Member postings for John Haine

Q1 basically no, as long as the diode breakdown voltage is as Frank says, bigger is fine.

Q2 - that method is not recommended! If the low voltage winding you connected to was 4v say there would be 230 v on one of the other windings. Also it may not even be a mains transformer, could be an audio one. Frankly I suggest that you buy the transformer you need so you have a known quantity. You could post some photos of what you have?

When it comes to the drawbar, the easiest thing to do is buy a length of studding the right thread for your collets and saw off a suitable length. Use either a big washer or if you want to be fancy make a bush to locate the other end of the studding for the nut to tighten against. You do NOT want a very high tightening force on a morse taper, it just gets stuck! No need for high tensile steel drawbars or anything like that.

Of course another approach is a sledge hammer...

Try looking at "all history" in your browser? Or do a site search on "cross drilling"?

Edited By JasonB on 23/12/2014 07:22:32

Actually you can use an induction motor as a generator, as described here: http://www.redrok.com/cimtext.pdf for example.

As there are millions of surplus induction motors all around the world they are of interest to build simple renewable energy generators. But for your application either a dc motor or a car alternator would be a better bet.

Neil,

"Compatible materials: ABS,PLA, Nylon, rubber, woodfill(?), timberfill, ceramics, CAKE, CHOCOLATE, metal engraving.

Apparently it also does object scanning."

Wonderful! So can it scan a chocolate cake then print one out? That's my sort of printer!

Once you get it out, don't over-tighten the drawbar when you next fit a milling chuck or collet. I guess there should be a recommended torque somewhere to avoid overtightening? The problem with the "milling a bit of aluminium" approach is that it may also pull the chuck off its mounting taper! This could be a bit nerve-wracking.... But still you are no worse off once you have stopped shaking!

I saw an MT drawbar design in ME once made of high-tensile steel - exactly what you don't want! I have also seen it recommended to smear a little light oil on the taper to facilitate ejection.

I'm not sure about the warming argument, presumably the socket and taper would expand at the same rate so if at the same temperature there will be no difference?

I just got 2 3-inch lengths of 2 inch f/c steel from College Engineering Supplies. Their minimum order quantity is 6 inches. Arrived very quickly, 2 days after ordering.

Why does it need to be hardened? If the thread is for fixing, few such threads are hardened. If for adjusting, then hardening will distort it so may lose accuracy (depending on how important that is. CES also stock EN8 and EN24 which are tougher, harder to machine, but could be quite adequate for the job without hardening.

As for fixing, the trouble with shrinking on is getting the dimension just right, and working fast (if you don't heat to high temperature). You start to fit the heated bit which is smaller and has lower thermal capacity, it cools a bit, sticks, and cools down more, before you know it it is stuck fast in the wrong place. You can't shift it because it is very hard to differentially heat the sleeve and shaft. The only times I have used shrink fit, I cooled the inside in the freezer (because it was small enough to go in) and heated the outer with a blowlamp until it was well over 200 C judging by the fact it was just starting to colour - went together OK but cooled and locked very fast, I wouldn't like to try this with a long workpiece unless I could get it nearly red hot.

Much safer to use Loctite! Dimensions not so critical, and you get some time to position the sleeve just right.

My understanding is that as standard metric lathes read in "diameter" mode and imperial in "radius". Myford imperial lathes are I understand "radius" but my metric Super 7 is "diameter", but the lead screw is 1/8 inch pitch!

This article appears to have been scanned from Guy Lautard's Machinist's Bedside Reader, judging by the page numbers, at least that's where I first saw it. It's slightly odd that the last page is a bit different, in this scan there's an extra bit about aluminium welding that's not in my copy. Guy's books are excellent, highly recommended, I guess he might be a bit cross about this copyright breach.

Regarding the hole in the spindle, it's not hardened to you can easily drill it out to 10mm and use a larger drawbar.

You can buy MT2 drawbar collets from several suppliers such as Arc and Chronos. A bit of studding makes a perfect drawbar. Using these collets means you get more working height and rigidity than using a collet chuck. Maximum size though is 1/2 inch, 12 or 13 mm. Both metric and imperial sizes are available. You only need a few sizes to suit standard cutter shanks.

Myford collets are nice if you can get them, I have a set of both metric and imperial, but these days they are like hen's teeth.

