Topics

1

General Mach Discussion / Trouble with parametrics & subroutines

« on: November 07, 2018, 01:09:52 PM »

So, here's some code I've been writing to try to get an exponential curve on a job. It's just a toolpath for now, no feed rates, spindle commands or anything fancy, I tend to do those later in the game.

g40
g0 Z5
#1=0
#2=0
#3=-5.2

G0 x-65 y0
(g41 p7) (this is what buggers it up)
g0 z#3
G01 X-55 y0
G01 X-45 Y0
G01 Z#3
#1=0
#2=0
g01 x0
M98 P2 L10
g01 X 0.86 Y-35.71
G03 X0 Y-35.5 I-0.89 J-43
G01 X-45
G01 X-45 Y0
#3=[#3-5.2]
g40
M30

O2 (Incriments X then recalculates Y, then moves there)
#1=[#1+26.0000]
#2=[[[0.495*[2.718**[0.020*#1]]]+[0.0320*#1]]*-1]
G01 X#1 Y#2
M99
%

Note the G41 offset is commented out - like this it should display a nice sort of boomerang shape, but of course there's no tool diameter offset. With the offset active, it runs O2 once then bails out and shortcuts back to the start of the g03 arc.
The really strange thing is, the blue toolpath line is the right shape - it just doesn't follow it with the offset on. it's as if it will only run O2 once when the offset is active.
Help me out lads, I'm losing my mind here. 

2

General Mach Discussion / Time for a rip-out

« on: April 23, 2018, 12:56:00 PM »

So it's been 11 or 12 years since I built my machine's control system. Since then it's followed me from one job to another, thrown numerous wobblies and been hacked and patched to kingdom come and I'm thinking ... I should buy an ESS.
This is looking even more promising now that I've got the hang of OEM inputs and outputs, those three ports will come in handy. I've got a long list of things I want the beasty to do, including being more operator friendly in service. Stuff like pushing a proper button to start a cycle rather than messing about with an increasingly gungy keyboard and mouse. Stuff you get on a proper machine. It's all a bit undefined right now but I'm getting places in terms of the ports and pins layout, panel layout basics and other conceptual level stuff.
Most of the limit sensors, contactors and relays were recycled from its initial build so they are a bit old. I think for reliability and a fresh start generally I'll just fit new.
I might even change the coolant this time. 
Anyway, wish me luck and I'll update when there's something worth a photograph.

3

Show"N"Tell ( What you have made with your CNC machine.) / Enormous turning job: 4.5m OD spinning tool

« on: October 25, 2015, 05:40:26 PM »

This is the story of how we built one of the largest spinning tools you are ever likely to see. This is a parabolic spinning tool for making aluminium reflectors for satellite antennas and weather radar systems. It weighs around 2.5 tons. We had a 3.0m tool which was bought as part of a factory closure. it had originally been the centre of a 4.5m tool, but the outer segments had been scrapped. so we had to remake them. It was no small job.

fig.1. The 3.0m tool


Fig. 2 After making a pattern and having the new segments cast, the machining references were milled and holes tapped for fixturing. They were milled on a large 3-axis machine, tilted as they would be in service to allow the sides to come parallel when assembled.


Fig. 3. Assembling the tool for finish turning


Fig. 4. The tool in position on the lathe headstock where it will be used, driven at around 60RPM using a 20hp motor. Note the pit needed to clear the tool to put the axis at a workable height.


Fig. 5. Turning the tool. The 2-axis slide is not at 90 degrees to the machine axis as this would require too much slide movement, Instead a minimal Y axis moving only 300mm or so is used, and an angular offset applied. The software is used in mill configuration using the radius of the lathe tool tip as an offset.


Fig. 6. The finished tool With its eventual operator for scale.


Programming was simple since a parabolic curve is simply defined mathematically, so parametrics are used to recalculate the next pair of X and Y coordinates based on a subroutine that runs several times a second to change the value of two parameters which are then translated to X and Y before movement. The program as it was run was about 30 lines long. This and the angular offset made the programming easy.

Turning took six days, day and night. This was a long job and the first I've seen where the job was bigger than the machine! a number of visitors called their friends and just said "get down here. You've got to see this". As far as we know this is the largest metallic spinning tool in europe - and it was made using Mach3.

4

Tangent Corner / World's finest work holding system

« on: May 30, 2012, 07:52:03 PM »

At first I was like   
But then I was like

http://www.ebay.co.uk/itm/Robust-Clamp-Fixture-for-Milling-or-CNC-machines-Secure-items-up-to-45mm-deep-/300714176245

I bet this would be just fine when I clamp down a chunk of 40mm square section steel and drive an 18mm slot drill into it at 1000rpm. Obviously "robust" has changed it's meaning some time this week.

