Here is a list of all the postings SillyOldDuffer has made in our forums. Click on a thread name to jump to the thread.
|Thread: Trouble Cutting Silver steel|
Don't worry Chris, engineers like to have all the details. Long painful experience has taught us that even carefully drawn and double-checked drawings can mislead. As we haven't read your project book and don't have access what's in your mind's eye it's really easy for chaps to get confused and give misleading answers! A picture is worth a thousand words; I reckon you mean one of these:
This object's a difficult challenge because long thin rods bend easily. You have to plan how the rod will be supported whilst being cut to shape : it's not as simple as gripping one end in a chuck and shouting 'tally-ho'. At least on a Sherline there's no risk of the rod kinking and whipping into the operator at high-speed. Many nasty accidents on big machines where several horse-power at high rpm can instantly convert a long steel rod into a lethal flail.
The answer is to plan some way of supporting the job during the cut. A fixed or travelling steady will be too big. Bob's suggestion of making a female centre is a good one. The idea is to put a short section of taper on one end whilst most of the rod is safely held by the chuck, then to extend the job out so the point runs in a female centre held by the tail-stock. A rod supported at both ends is much stiffer. Still needs a sharp HSS tool running at high rpm exactly at centre height (See Howard.)
Another method might be to support the rod with a block of wood opposite to the cutting edge.
Planning is an important skill because the order of operations can make life easy or impossible. I often rehearse various methods and sleep on ideas to make sure they're sound before trying it. Being self-taught is a disadvantage; apprentices get told stuff and lots of on-the-job training. The rest of us bumble about! A good trick is to delay cutting objects to final size for as long as possible because the base stock can often be used for gripping and support during manufacture. In other words don't start by cutting 1.25" of silver-steel off and then struggling to hold a small bit of metal. For the same reason, finishing the taper should be left late because a taper is much harder to hold than a cylinder. Also, avoid weakening the job until the last moment.
As Neil suggests, a good plan should look for ways for simplifying the job, in this example avoiding turning down to 2.5mm by drilling a 1/8" hole instead. Don't do that - at this stage of the game it's more useful to learn how to make the difficult object. Cheating comes later in the curriculum!
PS Must learn to type faster. Jason made one and posted photos while I was dithering. My work-rate is depressing...
Edited By SillyOldDuffer on 25/08/2019 15:29:14
|Thread: Current leakage om CNC|
May have been OK when installed but there's always the possibility of wear and tear later. I've had the neutral connection inside a well-used wall socket lose enough spring to spark due to a fatigue crack.
A socket tester would confirm all is well with the workshop wiring, this example is £7.99 from Screwfix.
Though I trust nothing I agree faulty workshop wiring is unlikely. A more likely cause is damage to the CNC machine's power lead, perhaps the earth connection in the plug has been strained or the wire pulled off inside the machine. Or a manufacturing problem left the earth disconnected.
Easy enough to test with a multimeter as Joe described. There should be close to zero ohms resistance between the plug's earth pin and all the CNC machine's exposed metal work.
Most likely the cause is simple.
|Thread: Ultrasonic toothbrushes|
My Humphreys Veterinary Toxicology says a dusting powder containing 40% Sodium Fluoride caused poisoning in a dog in 1946. I'm not surprised, that's strong stuff compared with toothpaste!
Also mentions castrated pigs bleeding to death after dosing with Sodium Fluoride - those poor animals certainly had a bad day. I can warn sheep owning members of the forum to beware of volcanic eruptions - acute fluoride poisoning is caused by high levels of fluorine in ash.
Reading on, I see I share most of the symptoms of sheep poisoned by Sodium Fluorosilicate pesticide: salivation, inappetence, dullness, dyspnoea and recumbency! Can't wait to tell my GP about it. She's always delighted to hear all the details of my latest self-diagnosed ilness...
PS. I picked the toxicology book up for 50p in a charity shop and everything else I know about Veterinary Science comes from watching the works of James Herriot on TV. I think that makes me an expert.
Got to say ""Paid instantly, seller said item not in stock & refunded - OUTRAGEOUS!!!" is over the top feedback in my book. Getting your money back rather than the item ordered is IRRITATING. OUTRAGEOUS!!!" is when someone sends you a turd instead.
Dozens of reasons why items might not be available. Gosh, Tesco's no longer stock my favourite coffee (Cafe Imperial) and they ran out of Peanut Butter one week. Last ebay item I bought was American made, ordered from a seller in Madrid, and delivered from Poland. Genuine item, works perfectly, and less than half Catalogue price : that's globalisation for you!
