Great War truck Posted July 5, 2012 Author Share Posted July 5, 2012 We do not seem to have posted much of late – but the work has been carrying on just the same! In addition to everything else that Steve has taken on, he is also building two 7 1/4” Gauge Hymek Locomotives for our Model Engineer Society – that project has been going on for sometime and Steve would like to get that one finished now and out of the way so that he can concentrate on the Thorny - that has taken some of his “Thorny” time of late! All the planning with the “Thorny” engine has taken more time. In between bouts of household maintenance, Tony has continued making engine studs and these are all now finished so that we should have a clear run when the re-assembly of the engine commences. Today, just for a change, Tony decided to make the two main fixings for the clutch springs – the originals are bent and corroded. This is just a simple turning and threading exercise. The first picture shows the clutch assembly – notice that the picture was taken nearly a year ago when we started to take the engine to pieces and you can see the original parts in situ with Steve gently attacking one of the nuts with a hammer and chisel! They are 7” in length overall with 1/2” and 5/8” Whitworth threads at the ends. The main diameter is 1” and they are machined out of 1” steel bar. These three pictures show the embryos taking shape. The threads are screw cut in the lathe to about 4/5 of the depth of thread and the last bit then finished with a die. The 1/2” threads are done but the 5/8” threads will be a “tomorrow job”! Quote Link to comment Share on other sites More sharing options...
Great War truck Posted July 6, 2012 Author Share Posted July 6, 2012 Finished! Well that bit anyway. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted July 7, 2012 Author Share Posted July 7, 2012 When we took the engine to pieces, we knocked out the eight valve guides – we found that those for the four Inlet Valves were still in good order and would live to fight another day. But the four Exhaust Valves were badly worn so that the valves were running very sloppily within them and that they must be be replaced. It was interesting to note that one of the four Exhaust Valve guides was quite non original – it was much shorter and had obviously been cleverly repaired at some time as it appeared to have split long ways and was brazed up along the length of it and filed round so that it would fit in the cylinder block again. The replacements are being turned from 50mm cast iron bar – a fairly straight forward turning exercise again. The outside diameter of the part which push-fits into the cylinder block is 3/4” plus one thou – and the replacements are being machined to an identical diameter. The other various measurements and diameters are being copied from the originals. The valve stems are 3/8” in diameter – new valves will be required and the new guide was drilled in the lathe to 1/32” under 3/8” and then reamed through with a 3/8” reamer. After that was done, the embryo guide was turned around in the chuck so that the other end could be machined to its finished size and shape. Three more to do! Quote Link to comment Share on other sites More sharing options...
Enigma Posted July 8, 2012 Share Posted July 8, 2012 And again I am amazed by the craftsmanship! Quote Link to comment Share on other sites More sharing options...
Asciidv Posted July 9, 2012 Share Posted July 9, 2012 Why just one thou oversize? Obviously a rule of thumb, but was it a Devonian thumb, or a Midlands thumb? Best wishes, Barry. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted July 9, 2012 Share Posted July 9, 2012 Why just one thou oversize? Obviously a rule of thumb, but was it a Devonian thumb, or a Midlands thumb? Copied from the original so I guess it was a "Basingstoke rule of thumb" - but copied in Devon! There was some thought that there should be two slightly different diameters on the outside so that they would slip in easily on a smaller diameter to start with and then tighten up on the slightly larger diameter as they were pushed in - but the originals were a constant diameter - and so are the replacements. Do you have other thoughts about this and is the "rule of thumb" in Geordie Land quite different? Tony Quote Link to comment Share on other sites More sharing options...
Sean N Posted July 10, 2012 Share Posted July 10, 2012 All I need now is a source of Loctite 620! Steve Should be able to get this at most bearing and power transmission / industrial fastener suppliers. If you're struggling shout and I'll try my local people. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted July 11, 2012 Share Posted July 11, 2012 Thanks Sean. For some reason, 620 is harder to get than most. Dad is investigating leads at the moment but we may be back! Steve Quote Link to comment Share on other sites More sharing options...
griff66 Posted July 11, 2012 Share Posted July 11, 2012 loctite 620 twenty quid from states ebay Quote Link to comment Share on other sites More sharing options...
Sean N Posted July 12, 2012 Share Posted July 12, 2012 Steve, I can get that 620 for £95 for a 250ml bottle (RRP £143), and they'll send to you FOC. It'll take about 2-3 days from order. Just let me know if you need it. Cheers, Sean Quote Link to comment Share on other sites More sharing options...
