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Member postings for mgnbuk

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

Thread: Blot On The Landscape
24/04/2020 14:29:33

I wonder if HS2 will ever have any of the promised benefits.

Many people think that the supposed "benefits" have been overstated period. A vanity project that will not be of benefit to the majority & will probably have unintended consequences, like raised property prices in areas that become a "viable" commuting distance from London.

Nigel B.

Thread: Centre finding
24/04/2020 14:04:24

I was referring to tram on either axis, not just in one.

Spindle squareness (tram) & column squareness to the table are different checks - usual practice is to set the column square to the table in both planes (X-Z & Y-Z) using a precision square, then check the spindle alignment to the table with a trammel check. If the spindle alignment (tram) is out, then the adjustment would not be made altering the column to table squareness.

Nigel B.

24/04/2020 13:04:24

it is also possible that the machine tram is not as it should be

Column to table squareness could also be an issue - something that is rarely mentioned as a check. Frequently the obssesion with "tramming" to the exclusion of all else recommends shimming the column to correct a tram error, but doesn't recommend checking that the column is square to the table afterwards (or beforehand come to that).

Why does this matter ? If the edge finder is short & the head wound close to the part to set the datum, moving the head upwards to fit a longer drill with the column not square will move the spindle centreline away from the datum - holes will not be drilled in the expected place.

Nigel B.

Thread: Fantastic British engineering
23/04/2020 19:16:47

But the shaper I've seen most recently cuts vertically down towards a 4-axis (includes rotary) table

That format is usually called a "slotter" in the UK. Used to cut keyways & splines in bores among other uses - the Ordnance factory in Nottingham had a CNC converted one for cutting the slot for the breech block in the breech rings for tank and naval guns.

but there seems to be some flexibility of terms

Usually in the UK if the tool moves over a stationary part the machine is s shaper, if the part moves under a stationary tool the machine is a planer. Capable machines all and, while not the fastest, they can do some operations better than the more "modern" machines that have supplanted them.

Nigel B.

Thread: getting MT3 tools to release from the taper on mill spindle
23/04/2020 13:17:55

Try ejecting a taper with the quill unlocked

No problem on an FB2.

If however the design of the ejector is such that it exerts a force betwwen the spindle and the drawbar then yes the bearings are not affected.

Which was what I thought I had described ? Must try harder !

MT or R8 ? Can't say I have a preference. I use a an XYZ Bridgeport clone at work & it works fine. I use a 2MT FB2 clone at home & it works fine. I have a reasonable selection of 2MT tooling, so wouldn't look to change to R8 particularly if I wanted to change the machine as I would have the added expense of re-tooling.

MT spindles are possibly more compact than R8 for a small machine - the recent thread on spindle runout issues suggests that one style of machine in R8 flavour may have a weak spindle as it was originally designed as MT & the change to R8 has left insufficent material.

Nigel B.

Thread: Fantastic British engineering
23/04/2020 11:06:04

These chaps don't need shop-floor experience,

I would suggest that, in reality, they do.

If they had such experience, it would cut down on the number of "unmakable" part drawings that come in for quotation - great CAD work, but with features that cannot be machined & un-workable tolerances. Not to mention the parts that prove not to be assembleable if they do get made - another "old adage" that went back to drawing office days was "any fool can tighten a bolt with a pencil" - still holds true with CAD.

Nigel B.

23/04/2020 09:13:02

caused by lack of skilled workers and lack of investment in equipment, I suppose the 2 go together.

Many employers don't want to pay to train skilled people, they would rather employ a skilled person someone else has paid to train. Attempts to raise the training bar through a "Training levy" don't seem to be delivering the desired results - "Modern apprenticeships" are nothing like the type I did in the late '70s & my older collegues thought that was "dumbed down" compared to their 7 year training. My current Polish collegues have had a far more thorough training that most UK schemes can provide. We won't improve until we rethink general education to provide 16-18 year olds who are basically numerate & literate to a standard high enough to be able to be readily trained to suit the needs of industry & commerce.

