Metric Hoglet

[GrahamSParticipant @grahams]

Hi

I am interested in building a Hoglet , have purchased the MEB plans and am working through whats needed to build, and trawling the internet looking at previous builds etc.

I have seen a few mentions of a Metric set of drawings for this, which I would seriously consider as most of my gear is metric, and metric metal and hardware seems cheaper !

But I cant find any metric drawings being offered for sale – any ideas?

Thanks

[GrahamSParticipant @grahams]

Are Metric drawings available?

[JasonBModerator @jasonb]

When I built mine I only changed the fasteners to metric but if I were doing it now I would go further. It's fairly easy to substitute shaft and hole sizes to the nearest metric, for example the 3/8" crankshaft can be done with 10mm stock, 1/4" pins rounded down to 6mm.

You could go further bringing the bore down to 25mm without too much hard work but if you go as far as using metric MOD gears then some more careful calculations are needed.

Some people simply express the imperial sizes as metric but that won't be much help to use as you want to use existing metric tools and materials and I don't tend to consider that a proper conversion as it's simply working in different units.

I've had a Hoglet Facebook group pop up a few times, may be worth asking there too

[GrahamSParticipant @grahams]

Thanks Jason

Good food for thought.

[JasonBModerator @jasonb]

Let us know if you have any luck on the FB group, the one by Achim mentioned on the other forum looks like it was just a fixings and shaft diameter change which would be a reasonable half way house and allow you to use metric taps, dies, reamers, etc without getting into much trouble.

Ask if any other queries crop up in your thoughts.

If you are going to do the kick start then the suggested part is hard to get now but there was a thread about alternatives which I'll look up. Also if you are buying in the gears metric MOD 0.8 are a lot less expensive than DP and would only need a very slight repositioning of the cam shaft bearing and the 3 screw holes that hold the cam housing in place, I can give you details of that..

[GrahamSParticipant @grahams]

Thanks Jason, this will be my first IC engine build , previous projects all steam, so I am sure I will have lots of follow up questions !

At this early stage a 'metric fasteners only' build for me looks like the way to go.

I have a set of quality metric taps and dies, and have recently bought metric change wheels for my imperial Boxford lathe, so I think I have the threading gear sorted. If I do have to buy anything else metric at this time it feels like it will get reuse in the future, not so with tooling up with UNC / UNF gear !

I have a metric mill ( with DRO which can flip to imperial ) , so part dimensions in imperial are no problem.

I am now investigating if buying material in metric ( for cost saving ) but building in imperial ( to match the plans ) makes sense, certainly for the ally parts and possibly the cast iron. Even if it makes extra machining – all part of the fun.

What effect does moving the cam shaft to suit metric timing gears have on the valve push rods? or is it so slight the adjusters can compensate with no other dimensional changes ? Details of this change in this area would be very interesting and welcome, thank you.

[JasonBModerator @jasonb]

Yes so slight that it would have little if any effect on the angle of the pushrods.

40/20T 32DP gears are 0.9375" (0.938" on drawing)

40/20T 0.8MOD gears are 24mm.

0.938" = 23.82mm

So you only need to move the cam shaft bush hole in the side frame up 0.175mm and set out the three now M4 tapped holes from that point.

Should not be a problem to make the cylinders from 50mm CI bar as it comes out a bit larger anyway and 70mm for the heads.

So did you not make the Parcell and weed?

[GrahamSParticipant @grahams]

I started the P&W , but to date have not finished it.

After making the bedplate through to top of cylinder I knew I was on an uphill battle without a mill and rotary table. I am happy with what I have made to date but equally happy to play the long game and get it how I want it when I am ready. I went down the road of UNC to BA with the fasteners on this, imperial and BA gear being the best I had at that time.

I could have progressed , but prior to retirement with a lot of other stuff going on the sensible thing at that time seemed to be to park it. Post retirement I joined the engineering crew on the Daniel Adamson heritage steam tug, which I really enjoy and feeds the engineering bug as well as being a social thing, and keeps me fit !

Recently I have bought a mill and and few supporting bits of kit and am ready to have a serious go again. Another retirement project was also running a Morgan three wheeler, yes it had a big V twin up front. So you can see the connection to the Hoglet, not identical but perfect as a demonstration piece and an incentive to make it. Also a good opportunity to pick up some skills and try new things out like camshafts. I am about to have a go making a test Hoglet camshaft out of scrap – I am still getting my head around the rotary table movements required.

Thanks

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