Member postings for SillyOldDuffer

Welcome Red Duck! Please let us know how you get on - what other people do with their machines is always fascinating.

Some bad news you'll gave to break gently to your wife though. Now you've caught the bug and bought a mill, it's vital to buy a lathe as well. Urgently. And then many, many other toys essential tools...

Dave

This is what their website says:

Crobalt® – An Ideal Cutting Tool For Wood-Working

Ideal Wood-Working Material :: Crobalt® with its inherent resistance to abrasion, corrosion, and certain acids is an ideal alloy for tools used in the woodworking industry. Crobalt’s characteristic ability to accept a keen edge makes it ideal for woodworking where work piece surface finish is critical; however, Crobalt®is not as brittle as some other cutting tool materials thereby making it less susceptible to cutting edge flaking. Additionally, Crobalt®, by virtue of its high red hardness, will retain its strength at the elevated temperatures sometimes found in woodworking operations. Crobalt®is not recommended for the maching or cutting of plywood or other composite wood materials.

That's OK because HSS is often used to make woodworking tools, and a variety of HSS that resists organic acids is advantageous, doubly so if it also takes a good edge.

An HSS that takes a good edge is also likely to work well on the less rigid, slow, and not so powerful lathes typical of Model Engineering workshops. Our machines have virtues other than metal-munching.

Be quite interesting for a group of Myford owners to compare the performance of:

1. M2 HSS (the most common variety)
2. M42 HSS (extra tough, with better heat hardness)
3. Crobalt
4. A sharp non-ferrous carbide tip

Which produces the best finish, which removes metal fastest, which has the lowest resharpening down time, and which is the most affordable?

I doubt there's an outright winner because they have different pros and cons. The type you want is the one that works best in your workshop that you can afford.

Maybe we're all a bit behind the times, HSS and Tungsten Carbide are so last century! Anyone tried Ceramic, Boron Nitride, Carbon Nitride, or Diamond inserts?

Dave

Agreed - I was trying to keep the example simple! I hinted it was more complicated, by saying 'Also, each house has it's own separate earth (details vary).' Here's an example in which an 'Extraneous-conductive-part' is connected, often not present. But note the 'PEN Conductor' is earthed by the supplier at the transformer, and also along the cable. One of these earths is likely to be nearish to the house. The Neutral wire is 'safe' because it cannot normally be above ground potential. Perhaps 'safer' is more accurate than 'safe' because there are faults that cause 'Neutral' to become 'hot'.

My main point though is that a mains safety earth is very unlikely in any configuration to be a good radio earth. The wires are too long.

Dave

I'm hungry for more on how Inspectors work please Bill. I know a bit about practical home measurement and fitting, and have an interest in Metrology, but there's much I don't know about the how, what, why, and when of inspection. I'm sure there's more to it than haphazardly poking stuff with a GO/NO-GO gauge. Might make a good MEW article - Neil's looking for new material.

For example, within tolerances, even a simple hole has to be made in the right place, with the correct diameter, and depth, straight, circular from end-to-end, and with a given surface finish. In my workshop, drilling is often imperfect, with holes off-centre, not perfectly round, veering off axis, tapered, depth off, and scratched. Mostly doesn't matter because what I do rarely needs better than about 0.05mm.

How would an Inspector check a Duffer built part, say 7 off 5mm holes drilled 10mm deep on an accurately centred 100mm diameter PCD, all dimensions within ±0.005mm?

Dave

A few clues. The clocks are:

• Bought for cheapness (mechanical issues)
• In a workshop
• Exposed to temperature cycles (hot, cold, and condensation)
• and, they fail by slowing down

Unknown:

• Battery type and make
• Battery voltage at fail
• Display type - hands, LCD, LED or other

Are the batteries the correct type, not too cheap or fakes, and in date? Could Iain's batteries all be from the same ancient package, perhaps stored badly in his workshop?

