[Swansea Hackspace] Laser cutter kerf

[Andy Rush]

Right. I think it's probably better to try the simpler approaches and seeing if/how they improve things before moving onto more complex solutions. I say we should get a proper bed and level it as a first step. Once we have a level cutting surface, we can work on improvements from there.

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From: hackspace-bounces at swansea.hackspace.org.uk <hackspace-bounces at swansea.hackspace.org.uk> on behalf of Justin Mitchell <justin at swansea.hackspace.org.uk>
Sent: 01 March 2018 11:18
To: hackspace at swansea.hackspace.org.uk
Subject: Re: [Swansea Hackspace] Laser cutter kerf

On Thu, 2018-03-01 at 11:00 +0000, Andy Rush wrote:
> I've made a few laser cut pieces recently, and as far as I can tell,
> the beam's kerf is near 0.3mm at its thinnest, 0.6 at the widest. All
> the dimensions are 0.6-1.2mm off what they should be on paper. I've
> had a quick google around, and most places suggest that a laser
> cutter kerf should be within 0.18-0.22mm at the thinnest part of the
> cut. Are there steps that we can take to improve how accurately the
> laser cutter cuts, beyond trying to to account for the kerf within
> the original design by padding out all dimensions in the original
> file?

The bed is very likely not perfectly level, the main bedding sheet
tends to get propped by pieces of scrap to an appropriate height for
the material being cut, and may not even be at the optimal focal depth
for you, depening what your doing.

there are things we can improve that cost varying amount of time,
effort, or money.

1) Someone can measure and build a focussing aid

this could be as simple as a cut/3dprinted depth gauge that you hang
off the top of the laser head to physically see where the focal depth
si supposed to be.

or as complex as finishing fitting the alignment head we 3d printed,
which has two line projecting laser to make a cross hair for lining up
jobs, add a 3rd spot laser at an angle and it could indicate depth as
well.

2) replace the current bed with one thats actually level, perhaps a
honeycomb type. There are lots of designs floating around for
adjustable (either mechanically or electrically) ones that would let
you easily change the focal point.

3) improved optics, i have read claims that you can buy replacement
focal lens that has a sharper kerf, but i dont know what the costs are
like on that.


4) if you care about accuracy of cut then you do always have to account
for the kerf in your design, at least once you have a stable idea of
what that value is.


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