Swifty's build of Nemett Lynx

[Swifty]

I have finally managed to clear a few thing up, so have made a start on preparing to make the Nemett Lynx 15cc SOHC Four Stroke. What material I didn't have on hand, I purchased this morning, all except for the cast iron needed for the cylinder liner. I have ordered the timing pulleys and belt, and will get the bearings shortly.

Apart from mine, Gus is about to start on his, and Doubletop from NZ has one on the go already.

I better go and clean my workbench up ready to make a start, the first piece to be machined will be the crankcase, fortunately I already had a machined block that was the correct size for the height, with minimum to be machined off the other sides. This was fortunate, as I don't have a bandsaw and I would have had to order a block cut to size. All the other material, I just call into my supplier and buy offcuts.

I will try and take a lot of photos and post often on the progress, so stay tuned.

Paul.

 

[gunna]

All the other material, I just call into my supplier and buy offcuts.

Hi Paul, care to name your supplier?
I will be following along with interest.
Ian.

 

[Swifty]

Hi Ian, I buy my aluminium from Capral, the nearest to me is in Lynbrook, but there are a few stores around Melbourne. There are always small plate offcuts available as well as rounds. I have in the past purchased aluminium plates from scrap metal dealers.

The plate aluminium is definitely better than the common extruded type, can't recall the grade without looking it up.

Paul.

 

[gus]

Here comes the Nemett-Lynx Engine Epidemic.

Tool Cabinet completed today. Looks like the C.I. Liner will be done Monday 12 2014.
Now looking for extended 12mm end mill to cut crankcase.

 

[gunna]

Hi Ian, I buy my aluminium from Capral, the nearest to me is in Lynbrook,

Thanks, Paul,
That seems to be the only one in the whole south-east according to their web site.

Ian.

 

[Swifty]

I started on the crankcase as I had a piece of machined aluminium that was a 70mm cube. I've had the piece for years and it worked out well as the crankcase is 70mm high, so all I had to do was fly cut 2 sides down to size. I'm not worried about getting a mirror finish as a quick rub with some wet and dry paper will clean up scratches.


Next step was to hold it in the vice and pick up the edges with an edge finder and drill a small center drill hole in the correct position for the main bore.


After mounting my 4 jaw chuck, I held the block against the face of the chuck using a center in my tail stock. The jaws were then tightened using some pieces cut from a soft drink can as protectors. This method of holding with a center while I tighten the jaws gets the piece very close.


I then used my dial indicator to finally zero the block in position.


After using a couple of different drills to remove a lot of material, I bored the hole to size.


I intend to bore the cylinder locating hole in my mill using the boring head.

Paul.

 

[gus]

Gus will monkey see,monkey do the crankcase.You beat me hands down. Still reading the C.I. Liner print and jotting down work instructions.Will be Monday 12 May to see some work done.

 

[Swifty]

I'm looking forward to seeing you make a start on yours Gus.

Paul.

 

[Swifty]

Mothers Day today, so not a lot got done in the workshop. However I managed to mill out the interior of the crankcase. The aluminium that I used was actually a piece of Alumold, a high grade tooling alloy used for injection dies and blow moulds, its very tough to machine, but I got there in the end. I roughed it out with a bigger cutter, then milled closer with a used 12mm long series end mill, then using a new cutter I finished it to size.



Here it is deburred and cleaned up.



Now comes the messy part, I have to clean up all the swarf produced.

Paul.

 

[gus]

Plan to machine the Cast Iron liner tomorrow followed by the cylinder jacket. Will shop for the long series 12 mm end mill. Looks like I need to buy two, to rough cut and finish cut. Not so sure I can get as good finish as yours.Will try and no rush.

 

[Swifty]

A little bit more progress, drilled and bored the cylinder locating hole in the top face. The boring head is a Koroda, dial 0,01 cut on dia and that's all it takes, love it.



Next, I drilled and tapped the oil union hole in the corner and the 6 cylinder hold down tapped holes. I tapped under power in the mill and used the pitch circle hole function on the readout for positioning.



