Wednesday, 21 March 2018

Re: [7x12minilathe] Re: Mini-Mill CNC, First Test of X-Axis.

 

Yes, you can make a pulse generator.   But when you have a lab bench full of test instruments you tend to use the instruments for testing.    The signal generator can do "sweeps".  this is where it changes the pulse rate per time.   I can sweep the step rate and in that way measure acceleration.  I get measurements good to more decimal points than I need and I don't need to build anything.

In the end the motor will be controlled by some kind of computer, likely one running Linux and LCNC or MK.

I think if I were building a simple power feed I'd want at least a tiny LCD screen that reads out the feed rate in units like mm per second or inches per minute and some stop/start and direction buttons.  The 555 timer can't drive the LCD.      And you'd want to be able to make it stop EXACTLY at some point (because maybe you are milling an internal pocket.)

The hard part of building a pulse generator for a power feed is getting the user interface right.   Generating pulses is trivial.   But I think the user wants to set the feed rate BEFORE he presses "start".  and likely wants to be able to set a limit.  I would like to be able toes and verify those numbers before I press "go". 

Cost for a controller of any kind is very low, so that is not the issue, the hard part is figuring out what it should do.

One use case of the CNC mill will be to design parts using Autodesk Fusion 360 then make parts.   But this is a long process.    For simple things, like boring a hole or pocket or face mining or  dozen other easy jobs I'd like to just tell the machine what I want done.     Where the current state of the art needs to be "pushed" is right there -- how to tell a machine what you want.  Current methods are primitive and limited

On Wed, Mar 21, 2018 at 9:52 AM, mark.kimball2@frontier.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
 

RE:  pulser for simple stepper control.  I made one for zero dollars -- I already had a 555 timer chip, and my electronics scrap box had the perf board, resistors and capacitors I needed to make a simple clock generator.  A slide switch allows me to select the direction, and I can adjust the clock rate with a pot.

I used the thing to run a stepper as a low-speed diamond grinder for shaping and sharpening carbide scrapers.  I bought a set of 6" diamond lapping disks from a lapidary supply outfit, 150 grit up to 3,000.  The low speed keeps everything cool (particularly since I run the bottom portion of the disk through a pool of water).  It does a good job for me.  I made a simple arbor to mount the disks using my lathe.

The ebay pulse generator looks like a good value if you're not able or willing to DIY one.

Mark




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Chris Albertson
Redondo Beach, California

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Posted by: Chris Albertson <albertson.chris@gmail.com>
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