Old Bill Posted July 12, 2012 Share Posted July 12, 2012 Thanks Griff. I hadn't thought of EBay and that is the best price yet although they may be a bit cagey about posting it. Thanks Sean, that is the best price I have seen for the big bottle. Any chance they could supply a 50cc bottle instead? Sorry to be picky but I am going to have an awful lot left on the shelf otherwise! Many thanks for taking so much trouble. Steve Quote Link to comment Share on other sites More sharing options...
gritineye Posted July 12, 2012 Share Posted July 12, 2012 (edited) Be careful buying Locktite products off Ebay, they are often very near their use by date, OK for most uses if used straight away, but in your case any deterioration in the products performance could possibly cause you grief in the future. Some sellers state the u b date, others may not, so worth checking. Edited July 12, 2012 by gritineye Quote Link to comment Share on other sites More sharing options...
ferret1958uk Posted July 12, 2012 Share Posted July 12, 2012 Thanks Griff. I hadn't thought of EBay and that is the best price yet although they may be a bit cagey about posting it. Consider trying Amazon then! Several automotive suppliers in the states sell it for around the same price. They will post to the UK. Example: http://www.amazon.com/Loctite-38652-Temperature-Bearing-Bottle/dp/B00070LQWE Quote Link to comment Share on other sites More sharing options...
Sean N Posted July 13, 2012 Share Posted July 13, 2012 ... Any chance they could supply a 50cc bottle instead? Sorry to be picky but I am going to have an awful lot left on the shelf otherwise!Steve Steve, it seems only the 250ml is listed over here - that might be why all the suppliers that list the small bottles are in the US. There does, as the guys have said above, seem to be plenty of choice for US suppliers though. How much do you think you might use - and are you likely to need it in the future? Just thinking if you have to pay £20 for a small bottle plus maybe the £20 carriage from the states that some suppliers want, you're over half way to buying the larger bottle anyway. I don't think Amazon will ship to here free from the US. Another alternative might be to find it surplus (though beware long out of date stock) - the NSN is apparently 8040 99 225 4168 ' Adhesive, Cylindrical Retaining' Quote Link to comment Share on other sites More sharing options...
Great War truck Posted July 13, 2012 Author Share Posted July 13, 2012 The four replacement valve guides were completed today and they are now ready to fit. The cylinder blocks are with a friend at the moment who has a big CNC Mill and he has kindly agreed to machine the liner rebates in the bottom of the blocks for us – rather too much for our modest machinery! Steve is on the point now of ordering the four liners after deciding the final measurements, checking them and then checking them again to make sure that we have them correctly. At something like £130 each before the “add-ons”, we do not want any mistakes! All four cylinders, thankfully, have come out at an identical size after being re-bored. I will post pictures of the Blocks as soon as we get them back so that you can see what has been done. So onto the next job. We started to machine the Valve Caps a few weeks ago but they were temporarily put to one side where there were other more pressing matters. The Caps for the Inlet Valves are quite different from the Exhaust Valves – the inlet ones were virtually finished but the flange on each of them has to be machined back to leave two “tabs” remaining on each which will lock into the tops of the cylinders. Only one Exhaust Valve Cap was started and now we get on with the remaining three – all to be machined from cast iron bar. Again, similar machining is to be done to the flange to leave two tabs on each of these so that they can be locked into the cylinder top. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted July 21, 2012 Author Share Posted July 21, 2012 The machining of the eight Valve Caps has now been mainly completed – the only job left to do on them is to machine the flanges back to leave securing “tabs” on them. Quote Link to comment Share on other sites More sharing options...
alixcompo Posted July 24, 2012 Share Posted July 24, 2012 Truly inspirational stuff. Fantastic. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted August 22, 2012 Author Share Posted August 22, 2012 We collected the cylinder blocks yesterday following the cutting of the recesses at the feet of the bores to take the flanges of the cylinder liners – so that the liners will lock in. A nice clean job made of it by another of our good friends, Andy who is tooled up to do it! The four sets of new piston rings for the intended reduced bores of 4 1/4” (instead of 4 1/2”) have arrived – we are now ready to order the liners. We delayed doing this as Steve who has done all the calculations over limits and fits wanted to be really sure that he had got them right but says that he is really confident now! Another job coming on is to make a pattern for the new pistons and get them cast. With the re-assembly of the engine now being thought about, it was decided that it would be a good idea to clean up and paint the rear of the flywheel at this stage as that would be difficult to get at when it is back on the engine. It was quite rusty and has been cleaned up with a fierce rotary wire brush, washed down with cellulose thinners and then given a coat of Bondaprimer. One part of the rim of the flywheel is quite pitted and presumably that part of it had been sitting in the ground for many years. It will not effect performance. The flywheel showing parts of it before and after the wire brushing. Another coat of Bondaprimer tomorrow – then we can think about Undercoats and topcoats! Quote Link to comment Share on other sites More sharing options...
