Topics

1

General Mach Discussion / Lathe Feedrate Problem

« on: March 06, 2013, 02:42:11 PM »

Hi, A couple of months ago my lathe computer died and I replaced it with another with similar specs.

I decided to install Mach3 version 43.066

I noticed that when programming a G95 the feedrate was alot slower if I set F0.15 the feedrate in the dro would be showing F0.09
The machine motion would be moving at F0.09 also.

I have been messing around trying to solve the issue but to no avail. I installed version 43.022 and also 42.040 but still have the same problem.

Things I have discovered,

When running any of my cnc files and G95 is read the feed rate is slower until about 12-15 code lines later the feedrate returns to the correct value commanded.

I can fool the problem by coding a G95 F0.30 if I really want F0.18 and then 12-15 code lines later set the feedrate to F0.18 but this isn't perfect as sometimes I end up with one or two passes moving at F0.30 which really upsets my machine.

This slower feerate problem only seems to be when reading the first commanded feedrate in my cnc files as later in the code the feedrate is changed and the machine moves at the correct commanded feedrate.


Any help would be welcome.

2

General Mach Discussion / Minor Threading Problem

« on: July 13, 2012, 11:11:33 AM »

Hi all, I've been recently trying to get to grips with threading on my Denford Orac machine it's not something I've done alot of on the cnc.

The problem I am having is that the thread is not cutting deep enough on an internal thread for the values I am entering into the threading wizard v1.17.

I have adjusted the backlash to zero in software (only 0.035mm in Z and oh my 0.09 in X)

I have adjusted the v point tool offsets (Glanz internal insert tool) so the point just touches the internal bore at 44.67mm

I require a thread pitch of 1.25mm and my math works the depth out using pitch * 0.866025 for crest to crest thread.

So in the wizard X start of 44.67. and the X end value of 45.7525. First pass depth of 0.15 which works out at 20 passes.

The lathe is started and threading commences, all sounds good and small swarfs of aluminium on each pass.

Removed billet and inspect thread, thread is cleanly cut, tracked perfect but the internal crest has a flat of approx 0.5-0.8mm on it.


I've done this thread several times and they all come out the same.

Is my maths wrong or is there something I have overlooked in software settings.

I know I can bodge the figures to "get in right" but I will be doing a large amount of threads at differing diameters so I am trying get the sums right first.

Any advice helpful.

3

Tangent Corner / Strange banding on lathe finished part.

« on: March 08, 2012, 12:08:34 PM »

Hi, Although probably not a Mach related problem this one has me head scratching once again.

I'm hoping one of you kind folks might give me some insight for the cure.


I'm cutting some thickwalled 6082 tube 34mm diameter and 150mm long on my Denford Orac running Mach3.

The tube is located in the chuck on the ID hard against the chuck nose and the other end is supported by the tailstock
with a revolving center and an ally slug fitted into the tube on a 45deg taper.

The turning tool is LH insert tool with insert CCGT 09T304.

When taking a cut from the tailstock end and travelling in Z 100mm the finish of the turned part has undulating banding the
peaks are approxamately 5mm apart. This is most pronounced at the tailstock end and diminishes as the cut gets nearer to the
chuck. If runnning a finger along the part, the finish has a ribbed feel to it.

Things i've tried to correct the problem,

Differing speeds and feeds.
Changing the tool height.
Trying different depths of cut.
Checking flexture of the chucked part.

None of the above made any difference to the depth or pitch of the banding.

So I changed the tool for a TPUN insert and tried again. Same effect even with a 0.2mm depth of cut.

I then had an idea and re-wrote the G-code to take the final pass starting from the chuck end and finishing at the tail stock and
the finish of the part came out perfect.

Any ideas to what the problem might be?

Cheers
John

4

General Mach Discussion / Just baffled by G54-56 Offsets

« on: May 14, 2011, 11:52:01 AM »

Hi, I've been trying to write a macro to set my Z offsets to the same number whether I am using G54 through G59.

See Macro below. I have noticed that without the wait states Mach will not update the Dro's quickly enough and the Z Dro's are still different even with running the macro.

