Web Goblin cnc has begun

[Jonathan]

Thanks. I really want to try some aluminium.

Walk before you run.

Admittedly the second thing I tried on my machine after the major rebuild was aluminium.

[Web Goblin]

I have made up a tool height setter. Its a bit rough but I will make a better one when I get more time.

The basic parts. The centre of the top section was a bit off so doesnt look quite right.



Hole drilled and tapped to PG7 to accept the cable gland.




The block was cleaned up a bit on the lathe and the inner edge recessed to accept the switch locking nut.


The finished parts before assembly.
I have also set up the block in USBCNC and calibrated and tested it. Working fine it is.

Regards

Ian

[Web Goblin]

I have posted a video of it in action on youtube. Link attached.

http://www.youtube.com/watch?v=AbBjttEyDQw

[JAZZCNC]

Nice that Ian, are you going to change the script to touch down faster.?
I've set mine up so does a double touch 300mm/min first then retracts few mill's, can't remember what I set it at without checking, then does slow 75mm/min for accurate touch off in case over shoot. . . . . Works very good and one of the best things I've added to machine.

[Jonathan]

Nice indeed. Can you link me to the switch you used? I had not considered using a switch, only measuring resistance. I thought at one point of using a piece of PCB as the contact as then if something goes wrong the PCB is weak (as long as it's not FR4) and will break instead of the cutter.

Have you checked the repeatability?

Your spindle mount looks a tad flimsy to me ... only one support.

[JAZZCNC]

Nice indeed. I thought at one point of using a piece of PCB as the contact as then if something goes wrong the PCB is weak (as long as it's not FR4) and will break instead of the cutter.

Jonathan PCB works great thats what I use for quick top surface setting, very easy very quick and super accurate. . . . Doesn't even leave a mark on the cooper. You won't belive how sensitive it is.

Brilliant when combined with edge,corner and centre probing routines save hours of setting up time. Just the top of surface alone is worth the effort. . . All 5 mins it takes to make. . .:tup:

[Jonathan]

Doesn't even leave a mark on the cooper. You won't belive how sensitive it is.

That's mildly surprising. Maybe the electrons tunnel across the gap :heehee:
If I put an op-amp in between it could be incredibly sensitive, though that may not be a good thing. Combine it with averaging of the readings ... assuming the difference is actually greater than the resolution.

[Web Goblin]

Jonathan,
the link to the switch is : http://uk.rs-online.com/web/p/push-b...tches/7082967/ Its a bit expensive but I chose it to take a bit of punisment.

I checked the switch a few times with my digital vernier and repeatability is within 0.3mm so its not too bad. I had also looked at making a voltage touch probe like Jazzcnc is talking about, that might be version 2 if I can get my hands on some solid clear perspex square bar or similar. The spindle mount is 25mm thick alu so its stronger than it looks but I have started on making another two to replace that one to strengthen it up.
The head comes down quickly until 20mm above the estimated tool block, depending on the guess value you input into the tool database, then slows down to touch speed.

Ian

[JAZZCNC]

I checked the switch a few times with my digital vernier and repeatability is within 0.3mm so its not too bad.

That wouldn't do for me.!! . . . 0.3mm is far too much for my liking.! . . . I would want 0.1 at the very very least.
My first thought when seen you where using a switch was it wouldn't be quick enough and your measurements backs that up.

Try pcb and you'll see what I mean by super sensitive, accurate and repeatable.

[Web Goblin]

I am going to try the tool measurement routine a few times and see what it says. It might come out better than that. If not I can always make a voltage touch one.