Member postings for Andrew Moyes 1

May I prevail upon any GWR experts out there please?

I have a treasured family photo showing my grandfather (a GWR driver) and his cousin (fireman) standing with their dock shunter at Birkenhead. The loco is an Armstrong 0-6-0 saddle tank number 1979 of the 1901 class built in 1890-91. Above the warehouses in the background are the funnels of steamships and masts of sailing ships. My father thought it would be Vittoria dock. The dock opened in 1909 and I guess the photo dates from around that time.

The sepia print is becoming faded so I am having it digitally restored and ‘colourised’ by a professional. My questions concern the colour of the loco. Would a dock shunter of that era been painted in GWR green? Was there only one shade of green prior to nationalisation? Any help or pointers will be much appreciated.

I have various items of memorabilia including a letter signed by CB Collet thanking my grandfather for his services when he retired in 1927. It's touching that the Chief Engineer should write to a driver.

…and there are power station steam turbines too. When I served my apprenticeship at Trafford Park, I used to make a point of walking to my place of work through the aisles where the turbines were manufactured. Those 1.5 million horsepower machines ran at high speed and high temperature on huge white metal bearings. Awesome and on a different planet of course to our humble applications. One day, I paused to ask a lathe operator turning a turbine shaft what would happen if he made a mistake. His reply stuck with me; “Yer put yer ‘at on and yer go ‘ome”.

Dave

You say '...it's safer to assume the designer knew what he was doing and stick within recommended limits'.

Myford were the designers and were very happy to have their lathes run at the same top speed as mine. Tri-Levas were especially used in industry, I wouldn't say they were lightly loaded and I haven't heard of failures.

Whose are these recommendations then? Have you any information, other than hearsay, that Myford were wrong?

Andrew

Stephen – I can say categorically, from first hand experience, that there is no problem with running the white metal bearings at double speed.

Soon after small inverters came on the market, I converted my ML7 using a 3/4HP 2850 rpm motor. I first ran it for over an hour at 1300rpm to check for signs of overheating and found the bearings only got slightly warm. I had rescraped the bearings to a better fit when I bought the lathe new in 1971. I sold the ML7 after some 40 years of use, the last 20 with the VFD, when I upgraded to a big bore machine. The bearings remained undisturbed from the original scraping with no measurable wear.

Fitting a VFD to an ML7 without fitting a 2-pole motor is a lost opportunity in my view. It certainly makes drilling holes under ½” diameter a much pleasanter experience, for example.

Myford believed the white metal bearings were good for the higher speed. Before the advent of VFDs, they advertised in their catalogues a dual speed 1425/2850rpm motor for use with the ML7, especially the Tri-Leva model, which all had white metal bearings. The speed change was achieved by switching from 4 to 2 poles. I’ve never heard of any problems on Tri-Levas.

Based on my own experience, I throw doubt on the scare stories and wonder where they originated. It wasn’t from Myford. They have spread like Chinese whispers even to the extent of now appearing on Tony Griffiths’ excellent website and therefore become ‘gospel’.

It may be that the change to bronze bearings has led to the belief that this was done because white metal bearings were inferior. That is not correct; there was a press release in Model Engineer magazine at the time explaining that it was because the white metal bearings had become prohibitively expensive to source. Myford said it was cheaper to supply a new hardened shaft with bronze shells than continue supplying white metal shells.

I’ve had my fair share of bad days in the workshop recently. In fact I told my wife last week I must be losing it.

Then yesterday was one of those perfect days. I was turning a 4MT taper adapter to mount a couple of small chucks for clockmaking in the Myford big bore lathe. Unable to use my normal trial and error method of testing it in the bore of the headstock spindle, I followed Joe Pieczynski’s method on YouTube for setting the compound to precise angles. Using a parallel in the chuck, a DTI to establish zero and the DRO to set the offset, I set it up as one would a sine bar. The EN1A took an excellent finish and when it was done, I took a deep breath, removed it from the chuck and tried it in the headstock spindle. It went in with a reassuring clunk and no shake. Out of curiosity, I put a light smear of engineer’s blue in the socket and tried the adapter. To my astonishment it was an absolutely perfect fit over the entire area of the taper. Something I have never achieved using the trial and error method. I’m converted Joe and think your videos are excellent.

I fitted Newton Tesla plug-and-play VFD packages to both my ML7 metalwork and ML8 woodwork lathes. That on the ML8 developed a fault after a couple of years; the speed potentiometer became noisy and the speed became uncontrollable. I took the sealed unit in person to the firm in Warrington and was told that the 10-year guarantee only applied to the inverter and not the peripheral switches and potentiometer. I was asked to pay £26 for the repair. So much for the 10-year guarantee, which I notice they still advertise without any qualification. I would normally replace a noisy potentiometer myself but as it was a sealed unit (pop rivetted), I didn’t want to invalidate the guarantee on the Mitsubishi inverter, so I paid up. Having paid over the odds for the complete package, I was not happy.

Hi Robert. The valve attached to the spring is a medium-hard rubber. The large diameter is 5.0mm if you want to scale one from the photo.

Andrew

My oil gun came from the Nottingham factory with lathe bought in the closing down sale in 2011. It looks identical to the one on the current Myford website. The assembly looks the same as Rod's but note the rubber seal in the nozzle.

