Barstock single cylinder in metric

Discussion in 'A Work In Progress' started by coulsea, Nov 16, 2019.

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  1. Nov 16, 2019 #1

    coulsea

    coulsea

    coulsea

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    A couple of years ago I built my first IC engine and my son really likes it so I thought that I would make him one for Xmas.
    IMG_2164.JPG
    There are no plans, I just made it up as I went along. I hope to make a few improvements to fix some of the things that didn't turn out as well as I would like.
    Some of the basic specs are: 21mm bore with O ring, 36mm stroke, 8mm fabricated crankshaft, 10mm plate crankcase, 50 mm cylinder, ball bearings on crank and big end.
    This would be a good first engine for anyone who wants to build along with me because I don't care too much about accuracy, if one bit is the wrong size you just change the next bit to suit. (Cylinder needs to be close to o ring size). build it in imperial if you want.
     
  2. Nov 16, 2019 #2

    dethrow55

    dethrow55

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    hello that a good looking engine . i will follow your build newbie to ic engines .:cool:
     
  3. Nov 21, 2019 #3

    coulsea

    coulsea

    coulsea

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    I have been building this for a week now an d haven't posted anything but it is getting hot now (40 C) so some computer time might be in order.

    I started with a length of 100mm x 10mm aluminium and cut off 3 pieces 60mm long. I cut over length to alow for milling the 3 pieces together to make them all the same size and they ended up 61mm. The height of the crankcase sides depends on the size of the flywheels used, I am using 100mm diameter so with the centre of the flywheel level with the top of the side there will be 10mm below the wheel

    IMG_2161.JPG

    The 3 pieces were then screwed together, the lower screws are centred 6mm from the bottom and the upper ones 45 from the bottom. the height of the upper ones is important as you don't want them to foul the cylinder which is 50mm. there is also a hole drilled in the centre of the front plate at the same height as the side plates, giving the centre of the cylinder the same height of the centre of the crank.


    IMG_2159.JPG

    IMG_2163.JPG

    the front plate was then trimmed on the rotary table to give the top edge a curve, you could just take a bit off each corner if you don't have a rotary table.
     
  4. Nov 21, 2019 #4

    Cogsy

    Cogsy

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    This should be an interesting build - I'll be following along. One thing I've learnt (the painful way) about flywheel to base clearance is to leave enough space for a finger to pass underneath when you're trying to hand-start it.
     
  5. Nov 21, 2019 #5

    coulsea

    coulsea

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    The next step was to make the bearing caps. I am using 19mm od 8mm id bearings so I cut off a 20 mm strip of the 100mm x 10 mm aluminium, by the time I cleaned it up it is 19mm. cut off two pieces 40mm long and drill two holes 30 mm apart, mine ended up 39mm so each hole was 4.5mm from the end, the main thing is that they both look the same. I used a 12mm end mill to countersink the holes just for looks. I am using 4mm cap head screws.
    IMG_2166.JPG
    I then drilled and tapped the holes in the side plates, they were supposed to be 55 and 85 mm from the cylinder end but I use a 6mm rod to zero the DRO on the end of the plate and I forgot to allow for the 3mm to the centre of the rod so mine are 52 and 82.

    IMG_2167.JPG
    with the end caps bolted on a 13mm hole was drilled, level with the top of the side and in the middle of the bearing cap. an endmill was then used to enlarge the hole to 19mm but only to a depth of 8mm from the inside of the plate, this will leave a 2mm flange on the outside to stop the bearing from escaping. I didn't have a 19mm end mill so I used a 3/4 which is a bit bigger and them filed a bit off the bottom of the cap to get a snug fit. when using small bearings be careful not to put too much pressure on them because they will distort quite easily.


    IMG_2168.JPG
     
  6. Nov 29, 2019 #6

    coulsea

    coulsea

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    The crankshaft is the next job. cut off two 50 round steel discs about 6mm thick and clean up on the lathe and drill a 8mm hole in the middle. the spacer in the chuck is a split collet from another job.
    IMG_2179.JPG
    I then used the mill to drill the 6mm bigend hole 18mm offset from the middle and chain drilled the bits to be cut out leaving 17mm wide up to the bigend and the balance weights starting 5mm below the centre hole. cut out and clean up on the mill.

    IMG_2180.JPG IMG_2181.JPG


    Assembly is done in the lathe. Each side of the crank is 80mm long, put the shaft in the lathe chuck with enough sticking out to go through the crank web and locktite together, use the tailstock to get the web straight. when the locktite is dry drill and pin (2mm) with more locktite.

    IMG_2182.JPG IMG_2183.JPG
    The bigend uses a bearing 6mm id 12mm od with a brass spacer on each side to keep the bearing in the middle.
    Put one side of the crank in the chuck and the other side in the tailstock and line them up by turning the chuck by hand.. I locktite one side of the bigend shaft and and let it cure before doing the other side because it is easier to line up one side at a time especially if it is hot and the Loctite goes off quickly. It can be a good idea to wait until the Loctite has properly cured before pinning.
    IMG_2184.JPG IMG_2185.JPG
    if all went well you should now have a straight crank shaft. make a couple of spacers to keep the crank on the middle of the main frame, 1mm or so slop is good, don't make it a tight fit.
     

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