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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: New Start on LBSC's 3.5" Petrolea
16/04/2021 20:22:01

A bit back there was a chap posting about modelling all lbsc designs in CAD. It might be worth contacting him to see if he has done petrolea, supplying him with a set of drawings might prompt him.

On the issue of suppliers correcting drawings, it's not that easy, and I doubt there is enough profit to make it worthwhile. It is however a shame that the website errata list has disappeared, perhaps SMEE or ME could set up a website like Wikipedia where builders could upload corrections direct.

Copyright of drawings would be interesting. There are several suppliers of lbsc drawings, did they all purchase rights from lbsc or whoever inherited his estate? I know of at least one instance where a supplier sells drawings without the permission of the originator.

Edited By duncan webster on 16/04/2021 20:22:43

Thread: 4662
15/04/2021 21:48:33

No response from MyTimeMedia, but me.secureorder replied reasonably quickly, they are sending me another copy

Here's hoping

Thread: Oddball inverter
15/04/2021 21:46:16

Found the reason for the lack of power, the primary drive belt was slipping. Should have checked that first, but it's not that easy to see the motor pulley, which is where it was slipping. What it needs is a flinger to keep the oil from the countershaft bearings away from the drive pulley. Another job on the to-do list.

Newton Tesla tried to help as usual, but he couldn't diagnose that one.

Thread: Myford 254 Plus toolpost type
14/04/2021 22:35:14

Dave, is your rear toolpost just GHT made a bit taller, or did you scale the whole thing up? It's on the to-do list, not hat I have any difficulty parting off, but it would speed things up when making multiple parts

Thread: 4662
14/04/2021 15:31:50

Me have anything to do with the Gas Works Railway! I think not

Thread: Myford 254 Plus toolpost type
14/04/2021 08:55:08

I use the Kit-QD as supplied by Greenwood tools. The only issue is the countersunk screws in shear, it would be a lot better with 2 dowels taking the load and the screws just holding it on. Not enough better to make me alter it in all these years!

Kit QD

Thread: 4662
13/04/2021 21:33:12

Should I have received my paper copy of 4662? I've emailed MyTimeMedia but had no response

Thread: Citric acid pickle
13/04/2021 18:28:09

Citric works a lot better if you warm it up. For small jobs I pour a bit into a glass jug, microwave it for a couple of minutes then put the job in, cover it with a towel to keep the heat in. I don't think microwaving with the job in the liquid is a good idea.

Thread: Oddball inverter
13/04/2021 18:21:34

Been busy doing grand dad impressions all day, but just had time to measure input current (single phase from the mains). No photo as that really was a lash up (take the fuse out of the plug and put attach the DVM to the clips, it's only dangerous if you touch it).

No load on lathe 0.3A

loaded enough to slow it down significantly 0.7A.

If it were delivering 0.54A to the motor I'd expect at least 0.93A, more to allow for vfd losses. I'll contact Newton Tesla ASAP but on hospital visit tomorrow (not me, SWMBO)

The print in the manual is too small to photograph, but the same inverter does both single phase and 3 phase input. Either connect 200V 3 phase to R, S, T, or 200-230V 1 phase to R & S, T left not connected. The motor is connected to U, V, W.

I've also checked the continuity of the motor coils, I get the same resistance (77 ohm) across any 2 out of 3 connections, which suggests no coils burned out.

Thread: Lathe DRO
13/04/2021 11:07:50

DRO is less use on a lathe than a milling machine, but I wouldn't be without it now I've had it. For a start it allows metric and imperial without a calculator, then when starting a job just take a skim off the bar, measure its diameter, set the X accordingly, touch the tool on the end, set Z to zero and you're done with measuring unless you're going for very good limits, even then you can get very close before stopping to measure. If you can understand the Chinglish you can tell it which tool is in use and it changes all the values to suit. As I said before I keep the topslide set over so it doesn't clash with the tailstock, so I apply Z with the saddle handwheel. On mine this works well. Perhaps someone needs to design a reduction unit for the WM250

You can just about do this with the manual dials, but you have to concentrate very hard!

