Messages

81

Show"N"Tell ( Your Machines) / Zero gravity Z

« on: November 07, 2013, 03:52:15 PM »

Must depend on the weight of the spindle or whatever is mounted on Z.

82

Show"N"Tell ( Your Machines) / Re: Z Axis Weight

« on: November 07, 2013, 08:32:22 AM »

I solved the heavy Z problem by using an air cylinder.  Let me know if you want further details.

-Nick

Dont know about the air cylinders but it will be interesting to see further details

Started a new thread about it.  http://www.machsupport.com/forum/index.php/topic,25826.0.html

83

Show"N"Tell ( Your Machines) / Zero gravity Z

« on: November 07, 2013, 08:30:58 AM »

The problem was that when Estop was enabled, the Z axis would come crashing down to the mechanical stop.

After looking into how rather expensive CNCs are designed, I found that some use a nitrogen charged counterbalance system.  So I decided to mimic that with compressed air.

I used a double acting air cylinder from McMaster-Carr (#6498K861).  The air is pressurized on the lower portion of the cylinder (pushing the cylinder closed, essentially).  The upper part of the cylinder has breather vent (#4456K11).

There is a 5 gallon air tank under the machine with a regulator on it.  I tuned the regulator to offer just enough air to the valve to keep the Z suspended.

I can turn the ballscrew with my fingers in either direction with very little effort.  The machine has no problem working against the air pressure during Z- moves.  I've been using it for over a year like this and it came out way better than I could have hoped for.  So now when the Estop is hit, Z doesnt go anywhere, it just stays where it is (encoder DRO proves that)  

Hope this helps someone.

-Nick

84

Show"N"Tell ( Your Machines) / Re: Z Axis Weight

« on: November 06, 2013, 04:28:09 PM »

I solved the heavy Z problem by using an air cylinder.  Let me know if you want further details.

-Nick

Dont know about the air cylinders but it will be interesting to see further details

Ok I will get some pictures and report back.

85

Show"N"Tell ( Your Machines) / Re: Z Axis Weight

« on: November 06, 2013, 02:03:22 PM »

I solved the heavy Z problem by using an air cylinder.  Let me know if you want further details.

-Nick

86

General Mach Discussion / Re: Constant Velocity problem with rotary 4th Axis

« on: November 05, 2013, 09:42:27 AM »

Smokingman: I sent you an email.

87

General Mach Discussion / Re: Arc issues with multiple offsets?

« on: October 28, 2013, 10:51:47 AM »

Nice!  That's the type of problem I meant when I said "Mach has bit me for less". 

88

General Mach Discussion / Re: Arc issues with multiple offsets?

« on: October 28, 2013, 07:53:52 AM »

The fact that you are using "Radius Format Arc" on one line and "Center Format Arc" on the next line stands out to me (page 10-17 in manual Rev 1.84-A2) .  If all else fails, try switching to one type. (Just sayin'... Mach has bit me for less). ;-)

89

General Mach Discussion / Re: Mach3 to VFD rpm difference

« on: October 19, 2013, 01:44:49 PM »

Just had a quick look at the manual for your VFD.  Try changing parameters PD004 (maybe PD003 also).

http://www.2shared.com/complete/tvddak-F/HuanYang_VFD_user_manual.html

90

General Mach Discussion / Re: Mach3 to VFD rpm difference

« on: October 19, 2013, 01:41:05 PM »

I do not have that brand of VFD, so I can not help you specifically.  For the VFD I used to be controlled by Mach (a Fuji), it was the "Base Frequency" that was the problem.  It was set to 60mhz as default and it needed to be set to 300mhz.  300 is what jived with my spindle nameplate (a Teknomotor), so your mileage may vary.