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Member postings for Martin 100

Here is a list of all the postings Martin 100 has made in our forums. Click on a thread name to jump to the thread.

Thread: Lathe tachometer
10/01/2018 11:45:10
Posted by Neil Wyatt on 10/01/2018 09:27:19:
Posted by Martin 100 on 09/01/2018 22:39:26:

The mill is much more sensitive to rotational speeds and while you can wing it, without a tacho you are just guessing. I'd class it as essential.

Just to be mischievous... how do you know the right speed before you select it?

Using a very big book from Sandvik with lots of formulae in it , spinning the spindle up and tweaking the pot to somewhere towards the bottom of the recommended range.

I can get the CNC mill working fine with quite acceptable rates of metal removal, surface finish, dimensional accuracy and cutter life. But then it's not me it's the machine.

A lot of my difficulty manual milling stems I think from my height and the lack of it on the X3 with the factory supplied stand, giving a very restricted view of the cutting action compared to turning on a lathe (my brace of Boxfords despite being early 1950's and early 1960's have the chunky 80's era yellow chuck guard affording very good visibility) I can, from sight of the swarf and feel through the handwheels know if the feed and speed is right or not on the lathe I very rarely get that when milling. At least with the tacho on X3 I know I'm somewhere in the right area and can eliminate one variable.

Guess it comes down to experience, I've maybe a couple of magnitudes more turning than milling experience. Decades ago as a engineering trainee I was twirling handles on huge very tired mills with worn leadscrews, sloppy gibs and less than perfect HSS tooling, and despite cutting speed calculations ahead of time the results didn't always match the expectations. Since then I spent many hours being frustrated using a Boxford vertical slide and setups that were not even remotely rigid. The visibility of the cutting action is about as bad as you could ever get. The X3 was a huge improvement, but I'd prefer something at least half as big again with significantly more rigidity. A hefty multiple horsepower motor with a VFD would be useful too. I might have even bought something 'big' from Warco last year if they'd have done the Doncaster show.

09/01/2018 22:39:26

The problem with a lot of modern kit is they have a speed adjusting knob that goes from say zero to max rpm with no real attempt made at the factory for calibration and a distinct lack of marking of intermediate values.

Couple of cases in my own workship with a Boxford lathe, with a 4 pole direct from mains motor running at 1400 ish rpm, the plate showing the pulley and backgear arrrangements closely follows the reality at the spindle.

For the Sieg X3 it's a knob a long reach away, only visible if you stand to the right side and towards the rear of the machine that does nothing for the first 20% of its travel and just a low and a high gear selection on the head. One gear apparently gives a top speed of 1000rpm the other 2000rpm, but confusingly with a minimum on both ranges is '100rpm' Work out the logic of that, a gear train that does nothing at one speed input but can also provide a 50% reduction at the top end.

Much of the work on the Boxford other than heavy drilling is performed either at the top 1300rpm or the slow backgeared equivalent that escapes me right now. Insert tooling lets you get away with that

The mill is much more sensitive to rotational speeds and while you can wing it, without a tacho you are just guessing. I'd class it as essential.

Thread: Sieg SX3 quill fine feed
04/01/2018 08:40:47

Many thanks all.

03/01/2018 14:39:51

I've had an X3 mill for quite a few years now but in an idle moment wondered how the fine feed on the SX3 is coupled /decoupled from the quill handle such that the worm is not jammed solid when the quill handle is used.

Can't see anything obvious on the exploded view nor the dismantling guide on the arceuro website

Sieg SX3 Exploded Parts Diagram

Sieg SX3 Dismantling Guide

Thread: How on earth do they calculate electricity and gas bills...
23/12/2017 15:57:36
Posted by Samsaranda on 23/12/2017 14:15:40:

As you explained balancing supply to demand happens very crudely at the moment with whole areas disconnected when the need arises,

Supply exactly matches demand + system losses. Any deviation and the frequency rises or falls, fall towards the proscribed limits and there will be an increase in generation (almost all generation is operated with some headroom) fall further and additional fast acting generation (hydro/open cycle gas turbines/interconnectors) will increase output, fall further and there will be a reduction of voltage (UK end user supply is technically 230v +10% -6% with a nominal 240v) the wide area voltage reductions being in one or two stages, then at a point at which generator/grid stability approaches there will be load shedding, in the first instance to large industrial customers with a prearranged disconnection agreement, then in an extreme situations wider areas.

