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Member postings for SillyOldDuffer

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: cutting a square end on a round shaft?
13/06/2022 16:17:53
Posted by Andrew Johnston on 13/06/2022 15:51:45:

A few tens of thou, not a few tenths. smile

Andrew

Is there a difference? Oh dear ... blush

Thread: CAD - Accessories Worth Having?
13/06/2022 16:13:23

Recently spent a lot of time with SolidEdge Community Edition, which is a feature packed 3D CAD package. At first, SE kicked me all round the car park, and still bites back occasionally, but I've mostly tamed the beast and come to like it.

Now, although 3D CAD is perfectly usable on a laptop, I've realised the advantage of a big screen, and - even better - two big screens! My main computer already had a 25" screen, and I was able to upgrade for nowt because my nephew gave me a 24" monitor plus a graphics card that's Windows and Linux compatible. Two screens excel because they almost eliminate the need to maximise and minimise windows: browse the web and do CAD without them getting in each other's way.

My nephew gave me the kit because the screen is too small and the graphics card too slow to play the latest games. He currently has three curved 32" screens showing high-speed high-resolution animation, and his graphics card cost nearly £1000. The inferior model he's given me 'only' has 2,700,000,000 transistors...

SE recognises the freebie graphics accelerator and the performance improvement is noticeable, going from good to excellent by reducing a multitude of tiny delays. Feels agile, like oil's been sprayed into it!

So far, the improvements cost me nothing. But now I've noticed a conventional keyboard and mouse aren't ideal for CAD, in particular the mouse is overworked, doing both drawing and tool selection, while my left hand is mostly idle. With an improved interface I could work faster, and not being able to is a little frustrating.

I have a birthday coming up, and could direct my relatives to club together and buy me a CAD mouse rather than the usual unwanted ties, slippers, pot-plants, unsuitable books and deodorants. (Get a lot of them.)

Does anyone have any experience of CAD mice? The SpaceMouse line vary from about £350 to £116 plus VAT, so quite a lot of money. I think the cheapest 'Compact' meets my needs, but I've never seen one, let alone tried it. Plenty of other things to spend my dosh on in the queue...

Dave

Edited By SillyOldDuffer on 13/06/2022 16:14:13

Thread: cutting a square end on a round shaft?
13/06/2022 15:16:34
Posted by Andrew Johnston on 13/06/2022 10:56:45:

Turn down the end of the bar to the required diagonal dimension, minus a few tens of thou. Then file the flats. Since the starting diameter is slightly smaller than theoretically correct, a small chamfer should be left on each corner. Keeping the chamfers the same size, and parallel, will ensure that the flats are just that, flat and parallel to the opposite face. Shouldn't take more than a few minutes.

Andrew

Like it, fiendish!

The diagonal is is square root of twice the flat and 'a few tenths' is about 0.01mm.

So, for an 8mm square,

diagonal = sqrt( 2 * 8 * 8 ) or 11.31mm

So the shaft would be turned to 11.30mm or a little less

Or for Imperial Fanboys, a 3/8" square,

diagonal = sqrt( 2 * 3/8 * 3/8)

diagonal = sqrt( 18/64 )

diagonal = sqrt( 9/32 )

diagonal = sqrt(9) / sqrt(32)

sadly, because I don't know how to calculate sqrt(32) as a fraction,

diagonal = 3 / 5.66 = 0.53", less a few tenths, say 0.5295 inches.

Dave

Thread: Change of direct debit for MEW?
13/06/2022 13:48:11

Me too, as expected.

MEW317 and ME4693 arrived together through my letterbox a few minutes ago, so no interruption to magazines.

Serious complaint: with one exception all the men on the front covers have more hair than me, and no pot bellies! Surely my bay-window physique and extra-wide centre parting is more typical of model engineers than the handsome hunks pictured...

Dave

Thread: Telephone Ringback Code?
13/06/2022 13:32:31
Posted by Swarf, Mostly! on 13/06/2022 13:26:32:

I've just noticed my spelling error in the title of this thread. I really do know how to spell 'telephone', honest I do.

