Cutting at last!

Its been quite a while since my last entry, but I've been busy. I have been trying to tweek the
electronics and hardware to overcome a few problems...

No.1 being a vibration or vibrations. Where do I start?
The worst direction was the Y axis. It was all over the place. During my initial cuts I got very disappointed. Pissed off even.
But I worked through a few options and it cutting fine now.

These are the points to be on the look out for-
1. Linear bearings work best in pairs and under load. Not alone and free running. I found there was quite a bit of play, not only between the bearing and housing but in the bearing itself.
So to counteract this issue I did this:

 There are bearing on the other side too.

2.Steppers vibrate at low speeds if not under load. My flying optic moved quite freely and was essentially no load on the motor.
- Imagine if you will, what is happening at low step rate -
As the stepper moves from one pole to the next, the mass of the rotor is accelerated around. Ideally, it stops dead in it new step position.
But no! it actually overshoots a little, only to be pulled back and eventually settle in its new position. This equals vibration.
It disappears at higher speeds as the rotor is caught in its overshoot position only to be pulled on by the next step.
So what can we do?
I believe... add load to the motor shaft(make a heavier flying optic) or reduce the current to the motor to the absolute minimum to move the FO.

3.fix the bearings on the flying optic.

4. Also microstep. I upped mine to 1/16 and it was a huge help.

 

I also upped my air pressure to 2 bar from a compressor. It made a huge difference to the cut depth. A Very noisy solution!

 To do: A water flow alarm. I'm working on that now. I will put up a post on that alone. Circuit etc. I managed to do a cut without the coolant water on at all. Crap! Probably 30 second or more.
Thankfully the laser survived.

And the lid with safety cut off switch to stop me burning my eyes.

Here's a couple of pics!

Some progress(is better than none)

 Above is the new table I built for the cutter, nothing to explain here, I think the photo speaks for itself. Thats 1" ply on the top. I will build a cover eventually...

This is a shot of the controller in its case. An old computer case, at first I thought it would be way too large but now that I realise how many wires are going to be in there I'm glad.
In the box are:
2 motor drivers,
1 Leetro Controller
1 old DVD player power supply(24v for the Leetro board){Accross -12v to +12v. Not sure if thats a good idea but its working!}
1 36v power supply (for motors and air solenoid valve)
1 Neon panel switch.
                 

Mirror video

Here is a quick video of the first mirror alignment test. I think it looks promising...

A lost camera, found again.

I have been working away the last few days without taking any pic's. So now, as I found my camera again, there is a bit of progress to be shown.
First here is a picture of the frame of the cutter itself. I was just laying it out to see the size and make a few decisions! Again the size being dictated by the belt length.(by the way, if you click any of the pictures, a larger sized slideshow should come up, nice!)

You can see the first of the X axis' supported rails here. The other is the gantry rail temporarily. I cut the box section with the bandsaw and finished it with the flycutter on the lathe. I really like the fly cutter, it such a lovely finish. Great for butt joints.

Below is the linear bearing and belt setup for the gantry. The "belt through the hole" idea is from the LightObject design. A nice space saving idea.

It allows gubbins to be directly above the bearing and belt. The clamping plate setup is the same as the gantry. One fixed and one adjustable.

In the picture above you can see the bolt holes for the motor mount and the access for the linear bearing bolts. Mine is off to the side a bit, due to the fact the I had to bolt the bearing and spacer on from above.
Here is a wide of the gantry minus the rail, motor etc.

Just tonight I finished drilling the 8, 22mm holes in the bearing blocks for the X axis belts. Each hole took 8  different sized drill bits. Spotter, centering bit, 4mm, 7mm 11mm 13mm 16mm 20mm 22mm. It makes it time consuming but the way the hole is still in the right place at the end makes worth while. More on that in the next post.