Whole area disconnections happen so rarely it involves thousands of man hours on investigations

BBC - Power returns following blackouts

OFGEM - System Events of 27th May 2008

There is a formal report on this incident, I'm not sure if it was ever placed in the public domain.

23/12/2017 12:51:09

Negative pricing has already happened here several times, all it needs is a sunny day with a few gusts of wind.

It's quite common in Germany too

https://www.ft.com/content/5164675e-1e7e-11e6-b286-cddde55ca122

https://www.independent.co.uk/environment/germany-grids-paying-electricity-customers-renewable-energy-power-surplus-wind-solar-generation-a8022576.html

Hinkley Point C is priced at £92.50/MWh for delivery in 2025 (2012 cost basis) (currently £97.14)

Current year delivery offshore wind like Dudgeon Phase 3 is as high as £161.71/MWh

Future nuclear (Wylfa/Oldbury/Moorside) will be much nearer £60/MWh which is significantly closer to what is being delivered with new builds worldwide (EdF excepted)

There are also lots of ways HPC would have been delivered at significantly lower cost.

See Page 68 of the National Audit Office Report

Other than hydro for which the UK has very limited potential there is no other way to secure low carbon dispatchable generation.

23/12/2017 11:34:35

Why people put up with fixed and escalating direct debits that exist only to improve the cash flow of energy companies escapes me.

Each month we get an email requesting we submit a meter reading, it takes five minutes max to read and input the readings, then a few days later a pdf arrives with the bill, the money is taken two weeks later. Even better the supplier is one of the cheapest suppliers in the market (within 3% of the cheapest, with lower risk of collapse than the very cheapest)

As for remote switching to manage demand, there is far more scope for this in a commercial and industrial environment, a process that has been happening for half a century for major consumers like steelworks, and has existed for all those in the >100KVA market for 25 years. Delaying operation aircon or heating in a commercial environment to save thousands or tens of thousands in peak demand charges for a handful of days a year makes sense for an office block or a department store.

Disconnects of selected appliances 'over the internet' or with 'smart meter switching' to manage peak demand will not happen for UK domestic consumers. Unlike the Americans or Australians or Canadians we don't rely on aircon or resistive heating. Just do the maths and see what deferring the load of something like a fridge freezer that uses less than 1kWh per day has on the demand curve. Deferral of larger appliances such as an  oven would not be acceptable to many.

Peak pricing to try and encourage load deferral may happen in the UK but there is IMHO far more probability of zero or negative pricing with solar peaks.

Edited By Martin 100 on 23/12/2017 12:01:30

Thread: Foundation under machine
21/12/2017 12:51:27

Can't you just build a proper shed instead rather than put it in the house?

Thread: Recommended lathe outside protection?
19/12/2017 16:22:45

Cleaning it off? Use just about any 'industrial degreaser' or car 'tar remover' or a non caustic cleaner like G101

Spray on, wipe off . No rust, no paint falling off. It's not a problem.

19/12/2017 15:15:30

As good as ACF50 is (and it is very good) for such a large object I would steer towards something like this

Dintrol 4941 black underbody wax (coverage is obvious)

**LINK**

or Dinitrol underbody wax clear (less easy to see where you have sprayed)

**LINK**

or Rocol Moisture Guard

**LINK**

Warm cans (10 mins in bucket of hot water) and a thin film are all that is required.

Edited By Martin 100 on 19/12/2017 15:17:01

Thread: Evading VAT and Import Duty
10/12/2017 12:04:22

Web hosting services (for example) from companies based outside the EU have been charging VAT (the rate charged being based on the country of the registrant) when providing services to customers within the EU, even if the domain is a .com or .org and not 'country related' for quite some time now In our case it's an American company, where, other than their VAT registration they have absolutely no UK or EU presence.

