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Finding the focal point for 7.5" Lens on C02 Laser

Finding the focal point for 7.5" Lens on C02 Laser

(OP)
So the books give us the old methods on finding the focal point for our Mazak U44 SpaceGear. It's pretty straightforward to say the least. You find the top of the focus by finding the blue flame on some stainless and getting an average of about 5 shots then do the same thing to find the bottom of the focal point. Then divide by two and bam there's your focus. I'm sure most people with lasers know the process very well and have done it a million times, but I have a question.

We don't normally change our focus enough to have to check it very often, but when we do have to do a blue flame test to determine exactly where the focus is sometimes our numbers don't exactly make any sense. We will go from -0.020" focus to -0.060" focus (with half turn adjustments I might add) and then sometimes even get 0.0 focus with three different tests meanwhile the focal point is SUPPOSED to be set at -0.040". After doing it long enough we finally will get a consistent number and call it a day (sometimes it can take up to an hour and a half of getting different numbers until we can get something within +/-0.010").

My question:

Is there an easier way to either get used to finding the focal points or is there another way entirely that we are missing out on?


I feel like entirely too much time is wasted sometimes just making sure that our focal point is correct. This time is eating into our production and often makes the boss a little restless. I feel like I'm missing something because the techs from the support like make it sound like we are either doing something wrong, or they make it sound a lot easier than it really is to get a consistent number.

If anyone could help, or even just point me in the right direction, that would be great.

RE: Finding the focal point for 7.5" Lens on C02 Laser

my reply doesn't help you. but man your situation sounds like a royal pain in the ass. and honestly I am clueless to the blue flame process. on an Amada it takes about 2-5 minutes to set your base focus. and it is never touched again until the lens needs replaced.

For amada's base focus is done this way, you take a piece of 0.060 or 0.075 piece of carbon steel. ( which is used doesn't matter as long as you consistently use the same) then the machine cuts a series of 2-3 inch lines at .02 focus increments based on your current base focus. then you take a set of feeler gauges, and find your tightest line. this is all done with an integrated program on the machine, so I just listed the basics. of how it was done.

RE: Finding the focal point for 7.5" Lens on C02 Laser

(OP)
Man that sounds really nice. I wish they had some sort of Auto-Focus feature on the Mazak machine that we purchased, but I don't think the SG-U44 had the capability to do that. This thing just specializes in shredding through incredibly thick material really quickly. It's just that our shop bounces between material thicknesses a lot so we are constantly changing our focus. We will go from -.320" to -.040" and then back up to -.320" sometimes twice or three times a day depending on how busy we are (note that this isn't a very often occurrence, but when it is we need to make sure that we are staying accurate).

RE: Finding the focal point for 7.5" Lens on C02 Laser

like I said, at least I think I said ? I don't know this laser. my experience is with Amada's . but this laser doesn't have saved M codes for materials and focus. you have to manually move your focus for every material you cut ? if you do have to manually adjust your focus. is there any way to document what focus works best for each material. and a way to get back to that focal point each time.

RE: Finding the focal point for 7.5" Lens on C02 Laser

(OP)

Quote (Chalked)

like I said, at least I think I said ? I don't know this laser. my experience is with Amada's . but this laser doesn't have saved M codes for materials and focus. you have to manually move your focus for every material you cut ? if you do have to manually adjust your focus. is there any way to document what focus works best for each material. and a way to get back to that focal point each time.

I mean there is a way to document it (the adjustment "wrench" has numbers and lines on it that can sort of count the depth of the focus for you ex: 1 turn = +/-.040), but the problem is in that exactly. There is no way to really tell if that is actually .04 a turn until we do a blue flame test and that's what gives us the most trouble.

I just hope someone out there has some pointers or something.

RE: Finding the focal point for 7.5" Lens on C02 Laser

The way I did a focus test on our first laser that had a manual focus was to make a program with 10 lines about 2” long and ½ apart. I would cut the first line and stop it than change the focus by ½ mm, make sure to write down where the starting focus is at, press start and cut the second line. Stop it after every line and change the focus by 1/2mm. You should see the kurf changing from one line to the next. If the lines just keep getting larger go back to the original focus and run it again but change the focus the other direction. When your lines go from large to small to large again pick the line in the middle and you should have a good base focus.

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