First IC engine design and build

Discussion in 'A Work In Progress' started by retailer, May 7, 2019.

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  1. May 7, 2019 #1

    retailer

    retailer

    retailer

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    Late last year as my Quorn T&C grinder was nearing completion I was planning on starting an O gauge live steam loco but I came across the Demon V8 build log by Steve Huck I must say it impressed me and and I decided then to put off the loco project and swap it for a running V8 - as I had a few months to go on the Quorn I decided to have a go at my own design.
    Not having any experience with model engine design there is always a chance that the design will be difficult to build or even worse may not be a good runner. In that event I would simply purchase a set of Little Demon plans, by all accounts Steve had done a great job of the plans and build details, the design is proven with quite a few examples built and running and being a forum member he is always ready to help out with advice.

    The Quorn is now finished to the point where it is use able and my plans have reached the point where I could start actual machining. Bore and stroke is .625" - if this sounds like the PeeWee V4and the Steve Huck V8 that is because I copied these sizes from those two engines, mainly because I know rings can be made that size, I have not made rings before and being my first IC engine there is a lot of info in the forum posts on ring making to help me - the rest of the engine is my own design.

    I started with the block, a square extrusion about 6inches long, final length will be a bit over 5.25 inches, extrusions may look square but are not good enough to use with out being squared up.

    For this I used the lathe checking each time that the newly machined surface was parallel to the lathe bed, once squared up I mounted the block onto a steel back plate that was drilled to be bolted to my rotary table. The idea is that once the block is setup parallel to the mill table I can machine each surface by indexing the rotary table.

    Before I set it up in the rotary table I spotted the holes for the crank and cam as I will probably machine away the face I am using as my datum point. Once bolted to the rotary table I set it square and parallel to the mill table with the rotary set on 0 deg. an angle plate clamped to the extrusion was needed to steady it as I could see it wobbling around once I started boring the holes for the cylinder liners. I don't have any sort of CNC setup but I do have the luxury of a DRO on my mill which does take some of the pain out of it.

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    Johno1958 likes this.
  2. May 8, 2019 #2

    stevehuckss396

    stevehuckss396

    stevehuckss396

    Model Engineer HMEM Supporter

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    I'm in! Lets do this! and yes we will be here if there is any questions.
     
  3. May 10, 2019 #3

    retailer

    retailer

    retailer

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    Thanks for the encouragement it is much appreciated. I've made a bit more progress and will get a post up shortly.
     
  4. May 11, 2019 #4

    retailer

    retailer

    retailer

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    I have progressed a bit further with my engine build, all of the bores for the liners have been drilled bored and countersunk, I plan to have liners a push fit and seal off the water jacket with O rings.
    I only have a set of expanding bore gauges for internal measurements and I find they can be a bit hit and miss - in the lathe is usually ok as I can move the saddle back out of the way and get the gauge nice and square, in the mill though the boring tool was partially in the way making in a bit harder to get the gauge square, I ended up turning up a go gauge - making small adjustments to the boring tool until my gauge was a nice push fit.

    The cylinder head bolt holes were drilled and tapped metric 3x0.5 and then the cutouts for the push rods were machined - all operations for each cylinder bank were completed before I rotated the block to do the other bank. While drilling the head bolt holes on the left bank I noticed that the holes looked to be displaced towards the front and on checking the front face of the block against my DRO I found it was set at .02" rather than 0" this threw out of the head bolt holes on the left side by .02", not a disaster as it is not a huge amount and I can compensate when I drill the head bolt holes but it is still not great . Theoretically once I shut down for the day as long as I don't move the mill table the settings should be the same next time it is turned on so that sort of thing should not happen, I'll be checking and resetting the x/y zero points each time I start up the mill from now on.

    I always thought that machining cast iron was messy but I'm starting to think AL is worse, a lot of the swarfe is thin flakes and when it is brushed away it ends up all over anything that's close by. At the end of the day the piece of AL was starting to look a bit like an engine block

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    michael-au likes this.
  5. May 15, 2019 at 7:11 AM #5

    retailer

    retailer

    retailer

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    Bores, tappet holes and valley cut out all finished the block was rotated 180 deg to cut out the crank web clearances, I did make a couple errors though - the final dimensions were not affected but it looks sloppy and is sloppy, not happy about it. While it won't be seen once the sump is on but I'll still know it's there. The final operation while it is on the rotary table will be to drill the sump bolt holes and also the main bearing cap bolt holes.

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