Getting everything square

[daveshorts]

I had a go last night with a 12mm ID perspex tube, there was definitely a problem with the bubble sticking with pure water. I added some glycol, which helped, but still wasn't perfect. I then added some mouthwash (don't ask) which seemed to help a lot.

I am not sure if it is the surfactant in the mouthwash wetting the tube better, or the alcohol pushing the glycol out of solution so that it preciptiated out on the surface of the perspex.

The bubble seems to move smoothly over the best part of a cm when I move the end up and down less than a mm, which isn't bad.

[HS93]

I am new so may be talking rubbish , but can you not test the setup when finnished by placing a cheap DTI on the motor head touching the bed and then send the head around the table to see if it is the same all over ?

Peter

[irving2008]

I am new so may be talking rubbish , but can you not test the setup when finnished by placing a cheap DTI on the motor head touching the bed and then send the head around the table to see if it is the same all over ?

Peter

Yes you could, but its still a good idea, and preferable, to get the frame square when building it. Waiting till everythings assembled is a tad late, by which time you are chasing shadows... is it the frame or the gantry or the bed thats not aligned?

[Robin Hewitt]

I am new so may be talking rubbish , but can you not test the setup when finnished by placing a cheap DTI on the motor head touching the bed and then send the head around the table to see if it is the same all over ?

Hi Peter

Unfortunately the bed and gantry can be far from flat, but, having the same distortion, line up perfectly with regard to tool height.

This may be fine and dandy, only becoming a problem when the thing you want to cut doesn't want to conform as well. Or worse, starts out by comforming then changes it's mind when you start to cut it smaller.

I still like my idea of gluing a laser pen to a lump then moving it around watching where it hits on the wall. It's simple, cheap, amazingly accurate and would save all this faffing about

Robin