Tormach Post Processor G53 Edits for Tool Change

The Tormach PCNC440 is a lovely machine and is more than big enough for my present needs.   The one problem I had encountered was when coming to a tool change on a CNC job sometimes there was not enough Z height to get the TTS collet out of the spindle.   This was particularly difficult when using larger diameter drill bits in a chuck style holder.

Once in program there did not seem to be any option to break the run and do a G30 or similar.   What I really needed was a move of the spindle upwards and outwards to get it clear of the job and allow TTS access.

Reading up in Peter Smid’s excellent CNC Programming Handbook I could see that care was going to be needed to ensure that any movement was first of all a Z action and then X and Y to avoid the danger of crashing the tool into the job or its fixtures.

I had some discussion with John Saunders at NYC CNC and John was working on a video around this subject.  He helped enormously.

The end result is to use G53 machine coordinates to first do a Z and then and X and Y to move the tool up and to the side for tool change access.

This involves edits to the post processor in three places.   The first two edits (Lines 44 and 66) are there to give an option for this movement in the drop down selection box.  (The line 24 edit is an earlier modification to allow Mill Turning – see separate post).

tormach, post processor, G53
Line 24, 44, 66 edits
g53 tool change edit to post processor
Change that appears in the Property selection box where the Custom Tool Change option now appears

The third edit gives the instructions for this as a G53 Z move than a X and Y move (Lines 543-538).   Note that I later found that I had to add a G54 after the G53 movements as some CAM actions did not include a G54 as part of a tool change.

custom tool change edit
Line 534 to 538 edits

I later on decided it would be nice to include this G53 movement at program end so this is a fourth edit (Lines 1404 – 1405) and not forgetting the change for Mill Turning edit (Line 25) there are five changes in total.

cnc g53 tool change edit
Line 1404 to 1405 edits

That concludes the changes.   I recommend that you spend time watching John’s videos on Post Processor edits on NYC CNC.

If you can’t read the edits then drop me an email and I can send you a full listing.

Note that these are changes to the Tormach standard post processor code and if you are tempted to do this you should do a ‘Save As’ on the original code and only edit the newly created and saved file so you have a fall back position.  Likewise I accept no responsibility in documenting this and putting you up to potential mischief messing with your machine and causing damage.

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A Parallels Rack in Fusion and Sindoh with free Spagetti

Some time ago I made a rough and ready wall mounting rack for my parallels so they would sit to hand adjacent to the Myford manual milling machine.   I used double sided printed circuit board for the construction and while not elegant it worked OK …. until after I had finished it when I found two of the set lurking in a box with a half finished job.   I had not allowed for them in the construction and being OCD me, it annoyed me to have two lose ones that did not fit in the grand order of things.

An idle half day lead to a Fusion design to replace the tired old PCB disaster.  This lead to some thinking on how to design it.   I wanted a rack that sat on the tooling board with the parallels stacked on it with a slight upward angle to keep them in place.   I chose therefore to draw it slightly strangely with the ‘back’ at an angle and extruded it accordingly.   See below.








All well and good you might say.  Less messing with angles etc.

I squirted the job into the Sindoh 3D driver software and then tried to be clever and print it with the backside down on the printer bed …. or at least what I thought was the backside down.   You will no doubt spot that that this is not a simple rotation of 90 degrees but I didn’t.

The printer began producing spaghetti that was not bonding to the printer bed.  After three re-tries I took a closer look at my design and realised that the only part of the job that was in contact with the bed was the leading edge (red arrow below).  The rest was airborne at an angle all due to the way I had chosen to draw the object and rotate it.

Reset brain and reset printing so it would be now vertical.   All was good and my nice new rack sits on the tooling board.

A little bit more brain engagement next time perhaps ?

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Shumatech DRO350 Experiences and Fixes

The Shumatech DRO350 is a kit based digital readout display for low cost vernier scales and can be bought for either a milling machine or lathe.   Shumatech appears to no longer trade but I managed to buy the full lathe kit including the box from the UK agent.  The US agent is Wild Horse.  See previous post from France.

The product is quite well conceived and has a wide range of functions beyond just a basic readout of X,Y,Z scales.  The kit was simple to put together and I quickly had it working as a lash up on the bench.

The first problem was the fact that all the connections are configured to come out of the back plate of the plastic enclosure.  For my application this was not ideal.   The connectors as supplied with the kit also were not the same as the RJ11 on my scale cables.

I created a ‘pod’ in Fusion 360 that would mount on the end wall of the box and carry all the connections.   This was 3D printed in black to match the enclosure supplied.  Space was tight to fit all the connections into the space and I had to resort to RJ10 style connectors for the scale leads as RJ11 were too large.  I had to extend some of the connecting leads. That aside the ‘pod’ concept worked well.

shumatech 350, DRO

There is significant debate on the internet about the Shumatech design and its apparent instability or flickering of the digits on the display. Opinion seems to be mixed as to where this originates.  The PCB design is not ideal with some very long thin power supply tracking and no ground plane screening.  My two small scales seemed to not suffer this problem but my long scale definitely had a problem.

Once again opinion on the internet is mixed as to how to overcome this.   This ranges from changing the wiring in the readout box for better earthing, leaving the batteries in place in the scales or replacing them with capacitors to add smoothing.

I tried all these to no real positive effect on the long scale.   I even tried inductive decoupling of the connections at the scale terminations.

I took a step back and tried to run the scale on a separate 1.5V bench power supply on long leads and lo and behold the problem still existed suggesting it was a power supply pick up fault and nothing to do with the Shumatech electronics.

I had to hand a small 9V to 1.5V power supply module based on the AMS1117 “3 legged” integrated regulator.   I connected this close to the scale and ran the regulator input from 5V.   The jitter disappeared suggesting it was really about the pick up on the supply to the scale.

I had stock of the AMS1117 chips and SMD caps so I made 3 regulator boards and in Fusion 360 created a small box and lid to contain the regulator module.

The pcbs were made as a first job on the Tormach 440.   I hand coded the G Code to run a dentistry burr in the chuck to profile the pcb tracking.  OK it was a simple job but it gave me some confidence on how to make the mill sing to my tune.

Paper design for the 1.5V regulator using the AMS1117
Finished pcb of just 5 components
Fusion 360, Shumatech
3D Printed enclosure for 1.5V regulator designed in Fusion 360
Shumatech, AMS1117
Power supply module mounted in the plastic box and in series with the lead to the scale.
Shumatech, AMS1117
Finshed module with lid in place

The finished assembly was then connected in line with the scale lead and close to the scale.  For consistency I modified all three scales in this way.

I needed a 5V feed at the display end and to achieve this I cut the display positive lead from the pcb connectors and connected them with a flying lead to the 7805 on board 5V regulator.

On power up the scales all worked well with no obvious jitter and my Myford Super 7 now has a nice readout facility.

For the full story see the following Shumatech DRO350 Experience.

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