Messages

961

General Mach Discussion / Re: Robot part loader for CNC Lathe

« on: October 25, 2016, 02:20:12 AM »

30 to 40 I/O would probably be the domain of a dedicated PLC, I am not sure of any PC stuff with that much I/O capacity.

962

General Mach Discussion / Re: Machine Coordinate

« on: October 24, 2016, 03:39:29 PM »

Its generally up to you, my home on the plasma table and the mill is front-left corner, seems a pretty standard location.

Its determined by the location of the homing switches and also where you tell the machine that "home" really is - the switches can be anywhere along the axes - on my plasma they are combined with the limit switches but on the mill i have limits at the end and homing switches in the middle as there was more room to fit them there, the offset distance is set by the value of "home offset" in config.

Many user don't even bother fitting switches, just tell the software to home without switches - this will just zero the DRO's wherever you want, but I couldn't work like that - if you have to restart after a quick stop or a crash you need to know exactly where home is so you can carry on easily

963

General Mach Discussion / Re: Machine Coordinate

« on: October 24, 2016, 02:25:43 PM »

How are you trying ? 

The only real way is to home the machine.

964

General Mach Discussion / Re: Make tool change not move in X and Y

« on: October 24, 2016, 12:46:14 PM »

Its possibly fusion doing this, I think my one did before i removed the code from the post processor, now it just raises and stops.

If it is, removing is not too hard.

965

General Mach Discussion / Re: Newbie needs help

« on: October 24, 2016, 10:47:24 AM »

My first guess is something mechanical has worked loose - you now have backlash - the tool is going wherever it wants to.

I would start by going over every coupling, joint, belt, pulley etc to check tightness on the motor or shaft or whatever. It only takes a little slop to make a mess

966

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: October 24, 2016, 04:28:58 AM »

Thinking out loud...

With the drive to the quill rack, probably from the left side as done in the FlashCut kits etc, without measuring i  think the quill pinion does 2 full turns for full travel so about 75mm/turn, with a 4:1 or maybe 5:1 belt reduction from servo to pinion shaft, would that give enough resolution/torque - the motor would only ever do 8 or 10 full revs??

Just working things through...

967

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: October 23, 2016, 10:04:48 AM »

Future thoughts...

Machine is working very nicely so far. However I still have big doubts about the weakest link in the system - the Z-axis drive, its a pretty tortured setup, the connection to the quill is poor being just one bolt, the block face is only around 15-20mm square where it bolts on, there is around 75mm from the quill to the ball-screw so there is a massive twisting moment acting on the joint and the ball-nut.

There is already movement visible between the nut and the quill - you can see the connecting arm twisting when nudging the ball-screw pulley by hand so it would be pretty rough under drilling or plunge-milling forces. I can see a very short life for the ball-nut as they don't like twisting moments, axial or radial but not twisting.

It was assembled with loctite but with only the one bolt I doubt that would do much.

I have a feeling it would have been better to go with the drive idea in the pictures below, the quill rack is designed to take all the Bridgeport can do, there is not much backlash and what there is could be helped with a gas-spring maybe to keep it under positive pressure.

No idea what the pinion gearing ratio is but likely something like 3" per turn so would use a bigger reduction from motor.

Just looking ahead, but as i said, I can see issues here already and thats only after a few jobs....

968

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: October 23, 2016, 09:20:35 AM »

No worries, its working now thats the main thing, it may have just been me being too tight with the settings.

I think the 300 limit i had equates to 0.15mm following error before faulting, too tight for rapid reversals?

969

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: October 23, 2016, 09:02:30 AM »

Running Mach 062, CS_Labs reckon 022 but have been told that one has many other issues that make it not a good choice.

The PC is just a standard Dell Optiplex GX520 no idea on specs but have them running Mach on 3 machines reliably.

Plugin version is the one delivered with system, not sure on ver but dated 27th Jan 2016.

Its the X axis that was faulting, maybe i just had the max following error setting too tight?

970

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: October 23, 2016, 06:16:12 AM »

Well, i lowered the acceleration to 350 and increased the max following error in Pid tuning to 400 from 300 on the X axis - this was the one that was faulting.

Seems to be ok now, it did the test run ok anyway.