Member postings for Chris Gill

David, Jason - many thanks. I read that lot three times and still missed it! And now for my next screw-up ...

Hi all

I've only just installed A3D but I've made it through the on-line tutorial (that 100-page PDF) and the first two parts of the MEW series. In part 3 I keep hitting a problem.

After creating two circles and three lines I created two tangent constraints and a dimension followed by trimming the excess off the lines. That leaves me at figure 7 but when I try to deactivate the sketch or extrude it, I get an error saying there are open loops. Selecting the "open loop" in the list of errors highlights the intersetions between the horizontal lines and the outer circle. I don't know if it matters but the tolerance is shown as 0.01mm.

So far I've tried three times without success. Does anyone know what I'm doind wrong?

Thanks

Chris

Just to prove nothing goes to waste ...

Here's my rendering of Andy Johnston's headstock handwheel (MEW Autumn special). All materials from stock and the piece of wood was left over from making a new seat for a commode. It could have given someone a nasty surprise if I'd left all that metalwork attached!

Sorry if I didn't reply to some of the suggestions - I had a couple of days away. Not a nice jaunt though - crammed into a corner trying to do a decent job of plastering around a load pipes without sticking my foot in it or plastering myself!

As always, something I thought was a simple job turns out to have many more aspects to it and I'm really grateful for the wealth of knowledge people are willing to share.

I used a light oil as a lube so that it wouldn't gum up but I never thought about how it handles pressure. OK, lesson learned, I'll add something better to my shopping list.

Given my uncertainty about the tap, I've got a decent set on the shopping list as well. I only had the one but all the others have worked well for years.

I drilled the hole with 8 then 8.6 (Dormer precision drill) and later 8.7 so I'd expect the hole to be very close to 8.6 / 8.7. I don't think my tap was off-axis but I'm perfectly capable of fouling it up! I've seen a drunken thread before, courtesy of yours truly.

Chris

Wow, thanks all. As ever, some real food for thought.

Just to respond to one or two - the work was in the lathe chuck and hadn't been moved since drilling and the tap was lined up in the tailstock. Although I said it was a taper I was wrong - it was a general purpose tap (shorter lead). I lubricated with 3-in-1 (always seemed to work in the past) and I always reverse at least once per turn (depends on tap size)

As for scaffolding ... I once had a Landrover serviced and some idiot used the wrong torque on the wheel nuts. I couldn't shift them so I went back and complained. They couldn't shift then even when warmed up with an oxy torch so they sent me to the nearest lorry service place. They simply attached a socket and bar, a long length of scaffolding and then jumped up and swung on it until the nuts came loose.

Aha! Didn't think of the blunt tap option - just assumed it was good. Sadly my grinder is just the off-hand type with wheels that tend to pummel things into submission.

I'm really hoping the 20mm-deep hole is straight, otherwise I've got serious problems. Though I can see the logic of that with much deeper holes.

Thanks all

Hi all

I was trying to tap a through hole with a 3/8" UNF tap but it got stuck half way.

The material was a bit uncertain but probably EN8 or similar (based on spark tests). The tap was an HSS taper tap, the pilot hole was 8.6mm (about 70%) and the hole was supposed to be about 20mm right through. But after around 11 or 12 mm of reasonably easy progress it stuck and was difficult to withdraw.

I'd already backed it out and cleaned it once and no end of cleaning made any difference. I tried opening the pilot hole to 8.7mm but it didn't help much.

My thread gauges agree the tap is 24 TPI (though they aren't as long as the tap) and a 3/8" bolt went into the hole easily to a point. I wondered if I'd managed to work harden the steel but it turned, drilled, knurled and parted quite nicely.

When I set the tap against a bit of threaded bar I discovered that there was a tiny discrepancy that looks like the tap is fractionally less than 24 TPI.

To my mind, if the tap isn't quite right it should go through the hole and the bolt should get stuck.

The tap is part of a set I bought years ago (UNC, UNF, MC, a few MF and others). This might be the first time out for this one but the others have been brilliant.

All I can think is that the pitch changes slightly along the length of the tap but is that feasible? Or have I missed something blindingly obvious?

