Messages

5181

General Mach Discussion / Re: Rotary Axis Help

« on: January 07, 2010, 05:39:42 PM »

Richard,
What are you planning on doing with the rotary on the lathe?

I am currently on a new adventure to utilize the spindle as an indexer on the lathe. The intent is to drill holes, limited decorative cutting, some minor profiling, some wierd stuff...., after a piece has been turned. It will save setups.
I am using the A axis for rotary motion.

If i didn't have some specific things in mind i would probably just mount the rotary to the  mill  ( or maybe in your case a router ) and not bother.  

You may want to have a look at the following posts since there are a number of things to consider.

http://www.machsupport.com/forum/index.php/topic,13639.msg89612.html#msg89612

http://www.machsupport.com/forum/index.php/topic,13604.msg89361.html#msg89361

http://www.machsupport.com/forum/index.php/topic,12484.msg89181.html#msg89181

http://www.machsupport.com/forum/index.php/topic,12484.msg88232.html#msg88232

http://www.machsupport.com/forum/index.php/topic,13548.msg88932.html#msg88932

http://www.machsupport.com/forum/index.php/topic,13400.msg87932.html#msg87932

http://www.machsupport.com/forum/index.php/topic,13040.msg89459.html#msg89459

I guess it can be as simple or complex as you want.
Just remember there are some 4 different feedrates, 3 feedrate modes, the gcode that needs to be appropriate, choice of screens to use.

No answers ...but some stuff  to think about,

BTW nice name sort of like mine,  
RICH

5182

General Mach Discussion / Re: deviations of 0.3 mm, in small parts: MACH3

« on: January 07, 2010, 09:41:04 AM »

Probably screw error as Gerry said along with different backlash.
I would profile the screw some by checking the differences if in actual movements.
Say, 1" movements in one direction over 12" and then reversing direction.
Usualy you will see constant gain or loss, but it could  also be more promounced in one section
of the screw. Check the backlash at different locations. Your  .3mm ( .012") seems excessive for just the
screw since many are in the range of .004" per foot accuracy. So seems like something more going on here.
Timing belt tension also can have an influence. Try to isolate the contributing problem.
RICH

5183

Works in progress / Re: Three Page Lathe Screen

« on: January 06, 2010, 11:29:50 AM »

Phil,
Thought the A axis was complete, but the manual screen needs the  Rotation Radius  "A" input ( right hand corner in Settings tab / of  mill screen) else the graphics display won't show the A axis and you can't set a feedrate.
I'll  repost with specific info later.
RICH

5184

General Mach Discussion / Re: Synchronise Rotary axis feed with X and Z feed

« on: January 06, 2010, 10:54:12 AM »

So the feedrate will not vary on the fly for multiple diameter changes? .....It's a fixed feedrate relative to a single diameter  .....Otherwise you would have electronic gearing / feedback such that a turn of the spindle will slave the Z  to the rotary movement which is currently not available. Now if the A axis is linear, and say an arc is broken into line segments, then all would be in synch?

OOPS,  ignore the above as i'm doing rotary control on the lathe.
 
I can confuse myself when i think,  
RICH

5185

General Mach Discussion / Re: Rotary axis help

« on: January 06, 2010, 10:24:15 AM »

The G203V is a more advanced drive than the G201's which i am using. Geckos literature says that it can survive
"accidental "motor disconnects. I can't speak for Gecko, so you should ask them directly this question:

Will the G203V survive deliberate disconnection of the cable at any time and condition?

I can't not tell you to do something or wire some thing in some manner with absolute assurance  that you will not blow a drive, other than, if the drive has no power going to it you can disconnect the cable.

Call them, as i found them realy great to deal with, and Mauries is a fantastic guy.

From one who has blown a Gecko drive in the past, 
RICH

5186

General Mach Discussion / Re: Synchronise Rotary axis feed with X and Z feed

« on: January 06, 2010, 08:55:58 AM »

Greg.
"Hope this is clear and helps."

Thanks for the reply and plain explaination and it does help. There are a lot of different postings  on Rotation DRO and 4th Axis and one would need to do a lot of reading / searching and filtering of the discussions to sort it out.

"have a near zero number (0.01)"
Art posted, back a few years ago  / before my time of using Mach, that a value of .0001 as a Rotation Radius will cause the feedrate to default to the linear axis feedrate. Just found that last night. Unless one is aware of rotary use along with the development over time, a user applying rotary to do something will end up with some basic questions. Thus finding answers can be difficult.

Exploring use of rotary in a limited different manner
RICH

5187

General Mach Discussion / Re: Rotary axis help

« on: January 05, 2010, 09:10:01 PM »

Would keep Mach from sending pulses to the drive. The drive is still powered from the controller power supply.
What Gecko drive do you have?
RICH

5188

General Mach Discussion / Re: Synchronise Rotary axis feed with X and Z feed

« on: January 05, 2010, 08:52:38 AM »

Is the following formula applicable in Mach?
Any comments on use?

RICH

5189

General Mach Discussion / Re: Synchronise Rotary axis feed with X and Z feed

« on: January 05, 2010, 08:28:49 AM »

Jeff and All,
In Mach Mill, Settings (Alt-6) Tab you will see Rotation Radius for the A/B/C axis.

Look in the Mach2MIll_6.11 Manual, 6.2.12 and you will find a very brief explaination and here it is:

" As described in the Feedrate control family, it is possible to define the approximate size of a rotated workpiece so the rotational axis speed can be correctly included in the blended feedrate. The relavent diameters are entered in the DROs of this family"

Anybody want to provide a simple explaination?
My guess on this:
 If the A axis was linear and had the same steps per units along with velocity and accel as the other axis then a point along / around a circumference  would be linear sych'd with the other axis exactly for only one specific diameter.

If the A axis was linear and didn't  have the same steps per units then the above would no longer be true  
for a given feedrate.

So by inputting the diameter that will be cut , Mach modifies the feedrate such that the linear moves will be
"APPROXIMATELY" snch'd for a commanded feedrate.
  
What formula is used for calculating the combined inch/degree feedrate( blended feed rate) ?

Does Mach read the diameter in the program and adjust the feedrate for a different diameter and adjust accordingly?

Based on what diameter....ie; define linear steps per unit based on a diameter of 1 in motor tuning?

RICH

BTW,you will not find those DRO's  a modified  lathe screen....Yet! 

5190

LazyTurn / Re: LazyTurn

« on: January 04, 2010, 11:57:19 AM »

Just a comment FWIW,
Your  tool selection will be important. The only tool that can be used to do it all, in general and depends on the profile, would be a point tool. So from a practical machining point of view, planning on how to do the cutting
is still required by the operator. So if the tool can't completely do all the finishing passes, then i quess you'll see what is left and need to apply the proper tool to accomplish them.

Here is a thought for you ART, realy lazy mode but maybe doable........
LT has a mode which has some basic tool set with some simple defined parameters, it automaticaly applies those tools to the profile / breaks the profile / generates the pathing, based on those tools and reports back that it can cut the profile with say these tools / parameters, and here is what's left and what can't be done. If you don't like that what LT did, then get out of that mode and define your owne tools to be used for pathing.  Just a cloud above my head!

RICH