I've given my keyboard a good ticking off so I hope it won't happen again.

Please, please, could one of the moderators insert the missing letter? Or will that muck up the search engine?

Best regards,

Swarf, Mostly!

Fixed. Your wish in my command!

Dave

13/06/2022 12:26:47
Posted by Howi on 13/06/2022 09:02:41:

just to point out, Virgin landlines are BT land lines, just provided to the premises by Virgin, so all BT "codes" will work.

ALL land lines will go as a consequence of going full fibre (FTTP), ALL the copper infrastructure will dissapear as it is too costly to maintain. ...

Bite the bulletr and move on.......

In the good old days, when telephony was king, consumers were connected end-to-end by dedicated copper lines arranged in a manually switched network. Didn't last long, the telephone system soon included various clever ways of multiplexing (multiple telephone conversations on one link, plus telex), where the link could be micro-wave, short-wave radio, twisted pair or coaxial copper.

Unfortunately time marches on remorselessly. When I was a young man, the UK telephone system had become an embarrassment because it contained a mix of everything from ancient equipment installed in the 1920's up to modern electronic prototype equipment. Much money was allegedly 'saved' by keeping old infrastructure going, but much more was wasted by the high cost of maintaining a complicated mix of old and new, where all the pre-electronic equipment had to be maintained by hosts of expensive skilled men.

In the usual British way, kicking the can down the road, led to a crunch - decades of government under investment resulted in an enormous cost-to-fix, not least the need to painfully dump large numbers of loyal staff.

Since then, the backbone network is almost completely modernised. Apart from the lines between local exchanges and subscribers, there is hardly any copper in the system at all. Though important, telephony has become just another service riding on the back of the internet. The internet uses the same packet switching technology to delivers all things communication from e-commerce, to x-rated porn. Most links are fibre-optic, carrying massively more information than copper, and much more reliably. There's nothing special about telephony.

Copper lines to the consumer have always been an anachronism, expensive to maintain, and requiring converters in exchanges to connect ye olde telephones across the backbone. At the same time, new consumers want high-bandwidths at home: these folk, spending much more money than basic phone users, likely don't have or want a land-line telephone, they want streaming services and mobile phone connectivity. So the pressure to get rid of copper entirely is enormous: it's happening. Mostly a good thing,

Unfortunately, every silver lining has a cloud. Although internet technology is highly reliable because it features multiple redundancy, automatic routing, error correction and recovery, without wobbly mechanicals, it is vulnerable to power failures. I don't know what's been done about this, but I guess it's similar to what's normal in important computer installations. The machines are powered via an 'Uninterruptable Power Supply', a device that filters muck out of dirty old mains electricity, and contains a battery big enough to run the installation for about half and hour, perhaps longer, and designed to give plenty of time for a standby generator to be sorted out if it fails to start automatically. (Standby generators have a nasty habit of not starting in genuine emergencies!) Assuming the maintenance team haven't nicked the fuel (they do), standby generators should run the installation on their own for several days.

This may not help a disabled person who has an emergency during a power-cut and only knows how to use a landline telephone. But I wouldn't have thought it difficult to fit their phones with a battery. Wot! spend money on a new-fangled phone, when the old one worked perfectly well. Not in my lifetime!

Having done some emergency planning, I'm fond of the truism 'Fail-safe systems fail by failing to fail safely'. An interesting paper on the subject discussed business recovery after serious earthquake damage in California and Japan. In both countries, many businesses found their well protected computer systems were fully operational, but they couldn't use them because the building was full of broken glass, flooded by bust water pipes, and had to be checked out by a surveyor in case it was about to collapse. In one case the the computer system was still running even though the offices above were gutted by fire, and the building had to be demolished.

What causes most of the trouble in disasters, is people, not technology! For good and bad reasons it often turns out that people don't do their jobs properly. Lazy incompetent know-alls, corner-cutters, thieves, drunks, bad attitudes, hangovers, domestic upsets, depression, exhausted by overwork, or ill, they all get it wrong. Men 'toughing it out' when they should be home in bed cause a lot of trouble, as do the dreaded 'willy wavers', and those for whom 'common sense' is automatically better than reading the effing manual!

