Member postings for MW

The real death knell for taps is when the edges of the threads start to visibly round and peen over. It tends to happen after they've been used on harder materials.

But once that happens it's only worthy of the bin at that point, otherwise it just kind of "extrudes" the thread into the material rather than cutting, you can feel it's just too hard going to still be good. The ones you get individually like from tracys also tend to be better quality than the ones that come in sets.

For silver steel/carbon steel tool treatment, Tubal Cain (Tom Walshaw) "suggests 770-790C heating slowly and holding the temperature for one hour per inch of thickness. This may be followed by tempering to improve shock resistance (and reduce hardness).... Final light grinding will then produce a keen edge"

I admit I misquoted the time reference, but the other thing is if you were to hold the temperature for this long in a furnace of some kind presumably, then you'd be better off quenching in oil, because I'd imagine it would be much more likely to crack after being in there for a while.

You can quench in water of course but I would plunge straight down, hold it there for a couple of seconds, to allow a steam jacket to envelop the tool, which would retard the cooling slightly, perhaps just enough to reduce too much shock, then slosh it around from side to side so that it quickly cools.

Michael W

I've made a similar tap to Daves, except I did set the edges to one side and used 3 flutes rather than 4 to make an M8 tap, it worked fine enough with a bit of a shove to start because the angle was a little steep. I could've done with a sharper threading tool at the time I think or maybe feed in a little deeper. 

One thing I know now that I didn't know then is that from the workshop practice series on the tempering and hardening of silver steel that the temperature needs to be suspended for 40 minutes per inch of thickness for full hardness.

Michael W

Edited By Michael-w on 12/05/2017 22:52:20

According to the fireman at the scene,

Do I detect a model engineer niche for alcohol brewing equipment emerging?

Did you know the first petrol was made in an alcohol still, by collecting the distillate of tar from tar lakes, This "petroleum spirit" was highly favourable because whale oil was too expensive, and this drove the need for petrol. Although I presume the inventor never made another brew for consumption using the same still!.

So one could learn a lot and get a small tipple for your trouble at the end of it? Does anyone need a better incentive than that?

Michael W

Edited By Michael-w on 11/05/2017 22:39:10

I think it's just that engines are far more efficient than they used to be and therefore less waste product involved to be put into the atmosphere. No more black soot and white smoke coming out the back of the average family car.

With Gas, this is slightly different, CO is given off as a waste product from gas that has not properly burned off. The actual LPG gas itself is also heavier than air, which means it sinks to the floor but it also displaces the air if in a confined area. 

A lot of new gas fires come fitted with a safety mechanism which switches off supply to the burner if dangerous levels of CO are detected. 

I wont go into too much detail, as neil says never a good idea to talk about dangerous methods even if it is on the net. 

Michael W

Edited By Michael-w on 11/05/2017 22:31:33

Yep, they're still with us, and they continue to quietly work under the radar of most peoples imagination, I personally think the work they do is fantastic and definitely a big social circle and support group that many people are denying themselves, people can come together in ways they never imagined through this.

Michael W

I honestly think, if I can get around whether the scraping is genuine, the dinked appearance, it could be the basis for a workable machine and a good solid bed at that, as well as a leadscrew. A few touches over with a diamond file could remove any burring and raising on the damaged areas that might affect the play on the table.

If the price is right and you want to make a lathe then go for it.

Michael W

My only wonder is what on earth was going through his mind when he did that. I just can't picture how you could "accidently" do that. Maybe he was just gauging his girth, lol?

Michael W

Edited By Michael-w on 11/05/2017 17:53:44

This provision was clearly placed so that fitters and mechanics could repair and modify the car while it's off the road and presumably in an unusable state, that they can do this without breaking the law.

However, like you said, this does not mean it can be used without it. Usage being the critical part of the legal side.

Michael W

When you get a larger shot of that picture you can see it more clearly, when it's up close it just looked like emery buffing here and there, now you can see that it at least has the appearance of being scraped.

Having seen it like this, now i'd say i'd buy it. 

Michael W 

Edited By Michael-w on 11/05/2017 15:50:16

Is there a historical equivalent for a man in his shed? It seems to be a very 19-20th century phenomenon otherwise?

The anchorite and hermit seem to have desired the same kind of escapism. 

I like to think personally that Sir Isaac Newton has a shed of his own.

Michael W

Edited By Michael-w on 11/05/2017 13:39:10

If they're just saying it's damaged then fine but not as a "hand scraped" example, it looks more like hand scrapped.

Michael W

Ok I think I may have gotten to the bottom of this. and the problem isn't the scales it's me! or very likely so. My test couldn't get it to go wrong a second time so I am going with that verdict. Anyway, i'll show below..

