Previously on Woody’s Workshop … I had spent time trying to get a consistently level PCB blank clamped to the tooling table ready to mill the traces using CNC. The results were not too bad but being anally fussy it left a bit to be desired, particularly if the board had a large area which magnified the variations.
Any variation of the level of the PCB top surface will produce variable width cuts when using a V shaped cutter. I had machined a clamping plate which was a simple open frame with a clamping step equal to the PCB thickness (1.6mm) and a sheet of MDF or hardboard as a sacrificial backing board.
Despite having more clamping screw holes than a magazine burst from an AK47 I still ended with the corners of the PCB being a few thou lower. Results were shall we say ‘variable’. I had reason to run a new prototype board this week and once again hit the same frustration. In the end it was a sit and look at it and have a think session.
The resulting revelation was maybe the sharp edges on the step are applying too much pressure ? What if I were to be more gentle with the clamping ?
I cut some strips of thin foam rubber and put this into the step such as to push down on the PCB. As a quick test I only fastened the frame down using the four corner holes.
Absolute magic. The PCB surface hardly moved the Hamer needle at any point on the surface. Milling result was an artwork to be proud of.
Issues – the current step on the clamping frame is meant to clamp to a hard stop based on the sum of the PCB thickness and the sacrificial material thickness. Adding the foam meant I had to do away with the sacrificial board. The frame step therefore needs to be deeper. The sacrificial material is essential to allow drilling to take place without breaking the drill as it runs into and potentially damages the tooling table. (For the board in question I drilled to only 1mm and then over drilled by hand off line to the mill).
So a worthwhile bit of experimenting and hopefully a better result going forward
Back from after a few weeks in France and back in the workshop.
Every now and then there is a project that is on the go and you can’t sit down and focus on it. It is a sort of mechanical procrastination. A reluctance to put the first pencil mark on the paper. You then suddenly find all sorts of other things that you kid yourself are more important / higher priority and you get distracted. You know that job will still be there but maybe tomorrow, not today. You suddenly develop a clear conscience about doing something else while you do some background thinking ….
This particular day started off by cleaning down the accumulated swarf (chips) in the 440 tray. Really important job. This led to a check behind the various 440 slideway bellows to see that all was well with the oiling mechanism on the slideways and the ballscrews. X and Y were fine but Z was dry. Not good news.
The 440 is supplied with a manual oiler as standard. This is a reservoir of oil and a pump/plunger which you pull out and release to initiate a slow pressure to the oil distribution pipes.
I checked the plunger and it didn’t feel like it was applying much pressure. This is not the first time I have experienced this problem. If I pumped a few times it felt better so something should have been happening at the oiling points on the Z. I disconnected each of these where I could and sure enough if I pumped hard enough some oil dribbled out but not with much pressure. Something probably not right with the plunger ?
Squeezing round the back of the mill I removed the top of the reservoir (4 retaining screws), disconnected the oil pipe union and lifted the plunger clear. The reservoir can be left in place sitting on the mounting bracket.
There is a large end cap at the union end of the plunger cylinder which I removed and sure enough I could see a mangled O ring. To get the plunger out you have to be a bit brutal. You pull the T handle plunger back out of its housing against its spring using the handle as shown above and then grip the shaft with pliers so you can then twist the handle off. What you don’t do then is suddenly release the pliers grip or the plunger will go into low Earth orbit under the pressure of its spring …
Having disassembled the plunger it was obvious that the O ring had failed quite badly. Tormach support do not offer spares as the oiler is a third party item. They do not know what size the O ring should be. Checking in my box of miscellaneous O rings it looked like a 9mm ID, 3mm thickness part would do the trick. Smearing the O ring with DC4 silicon grease allowed easy re-assembly into the piston bore and then back onto the 440. I now had lots of pressure and oil was apparent trickling down the Z slideways and ball screws. Job done. No pumping needed, just one pull out of the piston handle was generating a slow release of oil to the key areas.
The job I should have been doing was still sat on the bench glaring at me but psychologically I was doing something more important.