Thanks in advance ...

Hi Bandersnatch

The series started in ME 4383 - 30 July 2010 and ran through to the end of the year (4383, 4386, 4388, 4390, 4392, 4393 and 4394). Have fun

Chris

Thanks all

Geoff - it needed a good head magnifier, which meant I kept crashing into the lathe chuck (no milling machine)

Neil - I'm intrigued already. I guess I don't have long to wait

This little engine was certainly a challenge, not least because of the frequent need to make another tool. Still, I learnt a lot and probably swore just as much, especially when a tool jam shattered the first crank shaft. Thanks to Mogens for the original series.

Here's a link to a short video and a few pics .

Can you spot the crank shaft template in the above pic - I made it from my old corporate Amex card!

My favourite claim to stupidity involved a 14lb sledge hammer and a washing line. Unfortunately, I only remembered the washing line when I was face down on the lawn with a bruise on the back of my head. Didn't do that again

Hi Stew

Thanks for the PM.

They've been interesting projects - my first two engines. Which means I've been learing a lot and making all the usual mistakes (I assume). I was thinking about a half-beam engine next so number three looks spot on.

Thanks again

Chris

Hi Stew

I finally finished all the painting and reassembly. If the real thing ran at the speeds I got out of this little model it would have torn the building apart! Here's a pic you might like (not got to grips with posting to YouTube yet - strange the skills you have to acquire to get into engineering).

Incidentally, you mention a third engine in the series - did it ever get published? Thanks

Hi Stew

Will do - it's stripped down for painting at the moment so it'll be a few days

It runs! Just got to make a nice base, clean up and paint it.

The first attempt ended with a loud bang. Then I realised I'd connected to the unregulated side of the compressor and the short connecting pipe had migrated to the other side of the garage. Ho hum

Thanks Jason

Everything I came across seemed to suggest veneer was shipped flat so it's good to know it can be rolled for delivery. My remaining stock is very old (inherited) and crumbles when bent much

Last year I was asked to make a toy box for my grand-daughter and, as usual, I got a bit carried away with the project (interlocking drawers, nice bit of inlay, ...)

Then I discovered how hard it is to get old style veneer at a sensible price (yes, there is some but it all seems to be 3m lengths by 0.5mm thick. Ooh, posty's going to love that!) So I bought some iron-on, self-adhesive stuff that comes in rolls and is 250mm wide by 2 or 3m long.

The trouble is, it shrinks when applied and it's a devil of a job keeping edges straight (I needed three widths). The advice is to iron on the first piece then stick the next piece to it with old-style gummed parcel tape. But that doesn't really allow for inlay so I cheated.

I finished the veneer on the whole box and spent ages trying to wash off the gum from the tape. Then I traced the outline of the result I wanted and very carefully cut along the lines so that I cut all the way through the wood grain. After that, using the end of a pickle stick which I'd filed to a spatula I applied stains to the different areas. It took quite a while but the result was worth it.

I ought to admit I practiced a lot before the final version and I had lots of mis-shapen owls in the firewood box.

In case it's of any use to others, it can be done.

Love the picture.

This is the same technique we used when photographing large underground chambers in my caving days - camera on a tripod, B setting and a caver wandering around with a manual flash gun.

Much better than one of our club members who tried to do it the old way with flash powder and filled the main chamber of Gaping Gill with smoke (that's about the volume of St Paul's Cathedral)

I once saw something similar done in a pipe mill in the North-East (UK, that is). They had all the modern gear for the time (1970s) - X-ray machines, pressure testing and so on but they admitted they had no way to ensure that a pipe was truly round, as required for very high pressure work.

So they employed one little old man who was well past retirement and he spent his days walking up and down the pipes wearing heavy boots on his feet and carrying a sledge hammer over his shoulder. If he didn't like something he hit it. And they never had a complaint.

Sadly most of those industries are long gone.

I regularly curse the fact that I can't simply turn round and ask one of my engineering forebears why things just went wrong. There are loads of really sound tips and hints in the magazines (ME & MEW) and the forums but if it could, somehow, be gathered together I might not make so many mistakes. In other words, yes to the original question.