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Member postings for John Haine

Here is a list of all the postings John Haine has made in our forums. Click on a thread name to jump to the thread.

Thread: Need to drill a hole digital caliper
07/06/2019 13:23:45

Look for cobalt drills. I bought this set from Toolstation and they are excellent - went straight through my Dickson toolholder block. Use moderate speed, quite a lot of pressure, lubricate.

Thread: Recommendation for a 3 phase electricity book?
07/06/2019 08:12:13

The Wikipedia article is quite a good introduction, and the MIT document Robert links to looks pretty complete. There are lots of similar compendia of lecture notes on the web, they seem to have replaced the engineering textbooks I used to have to buy during my degree. If you want definitive guidance on installation etc then look at the IET books.

Thread: Myford Super 7 Bed for Power Cross Feed
06/06/2019 12:46:53

Nothing as far as I know, they're identical.

Thread: Salvaging Useful Parts from Printers
06/06/2019 10:03:18

Forget the electronics for making a 3D printer. The only parts useful would be the rods I think, and modern printers don't really have those. They used to use stepper motors which could be useful, but now have DC motors and encoders, much less useful because you need quite tricky real-time software for accurate control. The life of an ink-jet printer is so short that they have to engineer out every cent of surplus cost.

Thread: Quicksilver
06/06/2019 09:58:24

Never mercury, they used originally tin but now lead - see the informative article on Wikipedia. The bath has to be at the glass temperature so it doesn't freeze, mercury would boil away!

Thread: 1.1kw motor iffy
05/06/2019 14:17:54

Highly unlikely to be the winding, but could be the cap. Has it always been this way? I find when I start my lathe at a high speed pulley setting it takes a few seconds to get up to speed as the oil warms up.

Thread: before superglue
05/06/2019 09:08:40

I use soft electronics solder a lot, especially in conjunction with a non-corrosive white paste flux. For example, fitting "brass "collets" into wheels on the clock I'm building. Make the two parts a good fit; apply a little fux into the joint and fit together; cut small piece of fine cored lead-free solder and wrap round the shoulder where the two parts mate; and apply gentle heat with a torch. Takes less than a minute to reach temperature, solder flashes into joint, job done.

Normal "Araldite" type epoxy also very useful. I have a storage heater in the workshop, when I've assembled the parts together with the glue I pop it on top of the hot heater and leave overnight.

Thread: Quicksilver
04/06/2019 15:35:20

At least 1 747 has been scrapped after mercury contamination.

04/06/2019 13:07:00

The head of science at my school in the 60s was a crusty old gent who had equipped the physics labs after the war with surplus meters etc - you haven't lived until you've used an altimeter to balance a Wheatstone Bridge! Amongst other things he bought a crate of bottles of mercury which lived in the cellar - I think they had got through a couple of bottles by 1968, where it went who knows!

Regarding mercury arc rectifiers, these don't emit x-rays. In the machines lab at uni there was a test setup with a 3-phase one in a big steel cabinet where you could look at the arc through a strobe disc, if you got the speed right you could see the arc stepping from electrode to electrode as the phases changed. The technician used to warn us against opening the door because of the UV, but the machines lecturer encouraged it, pointing out accurately that the glass stopped nearly all the UV. Great fun.

Thread: Antikythera mechanism
03/06/2019 22:00:23

There's a nice story in one of Richard Feynman's books about visiting the museum, probably in the 1950s and seeing the mechanism, and being gobsmacked by it. Apparently he asked one of the curators what it was, who replied, oh it's just a bit of ancient Greek clockwork.... That was before people like Wright and de Solla Price took X-ray tomography to it. Of course they didn't have machine tools then, though of course any Super-Adepts would have rusted away completely...

Thread: Electronic Indexers - How Is Cumulative Error Avoided?
03/06/2019 10:49:39

Apologies Joe, but your reply seemed to indicate that the tool acceleration had to match the spindle acceleration in the run-up.

Thread: Super 7 - Best way to use ER25 Collets
03/06/2019 10:47:18

Unless you already have ER25 collets, maybe you should consider getting a larger size? I use ER40 on my big-bore S7 as you can hold 26 mm stock in it, if your lathe is standard bore ER32 may give you a wider size range than ER25.

