Flaming machine!

[kreativkatie]

I've been having niggly issues for some time with the power and speed and alignment which meant I have been getting ridges along a straight edge cut on 3&5 mm acrylic, I had a issue with the cut being slightly angled or flames being produced. I've so far spent hours refocusing the Mirrors, no matter what I do I can't get the beam to hit the centre of the mirror, however they all do align with each other. I've tried upping the power to get rid of the ridges and slowing the speed. However, this results in a flame being produced whilst cutting.
I can't win?!
I have a 600 x 900 bed, I was cutting 2 full
Panels of 5mm acrylic which was cutting fine. I had the standard air pump on and extraction running etc. On the very outside straight cut, right on the edge of the bed a flame just continued being produced for the full length of the panel. If I moved it the whole panel would have been ruined, so I just had to hit pause over and over again to try to stop a massive amount of damage. It was only the very outside edges that's flamed along the x axis, the material was raised off the bed.
Arrggghhhhh. Please help. I'm trying to run a small business, but feel I can't offer certain products to sell as I can't use the full size of the bed?
Thanks.

[Daven]

Does it cut other material ok (say thin card or ply) and all across the bed? If so the chances are the alignment is ok.

The flaming near the edge is possibly due to more oxygen/airflow which there is not a lot you can do apart from get the settings right. Maybe you could put a sacrificial bit of ply under the acrylic and see if that helps.

I use a series of test patterns (you can download the files from here) - just set the power or speeds over a range and see which is best - if they all cut out then increase the range if they don't then decrease the range! Place the material in the furthest corner of the bed away from the first mirror.

Best
Dave

[kreativkatie]

Does it cut other material ok (say thin card or ply) and all across the bed? If so the chances are the alignment is ok

The flaming near the edge is possibly due to more oxygen/airflow which there is not a lot you can do apart from get the settings right. Maybe you could put a sacrificial bit of ply under the acrylic and see if that helps.

I use a series of test patterns (you can download the files from here) - just set the power or speeds over a range and see which is best - if they all cut out then increase the range if they don't then decrease the range! Place the material in the furthest corner of the bed away from the first mirror.

Best
Dave

Hi Dave,

Thanks for your thoughts. I've not thought of putting other material under the outer edge, sounds like a plan, do you not think the ply would char and mark the underside of the acrylic?

Reading your reply I am thinking you feel I've got too much power?

Ta.

[Daven]

It is hard to say about power - I still get a bit of a flame once in a while - mainly when cutting complex shapes or as you have found close to the edge.

Finding the minimum power required to get a good cut is going to help. Also try and leave the mirrors alone (if you have concluded that they cut other material ok.) I don't remove the mirrors except the one in the head to clean, just wipe them over in place so I do not disturb them. Try to keep everything as constant as possible otherwise you can be chasing your own tail!

If the ply is far enough away from the acrylic (say 10mm +) and leave the protective covering on you should be ok.

The flame starts after getting a flash off the bed (as far as I can see) so anything to minimise that should help.

Best
Dave