Member postings for John Haine

I'm impressed (not!) by the ones that wrap a coil of wire round a copper pipe and excite it with AC. Er, copper pipe = shorted turn = no field at all inside the pipe where the water is...

Making Woodward's Gearless Clock. Pin wheel is being machined from a disc from an old hard drive, lovely bit of 95mm dia x 1.75mm thick hard aluminium. Backplate will use a rectangle of a material called Valchromat, a high spec version of MDF using a different type of resin and much more of an ekgineering material. I was able to scrounge an 18" x 6 foot sheet of 8mm thick which had been gathering dust and sun bleaching in a stockist's showroom, which will keep me going for years.

Or grind a small flat on the cylindrical portion of the cutter shank, drill/ream a 1/2" hole in the end of an MT2 blank, and use a set screw to hold the cutter. The thread is not meant to hold the cutter concentric, it normally screws into the Autolock collet to pull it snug - the collet holds the cutter true.

Here is the circuit. W1 and W2 are the windings. One end of each is commoned, the capacitor is connected between the others, and the changeover switch applies live to one end or other of the cap. To ensure the motor runs in opposite directions both windings need to have the same sense, I.e. Common the wires of the same colour. You need a separate zero volts on off switch in circuit too.

Why would springs break down in petrol? Certainly no more likely than the ball!

Yup, just the job Les. I'll post the wiring diagram with a reversing switch.

It's obvious that there isn't an internal capacitor, the motor is almost certainly cap start and run, you can see the ends of both windings in the connection box. I have a rather similar parvalux motor with an external capacitor which is wired in series, there's a neat little wiring trick that gives you reverse switching with a one pole changeover switch. Once the capacitor is wired in it "tells" the motor which way to run through the relative phase relationship. It's got nothing to do with where the motor came to rest. As the OP says it was removed from a machine and the capacitor was probably left behind. Just buy yourself a capacitor, they are easily available, problem will be solved. If this had a start switch you would hear it engage as the motor slows to a stop after running.

Yup. Capacitor start and run motor. Once fitted motor will start and run only one way.

On our first camping trip in Scotland I was worried that our Gaz cylinder would run out. Since it had tare and full weights stamped on it I thought it would be a good idea to buy a little spring balance to check it. So we went into a big hardware store and they didn't have anything but suggested we tried the fishing tackle shop. There I found a neat little Spring balance that would weigh up to 28 lbs, just the job. Stamped on it there was a brand name..."Gazweigh"!

Later on I developed an ultrasonic handheld gadget for a client, which had a piezo transducer you pressed against the side of the bottle. Based on a standard industrial level gauge the idea was if you were below the gas liquid level the ultrasound would pass through the fluid and bounce back from the far side of the cylinder with a significant delay. It seemed to work but we found that with many gas bottles it gave false readings because the sound rattled around the metal of the bottle and gave similar delays even if you were above the gas level. I discussed this with a metallurgist who wasn't surprised, he said that the average gas bottle was a "metallurgical dog's dinner". Shame really, it would have been a nice product for people depending on bottled gas. At one point I visited a gas stockist to try it out on a range of "empty" bottles, he told me he was able to keep his house warm and cook with what was left in the empties!

Actually in a couple of industrial research establishments I have known the place where apparatus was made, equipped with lathes, mills etc, was known as the "model shop".

I would also suggest 4 slots. 3 jaw chucks usually have 3 studs but don't bolt through because the scroll is in the way - so you couldn't mount one to a 3 slot table anyway! And 3 jaw chucks don't usually centre all that accurately, whereas by the time you are putting a job on the RT you're probably quite concerned about concentricity so best to use a 4 jaw anyway. 4J chucks have 4 bolt holes - so need 4 slots! QED.

You can get threaded nose adapters that bolt on an RT to enable them to take a 3 jaw chuck, or MT2 adapters with a Myford nose thread.

An RT that has the ability to disengage the worm drive is then useful so you can rotate the table freely for centering - or if you have a stepper controller like the Ward design you can just use the continuous rotate function.

IMHO 4 jaw chucks are undervalued on the mill - often they are a really good way to clamp small parts as they constrain the part around two orthogonal axes.

"It's very expensive". Hmm. Well I already had a normal lathe, converting that cost me probably less than £150 and half of that was a second hand PC for the workshop. Based on my experience with the Novamill converting a mill can be done for not a lot more than £150 (there's an extra axis) if you already have a computer (less if you don't mind sharing the drivers between lathe and mill). The electronics isn't rocket science, and you can buy pre-built boxes if you want to. As for software, yes I bought a Mach3 licence which costs a bit, but you can get LinuxCNC for free (but it's tricky to set up). I'm still trying to get to grips with CAD/CAM, but manage pretty well with g-simple CAM (free), the wizards in Mach3 and my own spreadsheet methods.

But I guess that when flint-knappers saw people smelting copper and tin and making fine, sharp bronze axes, they said that you could never make a proper bronze one unless you'd served an apprenticeship chipping flints.... I read Geoffrey de Havilland's autobiography a long time back, and he had a stroy about an apprenticeship exercise (at Cranwell?) for aircraft fitters where they were given a couple of lumps of steel, files, hacksaw and cold-chisel, and had to make a mating nut and bolt! (No, I don't know how they'd do it either!) Why deny ourselves the use of the best tools around just because we are amateurs?