Some of the garishly gold painted machines looked rather old even then - the general condition of the castings of the Ingersol horizontal milling machine milling the bed formation suggested to me that it was "War Finish" - the film was made early '60s by the look of the vehicles ?

The general process shown in the film was much like Boxford & Broadbent in the early '80s. No real change, no attempts to re-design to keep costs competitive. Neither make manual machines any more.

Nigel B.

Thread: getting MT3 tools to release from the taper on mill spindle
23/04/2020 07:47:55

Self ejecting draw bars must also exert a force on the bearing

No. The whole idea of an ejecting drawbar is that it puts not load on the spindle bearings.

On the Emco FB2 & clones. the drawbar has a collar - a cap is screwed on the the end of the spindle that retains the drawbar within the spindle, free to rotate but axially constrained . To release a tool, the spindle is held with a spanner on flats on the spindle nose & the drawbar unscrewed - when the collar on the drawbar touches the cap, further untightening generates an ejecting force within the spindle that does not affect the spindle bearings in any way. As the retaining cap has a finer pitch thread than the drawbar, the cap does not unscrew.

Hitting bearings (or shafts held in bearings) can never be considered a good idea.

Nigel B.

Thread: Hardened and chromed steel rod
20/04/2020 07:40:50

8mm chromed bearing rod is available in shorter lengths from UK sellers on Ebay

More expensive than buying what is probably the same stuff direct from China, but you get it more quickly.

Whether or not it is a suitable grade of steel is another question.

Nigel B.

Thread: Repairing a Mitutoyo DRO
19/04/2020 14:02:15

Got out into the garage this morning & to my suprise found the single axis readout and scale I mentioned. Even more suprising was that when the scale was connected & mains applied it still works - it has been sat up in the garage loft for at least 15 years !

I was also right about it being a "Magnascale", which means that it is a Sony device & not Mitutoyo, so no use for fault finding assistance in this case.

190420201229.jpg

Anybody have a requirement for an apparently functioning single axis readout with a 500 mm travel 0.005 mm resolution scale ? OTOH, maybe it could be used on the wheel downfeed axis of my surface grinder ....

Nigel B.

Thread: Airbrush
18/04/2020 17:46:04

My first Revell basic airbrush compressor suffered from pulsing & I made a receiver from a carbonated drinks bottle

180420201227.jpg

I used a smaller (bottle 1 litre, from the look of it), as all this type of bottle seem to be blown form the same basic injection moulded cartridge &. the smaller bottles have a thicker wall. IIRC the burst pressure of these bottles is well over normal working pressures for an airbrush (14 Bar rings a bell).

The fitting is an 1/8" BSP tee, with a male thread on the side & two females. A stainless steel penny washer is tapped 1/8" BSPT & screwed on to the male thread to provide a supporting & sealing face. The cap is drilled a close fit on the thread & a simple brass 1/8" BSPT nut holds the fitting to the cap. The whole lot was screwed on to the compressor outlet & the hose to the airbrush taken from the other side of the tee.

As a receiver it worked fine - no leaks - but the compressor didn't have the capacity to charge it. I ended up buying one of the small Chinese airbrush compressors with a built in receiver.

Nigel B.

Thread: Motorcycle General Discussion
18/04/2020 13:19:13

It would appear that Indian manufacturer TVS has bought Norton

£16 million cash deal that sees existing employees TUPED to the new company according to the report above, but the report doesn't say which assets are included. It has been reported elswhere that the 961 twin rights & tooling had been sold to a Chinese company just before Norton went under. Best guess would be the all new 650 twin that the failed Norton company had taken (unsecured) deposits on.

TVS are the third biggest Indian manufacturer & already manufacture BMW's small single cylinder bikes.

Nigel B.

Thread: Repairing a Mitutoyo DRO
18/04/2020 11:02:34

A period of swapping cables to find the cause resulted on the other axis not working.

The trouble with swapping cables around is that you risk doing further damage.