5

General Mach Discussion / Z plunges too far and ruins jobs; Mach misses lines; wailing/gnashing of teeth

« on: June 18, 2011, 12:11:47 PM »

I've had a persistent, if intermittent problem with Mach3: My Z axis tends to get carried away and plunge too far (or not retract fully). The results are as dire as you'd expect - Ruined work, lost time and broken tools. I've got a hole in the top of my vice with an expensive 8mm cutter snapped of in it from the last episode. This isn't something I can reproduce as it only happens infrequently. Any clues on this? I'm getting a bit paranoid about it since I've got some big milling jobs to get through shortly and I don't want them going wrong.

The other point that may be related is that Mach occasionally seems to skip instructions or stop short of a finishing point. This is usually when approaching the end o a cut with a G41 offset on - instead of continuing to the end of a a cut it stops significantly short before lifting the spindle. The only way i can correct this is by programming the same line twice.

Again, any clues on this? This BS is giving me ulcers just thinking about it 

6

General Mach Discussion / Mach skips lines: what's going on?

« on: May 24, 2011, 09:10:35 AM »

I've written a very simple program for Mach3, and running it in simulation on my laptop, it skips the first few moves and goes straight into the g03 from where it is. Needless to say this is a right old nonsense.

My laptop is a 64 bit Winows 7 Professional machine, and the error occurs in regualar W7 and XP mode.

G64 G21 G15 G40 G49
G0 Z20
G0 X0 Y150 {STARTING POSITION}
G41 P6.00
G0 X3.75 Y0
G03 X 3.75 Y0 I32 J0
M30
%

I've tried littering it with dwell commands to try to prompt it to find the first few lines but to no avail. I've also tried replacing the initial rapids with fast g01 commands, and repeating the first move to the starting position several times. It just starts from where it is and gets into the G03 move. I'm stumped.

Any ideas?

7

General Mach Discussion / tool offsets questions - G41/G42 and G43 behaviour

« on: May 31, 2010, 02:18:04 PM »

Hi,

If a manual toolchange is called (M6 T2) and G41 and G43 are already in effect, after a lead-out and lead-in move to get the spindle in position for actual toolchanging, will the new offsets be applied for the following cuts?

I know G41 and G42 use the values of the tool in the spindle (as shown on the "run" screen) if no offsets are specified in the code, but does G43 use a similar strategy or do i have to tell it which tool slot to get its length offset from? As ever, thanks in advance

8

General Mach Discussion / ebay stuff: selling Mach3 manuals

« on: May 31, 2010, 08:21:06 AM »

http://cgi.ebay.co.uk/MACH3-CNC-ROUTER-MILL-LATHE-GUIDE-CONFIGURATION-MANUAL-/110538458965?cmd=ViewItem&pt=LH_DefaultDomain_3&hash=item19bc9b0755

this lad is selling Art's manual for £3 when as we know it's available here for free ... who to contact? I've notified ebay already.

9

General Mach Discussion / cuting snails and helices (helixes?) - parametrics problems

« on: May 30, 2010, 10:18:58 AM »

Hi. Having a quick kickaround at maiking a snail, and I've run into some problems.

This is the code i was using five minutes ago, it worked then but not now.

#1=45
G0 X0 Y[#1]
G0 Z1.00
M3 M8
G01 Z-1.0 F200

M98 P1 L10

G0 Z10 M5 M9
M30
O1

G03 X0 Y[#1] I0 J0 F600
#1=[#1+7.0]

M99
%

this isn't for making anything, just a tester for cutting a jig for trimming a ring shaped part on, hence the locating island in the middle.

The increasing Y value in the subroutine should force the tool round in an outwardly increasing helix, and annoyingly, five minutes ago it did ... but not any more .. And i can't think why. Any clues?

G02 or G03 commands repeated with a decreasing Z are quite ok, I use these all the time for milling dead-fit holes for dowels etc. Never a problem there. Just flat helixes, or helices or whatever they are when they're at home. Any clues?  

10

General Mach Discussion / Mayday, mayday, mayday: Steppers thumping and banging and losing steps

« on: May 24, 2010, 06:41:04 AM »

Trouble at t'mill! I replaced the computer after the frost killed the old one off, and now it really won't play. 

It's a faster computer (1.5ghz Athlon over the 900mhz Pentium) and when jogging, with a 45khz kernel, it will easily drive at 2000 mm/min plus. However when executing G-code commands the buffer instantly exceeds 100% and the pulse train goes nuts, causing severe amounts of lost steps. I'm down to about 1200 mm/minute maximum now, and when executing a long, slow helical move it still loses steps, and the steppers thump and stumble.

Any common reasons why this would happen? I'm going to be in trouble if I can't get the beast dancing nicely, so any help offered would be sincerely appreciated. Thanks in advance