Now I have to drill and tap the other faces.

Paul.

 

[gus]

Will be tough for Gus to match up. Have mark,center punch,spot drill and tap the WW-1 way.
Just found extra length 12 mm end mill ex-stock Singapore. No HSS but Carbide . Will Gus a bomb. Landed cost still cheaper than buying from ArcEuroTrade,UK. Will use the roughing mill followed by XL Carbide Mill.

 

[Swifty]

Gus, having a digital readout sure makes things easy, but so long as you are careful, you will be OK doing it manually. Where you can, you should first drill holes in the pieces that get clamped down, then you can spot through these holes for a perfect match up.

Paul.

 

[gus]

Gus, having a digital readout sure makes things easy, but so long as you are careful, you will be OK doing it manually. Where you can, you should first drill holes in the pieces that get clamped down, then you can spot through these holes for a perfect match up.

Paul.

Will spot mating faces.This way the holes will align. Have to do it the WW-1 way. Will turn and possibly finish C I liner tomorrow. Then turn Cylinder Jacket.
Looks like major items done by end May.

There is an epidemic spreading. Nemett Virus has mutated---------Jaguar,Bobcat,Lynx etc etc etc and ha ha. Looks like the two of us spread the epidemic. After the Nemetts what else will happen???? Ha Ha ha. Will look out.

 

[Swifty]

I'm always on the lookout for my next project, maybe a 4 cylinder of some sort, water cooled.

Paul.

 

[Swifty]

I went out this morning and bought the bearings that I needed, the only hick up was with the hardened bush for the conrod big end needle bearing. The bush fits on the 7mm dia pin on the crankshaft, the supplier would have had to order one in, so I made a design change on the spot. I have a load of through hardened dowel pins, so I will change the original pin size from 7mm to 10mm, and run the rollers directly on the hard pin.

I've just ordered the cast iron for the sleeve, enough for 2 pieces, so I should get it in a couple of days. It's cheaper for me to pay the postage than drive a 3 hour round trip to get it. I plan to tackle the sleeve as soon as it arrives, I will bore out the hole first, then mount it on a mandrel and finish the outside. Next step will be to bore the aluminium cylinder and shrink it on to the liner. I will then use the same mandrel to finish the outside of the cylinder. I used this method on my Rupnow hit and miss engine and it works well.

Paul.

 

[Swifty]

I drilled and tapped the rest of the holes in the crankcase today, however, I decided to leave one hole out. There are 4 x M3 and 4 x M2.5 tapped holes holding the back on the crankcase, but the M2.5 tapped hole in the center of the top edge clashes with a tapped hole in the top face. If you look closely at the pictures in the magazine, you will notice that the builder has omitted it as well.



I used my tapping stand to tap all the blind holes. I made it using my ER20 collet holder.



Paul.

 

[AussieJimG]

I like the tapping stand, it just went on my Tuit list

Jim

 

[gus]

Paul,

You are making good progress. Liner done and moving on to Cylinder Jacket. And again a big dia. job for a small lathe.The next would be the elaborate outer-end. Too msny hole and some very unforgiving.Guess I leave the hole for day after. Buying material wise,I am a few train stations away from supplier.
My ceiling would be a two cylinder in-line or vee type.

 

[Swifty]

I machined the back cover for the crankcase today, clamped it down because I thought that it may lift in the vice when i milled the recess.



Next on the list was the 2 angle pieces that fasten on either side of the crankcase, I had some 10.8mm thick plate (where does that size come from) and not having a band saw I used a slitting saw in the mill to cut off 2 pieces.



After flycutting them to size, I machined them to create the "angle profile".



Drilled all the fastening holes, and here we have all the parts on the crankcase sheet finished.



My cast iron arrived today, so parted off a piece and drilled and bored it to size, came out perfectly parallel, just gave it a light hone with the brake hone tool. I intend to turn the outside whilst its mounted on a mandrel, in order to reuse a mandrel that I used on my Rupnow engine, I bored 2 short pieces of bar and shrunk them onto the mandrel. I will carry on machining that tomorrow.

Paul.