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Nalon Viper 2.5cc CI Engine

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Ramon

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Peter - Next to bad deformation marks on screw on cylinder heads where the wrong tool has been used for removal I don't think there is anything worse that offends my eye as much as seeing plier teeth marks on a prop driver !! Most collet types will ease with heat - I use a heat gun as opposed to a torch - but some just won't budge so I'm with you all the way using a puller. As I thought, it seems then the holes 'for the use of' are in much larger engines than I have handled.

The worst type of driver fittting in my view is the straight knurled shaft - the driver 'graunched' on and a devil to remove without loss of tightness when refitting.

Only engines I know with a flat on the shaft Jason are OS - that's not an OS in Peters image I recognise straight off - are there other manufacturers using that method? Thunder Tiger perhaps

Greg - Had some real problems at first but finally managed to get on Adrians site - fully up to date with the VIKHR 👍

Just found some still sealed Hoffman bearings too ;)

Tug
 

petertha

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The one in your first picture is not a even a collet type, it has a flat on the crankshaft and "D" shaped hole in the driver so could be overtightening or its been on there a long time.
You're right, I didn't look close enough. Was just referencing yet another jerry-rig puller pic, of which there are many.
OK probably beat this issue to death. Good luck with the build.
 

pat_pending

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Hi everyone, just a quick update. Not had a huge amount of shed time recently as I have been really busy at work. Every evening I think I'll give it a go but when the time comes, my brain just seems so fried that I'm worried I'll just fill the scrap bucket or worse still, have an accident. I have two weeks off over Christmas and really exited to carve out some quality time then.

Anyway, I've got going now. No turning back!

So this weekend I squared up some stock and started making plug gauges for the crank case and the cylinder bore. Still the gauges for the bearing seats and the cylinder heatsink to go. I used EN1A PB steel for these and it seems to work OK and get a decent shiny finish with a light finishing cut of 0.05mm or so at 1000RPM.

Squaring the stock is something that took me FAAAAAR too long (frustrating). I've only done it once before and really there are just so may things to get you out of whack. With a bit of patience and 8 machining operations per block (6 plus two to measure and mill to final size) I got there. A couple of thou under dimension on one of the blocks in the horizontal direction but this will be this will just be the mounting screw lugs so I'm not worried.

One thing which I figured out (no idea if this is silly or not) is Iremoving 2 of the cutters from a 3 cutter cheepo indexable face mill to use it as a flycutter gave me a lot more accuracy on setting the z-axis. One cutting tip was a lot easier to set accurately (with a thin cigarette paper Rizla blue). This seemed repeatable to 0.01mm ish. I wasn't in a hurry so took light cuts at 0.1mm and the vibration from the single cutting tip and interrupted cut didn't seem to be a problem

The front of the crank case and the top were left about 0.5mm oversize in order to be able to skim the face on the lathe before boring to make absolutely sure everything is perpendicular.

Next operations are to mark out everything, finish making plug gauges and then the fun starts.

I'm thinking it makes sense to drill/tap the cylinder head and crank case front housing mounting screw holes while I'm at it. Rationale is that If I do everything from a single setup/datum surface, there is less opportunity for errors to cascade. The other alternative is to make a PCD drill jig to fit into the crank-case openings later. I would be interested to hear people's thoughts on this. I got lucky on the BollAero and the holes lined-up OK but always on the lookout for tips n' tricks / better ways of doing things.

Anyway, please enjoy the most boring model engineering photos you've seen all week :). It will pick up pace soon promise!

Patrick

IMG_0417.jpeg
 

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Ramon

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A good start Patrick 👍

Given that you are making two a drill jig that could fit both case bore and front and back housings would be a well considered way to ensure compatability. Second option would be to wait until after the bores are done then do them on the mill using co-ordinates - much more reliable from a positioning point of view than marking out.

Good to see you making swarf on this :)

Regards - Tug
 

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