I needed some extra toolholders for my Boxford CNC lathe, and the following photos show some of the steps in making them on a vertical mill with a horizontal attachment.
The toolpost holder is a Dickson, beautifully made, precise. And it came with 6 tool holders. 6 should be adequate you think? Not so. You really need one holder for every tool that you might use, because with CNC, you want to do the CNC settings in the computer only once. And the Dickson holders are expensive, so I made the extras.
Today I drilled and tapped the holes for the bolts which secure the crankshaft main bearings. I had accurately marked the bearing mounts in the previous session (see previous photos), and calculated and recorded the DRO (digital read out) position for each hole. So going back to that position for each step in the process was easy and quick. The steps today were centre drilling, drilling the 3.3mm holes, and tapping the 4mm threads to a depth of 20mm.
Centre drilling is done with a centre drill bit in an accurate chuck in the milling machine. Centre drill bits are inflexible and will not wander over the work like an ordinary twist drill bit, The centre drilled hole is deep enough to create a chamfered edge to the hole. All 12 holes are drilled with the centre bit, then all 12 drilled with the 3.3 mm bit, then all 12 are threaded. The DRO positions the work within 0.005mm each time, and the repositioning is very fast, much faster than going to a position doing all 3 processes, changing the bit for each one, then moving to the next position.
The threading was done with a Tapmatic 30 tapping head in my milling machine. See photo. This takes about 10 minutes to set up, but the tapping process for the 12 holes then took about 5 minutes. I use Rapid Tap lubricant for tapping, even in brass. I guess that manually tapping the holes would have taken about the same time, but it was so satisfying to see the Tapmatic do its stuff. I use the Tapmatic for any tapping job involving more than about 8-10 holes. Fewer than that it is quicker to do them manually. The Tapmatic has a adjustable clutch. I have never broken a tap in the job using this machine.
Incidentally, I have decided to use nuts and bolts and screws and studs in preference to metric cap screws for this model. The appearance wins out over practical expediency. So why the metric threads for this job today? The specified thread was 5/32″ which is 3.96mm, so I decided to go with the 4mm metric, for which I have the tools already.
I had almost 8 hours in the workshop today. The base plate is progressing.
Then I spent an hour or so painting the machined surfaces with marking blue, and marking reference points and edges.
After carefully examining the base casting, and scrutinising the plans to discover all of the dimensions of the base, I commenced machining on my King Rich mill (Bridgeport clone, NT40 with DRO, an excellent machine). Since the base dimensions are scattered over 3 pages of very complex plans, and I am still relatively unfamiliar with them, I am approaching the machining with great caution. At this stage I am aiming to create some flat and coplanar surfaces, with a margin of material remaining, so I can hold the base flat, without rocking, roughing out the shape, and leaving finishing to dimensions at a later date. I intend to attach the base to a rectangular piece of aluminium, so the aluminium can be clamped or held in a vice, rather than risking damaging the brass casting.
Yesterday I cut some metal on the CNC mill for the first time.
I used one of the canned cycles built into the CNC controller, and faced and squared off a lump of brass which will be used for a hot air engine (The Ridder “bobber”).
Despite multiple readings of the manual, I got confused about which units required minus signs, and which ones the machine automatically assumed were positive and negative, and consequently, despite resting my hand on the emergency stop button in case such a contingency occurred, the head crashed straight into the milling vice, breaking 4 carbide tips and leaving a permanent love bite on the vice as a reminder of my incompetence.
After some expletives deleted, I re-entered the numbers, and next time, the machine went through its motions gracefully, purposefully, and quietly, leaving me with a nicely shiny and squared lump of brass.
It was so impressive, that I repeated the exercise, just for fun.
I had checked the squareness of the mill head to the table, and it was all within 0.01mm in 100mm, so nothing was altered.
I had bought a Z axis probe from CTC Tools in Hong Kong, and that was easy to use and accurate, for $a100.
Next step, to hook up a computer and try to download G code programs. Watch this space.
Another day, another problem solved….
I am sure that these ramblings are incredibly boring to everyone, so understand that I am recording them for my own benefit, as a diary, as much as for the interest of anyone else who might be thinking of leaping into buying an older CNC mill.
So today I looked at the lubrication pump.
The manual says that it operates automatically on machine startup, then every 30 minutes, as long as the oil pressure is not too high. But the pump showed absolutely no sign of functioning at any time. And the ways and ball screws were totally dry until I lubricated them with an oil can.
Today I spent hours tracing wires and looking at relays, until my friend Jason S, who is a machine designer, came and had a look for me. He put a multi meter on the wires, and everything seemed intact. Then he identified the appropriate contactor (which I gather is really a big relay), and held it in, and lo and behold the pump worked. So the problem was with the pump controlling mechanism. Then Jason surmised that if he had designed the mill, he would have had the lubrication pump working only if the ball screws and ways were actually in use, not just if the machine was switched on. So next test was to watch the pump with the ball screws activated. Lo and behold the pump worked! So what was the problem? Why was the oil not coming through?
We disconnected some oil lines, and they were dry. So we manually pumped the lubrication pump until the lines filled, (i.e. primed them) and tried the lubrication system again, with the axes working, and it worked!