If I single step through the macro, it seems to work as I intended.

Is there another way to achieve the same thing with one command?

5

General Mach Discussion / Wierd LPT problem

« on: January 12, 2011, 11:54:16 AM »

Hi all, I've been using my Mach3 lathe for quite a few years without too many problems.

Today, I was running the same code as always and in the middle of the run both axis stopped.

I checked through from drive power to the lpt cable and discovered that the computer is not outputting any steps
on the pins. I connected an oscilloscope to the lpt1 connector and checked pins 2 and 3, The direction signal on pin3
works ok but no signal on pin2.

I then swapped the pins in Mach3 and tested again and I have direction on pin2 but no output on pin3 so the lpt port is ok.

This 1200 mhz computer only runs Mach3 on Win2000 nothing else. I have not loaded any new software or done anything but use mach3
on it. I then re-installed Mach ontop of the existing version and still have the problem.


Any ideas..


Cheers
John

6

G-Code, CAD, and CAM discussions / Turning Aluminium Advise.

« on: May 05, 2010, 03:20:40 PM »

Hi, I've recently been cutting aluminium on my boxford cnc lathe, the swarf production is copius and I have to stop at each pass to remove said swarf.
 I've been trying to adjust the feed rate to produce short swarf lengths which will not gather up around the tool.

All tools have positive inserts and the surface speed is set at 200M/min and a feed of 0.06mm/rev, cutting 1mm per pass. I am using G95,G96.

What is the best strategy to produce short lengths of swarf in roughing passes.

Cheers
John

7

Tangent Corner / Super gearbox oil required

« on: March 16, 2010, 10:26:03 PM »

Hi, I have a milling machine which is only a couple of years old of chinese manufacture. Since I've owned it the gearbox makes a racket like shaking a tin can full of bolts vigerously. Whilst i'm standing near it I have to use ear defenders to protect my sanity.

Does anyone know of an oil I can obtain in the UK which will quieten the racket down a fair bit.


Cheers
John

8

Tangent Corner / First time making shims-Advice please

« on: February 03, 2010, 02:27:23 PM »

Hi, For the first time I need to make some steel shims for a couple of bearings on a project.

The dimentions are approx 50mm x 0.2mm with a 45mm bore, I have shim stock and thought the best way to do this
without making a "Tool for the job" would be to secure shim stock on a piece of flat wood to the mill table and use
a fly cutter to cut inside and then the outer cut.

Anyone have a suggestion whether this will work or perhaps there is a better method.

Cheers
John

9

General Mach Discussion / I thought this software was bug free by now

« on: November 17, 2009, 12:31:24 PM »

Hi, I have Mach3 Version R3.042.029 installed and I created a g-code file with the latest update of lazy cam and sent the file to Mach3.

I get a box saying Path Generation and then nothing happens.

I then save the g code to disk and open it in mach 3. I get the Path Generation box with 3 blue bars and then nothing.

Sometimes I wonder why I should keep updating the software at all.

10

General Mach Discussion / Speed and feeds wizard help

« on: January 30, 2009, 08:54:47 AM »

Hi, I need some advice about feed rates as I dont usually use such small cutters.

I'm cutting open ended slots to a depth of 2.5mm in 316 stainless with a 4mm 2 flute carbide cutter with flood coolant at a depth of 0.6mm per pass.

Using the speeds and feeds wizard as maths was never my best subject, It calculates for hard steel that I should use the highest spindle speed my machine offers
which is 1750 rpm for carbide.

What I'm not sure on is the chip load per tooth which I set at 0.02mm. This gives out a feed rate of approx 71mm/min.

I managed to get 5 of these slots done but could hear a bit of complaining and checked the cutter, the edges were rounded off.

I'm now down to my last 4mm cutter so I'm asking you, "Cap in hand" what might be my problem, Usually dulling of the ends means too much rpm but I've read that the big guys use carbide at thousands of rpm so my logic says perhaps I should reduce the feed rate.

My only worry is that if I reduce the feedrate work hardening of the material may take place.


G code attached so you may be able to suggest a better way of doing things

Many thanks
John