We live in an imperfect world!

Dave

Thread: cutting a square end on a round shaft?
13/06/2022 10:51:59

The easiest way is to fit a chuck to the rotary table. It centres jobs like your chuck key on the table's axis, making it straightforward to cut the four faces of the square with a milling machine. Might be possible to attach your lathe's chuck, but chucks for rotary tables usually have four bolts passing through the chuck's body so they can be undone from the front. The bolts engage with T-nuts in the rotary table's slots. If you haven't got a suitable chuck, welcome to the wonderful world of model engineering, in which there's always some new accessory wanted!

Rotary tables shine when other than right angles are needed, otherwise not essential because other methods produce right angles. I made my chuck keys by gripping the shaft in an vice on the milling table with the end sticking out enough to receive the end of the milling cutter. After the first flat was cut, I turned the shaft 90 degrees in the vice and used a set-square against the face to get it exactly* vertical. Then cut the second and other faces in the same way.

If you don't have a machine vice, the shaft can be clamped directly to the milling table. It's a little more bother adjusting it compared with a vice.

*exactly needs some qualification. A casually used set-square will get close enough to 90 degrees for most purposes, but on this job the short face length and fiddling with the shaft in the vice limits accuracy. The vice problem is much reduced if it already has a V-slot jaw, or V blocks are used, to keep the shaft horizontal. Good news, chuck keys don't need to be anything like accurately square! I wouldn't risk it, but I'm sure our more accomplished brethren could eyeball a good enough square end on a chuck key, not just with a milling machine, but by hand filing it in a bench vice.

Work-holding, especially of odd shapes, is a skill in it's own right.

Dave

Thread: Target for This Month: A 3D Printed Engine
12/06/2022 15:54:51
Posted by lee webster on 11/06/2022 18:33:03:

Dave,

I have 3D printed parts from SolidEdge using my Ender3. No problem.

Good news thanks, I'm getting close to printing the engine at half scale to see if it really does fit together. Might even run, though scaling down increases friction disproportionally .

 

3dengexploded.jpg

All seems to fit together apart from the conrod and crankshaft: one of them needs to come apart so the two can be assembled together.

Spent a good deal of today investigating a Solid Edge assembly-relationships problem. I designed this throttle valve, which animates OK except the flap rotates through the tube rather than the software recognising the tube is a physical obstacle.

throttleinnards.jpg

I've had several fights with Solid Edge where assembly relationships didn't work as expected, this latest being highly baffling because there are only two parts in it! They are related by an axial alignment between the through side hole and the tap shaft, and by a mate between the shoulders. The joint is set free to rotate. The handle's supposed to stop turning when the elliptical throttle plate hits the tube wall, and it didn't. A mystery because much more complicated relationships in the model work this way correctly. Very frustrating!!!

Until now, the main issue has been me getting relationships wrong due to not quite understanding how SE works. This one wasn't obvious - eventually identified the problem was a tiny geometry error in the through hole. I created one side manually and patterned the other from it, supposedly a 180 degree mirror image of the hole and shroud. Not sure why but the two sides were slightly misaligned, so the tap shaft was out of alignment across the tube. Tiny but enough to confuse Solid Edge's boundary calculations. Lesson learned: if relationships won't bind or behave strangely, double check the part geometry. Geometry has to be right, not nearly right.

Dave

 

Edited By SillyOldDuffer on 12/06/2022 15:55:40

Thread: Files,hacksaws etc
12/06/2022 15:03:59

Good question. I'd rather use a power tool than do it by hand, but fettling often involves removing small amounts of metal with careful control so that parts fit accurately together. A slip of the hand with a power tool might remove too much, whilst files in different shapes and sizes with different teeth provide a lot of slow but sure control.

Another common fettling job is removing burrs from edges: often quicker to do with a few strokes of a file rather than plug in a power tool.

