Each of my CNC mills has a home designed and produced tooling plate. Both have a 25mm pitch matrix of tapped mounting holes and a further submatrix of 3.7mm tooling pin holes. Why 3.7mm ? So I can turn down 4mm silver steel for the tooling pins to create a retaining shoulder.
My small CNC plate has M5 tapped holes and the Tormach 440 has M8 tapped holes. What struct me was that I has starting to create dual sets of hold down tooling, some with M5 and some with M8 mounting holes. Not a good idea. (Entertaining and therapeutic though it might be to have ‘tooling days’).
Clearly a mounting with M8 holes was not much use with tooling having M5 mounting holes but the other way round would work if I had M8 to M5 adaptors.
As a result I have spent the day creating adaptors which you could call male and female. Both are made from M8 hex head tensile screws with the female ones retaining the M8 head and the male ones utilising the cut off portion of thread. I had to undercut the thread ends behind the heads so the female adaptors would sit flush. Having undercut I then skimmed all the tops of the hex heads to be same depth.
All the turning was done with the ER25 collet chuck instead of the 3 jaw which is normally fitted to the Myford. The male adaptor versions were a pain to turn down to M5 diameter and had to be done incrementally as the M8 threaded end could not be heavily gripped in the collet.
The female versions are quite useful if a job is being run on the Tormach that needs suspending above the table so it can machined to full stock depth.
Nothing revolutionary or original but a day well spent.
After I decided to buy a Tormach milling machine I had debate whether to go for the 440 or the 770. This confusion was based on available workshop space and to a lesser extent on cost. I also did not have a feel for the total cost of not just the items I needed to buy but also what the total package would cost when it landed on my driveway. In the UK we pay VAT on not just the goods but also the delivery cost.
To help my thinking I put together a spreadsheet on Excel that split out the basic machine parts and then had a common section showing all the accessories I would need. This totaled everything up in USD and I then did a conversion to GBP at spot rate and then added VAT and duty factors for UK import.
This sheet helped my enormously and once I had all the key prices loaded from the Tormach site I could do ‘what if’ calculations to fit my budget.
I was recently contacted by another potential buyer of a Tormach and I sent him the sheet to help his thinking process. For anyone else thinking of buying either in the US or an overseas country I thought the sheet might help so I have spent some time cleaning it up and and I attach the new version below.
Simply put a quantity of each item in the column associated and see the impact of your shopping list at the bottom, either as a 440 or a 770. Clearly the sheet could be extended to a 1100 if that takes your fancy. (Don’t forget to check the current pricing from the Tormach site by searching on the product code shown on the sheet).
As part of my purchase package of the Tormach PCNC440 I ordered their granite block and height caliper. This meant I could measure and set tool heights directly into the tool table on PathPilot via the caliper USB connection. See the image below which shows the granite block, caliper and the associated dongle box.
This concept works really well and saves manual entry typo errors when measuring tool lengths. I have found one problem however and that is the caliper eats batteries at an alarming rate. These are CR2032 button cells which are not dramatically expensive, but the cost does start to add up. There is the added frustration of the caliper potentially not functioning at a critical moment when a new tool needs to be measured.
It struck me as strange that a device talking via USB should be dependent on a battery when 5V is available from the USB interface. The fact that this did not happen suggested to me that the connection from the interface box to the caliper did not have through continuity of the 5V supply. This wasn’t surprising given that the caliper runs from a 3V cell.
I connected the caliper via a standard USB cable directly to a variable power supply connected onto the 5V power pin on the USB cable. Varying the power supply from 0V to 5V showed that the caliper would work quite reliably over a range of 3V to 3.8V but above this the display would blank or just show 8888 at high intensity so masking the actual reading.
I found a couple of 1N4148 signal diodes in my component stock and put them in series with the 5V feed from the power supply to act as a series voltage drop. This brought the working voltage delivered to the caliper back into the 3V to 3.8V range where it functioned without any problems.
So the question was now as to how to implement this modification elegantly ? ….
Be warned that the modification to be described involves a change to the USB dongle box supplied with the caliper and as such will invalidate any warranty. Mimic what I did at your own risk.
The dongle box has four screws on the bottom cover and removing these reveals the controller pcb. Take care not to loose the three blue switch activator rods in the process. On inspection of the pcb, the USB cable entering the box has all four standard USB connections but the cable exiting to the caliper has the 5V lead (red) disconnected.
I found a pin quite close by to the output lead that was marked 5V. This was a possible feed for my two diodes. On measuring this I found it was at a lower voltage than expected suggesting that there was perhaps some circuitry between this point and the incoming 5V. I therefore chose to ignore this and looked instead to the input connection cable. I found the +5V connection (red) as it connected to the pcb. I connected the two diodes in series to this cable termination and then ran a connecting wire (orange below)across the board to the 5V output (red) cable which was previously not connected.
These modifications are shown below albeit with hot glue over the diodes and connections.
This completed the modification. I checked out all the voltages while the pcb was still outside the box and also checked the caliper was still working. I replaced the pcb back into the box and screwed the lid in place.
One final thing I did which is not necessarily essential but felt like a good thing to do, was to put a tantalum capacitor across the former battery contacts in the caliper battery compartment. This would act as decoupling should there be any ripple on the new supply to the caliper. See the image below. Note that the tantalum capacitor is polarised and its + lead goes to the former + battery contact (on the right as shown below).
While this is a potentially useful thing to do, it has the disadvantage that you cannot put a battery in the caliper if you want to use it ‘off line’ when not connected to a USB port. You could however plug it into USB charger via the dongle lead.
The other minor thing I did was to fit a small cable tie to retain the caliper connector in place as I found it easily become disconnected.
On putting the setup all back together, the caliper was working well with a nice contrast to the LCD display. Tool table updates work just as they did before so no issues there.
If you do this modification you might want to experiment with different diodes or the number of diodes needed to the drop the voltage from 5V to within the caliper normal voltage range. Note that you need to use small signal silicon diodes which will have around a 0.6V voltage drop per diode. Don’t use Schottky diodes as these generally have around 0.2V and so you would need at least 3 times as many to achieve the same overall voltage drop. You could try LEDs as they all seem to have different voltage drops but they tend to need a high drive current which if this is the case, makes them unsuitable for this application.
You could of course go really elegant and build a small integrated power supply chip into the dongle box such as the AMS1117. These are available in various fixed output voltages including a 3.3V version (which is popular for Arduino projects and available from Amazon). You can also buy a ready made 5V to 3V module based on the AMS1117 from Amazon. I like the AMS1117 and used the 1.5V version in my power supply modification to the Shumatech DRO systems.
Here is a printer friendly (and slightly updated) version of this article : –
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).
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.
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.
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.