12/04/2021 23:12:03

I use my topslide for screwcutting and turning short tapers, ie fairly infrequently. I have actually considered taking it off as unless it is set round a bit (which mine usually is) it is always in the way of the tailstock. More useful would be a saddle stop to limit the travel of the saddle towards the headstock, must get round to making one, but as I've managed without for 50 years it's not high on the list.

Thread: Winson Pug 0-4-0
12/04/2021 22:01:08

First thing I'd do is get a copy of Don Ashton's book on Stephenson's. I had one once but I lent it to someone and I've forgotten who. Start with Don Ashton Website

Then you need a good mirror on a stick so you can see what is going on with eth valve chest covers removed

The issue is complicated by the use of loco links, chap in our club worked out what angular relationship should be and pinned them together. This made setting them on the axle a lot easier

Thread: Cleaning a tacho glass
12/04/2021 21:38:58

I once tried to clean the insides of a speedo by pouring solvent in. Melted the little plastic gears, cost me a new speedo, and I wasn't flush in those days.

Thread: 24mm end mill for 16mm collet?
12/04/2021 21:36:35

If you only ever want to bore 24mm you can make up a boring bar to go in the 16mm collet and fiddle with the cutting bit till you get the right diameter. No more difficult than using a between centres boring bar on the lathe.

Thread: What Did You Do Today 2021
12/04/2021 18:14:19

Got my version Of Stuart Hall's grasshopper engine going, now to find a way of making realistic flagstones. Even SWMBO thinks it looks well


Thread: Oddball inverter
12/04/2021 18:07:49

The motor is by Exico exico an industrial type, so I'd expect the power quoted to be output. Part # is 1254689

Calling my set up a dynomometer is being kind, I call it a lash up, but it works, a bit of wood, the kitchen scales and a Chinese tacho with the magnet stuck to the chuck.


The photo of the motor plate is not readable, the details are


cosphi 0.74

A 0.31/0.54

I think this means input power is 400*0.31*sqrt(3)*0.74=158W

here's a couple of pictures of the VFD, the only adjustments are for acceleration and thermal cut out



I've got the manual, it says nothing useful. I'll try Newton Tesla tomorrow

11/04/2021 21:57:39

My little Cowells lathe is driven by an 80W 3phase motor. The VFD is Mitsubishi SC A2 400M, which is reckoned to drive up to 400W motors. I've checked that the motor is set up in Delta.

I've just measured the power at the lathe spindle, and I can't get more than 34W, see table below

Speed RPM Torque Nm Power W

1846 0 0

1670 0.148 26

1500 0.217 34

with the speed control set to about half way I get

Speed RPM Torque Nm Power W

880 0 0

793 0.091 7.5

668 0.183 13

I don't think you get to set parameters like current with these devices, anyone got ideas as to why it's not producing the expected power? I wouldn't have thought it was losing that much in the lathe bearings.

Oh and if you're wondering why I've got a three phase motor on a little machine like this, it came as part of a deal.

Thread: LED Tubes in the workshop
08/04/2021 19:40:16

I've gone for LED as fluorescents need changing, make sure you get the right colour temperature, the first (bulb) I got was a blue colour, so called daylight, no good at all.

Thread: How on earth do I build this boiler for my Fire King ?
08/04/2021 18:48:29

I'd make the shell from 4" 16g and the firebox from 3.5" 16g. Then you roll a ring from 3/16" square to make up the gap, a lot easier than making the conical firebox

Thread: Tich cylinders
05/04/2021 12:58:30

If you just change the throw without changing the lap you'll also change the cutoff. I've got Tich drawings scanned somewhere, they were a freeby pullout with ME at some time. If you pm me your email I'll see if I can find them

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