Skilled filing is a joy to behold. I wish I could do it. Experts seem to remove metal almost effortlessly, producing accurate neat flat surfaces and matching curves with a good finish. What I do with files is much cruder, but I couldn't do without.

I see a milling machine as my best replacement for filing. Grinding is the commonest way of removing metal in industry but the technique isn't as useful in a small workshop, where most jobs are done by sawing, turning, boring, drilling, milling and filing. Nonetheless most of us have a bench grinder for sharpening tools, an angle grinder for cutting, plus a Dremel for fine work.

Just as well I don't need a surface grinder - my workshop is already full!

Dave

 

Edited By SillyOldDuffer on 12/06/2022 15:06:04

Thread: Myford or Atlas lathe ?
12/06/2022 11:42:41
Posted by Brian Wood on 12/06/2022 10:08:42:

Now you have the choice between a Portass Dreadnought, the Atlas and the Myford. The advice has all been the same, chose carefully!

Brian

Very much so. Playing the odds, though:

  • Dreadnought is a pre-war lathe, bit old-fashioned, not that it matters, but sold for light-engineering work, too expensive for hobbyists. Light-engineering means the lathe is likely to have been worked hard for a living. Many, not all, finished up worn and weren't well maintained, especially as they approached end of commercial life. Except many of them went to the military for occasional repairs - lightly used, and well maintained, but likely to have been sold as surplus after WW2. Mostly went to industry because even surplus prices were too high for most hobbyists. So, could be in good or bad condition. Spares thin on the ground.
  • Altas, depending on model, spans WW2. In their day, good machines, also targetted at light-industry, so subject to the same risks as the Dreadnaught. Spares, I don't know. Popular machines in the US, so likely to be easier than the Portass.
  • Myford, post WW2, a well-balanced effective design, which hit the hobbyist bulls-eye. Not perfect, because they were made down to a price,but they tended to end up with hobbyists and light-industry for light duty work. Many led sheltered lives, which is good, but not all: a proportion have significant wear or damage. Over the decades I suspect a good many have been mistreated by enthusiastic beginners blissfully unaware lathes have their subtleties. Sort of chap who starts by stripping the machine down completely, loses the shims, and reassembles it incorrectly and maladjusted: half-nuts not meshing correctly; gibs upside down; grease in the oil nipples; giant motor fitted; everything polished with a wire-wheel; bull-gear broken trying to get the chuck off; incompetent rewiring etc. He might smack the tool-post hard into the chuck, have incorrectly gripped work spring out out of the chuck and ding the precious ways, or cause a serious wrenching stall due to not understanding which tool and how to align and use it. Perhaps ending up with the machine in a box of bits, which someone else gets back into working order - sort of, with a wonderful paint job, but who sells the accessories and change wheels separately on ebay. All part of the game except the Myford reputation forces prices up, even if the machine isn't in good order.  Spares: excellent, but the machines are out of production.

Bottom line, the maker's name or how good the machine was when new doesn't help much if the lathe has had a bad history. Much safer to buy a grubby lathe that can be demonstrated cutting metal than exactly the same model in shiny perfection where the owner is reluctant to switch it on... Of course condition matters less if you enjoy repairing machines rather than using them: refurbishing is a fascinating and rewarding hobby in itself. But it's probably not one a beginner wants to get into by accident!

Rather than get entangled in buying second-hand whilst inexperienced I decided to buy new Far Eastern from a reputable UK supplier. This makes a lot of problems go away - like delivery, electrical safety, and what to do if a lemon turns up. I intended to use the machines to gain experience and upgrade later to ex-industrial kit when I knew what to look for in a second-hand machine. As it turned out, my Far Eastern hobby lathe does all I need, and I'm unlikely to change it. But my needs are mine, not yours - if I spent a lot more time cutting metal, or was working against the clock, or the sort who enjoys using good tools or celebrates solid Western technology, then I'd probably move upmarket.

