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Another 4" CNC rotary table
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j45on:
I'm not sure this really warrants a new topic as I shall be shamelessly copying Craynerds stepper mounting and using Kwackers plans for the electronics  :bow:
Maybe I will detail the building of the electronic bits instead of what has already been done.
But it will be a good place to ask daft questions without filling up other peoples project logs  ::)
I know  :worthless: but until postie delivers my bits there is nothing to show

So far I have ordered the LCD display , 10Mhz crystal , 7805 5V DC Voltage Regulator , Microchip PIC18F452-I/P and a 40 pin dip socket
Well apart from the lcd I bought a few of each incase I cock something up  :zap:

I already have copper pcb , ferric chloride , toner transfer stuff and loads of resistors capacitors and possibly the diodes

The main bits I'm confused about are which stepper and controller ? to get.
For the controller It would be nice if I can find something to fit in the case along with the rest of the electronics DIY from plans or a kit would be good as well
And the stepper I don't want something huge hanging off my poor little mill but I would like to do some light milling as well so I'm unsure of torque requirements  :scratch:
Would the the stepper at the top of Arc Euro's page be to small ? http://www.arceurotrade.co.uk/Catalogue/Stepper-Motors/Stepper-Motors

I would also like to power the whole lot from my old laptop psu it outputs 19.5 volts 6.7A 130W this should this be enough right ?
Bluechip:
Jason

Just an observation.

Some SMPS power supplies don't like transient loads like steppers on them.

You can get the output voltage collapsing to a low value momentarily. ie a nominal 12V dropping to some 6V or so for several hundred uSecs.

Try your PSU if it is otherwise suitable . If you get mis-stepping, you might need to scope the PSU output before you look elsewhere.

Dave BC

 
Brass_Machine:
Absolutely it deserves its own thread. Please post away!

Eric
spuddevans:

--- Quote from: Bluechip on October 14, 2010, 07:34:47 PM ---Some SMPS power supplies don't like transient loads like steppers on them.

You can get the output voltage collapsing to a low value momentarily. ie a nominal 12V dropping to some 6V or so for several hundred uSecs.

--- End quote ---

Very true, but isnt that why god created 10,000uF capacitors :thumbup:

 Just bung a couple of 10000uF caps in parallel, or maybe just one if you are only driving one stepper motor and that should smooth out any of the voltage "dipping" effect that Dave was talking about.


Tim
Bluechip:
Tim

Yup, my first weapon of choice. A 33,000 uF Sprague Compulytic.

As ever, the Gods crapped upon me, the PSU would not fire up, 'cos it thought it had a s/cct on the output. ATX PSU btw.

So, nothing daunted, to 'prove' I got two wacking great stud diodes. Ran the contraption from the psu through one, and a 12V 40 Ah SLA through t'other.

Fault fixed. Eventually made the geezer a grunty LINEAR. ( T'was not my cnc thingy-wotsit ). I just got involved through a mate.

Dont do cnc. I can effectively make scrap manually. No need to automate.  :thumbup:

Dave BC
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