The ideal battery is an old-fashioned 1.5V Leclanche because their chemistry favours intermittent low power operation like clocks and doorbells. Hard to find these days because most battery powered devices need more power, usually in applications where batteries aren't expected to last for years. Ubiquitous when I was a boy and they always leaked!

Some modern types are prone to self-discharge, especially rechargeables. Too cheap batteries usually contain fewer active chemicals and/or the chemicals are a little impure. As a result they don't last well. The 'free' battery that comes with a new item is often weedy, maybe to keep costs down, or because its chemistry has been optimised for long storage rather than energy content.

As clocks and doorbells are a tiny proportion of the battery market, we're more or less forced to buy unsuitable batteries for them. Dangerous to generalise, but for clocks I avoid 1.2V types and go-faster variants. For example, Duracell sell Optimum, Plus, and Simple ranges, where Plus and Optimum deliver 100% and 200% more energy than Simple, making them suitable for power hungry motors etc. Clocks do not need more energy, so there's a reasonable chance 'Simple' is a better choice, not only cheaper, but potentially longer running.

Two ways of thinking about workshop clocks. One is to buy cheap because the unfriendly environment is likely to kill them, so treat the clock as a consumable. The other is to buy a well made clock in hope it's innards will be better protected against condensation, swarf and conductive dust.

My suggestion is to protect the clock or a bought movement with by enclosing it in a home-made box (wood and Acyrlic), and to power it with a bigger battery, a C or D rather than an AA. I'd solder the battery directly to the clock with a flying lead, but holders are available:

Maybe insulate the battery as well by wrapping it in some towelling or a polystyrene box.

I wear a wrist-watch!

Dave

Earthing is complicated and done for different reasons.

• In an electrical supply system, generators produce a 3-phase output which is distributed over three wires, with no earth. 3-phase is inconvenient for most domestic purposes: a 3-phase light bulb or TV would be bonkers. Also more dangerous in a home than need be because all three wires are 'hot'. Instead, 3-phase goes to a sub-station, where a transformer outputs 3 single-phase supplies, each of which serves different properties. Single phase has two wires, both of which would be 'hot', except one is earthed by the supplier at the transformer. Thus homes get two wires, Line (or Live), and Neutral. Although Neutral carries current, it's safe because it and anyone likely to touch it are all at earth potential. Also, each house has it's own separate earth (details vary). The house earth protects against failure of the supplier earth and also allows anything in the building that might accidentally become hot to be grounded. So if a bare Live wire accidentally touches a hot-water pipe, fuses blow rather than allow the plumbing to become shock hazard. House earths are designed and implemented in a particular way, affordably fit for purpose, but not suitable for everything.
• The movement of clouds often charges them with static electricity. The charge can become enormous because they're big and well insulated. Eventually the potential difference between cloud and ground breaks the insulator (air), and a lightning bolt jumps, often via tall objects like chimneys and towers. Several hundred amps flow causing considerable explosive damage. Bricks and mortar are blown apart when moisture inside flashes into steam; wood catches fire; and people are electrocuted or hurt by flying debris. The chance of a strike is reduced by fitting a lightning conductor, the wire and earth of which are much beefier than an electrical safety earth, which is inadequate for lightening protection. To avoid a lightening strike getting into a building's electrical system, lightening protection and supply safety earths are not connected together.
• In a long or medium wave radio transmitter, the planet acts as one side of a dipole antenna, BBC R4 LW transmits on 1500 metres. An efficient dipole at 198kHz would be 750 metres high. Instead, the planet is electrically balanced against a smaller aerial wire. Efficiency depends on achieving a very good earth at 198kHz, miles of wire spread over a few hundred acres. Although considerably more elaborate than a lightening earth, it isn't a good lightening earth, so at least one of those is required as well. Plus an electrical safety earth for the transmitter building. None of these earths are connected together.