I worked alongside a technician from a major CNC manufacturer on one of my company's installations a few years ago. The intial diagnosis was a failed encoder on one axis - to confirm this, the technician swapped the encoder of the "failed" axis with one of the other axes to see if the fault swapped axes. The result was two failed encoders reported. So he swapped with another axis - result 3 failed encoders reported. At this point I suggested doing checks on the board that the initial failed encoder had been connected to - it was found that the 5V output was actually 12V & every encoder connected to the faulty board had blown due to the overvoltage output.

Nigel B.

Thread: Does CNC use a DRO
18/04/2020 10:53:29

High end professional CNC mills may well have independent measurement systems as an option and would therefore be closed loop.

Not just high end - pretty well all industrial machines have been closed loop for the last 40+ years.

I was initially employed as a Technician Apprentice in 1977 specifically to learn to maintain the first two NC/CNC machines recently purchased by the company - the lathe was CNC (GE 1050) & the vertical machining centre NC (Plessey NC1l00). Both were closed loop systems, with DC servo motors & resolver feedback.

Moving forward, from 1983 I spent 27 years retrofitting machines. The only open loop, stepper motor systems, I encountered (i.e. replaced) were Posidata & some Bridgeport Boss systems on small turret mills. Posidata controls were typically used by Matchmaker (Shizuoka carcasses). Acton (Anayak carcasses) & Beaver.

Everyything else was closed loop, with either motor mounted encoder or scales. Both types of feedback were described as "closed loop" by most control manufacturers - the exception being Fanuc who refered to motor mounted encoders as "semi-closed loop" and scales as "closed loop". Some Fanuc controls could operate with both motor mounted encoders and scales simultanously, which IIRC they called a "hybrid" system. Only read about that in the manuals, though - didn't get to fit such a system.

Closed loop stepper motors have an encoder that connects to the drive, but it is only the drive system that is "closed loop" - the controls still run on step/direction pulses with no positional feedback, relying on the drive system to ensure that the motor moves by the number of steps sent out & stopping if the drive error output activates if the drive cannot keep up. So not "closed loop" at all in the sense that an industrial control is.

Nigel B.

Thread: Motorcycle General Discussion
18/04/2020 10:33:30

You have to remember too that the RE is pitched largely at the US retro market

Nope. RE is geared primarily to the India market, where an affordable middleweight twin is a "performance" bike. In the home market the RE twins are about a third of the price of a comparable "import". RE export volumes are a very small percentage of their annual production (and American exports a very small prportion fo the export total) - the Indian market is normally so large it swallows all they can produce, though there is a bit of a slump at present.

Beggars belief that producing around 50,000 350 Bullets a month still resulted in several month long waiting lists - 20 years ago before the Eicher takeover RE didn't produced around half that number a year.

The RE seemed more of a round town bar hopper to me.

But you are used to a 350+Kg Harley for distance work ? Knackered hands/wrists/forearms limit what I can do now, but I have comfortably done 240 back roads miles in a day on the Interceptor & usually 180-200 a day when in the Alps/Dolomites. Can't say I'd enjoy 500 motorway miles in a day like I once did on holiday, but I didn't particlularly enjoy that on bigger, faired bikes either.

Nigel B.

Thread: Direct morse taper collets
17/04/2020 14:57:34

This is not an option as the Morse taper is a locking taper

Not correct - Morse taper finger collets are a viable option, see here for a range of sizes

In my experience, they work very well for holding milling cutters. Never had a tool pull out using one.

Nigel B

17/04/2020 13:37:38

I mainly use 2MT collets to hold milling cutters in an Emco FB2 clone milling machine, mainly to keep the cutters as close as possible to the spindle bearings. 6,8,10& 12 metric and 1/4, 5/16, 3/8 & 1/2 imperial hold most cutters. They can only be used with very-close-to-size shanks, as there is little finger movement. They hold well but, as the FB2 has a captive drawbar, I can pull them up tight & not have a problem releasing them. IIRC I bought mine from Arc Eurotrade at one of the Harrogate shows many years ago.

RDG Tools 3MT collets go to 20mm metric & 11/16" Imperial - see here

Nigel B

Thread: Leaving filament in printer or not
16/04/2020 20:44:52

Many thanks for the feedback all. I'll make a habit of leaving it empty & bagging the reel from now on & see how it goes.

