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Member postings for Hopper

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

Thread: Increasing Friction??
15/01/2021 11:51:18

Posted by SillyOldDuffer on 15/01/2021 11:14:55:

Disc brakes are a sophisticated implementation; the disc is polished hardened steel,

As-machined grey cast iron more like it on most cars. Some motorbikes have a low grade stainless steel for appearance sake. But its never hardened or polished for obvious reasons, ie coefficient of friction.

When disc brakes first appeared on street motorcycles, manufacturers (including Triumph) used chrome-plated discs. Mediocre in the dry, but boy, were they a lot of fun in the wet! Slippery as snot. Then the chrome wore off unevenly and you had on-off-on braking every revolution. Ah, wonderful days!

Thread: Tubal Caine Wenceslas
15/01/2021 11:37:19

Lovely with all the brass work on show. Nice work indeed.

Thread: Standards of Electrical Wiring
15/01/2021 11:26:18

I saw some good examples in Kathmandu, Nepal, two years ago. (Sigh, remember when we could go places?)

Sorry about the sideways orientation of the first pic. Its ok on my computer but I cant change it. Maybe mods can?

 

20190106_102901.jpg

20190107_105740.jpg

img-20190112-wa0002.jpg

The streets are as hazardous as the wires above! All thoughts of renting a motorbike went out the window when I saw the combination of dealing with chaotic traffic while riding on a surface akin to a motocross track strewn with concrete blocks and boulders and potholes big enough to bust a wheel. This is actually a rare good bit with a strip asphalt down the middle to fight over.

Edited By Hopper on 15/01/2021 11:28:54

Edited By Hopper on 15/01/2021 11:32:53

Thread: Henry Greenly Model Engineering
15/01/2021 11:06:49

Is it on Google books? Just about everything else is and often you can print out a few pages.

Thread: Myford ML10 main screw skating
15/01/2021 11:03:24

Bob, I dont know where you can get a lower gear. But it should be possible to use an upper gear in the lower position if you mount it on the different spindle. They appear to be the same gear.

15/01/2021 11:01:49
Posted by Robin King on 15/01/2021 10:09:27:

The centre distance between leadscrew and handle spindle is fixed, leaving the only adjustment available by rotating the lower gear eccentric shaft

The upper gear is adjusted by shim between the saddle and apron.

15/01/2021 01:16:45

PS. Looking further at the pictures in the original post , it does appear that perhaps the original gears were throated worm gears made with the curved tops on the teeth for better engagement. The lower gear seems to have the same curved tooth tops so seems to be possibly original? Perhaps the new ones available today are made as the cheaper to manufacture straight variety?

If that is the case, then definitely try shimming between the apron and saddle to get fuller gear engagement. I know I had to put shims in that location on my ML7 to get the best engagement of both halfnuts and rack gear.

 

Edited By Hopper on 15/01/2021 01:19:54

Thread: What is it?
15/01/2021 01:00:17

Plans for a similar 4 facet drill sharpening jig were in MEW a good few years ago. Might be in the index online.

Thread: Myford ML10 main screw skating
15/01/2021 00:36:36

If you wanted to squeeze the last life out of those gears without buying new, you could possibly put a shim between the apron and saddle so the upper drive gear is moved down lower and thus closer to the leadscrew for better engagement. Then replace the worn lower gear with an oversized Delrin roller, as all it does is stop leadscrew deflection so does not need to engage teeth for any reason. YOu would then have to adjust the half nuts to engage in the new position.

It would be worth checking that the bolts holding your apron to the saddle are tight. If loose they could be allowing the whole apron to tilt, making the drive gear a loose mesh with the leadscrew, which could be the cause of the worn tips on the gear in the first place.

If you buy new gears, it would be worth shimming the apron so the new gear engages to the full tooth depth to avoid a repeat of the problem..

Thread: It Is A Steam-Engine... Using the term loosely
15/01/2021 00:15:32

And solar is only one, probably minor, source of ground heat. Heat from the earth itself is obviously huge. Will it flow quickly enough to replenish the cooled garden area? Obviously it does on the many of these systems in use. It would be a matter of correct design for the ambient conditions with a large enough area cooled, suitable depth etc. And as previously pointed out, even if the ground were to become frozen, there is still heat to be extracted until it gets down to minus 493 degrees.

Thread: Coronavirus death stats
15/01/2021 00:04:49

I guess next time we want to know how to silver solder a copper boiler or screwcut a lefthand internal Acme thread, we should ask an epidemiologist. As the model engineers seem to know more about Covid-19 than the medical specialists, the reciprocal must obviously hold true.