Asciidv Posted August 27, 2012 Share Posted August 27, 2012 We delayed doing this as Steve who has done all the calculations over limits and fits wanted to be really sure that he had got them right but says that he is really confident now! Steve, to what accuracy do you believe the cylinders have been bored to? Have you tried to measure them? How concentric do you think the recesses are to the main bores (although in this case this isn't really critical)? Do you know how your friend set up to find the centre of the bore before cutting the recess? Another mystery to me that you can perhaps explain is how do they set up the boring bar to the centre of the cylinder when what they are presented with is often a bore which is oval with non-symmetric wear? Barry. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted August 27, 2012 Share Posted August 27, 2012 Another mystery to me that you can perhaps explain is how do they set up the boring bar to the centre of the cylinder when what they are presented with is often a bore which is oval with non-symmetric wear? . Barry, You will find generally that the extreme bottom part of the bore does not suffer too much wear and so it is the most likely place to centre on. Quote Link to comment Share on other sites More sharing options...
mattinker Posted August 28, 2012 Share Posted August 28, 2012 Steve, to what accuracy do you believe the cylinders have been bored to? Have you tried to measure them? How concentric do you think the recesses are to the main bores (although in this case this isn't really critical)? Do you know how your friend set up to find the centre of the bore before cutting the recess? Another mystery to me that you can perhaps explain is how do they set up the boring bar to the centre of the cylinder when what they are presented with is often a bore which is oval with non-symmetric wear? Barry. As Richard says, the bottom of the bore doesn't wear much. The top of the bores, above the Piston Ring travel should have no wear. This area is one of the places that carbon can build up indicating that nothing is in sliding contact. You can feel cylinder wear with your finger nail, sliding up the bore. This is the first thing I do when I take a Cylinder-head of, to have a rough idea of the cylinder state. Regards, Matthew PS Nice to have a "Thorny post" glad to see your back at it! Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted August 28, 2012 Share Posted August 28, 2012 Re. Flywheel rust pitting: How confident are you that balancing will not be adversely affected by this? I only ask because I have no idea how sensitive engine running is to out-of-balance forces, and therefore how critical precise balancing of the flywheel is! Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 29, 2012 Share Posted August 29, 2012 Steve, to what accuracy do you believe the cylinders have been bored to? Have you tried to measure them? How concentric do you think the recesses are to the main bores (although in this case this isn't really critical)? Do you know how your friend set up to find the centre of the bore before cutting the recess? Another mystery to me that you can perhaps explain is how do they set up the boring bar to the centre of the cylinder when what they are presented with is often a bore which is oval with non-symmetric wear? Barry. Hi Barry. I am fortunate to have a bore micrometer (which I inherited from a Dunkirk veteran) and I have measured them all as 4.557" diameter in several directions and along the length of the bore. I then measured the mic with my vernier caliper and they agree so I am treating the dimension as gospel. I must admit that I am impressed with the consistency across them all. I have ordered the liners with a diameter of 4.555" + 0 -0.002" to give a clearance for the Loctite. In my limited experience, the bottom of the bore seems to suffer very little wear so I expect that he centered the boring bar there and relied on it being square to the bottom flange. The recess was milled on a CNC machine. The block was clamped to the table and the tool run up to contact one side, then the other and zeroed in the middle. This was repeated in the opposite direction and the recess machined out in two cuts using a carbide tipped tool. I have allowed a clearance of 0.005"-0.010" so the liner should just drop in. All I need now are the liners! Steve Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 29, 2012 Share Posted August 29, 2012 PS Nice to have a "Thorny post" glad to see your back at it! Yes, all been a bit slow recently. This having to earn a living really gets in the way! Steve Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 29, 2012 Share Posted August 29, 2012 Re. Flywheel rust pitting: How confident are you that balancing will not be adversely affected by this? I only ask because I have no idea how sensitive engine running is to out-of-balance forces, and therefore how critical precise balancing of the flywheel is! Insignificant and will make no discernable difference to it! Tony Quote Link to comment Share on other sites More sharing options...
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