This is the machine in question, You can see where the horizontal (x) scale is on the bottom front of the first picture, luckily that one and the only one, that required virtually zero mounting effort as the tapped holes just so happened to be in the right places, so it's all directly bolted to it. On my initial investigation, I noticed there was bit of play on the main scale body, but not an awful lot, after tightening up I couldn't get it to wiggle more than .05mm forcefully. So I ruled out that causing it. Backlash, if it could "somehow" affect the reading, wasn't the culprit either, I couldn't get the table to move by more than 0.1mm side to side, so that's nothing like a 1.5mm error. So I'm not left with a lot as to what could cause this so I decided to do a test.

(You can see why I call this machine "the frankenwarco" because the motor died sometime ago and it now uses a 750W 3 phase induction motor bolted directly to it. Believe it or not it's actually been a far better experience with this one over the original!)

Ok so I took a scrap piece of aluminium plate, big enough to get at with a ruler and plenty of space to run, ignore the mark on the metal in that picture, hence why it is scrap. And I basically repeated what went wrong before, I took a small centre drill 2.2mm Dia. or number 3 BS centre drill. drilled one hole, moved 10mm to the left including the diameter of the head of the drill, and did the same again to the right, to test the repeatability. In theory, this should give me exactly 10mm between holes either side.

Now just to make sure I used a ruler first, because my old tutor once told me, it cant tell lies and he's right, there's almost no way that scale is going to go anywhere, appears to be working. So now the Vernier test. on each side of course,

Bit of a blurry one but that is the Vernier as is clamped down on the edges of the holes, with a reading of near as dammit 10mm. So my scales appear to have passed the test, and there was no fault in my counting,always good to know, but so what went wrong the first time?

I'm not really sure, but I suspect that I wasn't actually on the centre of the centre bore, when I clocked it up, you see, I have a coaxial indicator but I think the head was set askew slightly, so it would read perfectly one side, and not the other and this would explain it, so my equipment is only ever as good as the operator, always be sure you're doing the right thing before you assume the reading is correct!

Michael W

Not a bristolian myself but they've got my full respect as someone from the home counties!

Theres the severn bridge ofcourse, very big piece of engineering there! But i'm not aware of any hidden gems... very near to cheddar gorge as well in that part of the country.

Michael W

Oh no Neil, not the MTM word, never say it three times in a row or it'll be bad luck for a month!

So what machinations does the New World Order have for MTM?

Michael W

I've got a Clarke too, AeroJet and you can probably measure whether it will fit, in my mind, I can picture that It will, but I know the shank of the repton is 10mm square.

The only difficulty you'd have is to adjust the centre height of the tool using shims to fit. In this particular circumstance i'd say you'd be likely needing to make your own radius turning tool from a design or pattern.

It wouldn't be too hard to modify a repton radius tool with a bit of creativity of reducing the shank size a bit since all of it is made from aluminium it's pretty easy to cut and re shape.

Michael W

It's probable that your both right, the cat was introduced and invented to filter the gases, to help the air quality and thus improve peoples lives.

However, it did put a sizeable dent into the number of people killing themselves using this method, it was fast catching on before they did this.

It's much harder to forcibly remove the catalytic converter then it was to just do the above. People may not be aware of it but part of the remit of law makers is to prevent harm to people where it is easily inflicted, whether the recipient intended to be harmed or not.

Suicide is now the most likely thing to cut men's life short, especially for under 40's and because of this, it is soon rising on the agenda, much in the same way the number of road fatalities caused a panic in the 80's and 90's.

Michael W

<Edit> I know this stuff is all over the internet, but having had to deal with the aftermath of suicide from different perspectives I'm acutely aware that it is not a good idea to post methodologies, no matter how simple or obvious they are - it 'normalises' suicide.. Best advice for anyone with suicidal thoughts is to contact CALM or the Samaritans. - Neil

Edited By Neil Wyatt on 10/05/2017 12:27:52

I bought a tool called the "repton radius turning tool" which seems to work satisfactorily, I did have to grind a hard edge of the mount so that I could swivel it the whole way round without fouling.

The tool uses a 30 degree or so carbide insert. The main benefit of it is you can accurately measure the size of the radius produced by using a ruler to see how far past the pivot point for either concave or convex.

All in all I would say it's well made, easily fits into a Dickson type adjustable tool holder and easy to master. However, for a very large radius then perhaps I would be better off to make a custom setup like Neil described above.

Michael W

I tend to use the more viscous molybdenum-disulphide for large threads into steels and for smaller threads I use the more liquid rock oil cutting fluid. Before then as a cheap substitute I used Vaseline!

Michael W

Oh, well my mistake, I thought that being a 2 pack It wouldn't be too deep a dent in the wallet.

Maybe you can flog them to someone as special, slow helix, negative rake wet mud/sand drills? 

Or how about this, they sell toffee hammers, why not a toffee drill?Just think, you can now fill your toffees with your favourite filling, or pretend a toffee has turned into a swiss cheese. 

Edited By Michael-w on 07/05/2017 22:31:49