Thread: It Is A Steam-Engine... Using the term loosely
14/01/2021 03:19:41
Posted by Nigel Graham 2 on 13/01/2021 21:42:18:

Recently my local paper gave a splendid diagram showing how the heat is harvested for a household ground-heat pump: fluid circulated through a large array of pipes at shallow depth below the garden. I thought, unless I am missing something, you need only school-level physics to see the obvious flaw.

'

 

Its possible the engineers who designed and developed these systems know more about it than can be gleaned from a newspaper diagram.

Even if the ground were frozen solid at that depth at 32 degrees F, there is still plenty of useable heat available to be extracted by a heat pump system. It works the same way the refrigeration system on a freezer locker works. Heat is extracted from the freezer, where the temperature is already sub-freezing, usually around 0 degrees F, and then blown out the back of the refrigeration unit as hot air. Check it out at your local supermarket next time you are there. Massive amounts of heat being dumped overboard after being extracted from their freezer cabinets and coldstore rooms.

That's basic physics.

So the ground in your garden could be 0 degrees F and still provide heat via a heat pump to warm your house.

But unless you live on the Siberian tundra where there is permafrost down several metres, it's unlikely your garden beds will get anywhere near that cold below the surface.

People make the mistake of thinking ice is cold. But it's not really. Anything above absolute zero (minus 459 degrees F) contains heat energy that can be extracted. So ice at around 0 Farenheit is quite toasty stuff, relatively speaking. And ice at close to 32 Deg F is just about tropical. The Innuit build houses out of it to keep warm.

 

 

Edited By Hopper on 14/01/2021 03:24:58

Thread: What nut and bolt material?
14/01/2021 02:43:31

Stainless certainly will resist corrosion better. But too much bling can look overdone. I see over restored classic motorcycles full of stainless fasteners quite often and they don't look authentic.

Gun blueing or chemical blacking or Parkerizing etc of mild steel fittings might look more in keeping perhaps? Kits are available. 

But its your engine so go with what you prefer. It is the kind of model that lends itself to bright work so stainless might fit right in if that is what you like.

A bit of Never-Seize on stainless threads helps minimise galling between stainless-on-stainless which otherwise can be a problem. And stainless can be a bit difficult to machine or cut threads on because it tends to work harden so be prepared for that.

 

Edited By Hopper on 14/01/2021 02:50:12

Thread: Myford ML7 mainshaft
13/01/2021 11:30:46
Posted by Ben French on 13/01/2021 02:09:53:

Hi All,

Similar problem here, my ML7 has too much spindle play up and down, I've run out of shims to remove. I could buy a new spindle and bearing set from Myford for 300 quid which apparently also requires bearing-scraping to work well. I was thinking alternatively, seeing as there's plenty of thickness left in the bearing shells and both they and the spindle are in good condition, could i just skim of a very small depth from the mating surface on the top bearing shell where it meets the bottom bearing shell, so that it once again properly grips the spindle? I guess the bearing cap mating surface might also need the same amount removed. This could be done easily on my milling machine.

It might also be possible to place a very thin shim between the the upper shell and cap, so long as it has an oil passage.....

thanks

The traditional method is to do as you first suggest, machine (or file) a suitable amount off the flat mating surface of the bearing cap and bearing together  so they can come down further. Ideally machine enough off so another full stack of factory shims can be inserted (only about 20 or 30 thou I think from memory) so you have a full range of adjustment again as you peel off the 2 thou shim layers. Ideally you might need to do a little light scraping of the bearings too to get full contact. The bearing white metal is plenty thick enough to do this. Well over 100 thou thick from memory.

I would not try putting shim between the top of the bearing shell and the bearing cap. It will make the bearing a loose fit sideways, ie toward the mating faces of the bearing cap and thus allow movement of the spindle anyway. When fitting similar type bearings and even bushings to heavy machinery at work we used to scrape the outside of the bearing to a good all-over contact fit into the bearing housing before even starting to scrape the inner diameter to match the shaft. It is just as important if you want a top notch job done.

Edited By Hopper on 13/01/2021 11:33:44

Thread: Myford ml7 about to buy
12/01/2021 10:41:28

The main bugbear is wear on the bed. Measure the thickness of the bedways about six inches from the left hand end compared with the unworn part next to the tail stock. If more than about 3 or 4 thou it will need an expensive regrind. Same applies to the width of the bed ways. Although, if it's early model, you may be able to salvage it with a wide guide conversion, on which there have been previous threads.

