Messages

81

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 06, 2017, 04:13:08 PM »

Half,
Since I got my BRX plc I have no need for another device I bought. It is a step pulse driver with a potentiometer input. You can have it free. If you hook a double pole double throw relay to be activated by a M code from Mach 3 you could then hook step and direction inputs to the drive to the common terminals and the step and direction output from mach 3 to the normally closed contacts and the pulser step and direction to the normally open. It is a mill with 4th axis when the relay is off and a lathe when it is on.

Gary Hi,  Please translate Brx plc... what does this stand for.

I will show this to my friend who is far more knowledgeable than I and see if we can do what you are suggesting...thanks... bob

82

General Mach Discussion / what kind of device do i need

« on: November 06, 2017, 02:07:09 PM »

Please look at the attachment jpg.  You can see I have a lathe-type device connected to mach 3, with some of the inherent issues that mach 3 has, that is I have a lot of problems just getting lathe to turn on at a certain speed and then have the x-y-z axis do their thing.  I have reached the conclusion that I need to run the lathe from a controller that is independent of a computer.  That is I would plug it into the wall socket and by adjusting a couple of knobs (whatever) the lathe would turn clockwise or CCW and with another knob or feature I could increase or decrease the speed.

Now what would I call a unit like that, and where might I look.  Looking for your suggestions.  Thanks, bob

83

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 06, 2017, 01:29:04 PM »

Rich, thank you for such a detailed set of considerations/recommendations...  I will study this and try to take the right steps.

In a few days I will ask for clarifications.  Basically, if I simply had a small separate wood lathe that would fit under the spindle mill end and where I could vary the speed, then I could do what I need to do for a lot of guitar applications... I will look for a controller to make the current 4th axis lathe independent of  mach 3... just so I can turn things when I need to.  Thanks again, let me go study all of this.

Can I go to Artsoft and download the particular version that you think I should be using?  bob

84

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 05, 2017, 02:07:30 PM »

Hi Rich,

The Mach3 version is  R3.043.066
running on windows xp

Y axis uses 2 ball screws and thus 2 stepper motors
B is slaved to Y axis for the 2nd motor

The 4th axis lathe head is stepper driver
Stepper driver is MicroStep Driver ST-M5045
The other four stepper motors
have similar stepper drivers

thank you for helping here... bob

85

General Mach Discussion / MDI question

« on: November 04, 2017, 10:31:48 PM »

Ok, I'm wrestling with MDI...its winning.

when I type in a line of code, and hit enter, it executes that line and puts it up above like its stacking and waits for the next line of code to be input.
my issues is that I want to clear that line out and start fresh... if I hit escape it clears any code from the big input bar, but the code still sits in in the small bar above.  What do I do to clear the old code out and start fresh...I have been having to exit the program and reload...looked in the manual under mdi but it did not state how to do this.

thanks bob

86

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 04, 2017, 04:35:14 PM »

Gary thank you for your response.  Let me go over what you have said... I am barely a week into fusion 360.  It will take me a while to get up to speed... but I will consider your suggestions... thanks

87

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 04, 2017, 01:30:10 PM »

Hi Bob,
extremely nice work, but where do you plugin the big fat amp?...LOL

My guess when I asked you about what you wanted a rotary axis for was that the subtle curve in the bridge and nut were what you had in mind.
Any decent CAM program can follow a gentle curve like that to well within the resolution/accuracy of your machine. We are used to manual milling
and cutting a curve by co-ordinating two axes by hand is beyond a human operator. Not so for a CNC machine. A rotating axis could potentially offer
accuracy in line with the Truth In Rotation of the axis, a few um with care. I would expect a decent hobby router to achieve some thing like 0.02mm
or 20um if the curve were generated by co-ordination of two axes.

I imagine 20um would be considered pretty fair when compared to hand worked.

Craig

yes learning all of this is the bugger in the butter...bob

88

General Mach Discussion / Reply to Gary Lucus

« on: November 04, 2017, 01:26:20 PM »

I am just starting.  I bought a cnc, a 4th axis lathe and mach 3.   I am slowing learning Fusion 360. And I am taking a cnc machining class at community college... so I can say I am swamped with learning all this...  so for now I am just trying to slowly move most of my hand skill over to the cnc processes without losing any tonal qualities in the instrument.  Machining is precise, but it can't "hear"  or experience the feel of a professional concert quality instrument. So I will have the cnc do all the rough in work and I will handle the art side. Thank you for your responses.  bob

89

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 04, 2017, 01:17:57 PM »

Thank you for your response.  Attached are 3 jpegs...

The "basic setup" is just to show how a mock up of what I am trying to do looks like... so you can see my general issue.  Now in a complete set up  I would have the wooden log with a 1 inch wide slot cut just deep enough along its length so that  the bridge blank would match up with a 3" diameter circle.  Then as the A-axis rotary turns it would cut the curve onto the wings of the bridge.  The "log" which is made of Spanish cedar is very light... slightly heavier than balsa, is 3 1/8" in diameter.  Now my first step is to turn the log itself and true out the log to be an exact 3" diameter.  So the log must turn at a speed that is slow enough that the end mill can keep up with it.  The mill end spindle runs up to 24,000 rpm and I simply turn it on manually for the time being while I am learning.  So I have to have the rotary turning at one speed and then the y-axis progressing down the length of the log at another speed.  All of this is just to get the log trued out.  Then I start facing the real issues of the bridge factors.  Now I am brand new at all of this and the learning curve is a bit daunting...but I will hang in there.

Now as you see, there are two slots of different widths and depths in the middle of the bridge.  The thinner of the two holds a piece of bone, (used to be Ivory, but we need our elephants now so its bone), and that slot leans slightly toward the back of the bridge to hold the bone at a slightly stronger position relative to string tension... so the rotary could then be moved to whatever portion of a degree etc., that would give the slot its proper back-tilt.

The transition from the wing of one side to the wall in the middle part of the bridge has to be ninety degrees so I do not have a good image of how that could be done with a ball end mill.

I am open to everyone's considerations and ideas on all this.  Right now I need to figure out how to get the lathe aspect to turn at a slow speed, and then have the mill end move down the length of the log so that it cuts the log and trues it out so there is no wobble that then translates to a wavy surface on the curve of the wings.

Sincerely guys,   bob

90

General Mach Discussion / Re: A-axis rotary lathe question for Mach 3

« on: November 04, 2017, 03:29:28 AM »

and the last jpeg