So i’ve gotten an Omtech Polar 350 recently. Brand new not used. I’ve went through alignment, focal adjustment etc. It comes with a 2" focal lens out of the box. I have problems cutting any thickness of acrylic material.
As it cuts, it is angled like in the picture below so I am unable to make a 90 degree right angle joining two pieces of acrylic at any thickness. 1/4, 3/8, 1/2" all the same result.
I’m curious if a 2.5" focal lens from American Photonics would improve this situation, or if there is something i’m not aware of that will help this thing actually cut straight down and not make this weird cone. I understand it may not be perfect but most of my cuts have a pretty hefty angle that even sanding just seems to take some time, it’s a solid like 8 degrees off.
I’ve also been looking for an alternative bonding agent. I’ve been using Weld On 4, but alot of people say to go with a UV type bonding adhesive such as Permabond UV 6302, but I can’t seem to find that. Are there any good relatively thin UV bonding agents? When making boxes it’s proved rather difficult to ensure every single bubble gets out of the acrylic before it sets and then leaves me screwed. Would a UV bonding agent be a better choice, and since I can’t find Permabond 6302 is there an alternative or am I just not looking in the right place? I’m in the USA…
Thank you for any help members of the community can give, this has been driving me crazy for several weeks now.
A couple things come to mind. If it’s actually v shaped like your drawing and not angled in one direction like this \ \ or / /, I would check to make sure you’re not too close to the material. Run a ramp test to find your actual focal distance. The focus blocks provided by the manufacturer are not always correct. If it’s skewed in one direction like my examples, your laser head may not be perpindicular to the bed. That would cause angled cuts.
And yes, a longer focal lens would change the depth of ‘in focus’, but going from a 2" to 2.5" would not make much difference.
Yea the cuts are like // or \ or sometimes / and \ it just makes no sense to me. Im hoping there is some answer i can find. I was truly hoping maybe the lens was the issue. Would going to a different lens help cut acrylic more efficiently or anything?
Ive also wondered if something on the mechanism itself was a degree off angle and it could cause the issue but no idea how to check. Omtechs build quality definitely was not the best.
Here’s the easiest way I know to see if you laser is burning perpendicular to the bed. Put a piece of cardboard on the bed and affix it in place with tape or magnets. Focus the laser to the cardboard and pulse the laser. It should make a visible spot on the cardboard. Don’t move the laser head. Lower the bed as far as it goes and pulse the laser again. The 2 spots should line up if the laser is perpendicular. If they don’t you need to adjust things until they do.
All of what follows assumes the rest of the machine is adjusted and working properly.
Ensure everything is square in 3 dimensions and aligned.
I use a 2" lens a lot with my co2… it’s depth of focus (dof) is ~3mm, so that’s the thickest you can cut with straight edges. That’s about 1/8".
A 1/4" piece is ~6mm, so you’d need a longer lens. I’ve done 10mm on my machine and it’s really slow, around a mm/s and about 95% power to get through that much acrylic on such a small machine.
There are a number of on-line calculators that allow you to compute spot size along with dof. Most manufacturers specify this if you hunt it down.
I believe my 101.6mm (4") lens has a dof of just under 12mm.
Hope some of this helps… You’re on your own as far as the bonding adhesive goes.
