was that you had.

I suspect that if you try to make it shorter, you will negate the function of it. I would assume that Fact Engineering made it as short as they could. Perhaps you should tell them what problem the device is creating and what they recommend before you buy the lens.

[John Noell]

I bought a 3" lens from laser research for $115. I have not seen a 3" (which is what I wanted), just 1.5, 2, 2.5 (what I got), and 4". Did you have to special order it?
I do a lot of curved material (esp. coconut shell) and the extra depth of field really helps.

[Kimmy Armstrong]

Thanks everyone! I think from what you all have said, the 2.5" lens will be our best bet. Thanks again!

[Albert Nix]

I have the 1.5", 2", 2.5" and the 4". I use the 2.5" more than any other lens. If I need a little more detail I drop back to the 2" or 1.5" if I am engraving leather shoe strings lol. The 4" only gets used when there is a clearance issue. Good luck