**LINK**

10/12/2017 10:09:53

Can we make a counter claim for extortion when we are charged £8 by Royal Mail for collecting less than £10 of VAT? I say extortion because given the time to read the declaration, enter the value into a computer, print the tax demand sticker and affix it to the item is less then 20 seconds, equating to £1440 per hour of revenue, or £3m per annum for one operative.

If a vendor correctly declares the value on the parcel and no one charges for it at the time is there a time limit beyond which an invoice for VAT and duty cannot be raised?

Thread: Are the Electrics Right in ME4575?
04/12/2017 18:24:19

Posted by Andrew Johnston on 04/12/2017 17:28:24:

this is a standard industrial setup.

I beg to differ. Good (aka sane) practice would have the contactor coil energised from live by just a push button switch (start) , the latching action by a dedicated normally open contact on the contactor (either a dedicated main contact or an auxilliary contact) connected across it and the release (stop) by another push button switch that is normally closed with an emergency stop (also normally closed) in series from the other side of the contactor coil back to the other supply leg.

The load current for the motor goes from the supply, through the main contactor contacts to the final load and nowhere else.

Sharing the contacts on the contactor between the final load and the control is questionable and 'cheap' but wiring the control circuitry such that ANY final load current passes through the start button, even for a short period until the contactor latches, is beyond ridiculous to suggest as being "a standard industrial setup"

If you are switching a single phase load then three normally open contacts on the contactor are sufficient, (live, neutral and 'control'  ) for a three phase load then you'll need four nomally open contacts (three for the phases and one for the 'control'  )

Also just using a contactor without any motor overload relay is just plain cheap, many connect direct to off the shelf contactors, cost next to nothing and should, if set correctly protect your motor from overheating.

But single pole switches, even when wired correctly are single points of failure and for emergency stop functionality may, by themselves, not fully satisfy the requirements in an industrial installation.

(spelling!)

Edited By Martin 100 on 04/12/2017 18:37:17

Thread: Drill out a ht c/s allen screw
22/11/2017 21:10:11

Just checked MG and you are correct about the hex across flats size changing between cap and countersunk sizes 5mm and 4mm respectively for M6 and I quite clearly recalled incorrectly.

That change in across flats size clearly has an impact on the recess depth.

I know at the time the recess on an undamaged screw was measured and checked against a British Standard (BS 4168-9:1983 would cover the period in question) and it was compliant.

22/11/2017 16:51:56
Posted by Michael Gilligan on 22/11/2017 12:45:20:

Martin,

I may be wrong, of course, but ... I think you will find that the opening post refers to 5/32" countersunk screws.

These would surely have significantly smaller hex-socket than cap-heads of the same thread size.

MichaelG.

Possibly, but I wouldn't be so sure the hex recess is by design actually smaller across the flats, It certainly isn't to my knowledge on metric fasteners. The recess depth is however slightly smaller at least at smaller thread sizes.

The first time I encountered this was on iirc M6 countersink screws in some high voltage air blast switchgear in the mid 1980's The 'usable' depth of the recess in the countersunk screws was something like 10% less than a comparable cap screw with the same thread but with only around 3mm recess on the screw anything other than a perfectly fitting hex key either with the formed end ground perpendicular by the end user or a perfectly formed relief at the bottom of the hex recess to match the off the shelf hex key would compromise removal from the start.

Despite the application of considerable end load damage to the hex recess often occurred with cam out and it made removal even with perfectly sized hex keys extremely difficult. Even more so when the orignal factory installation methods were 'dry' into the aluminium and with either uncontrolled torque application or overtorquing with slightly damaged / worn hex bits.

By using the welding method together with a tiny amount of specialist anti-seize* on the threads on refitment it ultimately saved a few million quid over the following years in significantly speeding up overhaul times and contact replacement.