Horses for courses and condition rather than 'quality' and 'accuracy'. Unless of course you can specify exactly how accurate, and what measurable features constitute the quality needed. Otherwise they're technically meaningless synonyms for 'nice', a word banned in my school!

smiley

 

Dave

Edited By SillyOldDuffer on 12/06/2022 11:44:31

Thread: Battery fire in electric cars after a collision
12/06/2022 10:22:57

This is a good example of a development where 'common-sense' has little to offer! What's needed is careful analysis of the risks and application of necessary mitigations.

Almost a no-brainer if a new technology is safer than what it replaces. The benefit outweighs the hazards. In this case there are serious problems with fossil fuel technology up to and including a climate catastrophe. Common sense fails miserably because climate change is big beyond comprehension, whilst most of us can grasp what happens when a car catches fire. Cars catching fire are exciting on a personal level, but don't make much difference to the world. Climate change does everyone in. Fossil fuels have a second serious global problem which is they don't last forever! Prices are going to rise sharply, and as we've seen this week petrol at £2 a litre is causing significant difficulty on top of rapidly rising gas and electricity prices. EV's offer an alternative, not least they run on clean renewable energy that doesn't depend on foreign imports.

It's not a no-brainer though, because batteries come with new problems. The risks have to be identified, their likelihood established, perhaps by experience, and then mitigated. Again 'common sense' fails, because it's based on experience with internal combustion vehicles. These have been developed over a 140 years and it's natural to assume that what comes next is a petrol car fitted with a battery. Not that simple: EVs eliminate old problems, like a petrol tanker delivering fuel catching fire, but bring new ones requiring fresh analysis and innovative thinking. Nothing new here - all technologies go through the process: early aircraft were the most dangerous form of transportation on the planet, now commercial air-travel is the safest.

Politics intrude into this space, which is a pity because it's really an engineering problem. A big C Conservative believes the best way forward is to minimise government interference and let the market sort out the details. He will only legislate after 'accidents', so the public pays in blood! A socialist might believe EVs should be managed for the public good and heavily regulated from the start, with everything nailed down beforehand. This is liable to cause serious delays and strangle development, ending up with an expensive EV that doesn't work well and is still dangerous. Most customers are small C conservatives: they fear change and would rather everything was left as it is despite clear evidence that change is needed urgently. All these folk are liable to make a mess of technical problems because they let emotion, beliefs and prejudice override the evidence.

Engineers, who are far from perfect when it comes to controlling gut feel, should coldly analyse the ways in which a battery could catch fire and design to mitigate them. Mitigate, not prevent. To benefit from technology humanity has to manage the risks, and risk management is a disciplined skill, not common sense.

Anyone reading this happy to blast allegedly weakling woke snowflakes whilst themselves being terrified of change? The two often go together...

Dave

PS. I hate change: it means something is wrong, and people always suffer as a result. The future always ends badly for individuals, we exist to propagate our genes, so should be careful not make life impossible for our off-spring. The sins of the fathers...

Thread: Myford or Atlas lathe ?
11/06/2022 23:00:58

Forget 'quality', it's all about condition and what you need. Many of the best lathes money can buy were worked hard until they became worn out beyond repair: scrap. 'Quality' or not, old lathes have history: you want one that's been lovingly cosseted by a few careful owners, not the same that's been mistreated for decades, and then left in a damp cellar before being tarted up for a quick sale! Best to see second-hand lathes cutting metal before buying. And even in perfect nick, an old lathe with several accessories missing can be expensive and difficult to get back into service: you can't get the parts guv!

What you need the lathe is important too: note Bob's comment about spindle bore. Though it's not a showstopper, a metric workshop is better off with a metric lathe. Bigger the better unless doing lots of small precision work. Altas vs Myford is interesting because it was a modern Atlas lathe that inspired Myford to come out with their bombshell design. In the UK Myford spares are easier to find, but if the lathe is in good condition they may not be needed. How much accuracy do you need? Worn machines aren't as good as new! But it's amazing what a skilled operator can do with a wonky lathe. Most lathes can get to about a thou without too much bother. What the better machines provide is the ability to work hard for long stretches plus various goodies that speed up production: a full screw-cutting gearbox means time isn't wasted fiddling with change gears, but change gears just as well. The gear box pays off in a busy jobbing workshop cutting lots of different threads: nice to have but they go wrong and most amateurs don't need one.