Fresh filament supplies have now arrived, so play will resume over the weekend - not going to be going out again it seems.

Nigel B.

Thread: Repairing a Mitutoyo DRO
16/04/2020 20:41:25

Does anyone knew if these are indeed three lights and should they light up when the unit is taken out of the track with the power switched on?

Don't know the Mitutoyo scales, but Heidenhain had a couple of systems. The early ones used a 12V filament lamp run at 5V - these could be seen as a dim yellowish glow. Later this was changed to infra red Leds, which could not be seen.

There is a vague possibility that I still have a single axis Mitutoyo readout and scale somewhere in the garage. I rescued it from the skip at my last employment, though cannot recall what it came off & it is possible that I got rid of it. I'll try to have a look over the weekend. I have a similarly vague recollection that it might be a "Magnascale" or something similar rather than an optical scale, though.They are not that popular here - the one I rescued is the only one I have come across.

Nigel B

Thread: Motorcycle General Discussion
16/04/2020 19:54:38

All its doing is providing a little lube between roller and sprocket.

After a bad experience with aerosol chain lube, I went back to using gear oil to do this. The Scott oiler isn't my prefered system - too variable in delivery rate with temperature changes. Currently using a fully manual handlebar mounted "Nemo" system on the RE, which dispenses a fixed volume of oil per actuation. I have only used around 30cc of oil in 3000 miles - not that much, but it still gets onto the rim & around the number plate.

It was an early VFR800 demonstrator that persuaded Mrs B that she "needed" to upgrade her ZZR600 to something that handled & stopped better - but that the "something" was not a VFR800 ! Too top heavy & generated a prodigeous amount of heat in traffic. She bought a new VTR1000 instead. Having ridden one at the same time, I prefered my friends' VFR750 - the last of the twin sided swinging arm models - as the 750 was more compact.

Its a shame that virtually all modern parallel twins have gone for this 270 degree crank fashion, basically making the motor feel and sound like a 90 degree v twin...

No shame - just a better engineering compromise. Triumph originally chose 360 degree cranks to allow the use of a single carb - something not possible with 180 or 270 degree cranks, apparently, due to uneven intake pulses. Trouble with 360 & 180 degree cranks is that the psitons both stop at the same time at each end of the stoke - with a 270 degree crank one piston is moving at the time that the other stops & reverses direction, so less flywheel mass required. It is true that a balance shaft is required, but there is less destructive vibration with this layout. And having had both 90 degree vee twins & 270 degree parallel twins I can say that, while the 270 degree paralle twin sounds somewhat like a 90 degree vee, they "feel" different.

... except.... IMHO, the most authentic of all the current retros...

the Kawasaki W800.

Now there is an overweight, underpowered, over priced motorcycle ! Frumpy styling and dull colour schemes as well. Shame they ended up this way, was the original W650 was a lovely looking bike - a more "authetic" retro bike than the Thaiumph Bonveville of the same period. The RE is screw & locknut valve adjustment too, though not sure why that is a great selling point - shims tend to stay in tolerance longer in my experience.

The RE is over weight

Only in your eyes, I think. You still have not highlighted a comparable performance bike at a similar price point that is appreciably lighter. The "price point" bit is important, as "adding lightness" costs money - all the examples provided up to now are substatially more than the RE's sub £6K OTR price.

I really hope that RE refine the design, get a good few kilo's off it but leave the engines performance alone,

Not going to happen. The current arrangement didn't disuade the 1400 buyers in the UK last year (a time of supply shortages), or the people who made it the No.3 best selling over 500cc model in the UK for the first couple of months this year (behind two versions of the grossly overweight BMW R1200GS). Figures volunteered by the owner of a Triumph dealership I have known for 30+ years that he got from a dealer conference. Might not push your buttons, but RE seem to have got the price/performance/style balance right in many people's eyes.

Good luck if you choose the Austrian Grenade route.

Nigel B.

(sorry for late reply - back at work now !)

Edited By mgnbuk on 16/04/2020 19:55:14

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