Twas ever thus. Ours is a broad church, and we need to recognise we all have different interests and methods. I've spent most of my life doing professional engineering which by its nature mainly uses paper, pen and computer, with no requirement since my days on the electronics bench for hand work. At this stage it's too late for me to build up the manual skills, but it's huge fun learning about computer controlled tools and how to apply them. But equally it is great to see the wonderful things that people produce from more "traditional" tools.

I'm a bit trepidatious weighing in to this thread, but here goes anyway! As I work in front of a computer all day long I never thought that I'd get interested in CNC, but 20 years or so ago I started to put a workshop together and got involved in "model engineering" (though I've never built a model and don't suppose I will). Initially I was getting fed up with changing change wheels on the lathe and never having a fine enough feed so started to investigate "digital screwcutting". The lightbulb moment was when Tony Jeffree published his ML7 CNC conversion and I realised that it would be just as easy to add a second stepper to the lathe and just use a general purpose driver like Mach3 rather than a single-use package. Since then I've added a CNC mill (not converted by big VMB yet) and digital dividing.

I really don't recognise what some people are saying about CNC in this thread. In my experience....

It isn't about "programming". I seldom or never directly write G-code. I use the wizards in Mach3 Turn a lot, but I must say that you need to keep a careful idea on their output otherwise the tool can do some unnerving and dramatic moves you don't expect! If I have to turn to a shoulder, that takes about 2 minutes setting up the wizard which generates the code and the machine runs. But setting the tool accurately, selecting the right feed rate and DOC, are key to getting the result you want, and you need to use the wizards as just a starting point if you really want accuracy. This takes skill and experience - just as much IMHO as manual turning, and at least you don't have to stand in front of the lathe inhaling coolant fumes while you twiddle handwheels. As for threading, there is no comparison - just look at the endless debate on change wheels on this forum, and "can you cut metric threads on an imperial lathe?". With CNC, it's a doddle, any (sensible) pitch, at normal turning speed, up to a shoulder, the machine does the pickup.

"CNC is only for quantity production" - rubbish. I have just started making Woodward's Gearless Clock, with the count wheel (which looked to me the hardest bit). I could have crossed it out with a piercing saw and filed to the line once I'd cut the teeth. But I would probably have made a mistake and might have had to start again. But I spent an enjoyably challenging hour or so writing a spreadsheet to work out the dimensions for any 4-spoked wheel cross-outs and directly generate the Gcode. I made a simple jig to hold the wheel, held it down with a bolt and some shellac, and did the crossing out on my little CNC mill. A job I found full of interest, and much more appealing than hunched over a cutting-V breaking saw blades and getting brass dust in my socks. There will be another interesting challenge in producing the 'scape wheel, and I'm especially looking forward to the design of the daisy wheel! When I've finished I'll have some jigs and programs to make more clocks if I want...

A while back I looked at producing gear cutters using the "button" method, and posted on here describing how I did it (the practical bit at least). Again that involved writing a spreadsheet that started with Mike Cox's formulae and generated the Gcode to drive the tool to turn the profile on the cutter. With this I don't have to make different buttons for each module, I can make cutters for modules and pressure angles that are impractical by the conventional method, and this would have not been possible without CNC! Similarly I've generated code for tapers that can't be made with the Mach 3 wizards. I have a plan for a pendulum compensation scheme that needs a carefully shaped cam - not possible manually, trivial with CNC.

How many plans have been published for ball turning tools? A hardy perennial. Redundant with CNC. You want to turn an ellipsoid? a hyperboloid? Easy.

Having a CNC mill, I was easily able to knock out an engraved plaque for a Jubilee Oak Tree in our village. And to produce a small memorial plaque for my woodworker father-in-law's ashes engaved on a sliver of oak from the Victory (don't ask how he got it).

I have a foot or so of (I think) WG16 (or maybe WG14?) left over from my PhD, I'll go and measure it, you would be welcome to a couple of bits if they would suitable. Waveguide of this size is nowadays totally redundant for its original purpose.

Would that be rectangular?

Or get one of these digital angle gauges - picture from my Acute construction thread.

Yes, the burring is a problem with the steel plate used, whatever the machining method. Like you I parted my discs off a bit of bar, but turned the grooves - can't remember what tool I used though!

As Gordon suggests, if the shape permits the work to be held in the 4J, or on faceplate, on a Super 7 it would be much easier to face the surface flat.

Using an eccentrically mounted end mill as a fly cutter sounds a bit dodgy to me, unless you grind off all but one of the teeth, which is a waste of a good end mill (unless it's EOL anyway).

Phil, I'm curious to know how the vertical bush which is bored out (presumably) for the tool post stud, is attached to the spindle housing - is it welded please?

There was an article in MEW some time back by Dick Stephen on making a new high speed head for an X3 mill based around IIRC an ER25 collet chuck of this pattern. Neil can probably advise which issue?