Apart from Myford the lathes mentioned so far are ancient. I'm happy with my Far Eastern kit, but if I needed better I'd look for something more modern. Over the last 30 years education and industry have been dumping wonderful manual machines in good order because CNC made them redundant. Colchester, Boxford, Hardinge, and others expensively made for the industrial market, smooth, powerful, hold their settings and user-friendly. Tend to be on the large side though, so make sure it will fit in the workshop and the electrics are up to running one!

I regret dithering before buying a lathe. I eventually bought new Far Eastern, which solves a lot of problems, and haven't regretted it. Much depends on what the lathe is going to be used for. What's your interest? (I didn't have one!)

Dave

Thread: Battery fire in electric cars after a collision
11/06/2022 22:22:39

Wrong way to look at it I think. Over course batteries can catch fire, but are they more or less dangerous than petrol? If battery accidents cause fewer injuries than petrol and diesel then which one requires action?

Don't imagine petrol cars are safe! This 2017 fire in Liverpool destroyed more than 1000 vehicles in a car park, also badly damaged.

Started by a Land Rover...

Dave

Thread: FORUM DOWNTIME AND RESULTING ISSUES REPORTING
11/06/2022 15:53:14
Posted by Dennis D on 11/06/2022 15:19:26:

Keeps logging me out today, was on all day yesterday no problems. Login time seems long but probably only 15-30 seconds. No access to digital copies displays 404 - File or directory not found.
The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

Logging fast and reliable to me but like Dennis I also get 404 from https://www.model-engineer.co.uk/digitalaccess

Thread: Telephone Ringback Code?
11/06/2022 15:48:56
Posted by Dave Halford on 11/06/2022 15:15:47:

Back in the day Faultsmans Ring Back was also FRB on the dial, for which you need the dial with 3 letters in each finger hole. You could also drop out incoming trunk calls by whistling 2280hz which was the tone frequency used by the AC9 relay sets.

Is that the one that reported 'Dolty Filing Pulzez'?

My GPO friend had a big list of local dial codes which could be used make long distance calls by connecting via a series of local to each other exchanges: not very practical.

When I was at school, the dial code from Bath to Bristol was 97, as was the return. So a friend of a friend used to dial 9797979797979797 until all the lines between the two cities were tied up. Seemed to work, and would have been downright anti-social if we'd thought of leaving the phone off the hook. And the Daily Wail moans about young people today...

devil

Dave

Thread: How to display an 80 character line length on my Android phone
11/06/2022 15:28:48
Posted by Russell Eberhardt on 07/06/2022 20:05:48:

Posted by SillyOldDuffer on 07/06/2022 17:38:11:

Many advantages in developing on a PC, not least they have big screens!

Dave

... My favorite editor for code is gedit running on Linux. It includes syntax checking for most common programming languages.

Russell

I like gedit too, but kate is better if you want to manage multiple files in one project. Recently I started using geany, not sure why but I subconsciously prefer it to kate. For single files I almost always use gedit.

In the good old days programmers argued ferociously about emacs versus vi. A religious debate that sometimes ended in an actual punch up! Both powerful rather than easy to use. I never got on with emacs, even though everyone agreed vi is short for 'vile'.

vi's latest incarnation is vim, quite hard to learn, but for certain rare types of edit it kicks the euphemism out of GUI editors.

Dave

Thread: Loose table on Fobco Star
11/06/2022 15:08:59
Posted by Hopper on 11/06/2022 13:58:21:

The easiest solution might be a strip of 5 thou shim or whatever takes up the gap. Make it wider than the clamp so you can cut small cuts top and bottom to bend the ends over to hold it in position when moving up and down.

Like Hopper's idea and it's easy to try. Drink cans are often made from soft Aluminium about 0.14mm aka 5 thou thick and it can be cut with scissors. (Hot tip: don't borrow SWMBO's dressmaking scissors...)