Next problem was the Fogbuster air activation valve. Under CNC control this reliably switched on but sometimes would not switch off when commanded to. There are various forum discussions on this problem and many contributors just replace the solenoid valve with a different version. Forum chat also recommended that electrical transient snubbers are fitted across various inductive loads in the Tormach control unit. I had some of these in my stock box (Tormach offer a kit for this). They are simply a series resistor and capacitor in an epoxy block. They are fitted across any inductive device to suppress switching transients. I dived into the control box and fitted one across the controller relay coil that switches the Fogbuster ON and OFF and another one across the outlet from the control box feeding the Fogbuster solenoid coil. See picture below.
The problem seemed to be improved but still occasionally the solenoid did not switch OFF.
The Fogbuster solenoid has a clear housing over the activation coil connections and there is a LED inside this that comes on when the Fogbuster is switched on.
This connection housing plugs into the coil and the mechanics of the solenoid body and is released with a screw in the end. Toggling the coolant ON and OFF via the PathPilot user interface I could see the LED responding correctly to the ON and OFF commands but occasionally the solenoid was not closing. It was therefore not an electrical problem but mechanical.
On top of the solenoid housing is a single large nut which when released allows the solenoid coil to be lifted off. This leaves two countersink screws which hold the mechanical plunger housing in place and if these are removed the plunger can be gently removed. Inside the valve is very simple. A central hole allows the air to pass through and when the solenoid is de-energised a spring forces the solenoid plunger to seal this hole. I gave everything a thorough blast with compressed air and re-assembled it. Care is needed re-assembling as there is a tiny O ring seal on the plunger cover. The solenoid now responds correctly to the PathPilot commands.
Another tick. Job done. Warm glow.
That other job is still sat on the bench glaring at me ….
Tormach’s PathPilot CNC control software offers a Tool Table facility that will accept up to 1000 different tool entries. This is more than enough tools for the small machine shop and if fully populated would represent a small fortune in tools and collet investment.
In PathPilot when you go to the Offsets tab to edit a tool, the following dialogue box comes up (sorry about the quality of the image ..) suggesting that you can be quite clever with the descriptions of your tools.
How you describe the tool helps local machining settings such as Conversational routines. It has no impact if you are loading an externally created GCode from CAD/CAM packages such as Fusion 360.
When I first started using PathPilot I had never bothered to add this intelligence when I described the tool. I simply wrote something that meant something to me. As time has passed and I have added more and more tools, the prospect of going back into the Tool Table and making edits to conform to these intelligent descriptions did not seem like a glamorous prospect, even for a rainy day job.
What has changed is that in the latest versions of PathPilot, Tormach has added a search routine for the tool table. This depends for its success in finding what you are searching for on the consistency of entries in each line description.
There is now an incentive to have a ‘rainy day’ session and clean up the table entries.
See Mill-tool-table-editor to download a folder containing the description of how to do this and also the Excel file used to manipulate the data.
I am quite anal in needing to have a tidy workshop with everything having a place where I can find it easily. It is a kind of insurance policy to perhaps give me a bit longer time in the workshop before I lose the plot altogether. (The less palatable advantage is the dealer who comes in to clear my workshop when I am in turn in ‘a box’ can easily see what a treasure trove he has stumbled on. We’ll move swiftly on from that thought).
To this end I have settled on using 5 Litre storage boxes for all my ‘stuff’ (technical term as defined by my long suffering wife). These are readily available in the UK at Dunelm and on the net. They are made from a very durable plastic and supplied with a lid which is rarely useful for my application. I believe they are principally intended for ladies to store their shoes. I suppose we could call them Marcos boxes ?
The boxes have a 6.5″x 12″ footprint and are 4″ deep. It is surprising just how much workshop kit can be stored in these (and of course nicely labelled). The 12″ is just not long enough for 13″ silver steel but a little hang over can be tolerated for such useful material.
I have accumulated a reasonable (by my standard) set of Tormach TTS tooling collets with my preferred tools permanently fitted. These are each numbered to match my tool table entries in PathPilot. The numbering is done using an Edding 750 white paint marker.
My solution to storing the collets was to use Marcos boxes. I used a sheet of Dural (150mm x 290mm) and punched a (3 x 6) matrix of 20mm holes into it to take the collets. The Dural sheet sits on 5 off 10mm diameter x 36mm long spacers.
