Here I want to show you another height adjustment option for the cheap chinese K40 Lasercutters that sell for around 350 Euros in the bay or from various infamous chinese warehouses using adjustable standoffs. There is already plenty of information on the internet for instance :

https://k40laser.se/

offers advice on aligning the mirrors, setting the focus, upgrading PSUs, controllers etc. Also this site :

https://www.lightobject.com/K40-Upgrade-Parts-C68....

offers various commercial upgrades that I will not get into further at this point. Please excuse me for not listing all sites out there.

That said I have not seen the solution I came up with to setting the workpiece's height so I though I'd share.

I simply use magnetic standoffs that attach to the bottom of the laser as well as a 3-d-printed angle glued to the bottom for alignment.

So - lets get started:

Step 1: Parts & Tools:

Here is what you need :

12 x N45 Magnets round 8x3mm

4x 40mm M8 threaded rod.

4x M8 Hex Nut

1x Callipers

1x 8mm Drill

1x superglue

either:

15mm aluminum rod + a Lathe + 7mm drill bit (or better 6.8) M8 thread cutters (way I did it - because I had those things)

4x M8 extension Nut, a Vise and a cordless drill (way that should work - please report back

Step 2: Preparing the Standoffs

First - if you haven't already - scrap the original bed - it is simply not useable and nobody seems to have any idea why they made it that way

If you have a Lathe and went for the aluminum option :

-cut 4 Pieces of around 40 mm length of the round aluminum stock

-center drill the aluminum pieces using a 7 mm drill bit - all the way through

- center drill using the 8mm drill bit on one side - around 3.2 mm deep

- thread from the opposite end and stop 1mm short of the widened piece

If you went for the extension nuts :

- put a nut in the vise

- use the 8mm drill in the cordless drill to remove about 3mm of the threads just so one of the magnets fits in there

Step 3: Glue the Magnets in Place

Put some superglue on the outer top side of a magnet while it is attached to some piece of steel (easier) or just while it is on a straight surface.

Place the 8mm bore of the aluminum rod or the bored side of the extension nut on top and let it sit until the glue is dry- its importand the rod or extension nut touches the surface as that will make the standoff stand much stronger in place once done

Use the superglue to attach a magnet each to one side of each threaded rod

Thread the nuts on the threaded rods and afterwards into the aluminum or the nuts respectively

Step 4: Glue the Angle Bracket in Place

Make an angle bracket of some sort - I chose to 3-d-print it but any other method of fabrication will do (cut wood and glue - or use your laser and some acrylic as you have one :)

The angle bracket should be about 80mm heigh and I chose roughly the same length for both sides.

Align it with the axis of your laser(See intro picture)

Use magnets to hold it in place and run superglue around it to attach it

Step 5: Set the Height of the Standoffs

I am doubtful the focus is the same ways away from the bottom for all K40s so you will have to find out what it is for you. I found it to be about 75mm from the bottom of mine so in the picture I set up the standoffs for 4mm plywood. Procedure is as follows:

-Set callipers to desired height (focus height minus thickness for engraving, focus height minus half thickness for cutting

-place the assembly into the callipers and extend until both sides gently touch the calipers

-Lock by threading the nut against the rod /extension nut

Step 6: Place Into Laser

-Place the magnets somewhere your work will not be on that workpiece.

-gently push the workpiece towoards the angle bracket

-Use the remaining 4 magnets to hold the piece in place

-Enjoy

P.S. Of course you can also use a steel mesh to attach to your standoffs and not use any top magnets. I chose not to in order to avoid reflections during cutting that I had trouble with earlier.

Also I really like this option for height adjustment as well although it uses a steel mesh it seems easy to set up for engraving but has its shortcomings for cutting.... :

https://www.youtube.com/watch?v=7cl0OkYHS5I