If it's a desktop with a separate power supply then new psus are fairly cheap and you wouldn't need to replace the motherboard. That's hoping that the board you have wasn't damaged.

Processors can run two programmes "at the same time", but I suggest you don't worry about the complexities of multi threading and interrupts just now! If you really want to check the right number of pulses are being generated it would be easier to either generate them very slowly, make them drive an LED, and just count; or use a second Arduino as a counter.

i suggest you get a modern bipolar stepper motor and driver, you can be sure that one pulse in will move it one step.

Nice engine! Took me back to those heady days of starting my PAW19, putting my hand round to lean out the mixture or adjust the compression and taking some skin off in the prop! Somehow the mixture of ether, paraffin and oil seemed to aCt as a good antiseptic....

> A good second hand machine is better than a bad new one and a good new machine is better than a worn out old one.

as you say Neil, very wise. As wise as "90% of what you spend on advertising is wasted! only 10% is worth it - but you never know which is which."

My point about float glass is YOU CAN CHECK IT! My lump is 9 x 12, a nice size to go on the mill table, when you rotate it around the axis of the spindle keeping the tram indicator still, you can hardly see the needle flicker. The thickness tolerance may be .13 mm but that will be all over thanks to Dr Einstein and the thickness doesn't affect the flatness. It may not be completely accurate, but I can determine its accuracy, and it was a sight better than Mr Myford managed when he set up my mill in his factory

Just a few random thoughts...

I don't agree with the lathe plus vertical slide approach. Nowadays and with your budget you could buy both a lathe and a reasonable small mill. There has been quite a lot of discussion on this forum about the relative merits of machines from for example Warco, that should give a reasonable view of the ones people find work well. A vertical slide is fiddly to set up, too small for probably the first real job you want to do, not very rigid, and lathe chucks aren't designed to take milling cutters so the cutter will probably move on you and ruin the work.

Buy a mill which takes R8 collets. These are quite cheap, grip like b*******ry, and since they fit right into the spindle give you effectively an extra inch or two of working height. I would avoid ER collets on the mill as you have to buy the ER chuck as well as the collets, it probably costs more than R8, and robs working height and rigidity.

A decent digital vernier is very useful even if not up to micrometer accuracy. I have one branded Trojan from an ME exhibition, actually made by Mitutoyo, it works very well and always agrees with my Mitutoyo analogue 25 mm micrometer. I also have a few of the Aldi ones, they are useful but I wouldn't rely on them. I bought an expensive Mitutoyo digital micrometer a few years back, I never use it, it is a relative reading one rather than absolute, the zero drifts, so every time you want to make an accurate measurement you have to wind it all the way closed, zero it, then wind it all the way back to measure. So I got a Mitutoyo analogue one off eBay. Over the years I've also acquired, surplus and from a sale, a M&W 50 mm mike and a "Linear" 75 mm one. The 50 mm gets some use, but most of the time for over 25 mm I use the vernier.

A piece of 6 mm float glass on a cork tile on a pice of plywood with a nice surround make a surface plate. 9 by 12 inch is a good size. Thicker float glass is better but hard to get and expensive. A height gauge is useful, mine is "analogue" but with a dial and counter readout. That was surplus from an ME show too and works very well.

A selection of engineer's squares of different sizes is nice, but if you buy only one it needs to be about 4" on its blade.

Then of course a clamping kit for the mill, but you could make that provided you buy a milling vice and the wherewithal to bolt it down. Lots of the time though if you get a clamping kit and an angle plate or two you don't need a vice very often in my experience. Look at Harold Hall's books and website. Actually some of the most useful tools I have are the ground all over angle plate and a selection of toolmaker's clamps that I have acquired over the years from a trader in our local Saturday market. With those and some parallels also from the same source I can clamp most things for milling.

The lathe will come with a 3 jaw chuck probably, but you will soon decide you need a 4 jaw as well, also a dial indicator for centering things. The old books will say you need a faceplate, I've got one with my Myford Super 7, used it once in about 10 years.

Your mileage may vary, and I'm sure everyone will violently disagree with everything I've said! Welcome to the world of tool collecting.

Jason, why go the trouble when float glass is is so chap, flat, and self checking?

Getting dust off magnet - try duct tape.