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Messages - BluePinnacle

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281
General Mach Discussion / Re: So n00b it hurts! Help please...
« on: February 29, 2008, 05:14:52 PM »
Hmm. If your customers are screaming for parts, satisfying them may be your #1 priority... sub  the work out, take a bit of a loss, clear your mind of panic and set to getting your machine going? at least that way your customers won't think of you as someone who delivers  late or not at all. It  depends how loud they're screaming really. just a possibility.

282
General Mach Discussion / Re: So noob it hurts! Help please...
« on: February 26, 2008, 04:17:30 PM »
Hello n00b, welcome aboard. I'm still learning myself but soft limits can be turned off - can't remember what screen it's on but it mihgt be Settings. Possibly too easy but just as easy to overlook.

283
I'm still very interested by the optical solution. I took a scientific approach to the problem today and plotted all the values of the three axes on 20 re-homing moves from a zeroed homing move. X and Z deviated by +/- 3 or 4 microns  while Y was sometimes as much as 90 microns out. I tried winding Y's sensor out a bit until the vane only just missed the front of the sensor, doing the same for Z as it was a bit further out than I liked the look of.
The second test run showed a marked improvement on Y with a slight improvement on Z, at this time I had around +/-3 microns on each axis according to the DRO. Certainly good enough for most work but there's room for improvement.

Ideally if I can get dead-zero rehoming I should have it - I am, after all, worth it. I'll prototype one with some RS clobber, screw it to the bed and wire it into a home switch input to test its repeatability. It sounds like a safer bet than the old hall effect sensors anyway.

The next step is to test the positioning accuracy of the machine and its steppers, drivers and software, and try out the leadscrews for backlash. more as it arrives.

Oddly enough, i asked our workshop manager about this lot and he reckoned that Y was always a bit dicky... Took five minutes to fix. That, and the brake contactor with the fried coil. and, of course, the control system that gave up its ghost, well that took a bit longer...   time aside, it's fun, isn't it? 

284
Tangent Corner / Re: Materials suggestion......
« on: February 26, 2008, 03:58:32 AM »
good point, FRP is very strong.

There's the added advantage that metal parts like pins, hinges, cable clips etc. can be moulded directly in without screwing or bolting.

285
Grand. Will look into trying one of these out. Thanks :)

286
thanks Hood - making waterproof boxes will be no problem. Have a look at RSwww, part number 304-560, a nice optical gate with a built in schmidt triger and logic output. Is this the sort of thing you're using? It''s only £5 and very neat - and would run off my 9V setup.

no encoders, sadly, I'm running three hefty steppers. Encoders would be nice.

287
General Mach Discussion / Hall effect home switches - Nonsense and bother
« on: February 25, 2008, 05:33:39 PM »
Well, I'm annoyed again.

My machine has three hall-effect proximity switches for homing. These have inbuilt magnets and react to plain steel vanes on the slides, or the leadscrew nut in the case of Z. They trigger a logic  pin on my second port with an arrangement that uses a 2k2 resistor in series with the sensor, and the whole lot across a 9V supply (these sensors originally had a 9v line). Across the resistor is the input side of a darlington-output optoisolator in series with a common LED to give a combined junction voltage of around 2.2 volts (plus a current limiting resistor). Effectively when the sensor is triggered its resistance rises from around 300 ohms to 13K; the voltage across the 2k2 resistor drops sharply to below 2.2 volts and the opto shuts off, allowing the logic pin on its output side to float high.

All this is very fine and well, but when I reference the axes, zero all, turn off the automatic zeroing and move all the axes -10mm, then re-home them all, they end up in slightly different places to where they started.. not usually much, 1-2 microns usually, with the exception of Y which can be much further out.

A few questions:

 - Do hall proximity sensors work best if the vane passes very close by it, or does a bit of separation help?
 - Can i expect day-to-day drift due to temperature and age affecting the interface circuit?
 - Is it really reasonable to expect a machine to home accurately to EXACTLY the same position 24 hours after it last did it?
 - if so, how?

I can find precision switches giving 1 micron repeatability on RS, but if I'm to have three of them they'll be around £500, and I won't be popular with the bean-countress.

Suggestions? I did consider that of "buy a new one from Haas" as very favourable, but... see above  ;D Thanks in advance.

288
Tangent Corner / Re: Materials suggestion......
« on: February 25, 2008, 04:59:26 PM »
Wood? Pretty robust and cheap. Wood plus concrete would be nice and stable.

289
General Mach Discussion / Writing macros, OEM inputs and outputs
« on: February 11, 2008, 10:07:32 AM »
Hello all

Is there a good tutorial or other thread on here which can give me a good overview of writing macros?

Also, how can I configure the OEM inputs and outputs (including renaming them if possible). I've looked though the manual but can't find either ... might just have missed it, do refer me back to the right page if that is the case.

Thanks :)

290
General Mach Discussion / Re: Changing the Sensitivity of Limit Switches?
« on: February 10, 2008, 09:34:33 AM »
Good going, some very clear thinking going on there. Well done that man :)

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