Chaps have short memories - remember 'Allow 28 Days for Delivery' and 'POA - Send Stamp Addressed Envelope'.
|Thread: Simple table of potential hardness of metals|
Ifs and buts off the scale on this question because there are so many variables. Roughly though, and with many overlaps, softest first:
Hardness isn't the whole story. Though soft, pure aluminium is nasty to work with because it's sticky and highly likely to weld itself to a tool's cutting edge. Quenching steel for maximum hardness is rarely done because the process leaves the steel brittle to the point it can shatter like glass. Balancing Heat treatment for hardness versus toughness can be rather complicated. O1 (aka Gauge Plate) and W1 are favoured in workshops because they are easy to heat treat. O1 is designed to be quenched in oil, a slow process that strikes a good balance between hardness and toughness, as is needed in knife blades. W1 (aka silver steel) is designed to be quenched in water without cracking. The result is a bit harder for making drills, punches, and screw-taps, and it often benefits from being tempered (cooked in an oven) to reduce brittleness. The two alloys are similar.
When buying metal look for mention of machinability in the description. Many alloys are tuned to make them more suitable for turning and drilling etc. and life is made easier by buying them. Ordinary mild-steel is neither awful nor nice to machine but it's well worth spending a little extra on EN1APb, aka EN1A Leaded, or 230M07PB. Most Brasses machine well, but the Bronzes can be a pig, especially Phosphor Bronze.
Edited By SillyOldDuffer on 22/08/2019 14:31:02
|Thread: Scale gauges|
Like Merlin I'm confused slightly by scale and gauge.
A scale of 1½" to 1' is 1:8 so standard gauge ( 4'8½" ) rail track should be modelled 7¹⁄₁₆" apart. Not that it makes any difference, but why jump to 7¼" or even 7½" as is popular in the USA?
Edited By SillyOldDuffer on 22/08/2019 10:45:12
|Thread: How can this work?|
I think that's an advertising photo - wow, look! 2 more belt ratios. It's not showing how the lathe was operated in practice. Easy enough to swap belts over when needed. The user photos on lathes.co.uk show only one belt in position.
|Thread: Garmin sat nav|
One of my Uncle's told a story about his contribution to WW2 and he may have been pulling my leg. Aged 18 in 1945 he was too young to see any fighting and found himself allocated to the Royal Army Service Corps as a driver, a skill he didn't have.
On arrival at Bicester instead of being taught to drive he was ordered into the cab of a large lorry, shown the controls, and told he was driving it in convoy to Greece! No map, street names, towns, or road numbers - the instructions for navigating across war-torn Europe consisted of a long mimeographed list of distances and turns:
I like to think the jeep leading the convoy had a map, but perhaps it was just following a well defined military route, no civilians allowed to get in the way.
Uncle's memory of his journey across a recent battlefield was probably censored to save my delicate sensibilities. (Soldiers don't like describing what they went through to people who can't understand because they weren't there.) He mentioned being constantly shouted at by Military Policemen racing up and down the convoy on motorbikes, the fact that the convoy rarely exceeded a fast walking pace, and that the lorries whining gears gave him splitting headaches. Other than that, it might have been a picnic.
|Thread: Piston/Cylinder Materials|
Graphite is fairly easy to buy - I got mine from Noggin End, other sources are available including ebay.
Many applications for it; good lubricating properties (unless it's mixed with something else); conducts electricity (motor brushes, electrodes and resistors); highly temperature resistant - it melts at about 3600°C, much better than steel at 1500°C, making it ideal for rocket venturi and crucibles. Also used to make high-strength exotics like carbon-fibre, carbon-nanotubes and aerogels (see 'Frozen Smoke' )
As a piston material, Graphite has the advantage of being about a third of the density of cast-iron. Light pistons are better than heavy ones in an engine. Downsides of graphite are it's brittle and burns in air. Being brittle means it doesn't scale up well for making bigger pistons, but it's an interesting alternative for small engines and Stirlings.
Edited By SillyOldDuffer on 22/08/2019 08:48:21
|Thread: Torx head variant or faulty batch?|
Apart from NDIY not knowing:
Three generalised assumptions from a commentator not involved in the purchase can hardly be described as 'correct' in the sense they are 'free from error; true; right'. Ironic that a criticism of a faulty product should itself be an intellectual quality failure. (A conclusion drawn in the absence of evidence.)
Personally I think it's a waste of time moaning about Chinese quality in the absence of affordable British alternatives. Whinging may be easy but it's also ineffective. The real challenge is to outperform foreign competition by doing the same thing better and/or cheaper here. Possibly it's not happening in the UK because there are better ways of making a living than making nuts and bolts, possibly it's because some mistakenly fail to believe other folk are just as clever and hard-working as them and go immediately bankrupt. Anyone wanting to bash China should look at their unpleasant foreign and domestic policies. Both are much better targets than cheapo ebay goods, but not really appropriate to this forum.
PS Jason asked for a shut-up while I was typing - sorry.
Edited By SillyOldDuffer on 21/08/2019 16:13:02
|Thread: Profiling tools|
Looking at it another way, what would stop a domestic lathe using wide form cutters?