Andrew

Yes, that's right. When you have aligned the centres, if you want, rather than advancing the cut freehand, you can use the crosslide feed. Align the centres, set the crosslide dial to zero and wind out the tool. Then you can start turning the ball and advance the tool using the crosslide until the dial goes back to zero. I found it’s important to lock the crosslide before each cut because you are pushing the tool into the workpiece and against the pivot pin. Otherwise the backlash in the crosslide feedscrew will catch you out.

Edited By Andrew Moyes 1 on 05/04/2020 14:09:04

Here are some photos of the centring pin.

Andrew

Edited By Andrew Moyes 1 on 05/04/2020 11:40:36

Edited By Andrew Moyes 1 on 05/04/2020 11:41:26

Edited By Andrew Moyes 1 on 05/04/2020 11:41:57

8mm nominal, 7.98mm to be exact.

Tewkesbury Saw Company can be recommended.

www.tewkesburysaw.co.uk/sharpening

Andrew

It certainly looks like an error in manufacture. That will be tricky to sort by redrilling. Perhaps an easier solution would be to make new fingers with offset ends. Or modify the existing ones by soldering flat pads onto the ends, marking where they touch the workpiece and angling the ends to suit.

Duncan, I'm sure you're right regarding siphoning effect when the oil flow is continuous, for example with a force feed system as in a car. But a drip feed won't provide enough oil to maintain a continuous flow. Once it stops, if my theory is correct, it won't restart when the engine is running.

David, I suppose the hydrodynamic theory could be checked on a model by experiment. Remove the connecting rod, wrap some kitchen paper towel around the big end and secure it with tape. Then run the crankshaft with a motor drive and turn on the drip feed lubricator. See if the oil gets through to the towel.

Was this method ever used in full size? On locos the lubricator was mounted on the big end. On many stationary engines, there was a ring beyond the end on the crankshaft and concentric with it, the inside of the ring being a channel. Oil was dripped into the channel and tubed from there to the big end. That clearly avoids the problem. I'm not sure what marine practice was on multi-cylinder engines which, unlike locos, couldn't be stopped to replenish big end lubricators.

Apologies if I didn't make myself clear. The oil is fed in at the main bearing but until it has travelled through to the centre of the shaft, against centrifugal force, it won't go any further. Or so it seems to me.

I am in the final stages of making a Stuart 5a and am making drip feed oilers for the main bearings to Myfordboy’s design. The big end is lubricated as per Stuart’s drawings by an oilway drilled at an angle through the web to the centre of one main bearing. I am wondering how the oil finds its way against centrifugal force to the centre of the shaft in the main bearing. Beyond that point centrifugal force will of course fling it out to the main bearing. I can see how it would work in a pressurised system such as a car engine with an oil pump but not with a gravity feed. It seems to be common practice in model engineering eg many ET Westury engines but not full size as far as I'm aware. Does it work in practice and if so, how?

Myford started listing the 5” SC chuck so big bore users could make full use of the 26mm hole and 4MT taper in the spindle. On a small bore lathe you will only be able to hold shortish stock before it bottoms out in the 2MT socket. So the benefit will be limited.

I rarely use the 5” chuck on my big bore lathe as I find the 4” more manageable but I guess it all depends on what you use it for. You could always use the 6” independent chuck or an ER40 collet chuck for larger stock. I believe ER32 collets are now available in the range 20-26mm too.

The Dickson style toolholders can be modified to take 12mm tools, see Steve Jordan’s video on YouTube "Easy method of modifying Myford Dixon quick change tool holders". The material is tough so doing several holders may be hard work.

Another alternative would be to remove the compound slide and substitute your own base with some gain in rigidity for heavy turning. Some have machined such a base using a 5” backplate casting (see post on this forum "Toolpost base for Myford cross slide". The compound slide is then reserved for turning tapers. You can machine the new base lower so the QCTP will accommodate 12mm tooling without further modification.

Edited By Andrew Moyes 1 on 13/08/2019 21:54:44

Edited By Andrew Moyes 1 on 13/08/2019 21:55:28

There is the adjustable backplate sold in kit form by Hemingway.

I too bought an American 'General' wiggler many years ago and encountered the stiffness described by you and George Thomas in his book. It was easily solved by mounting the body minus the nut in the three-jaw chuck then expanding the collet jaws by forcing them apart with a 60 degree centre in the tailstock. By going gently, I was able to achieve just the right amount of grip on the ball. Since then, I have had very satisfactory service from the wiggler.

More recently, I bought a cheap Chinese electronic centre finder, thinking it would be even easier to use and more accurate. I wasted my money. The ball was a couple of thou off centre from the body. I took it apart and re-machined the ball seating. Even then it wasn't satisfactory because any eccentricity in a three-jaw chuck is replicated at the ball giving an intermittent contact. The light starts to come on before true centre and gets brighter until you have gone a similar distance beyond true centre. It's impossible to determine the true centre. Whereas my old General wiggler centres itself regardless of any inaccuracy in the chuck. Has anyone invented a self-centring electronic centre finder?

I've checked mine and for all practical purposes it's a square corner. Put it this way, it's never been an issue with the radius on any workpiece. Perhaps the milling cutter had become worn when yours was made. There is a 1/16" X 1/16" undercut on the moving jaw that ensures the jaws close tightly. I think you would be justified in cleaning out the corner or undercutting but the problem will be avoiding spoiling the sliding surface. Perhaps go in at a slight angle with a dovetail cutter? It would raise the stress as has been pointed out but I'd have thought there is enough in hand in the design.