Swifty's build of Nemett Lynx

[Swifty]

Next item to machine is the con rod. I started off with some plate aluminium and bored / reamed the big and small end positions, and drilled where I needed a radius in the corner, the position for these was drawn up on my CAD and the sizes taken.


Next step was to set up the rotary table and indicate the centre, I then clamped down my milling plate. To make it easy to set the holes up, I turned locating pins that I held in the quill in the zero position, located the hole and clamped the con rod down. I then proceeded to mill the outside radius.





Here we have both ends done ready to be finished milled to thickness.


And here is the con rod, just need to drill an oil hole in the small end and clean up with some filing and emery.


Paul.

 

[gus]

Very well done con-rod.
As for mine it will be next week's.
Cam box just done. Poor poor productivity.
Six hours to complete cam-box and cover and mount on outer-head.:hDe:

 

[AussieJimG]

So it looks like we could have two Nemett-lynxs at Melbourne?

Jim

 

[Swifty]

Machined the piston this morning, nothing remarkable about the turning, although I did use 1"stock so I can grab it in my 5C collet block later. I left the piston attached and clamped the bar in the collet block and held it vertical in the mill to enable me to mill the slot for the con rod.


Next I clamped the block horizontal to drill the pin hole.


And here we have the finished piston loosely placed on the con rod.


Now I will have to make the pin and the rings.

Paul.

 

[Swifty]

A few more bits done today, although no photo's as it's all pretty simple work. I made the gudgeon pin (wrist pin) with brass inserts in either end, turned the spacers for the crankshaft, tapped my small timing gear and finally adjusted the slack in the crankshaft when everything is nipped up tight. All up, a pretty quite day.

Paul.

 

[gus]

So it looks like we could have two Nemett-lynxs at Melbourne?

Jim

The more ,the merrier. One in Singapore and all alone.

 

[gus]

A few more bits done today, although no photo's as it's all pretty simple work. I made the gudgeon pin (wrist pin) with brass inserts in either end, turned the spacers for the crankshaft, tapped my small timing gear and finally adjusted the slack in the crankshaft when everything is nipped up tight. All up, a pretty quite day.

Paul.

As for poor Gussy, its the Cam-Box rework. All done and quite fast too.The slot hole looks good compared to last. Now undecided which item to make next.

 

[Swifty]

After I realised that I had cut the ring grooves in the piston only half their depth, I set the piston up carefully and machined the grooves to the correct depth. Next step was to machine the rings from some cast iron bar stock. I rough turned the outside, drilled and bored the inside finished, then finished the outside.


Next I selected a narrow grooving tool that I would use for parting off, the tool was only 0.9mm wide, this allowed me to get the maximum number of rings from the bar.


I ended up with 7 rings to work with, should be enough to allow for breakages.


The next part makes me nervous, I have to split the rings.

Paul.

 

[Brian Rupnow]

Swifty--I'm glad you are doing this now. Like Gus, I have never made rings before either, but plan on doing so for the engine I am currently building. I am following with great interest. I made my cams today, and they are almost identical to the Lynx cams, so you may want to have a look at my cam journey!!---Brian

 

[Swifty]

Well, all that worry about splitting the rings was for nothing, it was the simplest operation yet. I followed Malcolm's advice and used No.3 Morse taper to place the rings over and tapped them down with a piece of copper pipe. The rings split at their weakest point, it was all over in no time.




Now I have to make the heat treating fixture, clamp the rings and heat them up to set the correct "free" gap.

Paul.

 

[Swifty]

Continuing on with the rings, I machined a clamp out of some 25mm mild steel bar, I previously gapped the rings at 2.5mm and measured the maximum inside diameter, this was 24mm as Malcolm states in his instructions, so I turned the step to this size and left the length 0.5mm short for clamping. Stacked up all the rings and tightened the end washer, then bought them to red heat for a few minutes, I concentrated the heat on the ends rather than directly on the rings.

