Messages

781

General Mach Discussion / Re: Constant Velocity settings worked out ... I think

« on: January 10, 2017, 03:33:50 AM »

Thanks Art for the response, nice and clear.

My main interest is reduction in jerk, i have acceleration pretty high to maintain contour but its an old Bridgeport with a 48" table and no linear guides of course so the direction changes seem pretty harsh, made worse by my machining aluminium with small cutters on a 24K spindle so they need pretty good feed rates.

I might try lowering the acceleration a tad and also lowering feed rates to suit.

In the mind it seems easy to think you can just throw some code at a machine and it will follow the path explicitly but as i found out myself with a junk part and after Arts' explanation this can never really happen unless all factors - machine drive, acceleration, feed rate are in balance.

782

General Mach Discussion / Re: Homing switch concerns

« on: January 09, 2017, 03:14:13 PM »

Probably because for a lot of applications, a microswitch is accurate enough - a good quality one is pretty repeatable.

I have not used 2-wire inductive sensors, i guess they are hall-effect maybe or capacitive (doubtful) either way i would not fit relays because as you stated it adds slack to the circuit.

I have a microswitch on the plate-sense probe of my plasma cutter and its accurate to 0.1mm repeatable, i used three-wire inductive sensors on my mini-mill and they are repeatable to <0.1mm, the big mill uses large lever switches but has index homing.

783

General Mach Discussion / Re: Homing switch concerns

« on: January 09, 2017, 12:51:29 PM »

Presumably the sensors were the originals? If yes then they should be ok as it worked before

There are some tricks you can do with homing - I have seen encoder disks fitted to the motor shafts, the sensor tells the system to look for a pulse from the encoder and this is then taken as home position - this can be very accurate and is very similar to index homing on servo drive systems.

784

General Mach Discussion / Re: Constant Velocity settings worked out ... I think

« on: January 09, 2017, 10:39:26 AM »

Its very interesting as i had suffered poor path following recently due to my machine having less than blistering acceleration, I'll wait to see what the response from others is first but i may play with this myself as i would rather run a bit lower acceleration and still get tight tolerances on my Bridgeport conversion.

785

General Mach Discussion / Re: Big trouble

« on: January 07, 2017, 10:04:16 AM »

have you checked all the connections at the BOB?

what machine process is this - plasma, mill, router etc

786

General Mach Discussion / Re: Big trouble

« on: January 07, 2017, 08:20:12 AM »

NC circuits are not usually prone to noise as there is a constant signal there - this is one of the good points of them over NO circuits.

I would engage the system, then start gently moving and wiggling the cables between the head and the control box, no need to go nuts, just a gentle wiggle, and see if you can make it trip.

787

General Mach Discussion / Re: Big trouble

« on: January 07, 2017, 03:48:06 AM »

Usually a broken or loose wire/connection.

788

General Mach Discussion / Re: Work piece outside of table

« on: January 06, 2017, 06:19:14 AM »

Sounds like the workpiece home reference is set wrong in your CAM program.

789

General Mach Discussion / Re: Tuning Slaved Axes Motors

« on: January 04, 2017, 03:15:19 PM »

The motors, drive settings, steps per, velocity and acceleration should all be identical really.

The setup should be tuned as one item so get the slaving working correct, set the steps per and tune from there.

790

General Mach Discussion / Re: Plasma , cuts offset problem

« on: January 02, 2017, 01:59:10 PM »

Did you compare the actual codes generated, i am guessing they will be the same, but interesting to know.

What post are you using in sheet-cam?

Have you got "delete duplicate layers" checked in setup??