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Monday, 28 June 2010

Turning Time

Last Thursday we stopped bench fitting in Workshop and begun learning turning on the centre lathes.  Unfortunately this only happened half way through Thursday, so I don't have much to show for it yet, however, it was really enjoyable as this is something I have always wanted to learn.  Of course, I used lathes at Paxman, but we turned everything using hand tools then and did some spinning too, so it was very different.  

To begin, we were each assigned to a lathe which we will use for the next few weeks.  Dave is teaching us the lathes, which I am pleased about as he takes you through it properly and thoroughly making sure you do a proper job. We first learned the anatomy of a lathe and each cleaned up our lathe so it was ready to go.  Next up was to start work so we learned how to centre the cutting tool at the correct height and what each control did, plus what speed we should be using etc etc.  We then learned two processes:  Facing off (this is creating a clean level end on the workpiece), and, turning the workpiece to a specified size (this is shaving material off the diameter until it is the size you want).  I turned my piece from about 46.xx mm down to exactly 43mm.  Check out these two links for a quick animation of what each process is 

Here are some photos of my lathe and the workpiece. 

 I'm really looking forward to this week as we continue on our workpiece and will learn more exciting processes.

Aside from workshop we have finally received some results for various exams and assignments.  I will email you all those.  Mostly pleased, although will want to improve on a couple by getting higher marks in the August exam, which will average out to the marks I'm looking for...

 Also, when I find out where I am going to sea, I will update you.  Hopefully I will find out soon!

Wednesday, 16 June 2010

Long time, no sea.

For anyody who actually reads this: sorry it's been so long without an update. In fear of writing just a few words, or sitting on here for hours when I should be working, I have not logged on at all. 

So, I'll try to give a brief overview of what's happened including lots of photos. In short, we've been working a lot, mostly in the evenings, but at weekends too as we are in 9-5pm everyday and there are various assignments and exams that have to be done around this. 

The subjects we've been studying are thermodynamics, mechanics, engineering drawing, marine legislation and management principles, and work based learning. Mondays and Tuesdays are pretty horrific including the mechanics and thermo marathons, followed by the engineering drawing. It is difficult to concentrate and learn continuously for so many hours! So aside from all this paperwork, we've been doing the normal two days a week in workshop.  One of the major workshop courses I covered during the time was the powerplant course.  This covers what we actually do at sea such as looking after engines, purifiers,  pumps, valves etc etc.  Photos of valves from previous entries are from the same part of the course.


Studied centrifugal pumps and performed experiments on what effects wear rings have on pumping rates...

Pump below

Impeller of the pump having been taken out of case.

We've dismantled a two stage reciprocating air compressor and measured the crankshaft bearing clearances...

Maidstone Chris (before his accident)

Fools at work

Cylinder head taken off.  On right is wide cylinder in which 1st stage of compression.  Then the air gets cooled and compressed again.  Second stage of compression is carried out by the smaller bore (thinner) piston on the left (shown sticking up out of the main block).  

Easier to see both cylinders in this photo.

View from the side of the crankcase (bottom part of block).  Silver bar that goes across is the crank.  Attached to this are two connecting rods.  Each one connects to a piston (1st and 2nd stage compression pistons).

 Why you shouldn't ride bikes under the influence...
(Maidstone Chris)
  He's now fully recovered.

We've studied steering gear - this is a small setup shown.  They can be absolutely huge.  This is hydraulic ram type steering.  It is controlled by a very cleverly designed radial piston variable delivery pump.  We took one apart, and I think that whoever invented this was a bloody genius!

 We also studied boilers in workshop and Marine Legislation Principles.  This is a safety valve from a boiler.  VERY IMPORTANT.  If something goes wrong in the boiler then these are life savers.  If the boiler malfunctioned and these didn't work then your ship could be blown apart by the explosion from the boiler.

This was my drawing assignment.  We had to do a freehand sketch of a valve.  Luckily we were allowed to use ruler for the title block and border!  Real photo shown below so you can compare.  I haven't had the mark back yet...

We've studied and distmantled purifiers.  These are generally used to separate water and contaminants from oil,  or to separate fuel and water mixes.

Looking into the purifier after running and then opening it.

This is the plate stack from inside.  There are lots of plates stacked up and the dirt from the oil get left on them.  We only ran the purifier on for a couple of minutes and you can see how much dirt has accumulated already!

We've covered 1st and 3rd Angle projection in Engineering Drawing.  And we've had an exam in it too.

 We've worked on the biggest engine they have in the workshop.  This engine used to run a big centrifugal water pump at a water pumping station.  It's a diesel of course.  It's also tiny compared to some of the engines we could work on at sea.  They go up to three storeys high on the biggest container ships, with piston bores of about 1m!!!

 We took crankshaft deflection readings (these show if the crank is straight or bent).  To get an idea of how accurate these are, the deflection we measure was about 0.2mm across the whole crank.  We also removed the cylinder head and a piston.

 I look a bit distracted here...

Looking into the crankcase

Perspective of size.

Looking into the oily sump.  Crankshaft deflection guage is in between crank webs.  You have to use a mirror to see what's on the guage. 

An unexpected bonus was finishing the powerplant course with time to spare.  This meant we could reset the tappets on the Gardner diesel engine.  This was really fun as it was a smaller high speed diesel (only 170horse power).  A bit more like you would get in a car, only this is the kind of engine you would find in a motorboat.

That's pretty much it for now.  I finished my male and female fitting plates in workshop today so I was very happy about that, as they have taken me ages - my perfection has been a source of amusement for the others.