In practice a hobby lathe should work reasonably well with larger form tools than might be expected especially if light cuts only are taken. I'd experiment to find out the maximum a particular lathe can do because so much depends on the machine and how fast you need to work. To find the limits start small and move up in stages. As an index Jason's encouraging example shows what can be done on a WM280, a lathe heavier and more powerful than a Super7, but smaller than a Boxford. Form tools on a mini-lathe would be more restricted, but scaled to suit they should still be usable.
Edited By SillyOldDuffer on 21/08/2019 09:03:09
|Thread: Piston/Cylinder Materials|
Bump really, as I'm no expert.
I think a Silver steel piston in a brass cylinder would work fine. Most engines I've built have used brass pistons in mild-steel cylinders. Also used graphite in brass and brass in aluminium. They all worked.
|Thread: Need a lot of help from you good people|
Not quite, Terry mentioned using an ebilke battery. They're Lithium Ion high current batteries capable of delivering quite a wallop. This ebay example claims to be good up to 1200W.
|Thread: my knowledge of steel needs improving|
Silver Steel is usually sold as Silver Steel, aka Drill Rod in the US, with no magic number needed.
O1 is an American specification for a Tool Steel, not an Engineering or Structural Steel. It's European Specification is 100MnCrW4, but it's often called O1 in the UK, for example as sold by Metal Supermarkets.
For historical reasons steel specifications are a confusing muddle. Nationally, internationally, commercially and over time. Following old plans can have you frantically searching for apparently exotic materials simply because the terminology has changed. Not many know what Muirkirk No 1 is, nor is it likely to matter much, because mild-steel is better!
Fortunately most of us only use a few common alloys and it gets easier once you know what 's needed in your workshop and stocked up, perhaps from a Horological specialist. However it's rarely necessary to use exactly the steel specified : for making a clock I'd think 4130, 4140, and En19 are so similar as to be indistinguishable.
|Thread: Anyone good at fault finding with amplifiers here?|
Maybe the can's seal gradually failed over the years and the innards are exposed to dirt and moisture. Perhaps Neil's transistor has gone rusty.
Ocean sounds invariably produced by my amplifier efforts too. Motorboating...
|Thread: All things Beaver Mill|
Now that is impressive! Despite being a committed Qcad fanboy I've never attempted any that complicated. Just shows what can be done.
|Thread: Need a lot of help from you good people|
An electric bike motor and controller would certainly work. The power needed is decided as per earlier physics by:
Other issue that might suggest a big motor is whether or not the engine is to be run continuously. A 350W motor run flat-out for hours will have a shorter life than a 1000W motor run at 350W simply because the big motor stays cooler. So motor size matters less on an engine run intermittently for fun at the track by the driver and a few bystanders than the same engine expected to haul hundreds of paying passengers continuously over a Bank Holiday weekend event.
A 15Ah battery can deliver 15 amps for an hour. That's 48V*15A = 750W for an hour. Actually, because deep discharging is undesirable, it would be unwise to assume more than about 75% of that, say 750W for 45 minutes, which isn't unreasonable for fun use. A 350W motor would use half the power and run for about 90 minutes, 500W about an hour. In practice because the motor probably wouldn't be run at full power all the time, it would likely last longer per session. But so much depends on stops, starts, how hard the driver accelerates, the rolling resistance of stock, slopes and the state of the track it's hard to predict.
I bet the original builder would have used a modern electric bike motor and batteries if they'd been available at the time.
Edited By SillyOldDuffer on 20/08/2019 14:21:55
|Thread: What coating/grease for long term tool storage|
Trivia: the proper name for the 'bunch of hay' is Excelsior.
The best known preservative used for long term storage of guns is Cosmoline. It's a family of similar products, all based on an oily wax. Cosmoline in an American trade-name and similar mixes under other names were used by the rest of the world.
I think Cosmoline is remembered because it's a right pig to clean off. No-one who ever had to apply or remove it forgot! A whole range of protective products are available today ranging from heavy waxes to light silicone spray-ons.
|Thread: Need a lot of help from you good people|
+1 for that; When I was growing up WW2 surplus was my playground. Motor/generators were the best way to produce the multitude of voltages needed in large aircraft, less desirable second-hand than motors and cheaper.
Frances suggests the control system is pre-electronic and I think she's right. It may even be cruder than a field-winding control system - big wire-wound resistors straight off the 'regulator'!
Except the potentiometer top right hints at electronics somewhere!
I'd give it a try before ripping it apart. The two doubled black wires ending in eyelets look like battery connections to me. One of them is marked Blue for negative. (Circled in Blue), the other will be Positive (circled in Red)
With the wheels free to turn, I'd try dabbing the eyelets on a car battery to see if there's any sign of life. Provided they've not been soaked electric motors are tough old birds. Any markings on the motors? I'd guess they're 24V or more rather than 12V, which effects the battery configuration.
Only a guess about the small motor dangling bottom right off a choc bloc; it might be belt driven off the shaft as a generator to drive a speedo in the cab. Or perhaps it drives an oil-pump.
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