DIY Laser levelling using webcam and laser level

[John McNamara]

Hi Pippin

X and y positioning does not need to be done to CNC milling machine accuracy standards. the pecks cut a small circle and can overlap each other enough to allow for any positioning errors.

Using a rail that will later be used on the machine (it needs to be a profile rail if only one is used round rails will work but two will be needed) the cutting head will be mounted on one of the rail runner bearings that will later be used on the machine. The cutter head will be small, not a gantry across the machine. At a guess maybe a 250mm cube should be enough to contain the components. made from laser cut and 3d printed parts.

If the rail used is not ordered a little extra long the cut length will be equal to the length of the rail minus the width of the runner block, not a huge problem the small section at each end could be hand finished. Or the rail could be ordered a little extra long to allow for this.

How to mount them?

My plan is to clamp a piece of say 90 x 45mm (4x2" imperial) dressed timber on the side of the frame member to be leveled this would need to be manually straightened to within a mm or so, not hard with simple tools Or better still buy a good straight piece from the local building materials supplier

I plan to mount the rail on this timber with stout wood screws!

This is where the laser or wire alignment system comes into play. The rail and cutter head assembly
only needs to provide solid support for the cutter head. Positioning the cut is done by the measurement system not the frame.

The X axis is possibly the weakest link in this design, as is as long as a simply flat area is all that is needed it should work fine. If however you wanted to pilot drill the mounting holes it would not be sufficiently accurate without setting up the laser reference or wire reference at 90 degrees.
Doable at the expense of complexity, probably unnecessary.

Regards
John

PS: Yes Pippin the epoxy mill begs me to finish it. 2019 was a big year for me work wise with a heavy smattering of other issues. I hope to get back on it soon.

[devmonkey]

So I have made a small amount of progress this evening. With the laser mounted solidly to the mill head I was able to map the my machine frame. I clamped the laser solidly then left it well alone. This meant the machine frame had to be adjusted to the laser plane, which is much easier than vice versa. I lifted the frame at 3 points and shimmed each to get the best coincidence of the two planes, this was just done with a steel rule with the end on the frame and reading off where the laser hit it.

This is the frame and I'm trying to create a planar surface across the top two beams:



I then mapped the surface, I have about 1mm total peak-peak error, basically each top beam slopes down 1mm from end-end but in opposite directions. This isn't too bad.

I also took delivery of a little Makita trim router, I think it is the same sort as used on some peoples cnc routers. Anyway for £100 it is a very nice piece of kit, no measurable up-down play in the spindle, I also got a 6mm collet for it.

The levelling process I'm going to attempt I outlined earlier in the thread, but basically it involves using a trim router and a laser aligned router jig to mill down material fixed to the top the frame to bring it into plane.

So what material to use? I mixed up some metal polyester filler of the type used to fix leaks on engine castings. This stuff has some nice properties but it is too brittle and I think too soft (definitely softer then unfilled epoxy).

So what about epoxying an aluminium strip to the top of the steel frame and machining that? Would probably work but more effort, I checked the little Makita is happy milling aluminium and it is fine.

Whilst I had the router in hand with a 6mm carbide endmill in it, I thought I may as well see what it can do against mild steel, not expecting anything other than chatter and heat. Anyway it cuts it like butter, very cleanly. I only tried 0.5mm and 1mm DOC and it was fine and this is within the range I need for levelling this frame.

So I will pick up some 30mmx4mm flat bar stock tomorrow and weld it to the top of the frame where the rails will be mounted, then build the laser/router jig and hopefully have a planar frame very soon.