* I think it contained glass beads as everything else such as oil, grease, nickel or copper was off limits.

22/11/2017 09:57:29
Posted by JimmieS on 21/11/2017 16:06:14:

Heating is not an option as the allen key holes have been distorted.

Ignoring that for now, a sacrificial hex key, tacked into place with a weld (stick or mig) keeps the key in place and thermally shocks the threaded zone. Use anti-splatter spray on the surrounding area to protect the casting. Oversize the hex key (4mm) or use a circa T25 torx bit tapped into the recess if necessary.

Thread: Myford Correct Oils
20/11/2017 18:11:08
Posted by Neil Wyatt on 20/11/2017 17:56:07:

One of the world's great unexplained mysteries is why Myford fitted grease nipples to their lathes for oiling them rather than oil nipples, leaving a legacy of grease-gunged lathes and frustrated owners with leaky grease-guns (less than) full of oil.

It is so generations of owners of said lathe could spend hours and many tens of thousands of words about procurement and use of the bodged grease gun to oil their machine, said bodged grease gun is not made like it used to be, and owners should buy brand xyz and modify it etc.

Boxford (and many others except Myford) Buy, grease the grease points now and again (or simply twist the grease caps) , oil the oil points now and again with an off the shelf oil can. The End

Thread: Wanted - a guide to adhesives
17/11/2017 11:40:45

RS has a quite comprehensive adhesives datasheet, it's over a decade since it was last updated though and I suspect many of the product codes are no longer available.  (225kB pdf file)

**LINK**

Edited By Martin 100 on 17/11/2017 11:42:23

Thread: Found these behind RPM readout plate on lathe?
10/11/2017 15:46:34
Posted by richardandtracy on 10/11/2017 13:52:52:

A friend/colleague of mine was once invited on a Dan Air D check test for a 737. The pilot threw it about a bit and an awful noise started coming from (as he identified) the wing box under the fuselage floor. On landing, they quickly whipped open one of the rivetted access panels and.. There was a 110 volt vacuum cleaner with a stencil on it saying 'Property of Boeing Aircraft Corporation'. It had been rivetted in without anyone noticing, and had stayed there for years. Only being noticed for the first time in the test flight my friend went on. So much for aviation standard QA checks...

Not quite a vacuum cleaner but the report on the 777 that 'ran out of fuel' as it approached Heathrow a few years back made interesting reading, one of the items of debris in the fuel tanks being a plastic scraper used when sealing the tank.

Pages 70/71

**LINK**

Thread: The true cost of Diesel?
09/11/2017 20:32:41
Posted by Phil Whitley on 09/11/2017 19:13:40:

One of the main problems is that renewable energy is shut down in order that nuclear gets paid for every watt it can generate.

Absolutely, categorically, incorrect.

Rather than refuse a connection until fully upgraded grid infrastructure is in place there has been a policy of 'connect and manage' for a number of years now where a grid connection that may be constained in output at times is offered to a potential market participant. This basis of connection is offered regardless of the 'fuel source' The grid operator is not allowed by law to discriminate. Constrained connections exist for gas and renewables (coal and nuclear being built in the days when the generation operator and the grid operator were the same entity and long term planning and long build times ensured some high degree of coordination in project completion)

Compensation to the operator of the generation is then paid for the restrictions on their generation as and when they arise. While there are constraints on wind generation the compensation paid per annum for restrictions to gas generation far outweighs that for any renewables.

In addition much grid infrastructure is now capable of carrying higher loads, for instance circuits in Scotland have been upgraded from 132kV to 400kV specifically to remove constraints for renewables and there is significantly higher transfer capability across the Scottish borders, and as part of that there is a new 2.2GW 600kV DC link from Hunterston, North Ayrshire to Deeside, Flintshire, around 260 miles, the majority underwater that is nearing completion. With closure of much of the fossil fuelled generation across the UK the majority of this £1bn investment will be used for renewables.

 

Edited By Martin 100 on 09/11/2017 20:38:44

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