So the bloody manual was misleading. The lubrication system does not work when the machine is switched on. It only works when the ball screws are operating. And the machine has been out of action for so long that the oil lines had dried out.
Another gripe with the manual, was when I tried to get a canned cycle working (dry run, with no work piece or cutter). I followed the instruction steps exactly, and nothing happened. I retried, with the same result. I tried another canned cycle… same result. Then Jason arrived, and followed the steps.. same result. Then he said “what is that DATA button for? I had no idea. It is not mentioned in the manual. So we tried pushing it, and halelujah, the canned cycle worked.
So why was it not mentioned in the manual ?????
Do people who write manuals, ever test their own instructions? Or try them with an end user???
So bloody frustrating and such a waste of time.
(note added a few days later… I found the DATA key described in a different section of the manual. My mistake, it was there all of the time. If I had read the manual from start to finish entirely, and remembered the entire 150 pages – or whatever – I would not have had the problem. Silly me. )
Anyway, another step towards making some chips.
So now for the final test, the hookup with a computer using a serial port. Fortunately I have an old computer with a serial port, and I will hook it up soon.
Z axis problem fixed!
My friend Stuart T methodically checked the wires and connections, and diagnosed a problem involving the Z axis encoder. He resorted to removing the encoder, to look at it more closely, and said ” that came off a bit too easily. I wonder if the shaft is connecting properly”. Sure enough, the shaft was loose, which explains the bizarre Z movements followed by a total loss of position information. Someone has joined the 6mm shaft to a 1/4″ socket, and it had probably worked loose during the transport from Echuca to Geelong.
So we quickly made a sleeve to join the 6mm shaft to the 6.35mm socket, tightened it all up, soldered a few wires which broke during the inspection, and hooray it all worked perfectly. Hallelujah.
Oh, and that $20 Chinese hand wheel. It was 10 mm thicker than the originals, and looked out of place, so I chucked in the the lathe, and turned it down to the same 18mm thickness as the originals. It was made of hard plastic-bakelite material which smelled really offensive while I was machining it, and was very abrasive. Tool steel lathe bits were just worn away, but a carbide insert tool coped OK. The reshaped hand wheel looks and feels much better.
Just the oil lubrication pump to fix, then I can start making chips.
I need a wiring diagram for the Extron mill.
It is a Hafco badged machine, but Hafco (Hare & Forbes) do not have wiring info. The Extron factory in Taiwan has not replied to my emails. Hare & Forbes apparently contacted the factory, and also drew a blank about wiring info.
That is pretty unimpressive. The machine is only 17 years old. In built obsolescence? Just not worth while supporting older machines? If it was a US or European machine there would be no problem getting info. It seems that this Asian factory has a different idea about what constitutes support.
Fortunately I have an expert friend who will, I am confident, be able to work it out.
The replacement folding handle hand wheels arrived from Hong Kong today. I was slightly disappointed in the quality, but then, for $a20 each, including postage, I am not complaining. They are close in appearance to the originals.
I was on call over the weekend, so I had today off, and spent it in the workshop. It was cold. Jumper plus oilskin cold.
I crow-barred the space for the new mill, levelled the mill with a machinists level. One foot was missing so I turned up a new one… 75mm dia, 16mm thick, with a 20mm dia recess to accept the levelling bolt.
Then I started to tidy up the awful paint job, scraping paint off the machined parts, and using my Dremel to wire brush it off plastic parts. Starting to look more respectable.
Then I found a hand wheel control lever stop made from a rolled tube which had broken off at surface level. It was hardened, as I discovered when I tried to drill it out… changed the drill bit to mush. So I used the Dremel with a carbide bit to grind it out. That worked, but it took a lot of time, and I ended up with an irregular hole which I then drilled out to 5mm and tapped 6mm. I have inserted a temporary 6mm cap screw as the stop, and it works but looks a bit gross. Needs a tidy up.
The 3 phase lead does not reach my converter, so I have to replace it with a longer one. The plug is new, so I will re-use that. I have some 20 amp 4 wire lead, so I will use that. Maybe next weekend I will get to fire it up. Saturday is out though. Geelong – Hawthorn AFL game takes precendence.
I need to make some T nuts to suit the 18mm T slots. They are bigger than any machine I have previously owned. I will tap them to accept 12mm studs, rather than the recommended 16mm studs. I already have the 12mm studs, and I cannot see that I will need the bigger ones. If i was to use the table capacity of 900kg the big ones would be useful.
This contraption is a toolrest for a benchgrinder. it was an early project when I started metalworking-machining, and was made mainly on a milling machine, and lathe.
The tool to be sharpened on the grinder (lathe cutter, chisel, screwdriver, saw blade etc) rests on the top platform. The top platform can be adjusted to any angle in 3 dimensions, using the brass handles. The 2 brass knobs are to present the work to the grinding wheel, and are graduated in thousanths of an inch. Sounds complicated and it is.
Designed by Harold Hall, with plans and instructions in his book “Milling, A complete course”.
The wine glass is for scale only. Although the level went down during the photography session. Must have evaporated.
I have nickel plated several components of this tool ,because of surface rust.