After taking my wife out for a stroll and coffee (have to keep in the good books), before unclamping, I gave the now cold rings a light wire brush to remove the slight scale and and a light rub with some fine wet and dry paper. I unscrewed the clamp, took all the rings off and gave then a light rub on some 2000 grit wet and dry paper on either side. I then held them in a toolmakers vice and filed the gap with a needle file, trying each one in the cylinder until the closed gap was about 0.1mm.

Here's a photo of the clamped rings cooling down.


And the now finished rings, the open gap is 2.5mm which I was aiming for. I think that all the mystery about making piston rings is now behind me, and will not hesitate to make them in the future.


Now Brian and Gus, go for it.

Paul

 

[gus]

OK. Maestro. Just waiting for good results. Best looking piston rings.The Nemett Engines sure led us to new discovery of our hidden talents.

 

[Swifty]

Hi Gus, we all need to challenge ourselves sometime, I think that it was fear of defeat that made me nervous about making rings. I have had the rings on the piston, they expand nicely to get them on, I won't actually assemble the piston to the cylinder just yet, will wait until final assembly.

Paul.

 

[gus]

Hi Gus, we all need to challenge ourselves sometime, I think that it was fear of defeat that made me nervous about making rings. I have had the rings on the piston, they expand nicely to get them on, I won't actually assemble the piston to the cylinder just yet, will wait until final assembly.

Paul.

I have been breaking rings and having to wait for new rings to arrive.

The Webster,Rupnow and now Nemett Engines are taking us to new grounds.
We no longer fear tuning carbs,valve timing and ignition timing. Spent too much time tuning Webbie and Rupnow engines.

I have yet to cut a conventional shaft. Seen the Power Press Shops in our neighbourhood cutting crankshafts for power press. Also watched the maestros using shapers to cut vee slides too. The vee ways were so smooth and they mated with some scraping.Scraping is an art.
Also seen them using hammer and chisel to cut ''X'' oil grooves into the cast iron bushes.

 

[Brian Rupnow]

In the Jaguar ring instructions, Malcolm shows the ring ends held apart with a 2.5mm thick shim while held in the fixture and heated up as you show. Has he changed that method in the Lynx instructions? There is no information about gapping the rings prior to the heat treat. It just says to split them as you have done, then put them in the fixture spread open with the wedge, and then heat treat with wedge in place. Gapping is done after the heat treat is completed. I don't see any wedge in your heat treat fixture.---Brian

 

[Swifty]

Brian, you are correct in what you say, Malcolm also suggests on the drawing of the heat treatment fixture, that you can adjust the small diameter on the fixture to hold the gap at 2.5mm without an insert. That's why I gapped a ring with a 2.5mm slip gauge and measured the diameter needed before finishing the fixture. I thought that it would save me making an insert and it worked out well.

Paul.

 

[Swifty]

I have been pecking away at a few small bits today, the bronze valve guides, the brass sump and filler plugs, and the breather. The breather has an M5 thread only 2.5mm long, so I made a short piece of brass threaded to M5, tapped the knurled top piece to suit and soft soldered the 2 together. This method gives me a thread all the way up to the end.



Paul.

 

[gus]

All these bits n pieces drive us mad when we about to cross the finishing line and there is still a pile of miscellaneous to machine. The " Carb'' is another trap.

I am about to move the '' bits & pieces'' territory.

 

[Swifty]

Hi Gus, I have been studying the cam manufacture, still not quite clear on it yet, I understand what they are saying regarding milling them, but still have to be sure before I start.

Paul.

 

[gus]

Hi Gus, I have been studying the cam manufacture, still not quite clear on it yet, I understand what they are saying regarding milling them, but still have to be sure before I start.

Paul.

OK Maestro.

Not a productive day. Boring Head must be modified to take it into smaller ID
boring. Made adapter. Big End bored to 14 mm but needle bearing O.D. is
14.04/5 mm. Could have used a reamer to drill and ream to 14mm plus and Loctited. Half morning wasted to modify BH.:rant:

But I did get a press fit using bench vice to press in needle bearing.
Will profile mill Con-Rod tomorrow. Perhaps made my own oil hardeded bush for crankpin.

Kind od enjoyed doing the bits & pieces.

As for the cam machining,I am a wee bitty lost. Have yet to read Brian's
thread on his cam milling.