A pair of Boll Aero 18s

Discussion in 'A Work In Progress' started by pat_pending, Mar 3, 2019.

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  1. Mar 3, 2019 #1

    pat_pending

    pat_pending

    pat_pending

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    Hi, after completing my first engine (Webster) and procrastinating for 6 months, I have finally taken the plunge and decided to build my next engine.

    After much browsing I decided I would have a go at an aero diesel this time. I remember them so well from when I was a kid (including the sliced up fingers from flick-starting). I heard the ether fuel is a bit tricky to come by but I found a few model shops still selling the Peter Chin model technics stuff so I'm good to go.

    Spending hours (days/months) reading Model Engine News/Motor Boys I was spoiled for choice on the model to choose. In the end I just went for it and chose one. The Boll Aero seems about as basic as they get (ML Midge design) and the plans were nicely put together.

    http://www.modelenginenews.org/plans/BollAero18.pdf

    I also realised that when working with engines that small, you use such a tiny amount of material that you may aswell build two as you go along. The time i typically spent setting up fixtures etc so 2 engines definitely doesn't equal twice the time. That way I can have one in a display mount and one in a control-line plane or something traditional. Just have to make sure my mistakes don't kill two parts at a time and become twice as painful!!

    Anyway here goes!

    CAD sketch for me to double-check plans and make any tweaks I want. + trying to learn cad anyway so this is good bit of practice for me.
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    Rough out some 1" bar on the band saw.

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    Square up to 25mm

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    Drill and tap. 16x without breaking anything! The money spent on a Dorma tap has been well worth it. I used to be pretty unlucky with broken taps before.


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    OK, run out of time for this weekend but I'm in business. Turning my mind to the boring operations at the moment and doing some research on how to centre on the lathe. A wiggler/wobbler resting in the hole I centre-drilled seems to be preferred but a D-bit in the mill might involve less setting up? Also I dont have a wiggler thing (always confuse which is which) so would have to make one. Any advice from members appreciated.

    Thanks,
    Patrick
     
    Last edited: Mar 4, 2019
  2. Mar 12, 2019 #2

    pat_pending

    pat_pending

    pat_pending

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    Finally managed to get a bit more shed time this weekend. First I solved the centring square stock on the 4-jaw issue. I ended up going for a simple centre-finder as detailed in Sparrey's The Amateur's Lathe book. That really is a treasure trove of great tips!

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    Now I bored as large as I could with a twist drill then boring bar the rest. A go-no-go plug was turned on the lathe first to get the bore as accurate as I could.

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    Well here they are. Please excuse the machining marks and burrs!

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    Next week the main bearing and back of the crank case.

    See you
     
    Last edited: Mar 12, 2019
  3. Mar 16, 2019 #3

    pat_pending

    pat_pending

    pat_pending

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    Bit more shed time!

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