Need Advice on Cutting

[Paul Torrigino]

Hey you all,
I'm having a heck of time cutting through 1/4" mdf recently with my Epilog 45w. When I first got it, it cut through like butter at 100% power and 4% speed. Now 5 months later I make two passes at the same power and speed and I still have to finish the cuts with an exacto or scroll saw - it won't go all the way through. I'm cleaning the mirrors and lubricating the bearings....
Any thoughts??
Paul

[Dennis Perry]

Hey Paul, A freind of mine with a Epilog 45w was having the same problem. It turned out it was a dirty lense, that had to be replaced. It now cuts at the same speed and power as new. I cut alot of mdf and veneer core plywood, the mdf is harder to cut maybe 25% slower.

Dennis

[Paul Torrigino]

Hey Paul, A freind of mine with a Epilog 45w was having the same problem. It turned out it was a dirty lense, that had to be replaced. It now cuts at the same speed and power as new. I cut alot of mdf and veneer core plywood, the mdf is harder to cut maybe 25% slower.

Dennis


Hey Dennis,
Thanks, I'll try a proper major lense cleaning and see if that helps. So far I've just done the Q-Tip swabbing thing.

[Garry McKinney]

Also be sure to check the lense for tiny fractures. Anything that might deflect the beam. Every time we had had a big change it has been to fractures in the lense

[Joe Pelonio]

Paul,

If you actually take the mirrors out of the holder and look at them closely you may find that some of the gold has come off, that happened to mine. I replaced both mirrors and the lense after 2 years or so.

Another thing is, check to see if it cuts better at x0,y12 than at 24,0. If it does it could be a focus issue, maybe table not level, x bar not level, or even tube going weak.

[Jim Good]

Joe beat me to the punch but your focus could be out. If you are using Auto Focus, take a look at the tip of your focus probe. If it has some "crud" on the end of it your substrate will be further away than your laser thinks. You will lose some vector cutting capability.

Just a thought.

Jim

[Frank Corker]

Well I'm glad this subject has been brought up. Not long after I got my machine, I tried going through the lens cleaning process - I'm talking about the one that runs horizontally. These are the ones that need to be cleaned more than any (all the other ones so far I haven't even touched as they have no dust or muck on them). That said, I did get confused and never quite known if I have them in the right way.


Okay, so we have a mirror and one lens.
The mirror (with the retaining screws and back off) and an O ring.
On the lens (retaining screws and back) and one O ring.

What order are they put in. The mirror on mine goes straight onto the metal with the O ring at the back.

On the lens part, the O ring goes onto the metal with the convex curve facing upwards away from the bed. However it is easy enough to have it facing downwards and yet amazingly enough I couldn't find anything in the manual about it.

Now is it possible that Paul has his lens (the one directly above the workpiece) in the wrong way and if he has, how much of an effect will it have on it? If the O ring on the mirror was put in the reverse way, would that change the diversion of the beams and make it less effective.

I'd be very happy to hear if any or all of us have the right settings.
That said I did try the lens with the convex pointing downwards and it didn't seem to make much difference.

[Rodne Gold]

If you have lest 1/2 your power or more , its highly unlikely to be optics , its gonna be an alignment issue or a tube issue.

[Dean Carpenter]

1) use the right f/l lens: 2" or 2.5"

2) check for correct focus accross the table: make sure the table is level

3) Check optics (mirrors & lenses) for damage/debris

4) Check for beam alignment

5) if not, must be the tube. With this design make sure the machine has lots of free space around the laser for sufficient airflow. As with all air-cooled lasers the room temp should be within 17-27c for optimal operation

Dean

[Peck Sidara]

Paul,

All of the members suggestions will lead you to the solution. Just to re-cap what has already been said:

Check the lens and mirror assembly by actually removing the assembly from the engraving head. Clean and inspect for cracks, pits, discoloration, delamination.

Check the steering mirror and window (can't tell you where it's at as I don't know what model you have)

check all of these optics for the faults stated above.

When you're done. Do it again! There has been many times where the techs trouble-shoot the problem to be something other than the optics and when they go to replace the said item, nothing changes. After coming back to inspect the optics again. It turns out to be an optic.

Another thing to check would be your air-assist nozzle right below the lens. I've seen a few times where the nozzle gets in the way of the beam causing a loss of power.

As the other fine members has suggested; check the alignment, auto-focus.

If you're still having difficulty, call tech support.

[Nigel Morgan]

Interesting threads as I have also posted simular problems, have been advised to change the lens and mirror, this would be the second time in one year. How important is the room temp Peck?