EMC is yet another case, albeit closer to the radio example than the others. EMC uses shielding to stop inductive, capacitive, and electromagnetic coupling. As the coupling is usually electrically unbalanced, shielding won't be effective unless it too is earthed. And because shielding often consists of bare metal, it's necessary to ground it for electrical safety reasons. Unfortunately electrical safety earths are rarely good Radio earths. One problem is the earth wire on the lathe connects through a longish lead to a power socket. Then the supply earth wire runs around the building until it reaches the Consumer Unit, probably tens of metres away. From there, it's connected to the supply earth, probably some distance away. To a high frequency wave, all this wire looks more like an antenna or transmission system than an earth. It becomes a good way of transferring EMC further, not a way of stopping it. And when it gets to the actual safety earth, perhaps just a few feet of copper rod banged into the ground, 1ohm at 50Hz can behave like thousands of ohms at Radio Frequency.

Ideally, there should be an EMC earth near the VFD. However, as this could be difficult, expensive, or break electrical safety rules, it's usual to use the electrical safety earth and hope it will do. The safety earth may need help! I see Robert supplied a Ferrite: I have no experience with these and VFD interference, but in principle they 'choke' wires, making it hard for EMC to get further whilst having no effect on normal function. Not as effective as a properly designed filter, but might be good enough, especially in conjunction with other measures, In that vein, experiment with earth points on the machine. Sometimes adding another earth point will successfully short out the EMC. In other cases, a new earth point creates a loop that makes it worse. Finding the best combination can be hard work, and maybe there isn't one.

Professionals approach the problem rather differently. When money is no object, EMC is conquered simply by following best practice from end to end. Everything is comprehensively shielded and filtered to stop electrical muck getting in or out. Not cheap...

Dave

I avoid machining Stainless because most of them work-harden. By no means impossible, but expect trouble. Here's what the British Stainless Steel Association say, my bold:

When machining stainless steels it important to ensure that there is no dwell or rubbing caused by machine vibration or tool chatter. Machines must be ‘substantial’ and capable of making the deep cuts needed in machining austenitic stainless steel without slowing down the set feed or surface speeds. Small training or ‘hobbies’ lathes and milling machines intended for machining mild steel, brasses etc. are unlikely to be substantial enough for the successful machining of stainless steels.

By 'successful machining' they mean reliably cutting metal to size and finish commercially without needing a skilled operator to experiment for best results. All will be well using a rigid powerful machine fitted with the right type of cutter, spinning at the correct RPM, with a suitable Depth-of-Cut and steady Feed Rate, suitable lubrication/cooling, and a way keeping swarf out of the cutting area.

Of 316 Alco say:

316 stainless steel has good machinability. Machining can be enhanced using the following rules:

• ‹ Cutting edges must be kept sharp. Dull edges cause excess work hardening.
• ‹ Cuts should be light but deep enough to prevent work hardening by riding on the surface of the material.
• ‹ Chip breakers should be employed to assist in ensuring swarf remains clear of the work
• ‹ Low thermal conductivity of austenitic alloys results in heat concentrating at the cutting edges. This means coolants and lubricants are necessary and must be used in large quantities.

So the odds are stacked against small workshops. My WM18 does what I want, but it's not particularly rigid, or powerful, I only own a limited range of cutters, they're not all in good condition, my experience of stainless is limited, and I'm not a naturally talented machinist. Whilst I and the machine cut machinable alloys reliably well, I'm not surprised when any of the many difficult Alloys turns out to be a challenge. I avoid scrap unless I know what it is.

SD's photos show, I think, the result of work-hardening. Rather than cutting, the cutter is rubbing and bouncing along the surface. Rubbing hardens the surface so effectively that HSS struggles to penetrate and is rapidly blunted, the end.

All is not lost! The finish can be improved by using an inexpensive Belt Sander like this example as a Linisher:

Not sure what others find, but in my workshop milling and lathe cut surfaces often benefit from a mild abrasive touch-up. Depends on the material, but ordinary mild-steel usually gets a licking because it's a bit smeary. Leaded mild-steel, 6082 Ali and Brass are more likely to come clean off the machine.

