Help with Cutting

[Mr Bea]

Hi I am a newbie at this but am having a few problems and wondered if anyone could point me in the right direction. I have a HPC 6840 and am cutting 3mm MDF. When cutting a simple rectangle I get one side and one length square but the remaining 2 edges have an angle, as if the laser is cutting at an angle and not straight down. I have tried altering the 3 thumb screws but don't seem to be able to improve it at all. If anyone can help it would be appreciated.

Many Thanks
Mr Bea

[Spooky]

Could be a whole load of different thing?

Is the MDF flat and smooth?
Is the laser hitting the middle of the mirrors?
Is the laser exiting the aircone at 90% to the material?
Is the beam hitting the side of the aircone? (side scatter)
Is is laserable MDF or just B&Q stuff?
Is anything jamming the slideways and do you keep them lubricated?

If possible some pictures of what your describing may help? and the settings you are running ?

best wishes

Dave

[Mr Bea]

Hi Dave and thanks for the help.

I have done a mirror alignment check (or whatever the technical name is) and have noticed that the check from the last mirror to the laser head seems to fire the beam to the lower half of the circle and not in the middle, I did wonder if this was part of the cause. I have also noticed that by altering the thumb screws I can get the laser not to cut at all and guessed that it was hitting the laser cone. I am not sure if the laser is hitting the material at 90 degress but would guess that it is as 2 of the sides cut perfect, but how can I check this. The MDF is laserable and has been stored flat and is smooth. The settings that I am using are the ones set up by HPC I can confirm these later if need be when I fire the laser up.

The uploaded picture shows the issue I am on about, the left hand side is the angled cut whilst the right hand side is straight.

Many Thanks for your help

[Spooky]

Hiya,

A quick first thought is side scatter looking at the picture, as the final slideway moves left and right if the beam is not striking the mirror in the middle the exit angle will change (hence cut angle will change).

My first recomendation would be to adjust the mirrors (starting at the second mirror) right the way through to the final exit mirror. It's very rare that the initial mirror (the one the beam hits first) goes out of line so I wouldn't be moving that one about. The closer to dead center you can get it the better, it can be the difference between cutting 5mm plastic and 8mm plastic in one hit.
Experience so far has taught me that laser exit angle is quite critical to a good cut and low power requirements.

Give that a go and let us know if there is any improvement or not

Chris or Charli may know more and their after sales support is fantastic

best wishes

Dave

[Mr Bea]

Hi Dave
I have lined up the mirrors to the laser head, but one daft question, how can I make sure it is coming out of the cone at 90 degrees.

Thanks again
Tony

[Spooky]

Hiya Tony,

Drop the laser head to within say 3mm of the piece of wood. Hit the "Laser" button on the control panel to generate a spot then visually check to see if the burn dot appears to be in the centre of the air cone.

Not the most accurate way but a very good quick check for a starting point.

best wishes

dave

[Mr Bea]

Hi Dave
I thought that was how you did it so, or at least that was one way. I have made progress now but the only way that I could get the cutting angle anyway straight was lowering the bed. I think that the focus point may of been set too high as now the cut seems neater and can be carried out at lower power and speed. Does this sound feasible to you.

[Spooky]

Quite possible Tony, I reset the twin red lasers on mine a few weeks back and it made a BIG difference to speeds + power.

Chris or Charli will know the exact height for cutting ( on mine its 41mm from lens holder to workpiece (50mm from lens itself))

Set the height with a vernier or gauge block then adjust red dots to suit.

best wishes

Dave

[Mr Bea]

Hi Dave
Thanks for all your help, it has been greatly appreciated.

Many Thanks again.

[Spooky]

No problem Tony,
If you ever get stuck I'm only an email away

best wishes

Dave