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Member postings for duncan webster

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

Thread: Inverters? Talk to me.
09/03/2016 14:43:01

In answer to RussB, I wouldn't be without the variable speed. I just leave the belt on middle speed and ramp it up and down with the VFD. Mitsubishi inverters have an output which you can just feed into a moving coil meter which tells you the % of top speed, so a simple table converts that to spindle RPM. Be careful as the output is at a highish voltage. Better is a tachometer gismo from e_bay, very cheap.

I made my own tacho for the Centec as the pulley on the back is geared to the spindle so it had to have a factor in it to compensate

Edited By duncan webster on 09/03/2016 14:43:37

08/03/2016 23:24:45

I've now bought 3 from Newton Tesla. Very helpful chaps, helpline 7 days a week and in English!

Thread: Miss Britain III
08/03/2016 18:02:27
Posted by Neil Wyatt on 08/03/2016 17:22:56:
Posted by duncan webster on 08/03/2016 17:03:19:

Very nice. What you need now is a sound chip, amplifier and speaker, then you can make it sound like a Merlin.

Sacrilege! It's a Napier Lion!


So find a recording of one of those!

Edited By duncan webster on 08/03/2016 18:03:26

08/03/2016 17:03:19

Very nice. What you need now is a sound chip, amplifier and speaker, then you can make it sound like a Merlin.

Thread: Best place for offcuts
08/03/2016 17:00:23

If you're just starting out you would be best to get hold of steel of known properties. EN1a machines very well indeed, some of the stuff I've picked up over the years has been awful. Doesn't mean you can't use offcuts, just try to find out what it is.

Thread: Backlash - Steppers, Toothed Belts & Ballscrews
07/03/2016 16:38:47

Your last post beat my reply, 0.04" is a lot. If you can't adjust it out then it's new leadscrew and/or nut time. I've done away with the fast feed pinion on mine, if I were replacing the nut I'd just have it solid, permanently engaged.

07/03/2016 16:36:16

I'd be ecstatic if mine was that low. I don't have any problems, but get involved with climb milling apart from just running back at the same setting to improve the finish, I think that is best left to big industrial machines

Thread: Magnetic Bench
06/03/2016 22:09:12

None taken I didn't express it very well

06/03/2016 19:52:06
Posted by Les Jones 1 on 06/03/2016 18:28:31:

I think Duncan Webster's intention was that the high voltage secondary was removed and replaced with a few turns of very thick wire (Hence the reference to welding cable.) to make it into a low voltage very high current transformer.


Exactly what I meant to say, as described in recent MEW for making a spot welder, but it would still be a lot of effort.

06/03/2016 10:58:17

WW2 ships were demagnetised using a large elctromagneti coil surrounding the ship, see


It would be a lot of work, but if you want to go down that route you could start with the transformer out of a microwave, a length of welding cable and a variac to control the current. Noneed to move the bench through the coil, wrap it round, then ramp the current up and down. Having set this running hopefully someone with relevant experience will tell us where I've gone wrong.

Thread: Expensive CAD and CAM software treated like a physical asset?
06/03/2016 00:55:04

If you're after 2D CAD, don't part with hard earned money, there are several perfectly useable packages available fro free, I use Draftsight. If you're after 3D then Fusion360 is getting good reports

Thread: Myford 280 lathe
05/03/2016 21:02:10

Pity they didn't carry it on. You can see the Myford 254 hiding inside tho'

Thread: Motorcycle General Discussion
05/03/2016 01:19:18

I was suppoosed to start at BSA as a graduate apprentice in sept '71. About August I got made redundant! Shame really, but I went into gas turbines, gas centrifuges and nuclear power so a pretty interesting life all round. Now I play with silly little steam engines as SWMBO won't let me have a bike!

Thread: chocolate block jumpers
03/03/2016 21:12:12

The link from ClveL is for the type of terminal blocks you used to get in old telephones, not choc blocks.

Grizzly Bear's is for making terminal blocks into a sort of plug/socket. I want to join adjacent connectors in this type of block **LINK**

so that I can join lots of wires without pushing them in the same hole. I like the Wago suggestion, but they are not cheap, 40p each for the 5 way ones. Tempting tho' not having to fiddle around with screwdrivers on site when it's cold and raining. It's for the field wiring on our signalling system.

Thread: Tailstock height
03/03/2016 17:46:44

NigelB and AjohnW, you can do both these tests without a test bar using the Rollie's Dad method and a simple parallel bar with a centre each end. Of course if I were rebuilding machine tools for a living I'd get a proper test bar, makes it easier, but not for a one off.

Thread: chocolate block jumpers
03/03/2016 17:42:44

I'v sen some material cut out like a short legged blunt steel comb for connecting adjacent ferrules in chocolate blocks, proper name terminal strips. These would be very handy when I want to connect more than 2 wires together, but for the life of me I can't find a supplier. If I knew what they were officially called it would help. Anyone out there know?

Thread: Tailstock height
02/03/2016 18:33:11

Nothing wrong with Rollie's Dad's method, in fact I've advocated it here before now. However it won't do anything about tailstock alignment, for that you need a parallel bar with a centre in each end. The centre doesn't have to be in the middle of the bar (it's easier if it is), just adapt Rollie's dad's method as appropriate. The only time you'd vere need a test bar with MT on it is to check the centre in the spindle is concentric

Thread: Ceramics in the Workshop
02/03/2016 17:47:15

If you dig deeply enough into back issues of ME I'm sure there was an article about using PTFE insulators in small spark plugs. Wouldn't have been my first choice as I would have thought the face exposed to the combustion side would char and then conduct, but it must have worked for the author

02/03/2016 12:59:50


RS usec to sell it, quite expensive, and that's as much as I know!

Thread: Sterling Engined Submarine
01/03/2016 23:37:54

So it uses diesel as fuel and liquid oxygen as oxidant (because it's underwater and there is no avaiable air). They could have used a steam engine, much more fun! However unless they have some means of storing the CO2 on board it will leave a trail of bubbles, bit of a give away

For a description of British steam submarines see **LINK**

Why did anyone think this was a good idea?

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