To give you some idea of the strength of the boxes, you can pick up one of these fully loaded with tools by the front wall and your wrist will break before the box does. (Well you know what I mean).
You will notice in the above photo that after some expensive clumsy breakages I now fit 3D printed caps over the most fragile tools such as carbide PCB drills.
So a bit of a slow news day but thought this might stir an organisational initiative somewhere ……
I bought one of the Wildhorse Innovations Passive Probes some time ago and it gets used occasionally (usually when I have dispatched another Haimer tip to happier hunting grounds).
The Wildhorse design is nice and simple and it can be bought with a ‘Tormach Option’ which is a cable with a ready fitted 5 pin DIN that is pre-wired to plug straight into the Tormach 440 accessories socket. I have to say it did not talk to the Tormach PathPilot interface immediately. I had to snipped the pull up resistor inside the unit to solve this. When in use on the Tormach you have to designate the probe as Tool 99 in the tool table so as to be able to utilise the PathPilot probing routines (which are very good).
So where is all this going ? Well it is a A to B to C progression …
I dusted the probe off to use the other day and as I had not used it for some time, I did a centring calibration of the probe ball point while mounted in the Tormach spindle. This is a real pain to do as the three centralising adjustment screws are on the bottom face of the body. As a result you can’t see what you are doing and there is a danger of knocking your dial gauge in the process and having to start again.
This got me thinking about whether I could do this adjustment off line in the lathe. This way the adjustment screws on the bottom face are readily accessible. This seemed like a good idea except the umbilical cable is permanently wired into the unit so it needed to be protected from a disastrous wrap round the chuck. Initially I wrapped the cable around the body of the probe and held it there with masking tape but it wasn’t ideal.
Watching the probe spin in the lathe chuck made me also realise that because I had mounted the probe in a Tormach TTS collet this was a waste of a collet. It might also be adding to eccentricity through using such a combination. So you see that one thing leads to another and to another. A workshop wormhole.
A plan was made. Fit a connector on the probe body to allow the cable to be disconnected and replace the existing mounting rod with a TTS equivalent.
Finding a suitable connector was a bit more tricky than expected in that there is not a lot of room inside the probe body and a connector that protruded too far would foul the spring loaded mechanics. My search for a suitable connector combination Iead me to a 2 pin Binder rear mounted socket (Part Number 09 0074 00 02). Being pedantic it should be a fixed plug as the connecting cable connector (Part Number 99-0071-100-02) would now have two exposed pins carrying a voltage. The supplier only had the fixed socket version in stock so I conveniently looked the other way on that argument – the cable would rarely be unplugged so not likely to be a problem …
The circular body of the Wildhorse Probe is quite substantial. When the connector arrived and I was ready to proceed, I took a picture of the existing wiring and then snipped the cable clear. I enlarged the hole in the body wall to 9mm but then discovered that the mounting thread on the connector was not long enough protrude through the probe body wall far enough to pick up on the retaining nut. To overcome this I milled a flat area on the shell outer surface. The two connecting wires where then soldered in place on the fixed connector and then on the mating male connector on the free end of the cable.
The next job was to make the new fixing rod. I always try to have 19mm silver steel available in my stock box. This matches the TTS collet outside diameter. I decided I would make a new mounting rod with the silver steel and I would increase the threaded mounting hole on the probe top to M8 from the 1/4″ size as supplied .
The larger diameter would provide a larger shoulder on the rod to tighten against the probe top. Using M8 would allow the stud mounting hole to still sit within the pocket that retains the pressure spring. The rod was faced and turned to 8mm for 5mm or so and the M8 thread cut and undercut with a graver. The other end of the rod was faced and then a 45 degree chamfer turned on it. The finished rod screwed nicely into the top plate and the body now seemed to run solidly square to the central axis.
All operations were now complete and I mounted probe with its cable unplugged in the lather chuck with the new 19mm rod. I mounted my dial gauge on the lathe bed and set about centralising the probe ball. It was so much easier in the lathe with no cable to get in the way of things. Transferring the modified probe to the Tormach afterwards gave very similar centralising results.
So a typical workshop wormhole progression from job to job but as ever it was time well spent.