Essex hot air engine from MyfordBoy's castings

Discussion in 'Engines From Castings' started by deverett, Jan 23, 2019.

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  1. Jan 23, 2019 #1

    deverett

    deverett

    deverett

    deverett HMEM Supporter

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    I've had the castings lying about for more than 3 years. As they are aluminium, I can't really claim that they have been waiting to be normalised. MyfordBoy did a very good series of videos on how to make the engine and it was after watching them that I decided to get the castings. They are of excellent quality, some other casting suppliers could learn from him.

    I met David Abbott (MyfordBoy) at the last 2 Bristol shows and both times he asked me if I had made a start, but meekly replied that it was on the 'to do' list. Conscience pricked, when I got home I blew the dust and cobwebs off the castings and made a start.

    There is no point in giving a blow by blow account of my work because I mostly followed MB's construction videos. All I have done here is to mention any major differences in my way of working. The squeamish might baulk at some of his methods, but using that rare commodity Common Sense, I have no issue with his ideas.


    Cylinders

    I smoothed the castings around the parting lines before mounting them in my 4 jaw independent chuck. MB obviously has more faith in the accuracy and holding power of his 3 jaw chuck than I do of mine. I was able to clock both flanges reasonably true prior to turning the extensions slightly oversize after drilling a centre hole to take the supporting revolving centre.

    1 Cylinder machining 1 (Medium).jpeg

    Once that was done, I put up the steady to hold the extensions while they were drilled, bored and reamed. Putting the revolving centre back into the extension end allowed me to turn them to the correct size. The extensions are supplied overlength and they will be trimmed down later on.

    2 Cylinder machining 2 (Medium).jpeg

    Before reversing the castings onto the faceplate, I turned up the 2 plug gauges required for the bores.
    The remainder was as per MB's video.


    Engine frame

    All pretty straightforward, really. I followed the video.

    6 Engine frame (Medium).jpeg

    Dave
    The Emerald Isle
     
  2. Jan 24, 2019 #2

    idahoan

    idahoan

    idahoan

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    Hi Dave

    Good to see this build, I too have a set of these very nice castings ageing under the bench. Looking forward to seeing your progress on this one.
    I built a full sized Essex hot air fan replica from Myers castings a number of years ago. Someday I hope to have the Essex engine completed to go along with it.

    Dave
     
  3. Jan 24, 2019 #3

    deverett

    deverett

    deverett

    deverett HMEM Supporter

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    Dave
    I remember seeing your Essex fan at GEARS. A very impressive piece although at the time I did not appreciate it, unfortunately.
    Dave
    The Emerald Isle
     
  4. Jan 25, 2019 #4

    deverett

    deverett

    deverett

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    Crankshaft bearing

    The extension was smoothed off before holding in the 4 jaw SC chuck. I didn't have the correct size reamer, so after drilling I used a boring head to get the correct size bushing hole, running the boring tool through a couple of times to work any spring out.

    3 Crankshaft brg machining 1 (Medium).jpeg

    Then over to the milling machine as per MB, but I did not have suitable clamps to hold everything like he did. Instead, I put a long bolt through the bushing hole to hold everything tight.

    To get the platform level, I had previously marked the leg in two places and used a height gauge on them to set the casting level.

    4 Crankshaft brg machining 2 (Medium).jpeg

    The platform really is horizontal!

    The rest was done as per MB.
    The drawings gave no dimensions for the lightening hole so I traced the hole in the frame casting and used that for sizing.
    5 Crankshaft brg (Medium).jpeg

    Dave
    The Emerald Isle
     
  5. Jan 26, 2019 #5

    deverett

    deverett

    deverett

    deverett HMEM Supporter

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    Carrying on with the crankshaft bracket...

    I cocked up drilling the top and bottom securing holes in the end of the power cylinder. Instead of doing them as per MB, I relied on measurements from the drawing. Somehow they ended up 1/16" too far apart. Isn't JB Weld wonderful stuff!

    The middle hole was in the correct place, so with the bracket attached to the cylinder with this one screw, I lined it up by putting a length of bar through the bearing bore and used a scribing block to set the bar parallel to the mill table. Then it was just a case of marking the new hole locations with a transfer punch, drilling and tapping.
    5a Lining up crankshaft bearing (Medium).jpeg .
    When the bracket was secured to the cylinder, levelling off the foot was done as per MB.

    Dave
    The Emerald Isle
     
  6. Jan 28, 2019 #6

    deverett

    deverett

    deverett

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    Water jacket

    Straightforward, but I did make several checks to ensure the screw holes were in the correct position. There is not a lot of room for error in the water chamber. The build notes from MB gives suitable warning.

    7 Water jacket (Medium).jpeg
    The core plugs were next. A gash piece of ali long enough to make both plugs was turned to fit the holes and then transferred to the milling machine to put the square on each end. I didn't glue them in just yet; I'll wait until the engine is painted before putting them in place.

    8 Core plugs 1 (Medium).jpeg 9 Core plugs 2 (Medium).jpeg

    Dave
    The Emerald Isle
     
  7. Feb 1, 2019 #7

    deverett

    deverett

    deverett

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    Transfer cylinder

    My transfer cylinder is a piece of 2" stainless steel with quite a thick wall so to start with this was machined down at each end and in the middle to the required 26 thou.

    Furnace

    I was able to get hold of a piece of 3" stainless steel tube to use for the furnace, instead of having to roll up a piece of steel plate and solder it into a tube. There are plenty of bits available on eBay.