Headstock bearing wear is common and can be felt or measured by yanking the chuck up and down or side to side by a bar held in chuck jaws. More than a thou or so of movement requires the removal of some shims from the bearing halves. Or if excessive, some rescraping might be needed.

Be aware the cost of tooling and changegears can equal the purchase cost of the lathe if you are not careful. If you are getting it genuinely cheap, all good. But often it works out better to buy one with the gears and tooling as a job lot. If you go down that road, be aware too that often very nice Boxfords and Raglans are cheaper than Myfords and are better machines.

Edited By Hopper on 12/01/2021 10:44:02

Thread: Nitrogen as an Energy Store ...
12/01/2021 10:33:24
Posted by Michael Gilligan on 12/01/2021 10:10:28:

A little more information, to fuel the discussion:

**LINK**

https://www.rechargenews.com/transition/work-starts-to-build-worlds-first-commercial-liquid-air-energy-storage-plant/2-1-908259

MichaelG.

That's the plant I was thinking of. Same principle as the gent's engine in the OP but not on a transportable scale.

I read somewhere that to super cool nitrogen they use either cryogenics or a reverse cycle Stirling engine. Not sure how that would work?

12/01/2021 08:57:40

Turns out the first nitrogen powered car was made in 1902 in the USA and ran at 12mph. Flying for its day!

So Dearman's idea is not a new invention. But I think what is innovative is its combination with refrigeration to make use of the latent heat absorbed in converting the liquid nitrogen into a gas. Which the journalist does not really make clear.

But what happens if the fridge compartment is already cold enough? Run atmospheric air through it? Any humidity condenses and forms frost on the exchanger? According to wired.com they were getting ready in 2016 for a trial with some supermarket trucks. But no further word...

12/01/2021 03:35:52

Hardly an original or unique idea. I'm sure we had a forum thread recently that included a drawing of a proposed nitrogen power station, full sized gigawatt type thing. Based on sub-cooling nitrogen via refrigeration with cheap green power when it was available on sunny windy days etc then releasing the liquified nitrogen to drive turbines and the like when extra power was needed on cold windless nights etc. Perhaps someone with better search skills than mine can find it. Seemed like it was getting ready to start construction?

This latest story seems a typical example of a technologically illiterate journalist waxing lyrical over some old git in his workshop with a dream project that the rest of the world has discovered and discarded for various reasons, including probably the practicalities of producing, storing, shipping and dispensing liquid nitrogen.

Our local paper used to run a story every year or two about the locally made Lutec 1000 generator that was claimed to produce more power than it took to run it and included all the usual perpetual motion speak of motors driving pivoting magnets and then the increased power driving generators etc. LUTEC FREE ENERGY

500 per cent efficiency, the Cairns Post journalist reports. 500 per cent compared with a car's 40 per cent!!! Scientifically radical, to say the least, but it never stopped the journalists -- who majored in English not Science -- from spruiking it year after year in breathless terms about saving the world etc. You could plug it into a wall outlet in your house and produce enough power to run the whole suburb etc etc. Saaaay whaaat?

I don't know if their investors, impressed by such reports no doubt, ever got their money back let alone a dividend.There were, apparently, millions to be made but it seems to have dropped from sight.

Not that old mate in his shed with his nitrogen engine is perhaps the same thing but the willingness of journalists to take the word of a lone old git in his shed against the scientific and industrial establishment's is the same.

Edited By Hopper on 12/01/2021 03:39:56

Edited By Hopper on 12/01/2021 03:41:31

Thread: Chuck backplate error
09/01/2021 01:00:15
Posted by Anders Be on 08/01/2021 19:00:53:

I like to add a smal aditional question I'm thinking about: How does the clearance affect the bending stiffnes of the chuck (i.e stiness from the moment arised on the chuck from the cuting force).

Best regards

Anders B

It doesnt have any effect.. The thread rides up on the V form of the thread and against the register face on the spindle and stays there under normal cutting forces. It is best to have some healthy clearance on the thread to make getting the chuck on and off in a swarfy environment easier. (Is swarfy a word?)

Thread: Myford MF74
09/01/2021 00:54:39

There was a thread on here recently about somebody had one. Look like a nice machine. Would have been more expensive than the M-type of the day or the later ML7 so were probably well cared for.

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