Dave

Keeping cables apart helps. Try to run them so they're not parallel. If they have to cross do it at a right angle.

Earthing - try both. I'd start by earthing the VFD to the mounting plate, and if that doesn't work try earthing it separately.

Which end to earth, or both is much debated. The only printed advice I've seen was for double shielded wire, which suggested the inner be earthed at the noisy end, and the outer at both ends. I'd start by earthing only at the VFD end, and if that didn't fix the problem, both ends. Note that an earthed shield shouldn't be used as a safety earth. The safety earth has it's own wire, preferably inside the shield.

The cure is uncertain because EMC travels by 3 different mechanisms and what needs to be done varies by frequency. A Radio Engineering problem, Electrical, and the way wires behave when high-frequency power is applied to them is counter-intuitive and unpredictable. So expect to try different combinations.

If Robert RPI reads this, would Ferrites help? My feeling is not.

Dave

Only a lost cause when the owner surrenders! Taking a break is allowed but Model Engineers never give in.

The faults that frustrate me most are those that have me going round in circles. This could be an example.

• One cause is a level of skill and judgement is needed that I haven't attained yet. The only cure is to acquire the skill by patient practice. (Or get outside help, which is why clubs are recommended!)
• Most difficult are an interacting combination of two or more faults. Adjusting 'A' puts 'B' out of kilter, which upsets 'C', and 'C' being wrong misaligns 'A'. Problems like this can take a long time to diagnose. They occur most with older equipment due to wear, damage, or bodged repairs. Rarer on new equipment, but assembly errors and faulty parts do happen. Also caused when a new owner dismantles a new toy to see see how it works or to improve it, without quite knowing how to put the thing back together again! (You can guess how I know, blush..) Cure is to identify and eliminate all the faults one by one, which may require several serious debugging sessions.

Unfortunately it's rather easy to get things wrong when fixing machine tools - they appear simple but have hidden depths. Issues are easier to diagnose when one has a dollop of experience. In the absence of experience, assume nothing and ask the forum! Photos plus full lists of all faults and what's already been done to the machine would help.

I empathise. I'd much rather make things than waste time fixing tools.

Dave

I think what's happening is Windows has lost the file association. When a file is opened with Explorer, the file extension is used to identify whatever program will work with it. So if the extension is .TXT, Explorer usually launches Notepad. As almost every computer is set up differently, File Associations can be added, changed and removed. Normally by installers, also manually. Several ways File Associations can be lost. Installing and uninstalling applications, malware, malfunction or owner messing with the Registry, and even Alpha Particles!

If Explorer doesn't have an association, it may default to a general purpose action such as 'show what's inside' rather than the expected 'launch the application'. Sounds like your problem. Explorer doesn't know what to launch, but its smart enough to name what's inside.

In Explorer, try Right-Clicking on the file. Should get a menu with an Open option that lists Applications, one of which can be selected manually. For example, if the file is a PDF, a PDF reader such as Adobe, Foxit, Word, OpenOffice etc. Look for the name of the application that created the file in the first place.

To restore automatic recognition : How to set a File Association.

Dave

Strong smell of fish, even on this side of the Atlantic!

Unlikely in the UK for anyone to be sent money out of the blue in this way. When companies are fined here after breaking the law, the government gets the money. Individuals seeking damages have to go through the courts. There are no Fairy Godmothers showering victims of crime with money! May be different in Canada.

Why not ask Competition Bureau Canada for their advice? They cover Fraud and Scams!

Dave

There's a book to be written about how machine tool colours changed over time!

Early machine tools often came with Corinthian pillars, gothic arches, bright colours and gold leaf. Didn't last long because factories were filthy, so Black rapidly took over - very suitable for cutting cast-iron. Black was favoured until just before WW2, when shades of grey gradually became fashionable. After the war, Blue and Dark Green started to push grey out, then lighter greens etc. Bright colours like yellow appeared in the late 1950s. Older machines sometimes have evidence of 3 or 4 paint changes. Today's Machine Centres seem to be mostly White.

