Messages

11

General Mach Discussion / Re: cnc4pc multifuncion cnc board

« on: January 08, 2010, 07:02:03 PM »

You need Stepper drivers?

Look at Gecko's.
http://www.geckodrive.com/

12

General Mach Discussion / Ball Endmill Profile Machining.

« on: January 07, 2010, 09:27:45 PM »

This video is of AJAX machine cutting a raised 3d pattern in wax.

http://www.youtube.com/watch?v=rr0DC3R_iNk

Notice at the very end of the video how smooth the flat lowest Z surface is.
You would never know it was cut with a ball endmill if you did not see it
for yourself.

My question is, is there a rule of thumb for the step over of ball mills
when doing this kind of work? 

13

General Mach Discussion / Re: Mach Workshop at Cabin Fever Expo

« on: January 21, 2009, 06:37:15 AM »

I walked away with some loot also:
8"x18" CNC ready machine.






I paid a lot less than asking price.

These machines were not properly protected on the overseas trip so they
have some rust scattered about.  Dealer just wanted to unload rather than
sell a "blem" machine.  The rust spots cleaned up nice.

They come ready for servos and controller.
Also supplied is a second set of ballscrews and thrust bearings to replace
the ones on the machine that have some rust spots.

Spindle motor is 3/4 hp inverter duty.  2000 rpm spindle.

The hole on the left accepts a 15" monitor.  It looks like the whole
control can easily be incorporated into the cabinet.  The dealers machine
had a huge electronics cabinet on back. 

Toolpost has a 3 phase motor to rotate it.  Also has a position sensor.
Figuring out how to make that work will probably be the biggest problem
in this retrofit.

It would be something to bring this machine back next year and have it
banging out parts running Mach, while it sits next to their $14,000 machine.

Have to finish my latest 4 axis mill first....

Scott

14

General Mach Discussion / Re: Mach Workshop at Cabin Fever Expo

« on: January 18, 2009, 08:44:38 PM »

I found there was a peck drill pull back setting in mach.  Mine was set for .1".  I always wondered why my mill would pull up so far when peck drilling.

Mind sharing where that setting is.

Scott

15

General Mach Discussion / Re: GROUNDING - what is the correct way to ground a CNC machine?

« on: November 24, 2008, 06:04:29 AM »

I am always interested in improving my knowledge, can you give your reasons for making this statement please? ( Even at my age I am still light on toes , I might be able to keep them out of the way!)

Ian, I think Jeff explained the reasons in his last post.  He gave one example with the
switching power supply common.

Scott

16

General Mach Discussion / Re: Accuracy or repeatability of homeing switches, something to worry about?

« on: November 10, 2008, 07:31:17 PM »

Automation Direct has many types of environmentally sealed limit switches for about $38 each.
They are quality made in Italy units and similar to the original Bridgeport units.
May be a lot easier to go this route than mess with making up optical ones that are sealed.


Scott

17

General Mach Discussion / Re: Z AXIS KNEE

« on: November 08, 2008, 09:37:16 AM »

I'm with Hood.  I think the smart way to handle Z travel is as he proposes.  Use the knee for TLO's.
My Series II knee has huge box ways and an air assisted knee.  I am sure I could get the
knee to some serious rapids.  I have seen knee's driven with 40 in-lb servo's  (read huge), and
the servo's were driven by Gecko's.  These knees were able to drill holes in 3/4" steel plate
all day with perfect reliability. 
I think driving the knee is going to wear it out prematurely.  I have heard other state that this
is the case.  Looking at the wear on some older machines that never had a power knee
seems to indicate that this is indeed the case.  The tremendous weight on the dovetails
makes them prone to wear just under normal (handcranking) use. 

My series 1 cnc is a bit restrictive with the 5" of quill travel, but as Ed says, it is certainly still
capable of doing most jobs.

Scott

18

General Mach Discussion / Re: Quastion about 2 motors on one ax and correcting by encoders

« on: November 07, 2008, 11:13:13 AM »

I never understood this. If mach can monitor the encoders why can't it also correct the position. Is it a timing issue of using a PC?

Mach CANNOT monitor the encoders. 
It runs only open loop.
It can only give a position command to the drives.
The encoders are ONLY monitored by the servo drives (or stepper drives) to get the motor to the proper position.

Scott

19

General Mach Discussion / CNC'ing both quill and knee

« on: October 20, 2008, 07:12:06 AM »

Hi,  Have a Series II CNC machine that I am currently working on.
Not my first, but I want to make this my last mill.   

Quill unfortunately is a QC30 with 5" of travel.
The knee has huge box ways and is air assisted.

In most instances the quill is the better way to approach the
Z axis as long as you can get away with the 5" travel.  And yes,
I want to keep the quill as my Z axis.  But I would like to open
up the possibility of having more than 5" of Z travel using the knee.

My idea is to put a servo and drive on the knee and run the knee
under Mach control.  Technically it is the " W" axis-  because it is parallel to
the Z axis.

I don't know if it is possible to run these axis in concert with each other.
I guess if a job required more than 5" travel I could swap axis and
use the knee as the Z.  This swap could be done in the mach settings
I guess?   

Any input on my idea would be appreciated.

Thanks,
Scott


Edit:  I see looking at Mach's config screen that the only names for axis's are XYZ and ABC. 
I guess I would have to use B or C as the W axis. 

20

General Mach Discussion / Re: servo selection.......

« on: October 01, 2008, 08:26:06 PM »

What kind of travels do you have on the Beaver?

My next retro is a Series 2 CNC.  15" x 30" travel,
huge box ways, table never overhangs saddle, 5000#.
Pretty much as close as a knee mill can get to a VMC. 
The iron is fully rebuilt and I am heading into the controller
now.  I don't know if the SmoothStepper is worth the
extra money for this machine.   So many machines running solidly with
just the PP.  I ordered Granite drives for this one.  Geckos are to
"hobby' for me.  They run my Series 1 Boss-  but not without
occasional problems.

Scott