[Rodne Gold]

Even with really poor optics and scratched mirrors , we have at worst had perhaps a 5-10 watt drop on output , im talking mirrors with lots of microscratchs and a lens where the coating has worn off (obviously a totally destroyed lens is a different story)

I have 6 lasers , what we do every week is test em by cutting a 3mm thick pex square at all points of the table. We know at what speed these should cut and thus can see if there are any power drops and alignment issues developing. Apart from that , we enter the speed into our spreadsheets and or database for each laser and this then recalculates settings if there is any change and thus each laser is optimally calibrated for the power available at that time.

Room temperature makes very little difference in terms of laser power barring overheating of the tubes if ambient temp is real high, but if one is spending like $20k on a laser , it makes sense to spend a little more on an airconditioner which will maintain a stable temp in the room and make the operators life more comfortable to boot.
We regularily strip our machines down and blow off the motherboards and laser tube fins and the cooling fans with canned air to remove dust build up.

[Nigel Morgan]

Thanks for the tips, it is safe to use compressed air or are you using the canned stuff they use on PC's. I asked about temp as my Laser is down in the sleepout which gets pretty cold in the mornings.

Cheers

Nigel

[Peck Sidara]

Interesting threads as I have also posted simular problems, have been advised to change the lens and mirror, this would be the second time in one year. How important is the room temp Peck?

Nigel,

Room temp should not have any bearing on the optics. I agree w/ Rodne regarding the room temp and the laser tube. Life expectancy of the optics is more dependent on your application (what materials you'll typically engrave and cut) and how well you maintain/clean your optics.

[Dean Carpenter]

Hi Guys,

Room temp: it has a big influence as far as air-cooled lasers are concerned, but this is very model dependant.

Not only does it influence the current performance of the laser it really does impact on the overall working life of the laser module, so you should strive to get the room temp right.

Air-cooled lasers in a very cold environment will be slow to react, especially if the jobs are very fast, processed at low duty cycle (power) and you have the lid up a lot of the time. This prevents the tube from achieving a stable heat. Think of it like a car engine, more efficient when it is warm.

Too cold an environment and you'll get condensation on the inside of the tube and potentially....BANG....!!

If the room is too hot then the laser will become too 'excited' and start to leak laser. For engraving fine detail to, for example, brushed foiled laminates this can be a real pain as you'll see shadowing.

best to keep the room temp within 17-27c all the time. This is actually a very comfortable temp for an office worker, so if you are happy with the temp the laser is too.

Regards

Dean

[Peck Sidara]

Hi Guys,

Room temp: it has a big influence as far as air-cooled lasers are concerned, but this is very model dependant.

Not only does it influence the current performance of the laser it really does impact on the overall working life of the laser module, so you should strive to get the room temp right.

Air-cooled lasers in a very cold environment will be slow to react, especially if the jobs are very fast, processed at low duty cycle (power) and you have the lid up a lot of the time. This prevents the tube from achieving a stable heat. Think of it like a car engine, more efficient when it is warm.

Too cold an environment and you'll get condensation on the inside of the tube and potentially....BANG....!!

If the room is too hot then the laser will become too 'excited' and start to leak laser. For engraving fine detail to, for example, brushed foiled laminates this can be a real pain as you'll see shadowing.

best to keep the room temp within 17-27c all the time. This is actually a very comfortable temp for an office worker, so if you are happy with the temp the laser is too.

Regards

Dean

Dean, I'm not sure I would totally agree with your statements. I too have an opinion on room temp and how it affects air-cooled lasers. My opinion is based on what the mfg. of the tube says as well as nine years trouble-shooting C02 lasers, both air-cooled and water cooled.

I don't believe that a colder environment will cause the laser to be slow to fire/pulse. Once the gas is excited, it should remain consistent regardless of the room temp. A cooler room temp won't necessarily cause condensation within the tube, I think relative humidity has more to do with condensation than the actual room temp. Additionally, it'll need some serious condensation to short out the boards within.

I also don't believe a hotter environment will cause a leaky laser. A leaky laser is caused by a poorly modulating RF driver that can not shut the laser off quickly enough. I don't think a hot room is enough to cause the electronics to go haywire. I do beleive that if there's no air-cooling (cooling fans) to help keep the laser tube cool, then perhaps the laser tube will eventually overheat, possibly causing the leaking of a laser but then again, the air-cooled lasers we use have an internal thermal switch where the laser tube shuts down completely before anything gets damaged.

Enough with my disbeliefs, here's something we do agree on. So if you're happy with the room temp, the laser is too.

I recommended a climate controlled room for air-cooled lasers. The AC will keep the humidity down to prevent any type of condensation from occuring and will keep the laser's temp down. Additionally, there should be some space (1-3'?) to allow the cooling fans to circulate air in and out of the laser compartment. I realize that a nice air-conditioned room isn't always available, work with what you've got and try to stay within a comfortable range.


Dean, I respect your opinion and the opinions of fellow members, not trying to stir up some controversy but instead would like to give the readers a different source to reference regarding this topic.