    My S7 has 1/4" extra centre height compared to MB's ML10 and this allowed me to mount the tube directly on the cross slide. I had previously marked the position of the 3 holes and deeply centre-popped them. It was easy then to support the tube by centres in the dimples, shim it up to the correct height and clamp ready to drill/bore for the transfer cylinder.
    11 Furnace 2 (Medium).jpeg
    I drilled/bored the first hole to size, then carried on through the tube without moving the cross slide for the second hole.

    12 Furnace 3 (Medium).jpeg
    The extra clamp clamped the first one. Not sure that it did very much but I felt happier with it there.

    For the inspection hole, the tube was mounted to an angle plate on the cross slide.

    I had not been looking forward to this operation and had been putting it off for a while, but it came out alright in the end and I breathed a sigh of relief.

    13 Transfer cylinder (Medium).jpeg
    After the three holes were done and cleaned up, I had a trial assembly of the furnace and frame.

    14 Furnace 4 (Medium).jpeg
    Looking good so far, at least to my eyes!

    Dave
    The Emerald Isle
     

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  8. Feb 6, 2019 #8

    deverett

    deverett

    deverett

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    Trial assembly

    Next job that to be done is to secure the two cylinders and frame together. MB relied on measurements to drill/tap the holes in the cylinders, and used a stack of washers to measure the height of the engine frame above the transfer cylinder. At the time of watching his video I didn't really understand what he was describing so I resorted to a simpler (for me) method.

    The crankshaft bracket is not flush with the outside of the power cylinder, there is a gap between the bracket and cylinder edge so after temporarily assembling the transfer cylinder, I adjusted the height of the frame manually until it matched the crankshaft bearing 'underhang'.

    The assembly was held with a couple of small clamps and put on the mill table; the furnace was then aligned vertically with a square. A quickly made small pointed punch was used to transfer the holes from the frame to the cylinders which were then drilled and tapped.

    15a Temp assembly (Medium).jpeg

    Dave
    The Emerald Isle
     
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  9. Feb 9, 2019 #9

    deverett

    deverett

    deverett

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    Securing engine to base

    The holes in the base had previously been drilled. The engine was clamped to the base and using a transfer punch, the position of the screw holes in the cylinder standards were marked.
    29 Securing to base 1 (Medium).jpeg
    Dismantling the engine, I put the cylinders in the machine vice on the mill and after levelling them, drilled and tapped the screw holes.
    30 Drilling standards (Medium).jpeg
    Slower perhaps than MB, but I was pretty much assured of success my way. I didn't want to use any more JB Weld!

    Dave
    The Emerald Isle
     
  10. Feb 11, 2019 at 9:48 PM #10

    deverett

    deverett

    deverett

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    Some cast iron machining coming up next, but before this I made up the small end bearing from steel as per MB and this was put on one side afterwards.

    Cylinder Liner

    I didn't have a long enough piece of cast iron to get the cylinder liner and piston from. I did have two suitable shorter pieces - one piece for the liner, the other for the piston.

    With reduced overhang of the shorter piece, I held it in the 4 jaw chuck. The outside was turned to a nice slip fit into the power cylinder casting, ready to be secured with Loctite in due course. The bore was left about 2 thou too small ready for the lapping process described by MB.
    15b Cylinder liner (Medium).jpeg
    Piston and Extension

    Wanting to get the cast iron machining out of the way, I next did the piston. The CI was again held in the 4 jaw chuck. The bore was left the correct size and the outside was left 10 thou oversize until the cylinder liner was lapped.

    Next up is the piston extension. MB suggests a cheap rolling pin as a source of stainless steel. They are usually 2" in diameter, so to reduce to the required 1.862", the tube is cut lengthways and MB silver soldered it with a simple lap joint. The same process is used for the displacer piston. He obviously found it satisfactory, but I thought a joggled lap joint would be better - more 'professional'!

    Never having joggled a joint before, I practiced on the waste piece of tube.

    A piece of steel the same thickness as the tube material had a saw cut put in it.
    16 Joggle 1 (Medium).jpeg
    The cut steel tube was marked where the joggle was to go and then put through the slit. It was just a simple task of putting the steel plate and flattened out tube in the vice and squeezing.
    17 Joggle 3 (Medium).jpeg
    Hey presto: one joggled piece of steel.
    18 Joggle 4 (Medium).jpeg
    So, now to put my new skill to the test. Some years ago I made a set of rolls to the GHT design but they have had very little use until now when I was able to roll the piece back to quite an accurate tube.

    MB silver soldered the tube and two end plates in one heat, but I didn't trust my silver soldering ability to do that, so I did it in three separate heat sessions - tube, end plate 1 and end plate 2.

    First part - soldering up the tube was acceptable, but oh what a disaster when I tried the first (bottom end) cap. Scrap one extension.
    19 Piston extension mk.1 (Medium).jpeg
    Fortunately, there was enough spare tube to have a second try. Still going with three heats but this time, putting the thick top end in first to help give some rigidity.

    This time I called it a winner.
    20 Piston extension mk.2 (Medium).jpeg
    The displacer was done the same way (without the cock-up!). MB shows a small hole in the top end cap that prevents an air lock during the soldering process, later to be plugged. I just drilled the central hole for the displacer rod right through the cap and will rely on sealant round the thread to make the displacer air tight.
    21 Displacer and rod (Medium).jpeg

    Dave
    The Emerald Isle
     

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