Tag Archives: technique

Fuel Tank, Mast Structure and Galvanizing

This is a hotchpotch of notes on progress we have made in the last few weeks.

I am now focusing my attention on the internal fit-out. We need to get Befur in a state to move her on a trailer to our new home in Cumbria in August, this is adding some needed pressure, to ensure we get everything done in time… Continue reading

Oh Mill, heal thyself – and pump progress

The last 2 weeks have been devoted to two topics:

  • Getting the new mill into service &
  • Completing phase 1 of the pump drive for Befur’s engine.

The New Mill

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Retirement Beckons!

A change of pace and circumstance

Well it seems I have not posted since November and the arrival of Befur’s trailer. Since then a lot has happened (so Happy Xmas, and Happy New Year)… I have had the fortune to be made redundant, and have (with Louise’s kind support) agreed to turn that into retirement – so from the end of February there will be no more working interruptions, and as I am only “on call” now, progress should be faster. So with the shingles finally subsiding, and hopefully the last of the winter colds and the left shoulder starting to free up,  there can be no more excuses – so 2015 looks bright indeed 🙂 Continue reading

Connecting Rods & Big Ends

The connection rods were a nice between-centers turning job, and then a selection of milling set ups.

Rather than write a lot, I will put some pictures below – the main thing to note was that almost all of the milling and boring was done with the partially machined big-ends attached to the partially complete rod – in order to ensure a good level of concentricity….

Nice New Main Bearings

As discussed in the last post, I decided to remake the bearings as drawn/described from  a solid Phosphor Bronze (SAE 660 aka Gunmetal) block – being as how I had needed to remachine the crank journals after assembly, and the first set of fabricated bearings were a bit “naff”..

So the first job is to cut the block in two (longitudinally) clean these two pieces into neat cuboids, and then soft-solder them back together for machining.

This time I decided to machine the bores first, and then mill the seatings for the housing by measurement from the bores – in this way you would be able to “guarantee” that the resulting bores all lined up!

Much more success!

One of the problematic things was how to measure the distance from the bore to the outer facing – this would need ball-faced micrometer, not something I had. After some thought this idea occurred: by hot gluing a ball bearing to the anvil (and remembering to subtract the diameter of the ball from what I measured) everything would be fine – and it was!

Home made ball-headed micrometer (ball bearing hot glued to anvil)
Home made ball-headed micrometer (ball bearing hot glued to anvil)

So  by first machining the back face of the bearing housing, and the bottom of the bearing housing to the correct dimension from the bore we knew that things would line up. Then the forward face could be machined to be a snug fit in the housing.

Lastly the top surface was machined to ensure the bearing keeps would provide a little “crush” when tight.

I cut everything to allow for a little hand-finishing (to make sure there was no slop), and then unsolder the two halves, clean up and try them on the journals – they were too tight!

But this was “kind of what I had planned”, so then fitting the bearings in place, and a few hours with the engineer’s blue and hand scraping we wound up with a crank fitted and turning pretty freely. (this description skips over the machining of the ends of the housings to provide for the correct end float, which was a bit “trial and error” – but all came out OK.

A slide show of the process…

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So Far So Good

Well I  have turned the first 7 sheets of chipboard into moulds and am half way there…

Paul (from SFD) clarified my confusion, I was thinking that the frames marked on the drawings were like the ribs on some of the pictures of his designs, just square and laminated onto undersized moulds – but they are full bulkheads cut away as needed to fit under sole and behind seats and lockers – at least I figured this out before I cut more than one undersize 🙂

plastic batten providing a smooth curve from the marked offsets

plastic batten providing a smooth curve from the marked offsets

Using the plastic batten to produce a smooth curve round the offsets from the mould drawings really works well, and has highlighted 2 or 3 occasions where I had miss-measured or mis typed a dimension, so hopefully we are going to wind up with a fairly fair jig!

The game plan is to a few 3/4-inch panel pins into key marks, and then pull the batten round… normally 3 or 4 are enough, and the fact that the batten will normally then automatically align itself with the other poinst marked from the offsets  from the plan show wat a good job SFD’s computers do in fairing the design.

clamps hold the batten in place, and a few panel pins set the line of the curve

clamps hold the batten in place, and a few panel pins set the line of the curve

The ally clamps just hold the batten down and stop it jumping out. Then when it’s all in place you just draw round it, pop it out, pull out the pins and break out the jig saw!

…and tonight Paul from the Castle of Comfort (my local) came round to help move the next 8 sheets of chipboard in to cut the rest of the moulds…

 

Sawing Straight (not)

Having clamped a pair of mould-half panels together, I figured I could just cut them out with a jig saw….

The "Offending" Saw - as always it's the bad workman who blames his tools!

The "Offending" Saw - as always it's the bad workman who blames his tools!

So off I set, slowly and carefully sawing along the line – 2 inches in I  encounter the first problem – there is so much dust I can’t see the line… At this point I engage “smug-mode” and pick up the shop airline, and with the spare hand blow the dust clear as I saw…

… I reach the end and discover (horror) that the b*&^&^y saw has cut at an angle to the vertical – and (double horror) this mis-cut has resulted in the lower panel being significantly undersize (we are talking about a ~5mm undercut!) grrrrrr….

I check the saw and the blade is square to the foot, so I am mystified…

A number of posts to the Selway Fisher Builders Yahoo group follow… (this really is a great group of people) and a deal of suggestions emerge within a few hours. These range from observations that cutting 1.5inches of chipboard in one go is too ambitious, thru to real Zen-like encouragement to chill more, take up a pipe and cut them with a Japanese hand saw – excellent!

So, I take some of my scrap chipboard (I just made a nice new bit of this) and draw curved lines and practice my sawing (by hand and other approaches) – including sawing it an inch oversize and improving my planing and surforming technique.

In the end two key factors emerge 1 – you cannot saw two at a time (you were right Graham) and 2 – I was going too slow! By setting the variable speed JigSaw to “flat out” and keeping my feed rate slow the desired results emerge….

The first three moulds - halves bolted together, showing the marking out

The first three mould-halves bolted together, showing the marking out (Nos 1,12 and 16)

I leave the workshop with three assembled and very “boat shaped” moulds – life is good again!