Sensitive Drills are a Victorian design, and if there was ever a patent, it must have expired in my grandfathers time because the style was extremely common. They could be made by virtually anybody, including home-made - Rolls Royce to Bertie Bodger! May not even be possible to identify the nationality. Over the decades many were made and exported from the UK, and later many were imported from almost any country with a smidgen of engineering capacity. The Victorians invented unbranded goods for retailers to slap a label on, and the British press from about 1890 onwards is full of complaints about the country being flooded with cheap German, French, Belgian, Spanish, and USA tat!

Dave

Could be except I don't think the VM210 mini-lathe has any way of rear-mounting tools. Unless the owner modifies the saddle himself. It's allowed!

Dave

+1

The plates holding the carriage on don't (I believe) contribute anything to a lathes accuracy. Cutting forces normally press the carriage down on the bed, so it's this interface that's has to operate smoothly and fit accurately.

Underneath, the plates stop the carriage lifting off when something unusual happens, most likely an accident, or maybe a dig-in whilst parting off in reverse. The underside of the bed may not be machined accurately because the plates don't normally touch it. Reducing friction and allowing space for oil to get under the bearing surfaces are reasons for not clamping a carriage firmly to the bed.

My guess is shimming has brought the holding plates into contact with a bulge in the roughly machined underside. Could be scraped off, but is it worth the bother?

Presumably the shims have been installed because the carriage lifts. In what circumstances does that happen? There's a risk shimming is fixing the wrong problem, and it's whatever that causes the carriage to lift that needs attention.

Dave

Not good is it! Though the fuse holder in question may be the 110VDC motor, not mains, accessible conductors are an old problem.

Exhibit A is a well-made British fuse-holder of the last century:

And here it is successfully rendered dangerous by a whisker of wire despite the cap being fully screwed home.

By far the most dangerous electrical devices I grew up with were valve TV sets. Users were protected by a flimsy compressed cardboard back, punched full of long ¼" wide slots for ventilation, and held on with a few self-tappers. Inside, the power supply was super-dangerously rectified direct off the mains, no transformer, and included an 15kV plus Extremely High Tension output to drive the Cathode Ray Tube. Many early TV sets emitted dangerous levels of X-rays too!

I've never understood why the safety standard for 13A plugs and sockets was so much stricter than those applied to TVs, Wireless, and Gramophones.

Dave

Edited By SillyOldDuffer on 29/06/2023 19:08:07

The vacuum tube (a length of 4" diameter PVC soil pipe) is the biggest item I've turned on my lathe.

Only needed to put it in the lathe to turn the rough sawn end of the PVC pipe flat, and far more work went into holding the pipe than to cutting it. Apart from being close to the maximum length that will fit my lathe without taking the tailstock off, PVC pipe is bendy, prone to dig-ins, and liable to melt. Needs to be held firmly whilst being attacked with a sharp cutter.

A sharp carbide insert at low RPM and low depth of cut worked better than HSS. I'm not convinced either is a good choice for turning PVC, but the insert got the job done.

Took me about 10 hours to design and make a mandrel:

It's a length of steel gas-pipe with 4 tapped collars holding a pair of chipboard wheels turned to fit the PVC pipe. . One end is held and spun by the 3-jaw, the other is supported by a dead-centre.

Sod's Law ensured that my live centres are either just too big or just too small to fit gas-pipe, but there's just enough room for the saddle at the PVC pipe end. That was lucky, because I expected to have to take the swarf guard off the lead-screw to get enough travel.

After all the preparation the actual cut was an anti-climax. The HSS tool was rejected after a couple of minutes of nearly cutting, short pause whilst I switched to carbide, and then the real cut took about 30 seconds.

A problem I hadn't anticipated was cleaning the pipe. Wiping off attracted a mass of sawdust and cat-hair due to static electricity. The amount of sawdust made me wish I'd worn a mask: the air was still full of dust at least 90 minutes after I'd made the wooden discs.

