Topics

11

General Mach Discussion / Lathe tool change problem

« on: January 14, 2013, 05:32:10 PM »

This problem has existed since I started using my lathe, but I managed to tweak the g-code to get around it, but having just hit the problem again tonight, I want to figure what is actually causing the problem.

When changing between tools in the g-code, if there is a large distance on the X-axis needing moved, lots of steps get lost/the stepper stalls.
Tool changes are fine as long as the x-axis distance needing moved after the tool change is minimal (or is combined with a long Z move).

For example, if the new tool offset is 80mm different, and needs a physical movement of say 2mm to get to the next commanded position things are fine, or if it needs to move 100mm in the Z and 80mm in the X, things are fine.
However, if the physical movement needed is say 50mm in the X alone (or combined with a few mm in the Z), the x-axis will stall.

It's as though Mach ignores the max speed of the X-axis for that first move after a tool change.
If the first move is combined with a long Z move, because the two are interpolated to move diagonally, things go fine.

I'm not sure if it's related to some setting (G0 moves never cause any problems, and I've even tried reducing the X-axis max speed when I first had the problem), a bug with the SmoothStepper, or something wrong with Mach.

Anybody got any suggestions?

12

Show"N"Tell ( Your Machines) / Matchmaker Revival

« on: January 13, 2013, 06:52:36 PM »

First off, I'm blaming Hood for this. If it wasn't for him pointing me in the direction of this mill, I would of been happily on my way to building a nice desktop sized router!

Anyway, after Hood's help, a few months ago I became the owner of a Matchmaker mill. The actual knee mill is a Shizouka ST-N, with a Summit aka One Arm Bandit tool changer.


Shizouka ST-N by mc_mtb, on Flickr

After removing the head, and with some questionable use of a forklift and some skates, it made it into the workshop.

In Position by mc_mtb, on Flickr

I'm not in a great rush to get this machine up and running as I've got various other projects/jobs that have priority, but inbetween swapping bits in my lathe, I've been tracing wires, doing some cleaning, and getting the autolube up and running. After cleaning out the autolube unit, I filled it up and left it running overnight to see if any oil appeared on the ways. And despite managing to pump half a litre out the resevoir, nothing appeared anywhere it should, or even on the floor. The oil was finally located sitting in a recess under the table, which had a blocked drain hole, and was getting there because of a burst alloy pipe.
While having the ballscrew support of the end of the table, I stripped and cleaned the distribution block, and found two of the Bijur metering units are blocked, so I stripped the other distribution blocks, and found one more blocked on the knee, along with the main quill one. Buying some new metering blocks is on this weeks list of jobs.

Here's the distribution block refitted with a new copper pipe -

Autolube Distribution by mc_mtb, on Flickr

As it stands, my plan is to use a Kflop with Kanalog running through Mach for the main control, with high voltage steppers and drivers for the axis running closed loop through the Kflop.
I'd like servos, but I can't justify the cost at the moment. 3 steppers and drivers are roughly the same cost as a servo for a single axis, so I'll live with the slowness of steppers for now, however by using the Kflop upgrading to servos later will be a pretty straightforward job.

13

General Mach Discussion / Drilling 3 holes on a lathe

« on: November 28, 2011, 03:35:43 PM »

Sounds simple, doesn't it?
And I'm sure it should be, but I'm really struggling to get my head around it!

I'm working on a gang tool bar that fits in the QCTP to mount drills/reamers in via ER25 collets, and I'm now at the point where I need to drill 3 holes, 40mm apart.
I've managed to turn a few bits, including a couple threads, using the wizards, but I figured I should really learn a bit more about G-codes instead of relying on wizards.
So, after reading the manual, and trying various options, I finally tracked down the lack of movement to the G83 macro being missing from the profile folder, so I copied the standard one across from the default turn profile folder (I found the thread with the 'fixed' M83 version, but I figured I'd stick with the original one for now)

However, although I can get movement in the Manual screen by typing in G83 X0 Z-5 Q1 R1, the line doesn't even show once saved to a file and loaded in the Auto screen.
I'd like to create a file that will drill the three holes in one run, so I can edit it as I swap drill bits.

Anybody got any pointers on how to achieve this?

14

General Mach Discussion / Diameter or Radius mode for a lathe?

« on: April 02, 2011, 05:18:00 PM »

What is the general opinion on this?

I'm pretty new to CNC, and I've currently opted for Diameter mode, as that's most practical when measuring things.
However, during setting up the various bits of the lathe and seeing the X-axis DRO show twice the distance of what the axis has just moved, I'm wondering if Radius mode would be more suitable, as that way the DRO corresponds to the actual movement.