Thread: Electronic Indexers - How Is Cumulative Error Avoided?
03/06/2019 07:27:04

Mach 3 doesn't work quite like that, in that the spindle is running continuously throughout. You start with the tool at some known position say 1 mm clear of the end of the work, adjusted for the right doc for the first pass. Then it accelerates at a known rate to the threading speed to give the desired pitch, started by receiving an index pulse. Af the end of the thread, the spindle keeps running, the tool withdraws while still being fed at the thread rate over usually a quarter revolution, then the feed is s topped though the spindle continues. The tool then runs back to the start position, and waits for the next index pulse to start again. It depends on the initial acceleration being fast enough to get to the right speed before reaching the work and always following the same profile so the tool is always starting the cut at the same point. This means using an acceleration which is well within the maximum capability of the Z drive and allowing sufficient lead-in. It also needs enough inertia in the spindle drive and a constant speed motor, or a closed-loop speed control with tight regulation, so the spindle keeps going at a constant rate.

People are sniffy about Mach3 threading, and I've had a couple of disasters with it, but once you understand its peculiarities it works pretty well.

img_0129.jpg

Not a good photo, but the er16 chuck for my Acute grinder was threaded for its nut using Mach, without a hitch, on my cnc'd Super 7.

02/06/2019 18:47:58

Mach 3, when it gets an index pulse at a known position, just starts accelerating to a velocity that it calculates from the index pulse frequency (from which it has computed the spindle revs), will cut the required thread when it hits the material. When it has moved the Z axis the requisite distance it pulls the tool out, stops feeding, and returns to the known position. If the spindle slows down when cutting starts, it's too bad! LinuxCNC has the index sensor giving 1 pulse per rev and also an encoder with much higher resolution, and continuously matches cutting speed to spindle speed.

Thread: Super 7 - Best way to use ER25 Collets
02/06/2019 15:31:25

Much the best is the first - a chuck that screws on to the spindle nose. This will allow you to pass long material through the headstock, and will have less overhang than the second, which is really intended for milling machines.

The best chucks are two-part. You screw the first part on the spindle nose and turn the (initially oversize) register to a close fit in the actual chuck bit which bolts on. This makes everything concentric to the spindle.

The second type has quite a lot of overhang (less rigidity), limits the length of work you can hold, and if the chuck you buy isn't quite true you're stuck with it.  

Whichever, drawbars are easy, just use a bit of studding and turn a top-hat collar to centre it in the back of the spindle.

Edited By John Haine on 02/06/2019 15:33:51

Thread: Does Not Compute
02/06/2019 11:01:54
Posted by Plasma on 02/06/2019 09:02:33:

Have to be so careful these days. I unplugged my home phone and just use the line for internet saves on a lot of junk calls. But mobiles create their own problems, especially when the scammers can clone genuine numbers.

Reminds me of an old police adage the A B C of investigators;

Accept nothing, Believe no one, Check everything....Mick

This is not a mobile issue. It is very easy for an automated calling system to spoof the caller ID, whether calling a mobile or fixed number.

Thread: Just for the Record
31/05/2019 22:18:46

Aka the Toyo 210 lathe. Interesting write up on lathes.co.uk. I always wanted one, ended up with a Unimat 3.

Thread: Hello from Surrey & Help
31/05/2019 20:39:38

An advert in the Horological Journal will reach the target audience, at least in the BHI's membership, but doesn't support auctions. On the other hand, eBay is seen by millions and as people bid competitively you can get spectacular prices even though you also pay a selling fee. You might consider scanning ebay to get an idea of a fair price then advertising it in HJ.

Thread: Making a Silicone Soldering Brush
31/05/2019 09:59:54

Like this? Other designs available from various cookshops

Thread: Myford boring bar help
31/05/2019 09:35:14

One of the ME books describes a gadget with a micrometer screw and presumably some sort of vee block that bears against the bar, so the screw can adjust the cutter by small amounts. Obviously applied between cuts. Can't remember where I saw it, Quorn book maybe?

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