Next step is to make or buy a bulkhead penetrator for the wiring. Once that's available, I can take the clock apart and drill the base to fit the penetrator and the vacuum tubing.

Although the pendulum, electronics and software aren't really working well enough to justify running the clock in a vacuum, I feel the need to get on with the mechanicals. Trouble is testing the software takes at least a week because the clock achieves accuracy by learning how to compensate for temperature and pressure changes. As Mother Nature is fickle and slow, she takes a long time to provide all the combinations. It's caused long delays.

With hindsight, might be quicker to fit the vacuum containment and run the pendulum at a series of fixed low pressures. Running in a vacuum would also validate my assumption that the temperature-pressure formula derived by analysing normal weather is OK for a pumped low pressure. I'm fairly confident but nothing about this project has been straightforward...

Dave

Edited By SillyOldDuffer on 29/06/2023 18:09:20

A glorious opportunity to replace the original mildly unsuitable single-phase motor with a VFD and 3-phase motor. Myford only fitted a single-phase motor because at the time most purchasers were stuck with an ordinary AC domestic supply and DC and 3-phase motor control were impractically expensive. Not an obstacle now. It's not just a new motor, the lathe works better too. (Smoother turning, improved torque, and speed control.)

As far as I know, no-one with a duff motor who upgraded their Myford to 3-phase has ever regretted it.

Dave

Edited By SillyOldDuffer on 29/06/2023 14:29:13

Had to follow that clue up, and yes, Rudolf Ackermann was Georg Lankensperger's UK patent holder, whilst Erasmus Darwin had the same idea earlier but was too posh to patent it. Erasmus Darwin belonged to the Lunar Club with James Watt and other leading Industrial Revolutionaries.

Andy's lead turned into another humiliation. Until today I thought I understood Ackermann Steering. Now I find there's Full Ackermann, True Ackermann, Dynamic Ackermann, Adjustable Ackermann, Anti-Ackermann and Pro-Ackermann. The one I thought to be the one and only Ackermann is Pro-Ackermann, and my understanding of that is a simplification.

However, I don't think Nigel's wagon needs a well thought out steering geometry unless the turning circle is very tight. I suspect the same was true of the original because a fair bit of inner wheel slip can be tolerated at slow speeds. An Ackermann-like approximation would do. Just a semi-educated guess though - don't bet the farm on it!

Dave

Stainless 304 wouldn't be my first choice. Mainly because it work-hardens, requiring sharp-tools that are kept cutting by the operator at all times. Rubbing a tool on 304 hardens the steel and blunts the tool pronto.

Cutting work-hardening stainless isn't horrifically difficult, but it's risky enough that I avoid 304. Also, stainless is unlikely to be cheaper than mild-steel.

Bear in mind too that the existing thin bendy handle may be deliberate. It's because vice handles are usually sized to bend just before the vice breaks...

Dave

I had a similar problem with my mini-lathe. A ribbon of swarf penetrated into the control box through the lead-screw hole and shorted out to earth. Presumably the rotating screw pulled a dangling ribbon inside.

Didn't do any damage - I was lucky. I took the front panel off to reveal the control board, and removed some obvious bits of swarf ribbon. Then I hoovered the innards and went round the components with a Q-tip to make sure no tiny bits were left behind.

I stopped it happening again by taping around the hole to reduce the gap and by sticking a short plastic shield over the lead-screw at the headstock end. Some mini-lathes come with a plastic bush to keep swarf out. I also cleaned the lead-screw more often in case the ribbon had been drawn in by catching on dirt.

Good chance this is your problem. I can't think of an electrical fault that would cause sparking between chuck and tool-post. In a mini-lathe both are firmly bonded together and can't be at a different potential. But after being drawn into the control-box. my ribbon of swarf burned out after earthing near the chuck. Hard to tell exactly where because a a few centimetres disappeared in a flash.

Dave