Dave

Thread: FORUM DOWNTIME AND RESULTING ISSUES REPORTING
11/06/2022 14:56:43

There's a danger that poor old Darren will find himself being asked to fix everyone's IT problems! For example, my Windows 10 doesn't recognise Daylight Saving Time unless I sync the time server manually . Love to blame this bug on the Forum upgrade, but it's a long-running Microsoft glitch effecting a small minority, cause unknown.

I mention my date/time problem because it's one of several issues that can cause a client to mismanage a new certificate. Pinched this list off an Android site, but Linux, Apple, and Windows are similar. Suggestions:

  • The operating system is out-of-date. (upgrade if possible: buy new kit if necessary, old hardware doesn't last forever!)
  • The browser is out-of-date. (upgrade)
  • Operating system date/time is wrong. (reset it)
  • Browser has cached information. (Go to Browser settings and clear data and cache.)
  • Anti-virus software is blocking the new certificate. (Temporarily turn it off)
  • The problem may be in the network (shutdown and restart router, or connect to a different WiFi.)
  • One or more of the data structures used to manage the computer is corrupt. (Power the device off, wait at least one minute, and power back on. Doesn't fix all such problems, so if it fails try a factory reset.)

Dave

 

Edited By SillyOldDuffer on 11/06/2022 14:58:08

Thread: Target for This Month: A 3D Printed Engine
11/06/2022 10:30:59
Posted by lee webster on 11/06/2022 08:05:59:

Dave,

You said " Finish tends to be poor, with ridges and blobs. " Are you planning to print using FDM printer? Like my poor old Ender3? If so, what filament will you use?

...

Yes to FDM, I have an Ender3-Pro. Does a reasonable job and I should have put a scale on the 'ridges and blobs' comment, because they don't matter for many purposes. This is the worst bit of the cotton-reel example, which - to save time - was printed in low quality mode:

dsc06604.jpg

Low quality is 0.28mm. 0.12mm High quality, is roughly twice as smooth provided the printer and filament are tickety-boo.

Low quality plastic finish is OK for most of the engine apart from the bearing and sliding surfaces. Unfortunately sanding and polishing them might still not be good enough. I don't know what the coefficient of friction of 3d printed plastic is.

A hybrid engine would be better, such as designing in off-the-shelf roller bearings rather than scraping plastic on plastic, but I'm trying to stay pure plastic hoping I can make it work. I'll try ABS first because that's what I have, but combinations of other plastics would be superior.

Another constraint: the printer's platform limits the size of the engine's biggest part. Have to keep an eye on that, unless I pay to have it printed professionally! While 3D-CAM opens many useful doors, the designer has to keep a close eye on production limitations; it's not difficult to CAD impossible to build assemblies!

Before I go further I need to confirm SolidEdge will work with my printer! Should be OK, SE has an entire 3D section, but I haven't looked at yet and the proof is in the pudding.

Unfortunately out today to fix my daughter's plumbing problem. When the kids were little, my life was dominated by buying them new shoes; then I became a teenage taxi-service; now they've left home I've been promoted to Bank of Dad and all-purpose handy-man. The latter has ruined my Alpha-male reputation - conclusive proof I don't know what I'm doing...

Dave

Thread: FORUM DOWNTIME AND RESULTING ISSUES REPORTING
11/06/2022 09:11:27
Posted by Derek Lane on 10/06/2022 22:06:36:

Posted by Neil Wyatt on 10/06/2022 10:41:21:

...

But is the spell checker not a function of the web site...

Although the forum has a built-in spell-checker, putting it politely, it's not wonderful. Clunky and it defaults to US English and disgracefully complains about Aluminium. Never got it to remember I write British English and have to reset it manually every time.

The forum's spell-checker is a relic, more trouble than it's worth, and a better alternative is available! These days it's usual to use a Browser spell-checker rather than whatever happens to come with a forum: browser spell-checkers are up-to-date, work the same way on all websites and, once set up, are easier to use.

Which browser are you using? Whatever it is someone on the forum will know how to switch spell-checking on.

Dave

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