Aside from gear cutting, I also need to be able to cut splines, key ways and serrations. I recently got asked to make some tooling to restrike the serrations on a special application adjusting screw. It just wasn’t going to work, but I did mention in passing that I was pretty confident I could make them on my small cnc lathe. So, the challenge began. M5x0,5mm pitch screws with 36 serrations under the head with a 120 degree tooth form…
Whilst my small cnc lathe does use a servo motor as the main spindle drive,the software is such that it won’t allow you to use it for incremental positioning….or so they thought 🤣🤣. Primarily you can only use it to position the spindle that one jaw faces down when you open the chuck. You need this feature if you are using a bar puller or feeder. Basically the reason why it won’t work in incremental,is that it needs a rotary feed rate in Radians per second whilst machining is either done in Meters per minute or millimetres per revolution. You cannot run the two different types of feed in the same program. So, after much head scratching I beat their Protocol…🤣🤣🤣. Simple when you think about it,run one main program that calls a sub program. Job done on the program side
Needed to grind some special geometry tools. This also highlighted the fact that a wire edm machine would make my life so much easier
Tools ground,and off we went Anybody tells you you can only make round things rounder and smaller on a lathe has no sense of adventure 🤣 Customer over the moon and it should become a regular job.
In the meantime I need to get a wire edm machine……
Awhile back I heard of an old wire edm machine up in a Watchmakers workshop up the top end of London. Sticking to my usual plan of only buying scrap,non working machines, a deal was struck. With the help of v8ian we organised to get it out. Last time I buy anything from London. What with LEZ charges and the like, the transport cost me over £1000 to get it out. 🤬😳😳 Given that kind of money,seeing I was paying dearly for the use of the road,I made sure we went during rush hour and disrupted the traffic as much as possible to get my money’s worth 🤣🤣 Back at my workshop in three pieces Another quality Japanese machine,but with some quirks. Not going to be a quick thing to get it up and running as it requires it’s own dust free room to be built. But in the meantime,let’s see why it died…..
This is a wire edm machine. The one I scrapped was a spark eroder/ die sinker. This uses a roll of thin wire to cut the programmed shape, where as the spark eroder uses an electrode machined to size and shape
I've heard of spark erosion before but never looked into it so that video was a real eye opener. I'm sure JB could do most of that with a lump hammer and a bastard file though.
So a quick look at the wire edm machine. The previous owner had yielded to the agents telling him it was uneconomical to repair and had spent £18k on a slightly newer machine.( and when I say slightly, we are talking a couple of years). I was curious to see what ,” uneconomical to repair” actually consists of.Opened the main electrical cabinet Hmm, very obvious signs of somebody being here before. Here being the back of the computer that runs it . A NEC PC 98 personal computer. Japans top selling PC for many years. Had some serious quirks to it. Off to do research….
Post by toomanyprojects on Nov 13, 2021 23:45:04 GMT
Wow, that brings back some memories/nightmares, rebuilt a couple of very similar machines Way back when they were quite the competition for the 16mhz equivalent from IBM's efforts. quite the contrast to what you'll find in your mobile phone now let alone your home PC
They were in a different league to IBM. Streets ahead on graphics and sound and just incredible to see what the Japanese could make fit in a small box. It took IBM a further ten years to be able to come up with a computer that displayed Kanji. All in all ,that series of computers production run ended after 18 million of them were made. Apart from being used in industrial Japanese machines, they were never sold outside of Japan. Interesting set up that it runs a proprietary Japanese kind of DOS. Runs two floppy drives ,it boots from one and gets data from the other. The drives use normal size discs but they run at a different speed to the western type floppy drives.
With the whole boom in Retro gaming, a lot of upgrades have been done. They are highly sort after in the gaming world, something I knew when I bought the machine. The PC would fetch more than what I paid for the whole machine. You won’t find a genuine power supply for one under £400, as I was soon about to find out…
The bandsaw… Whilst it was capable of chomping its way through whatever you put in its hydraulic vice,it didn’t quite seem right. It’s an old West German machine from the nineties,streets ahead of the Chinese or Italian rubbish I had to endure the last couple of years, but I felt it wasn’t as good as it should be… It soldiered on, and I began to wonder if my expectations were too high. I couldn’t really fault it, but a niggling feeling wouldn’t go away…..🤔
It then developed a bit of a quirk. It wouldn’t consistently switch off at the end of a cut. Everything was clean,so it wasn’t swarf build up. I adjusted the limit switch. Couple of days later,same story….I adjusted it again. This happened on a more and more regular basis. Something was amiss…
Then one day it really sounded like a bag of nails. So, time to sort this out….I It has this type of top guide. It should be in one piece The pocket facing the camera should contain a carbide wear strip… Some muppet had put the guides in upside down, carbide at the top and the top of the blade running on the mild steel holder 🙄🙄. Unbelievable.. So the top of the blade had worn all the way through the guide until it hit the carbide on the other side. This explained the ever changing switch off point as the blade wore through the guide. The noise at the end was the now unsupported bit of carbide vandalising itself to death.
Pantomime season with the agents lasted three weeks until it came clear that all was not well. The agents were adamant there were guide roller bearings, I was adamant there were only carbide guides. Turns out we were both right. It left the factory with guide rollers The guide rollers and brackets are missing. Remarkable that it still cut straight with just the carbide cheek blocks 🤣🤣
After all we're just cogs in the wheels of life.
