Swifty's build of Nemett Lynx

[gus]

You are making good progress. About to finalise the Fishing Line Power Spooler Foot Pedal Speed Controller.
The mockup is 100% ''Bush'' from Crocodile Dundee. Latest by this Friday should complete and run.
Looks like nrext week will be ''Cam Prepping Time'' follow by Cam Cutting Time.

 

[Swifty]

I've made a start on the carburetor, here is a picture of the basic pieces, there is still a bit more machining to do yet. I still have to have a close look at Malcolm's drawings, as his photo's are different from what he has drawn.



Paul.

 

[Brian Rupnow]

Swifty--That looks great. I built that same carburetor last week, only converted to inches using imperial #4-40 fasteners. It works great.---Brian---(send me your real address to [email protected])---Brian

 

[Jasonb]

Couple of pics of my one assembled if that helps, as drawing except trumpet shape to outside of intake.

 

[Swifty]

Thanks for that Jason.

Paul.

 

[Swifty]

Well, with a bit of help from Jason and Brian, I now have my version of the Lynx carburetor. Despite the drawings being hard to interpret, I only ended up with 2 extra holes, one M2 hole I plugged, the other doesn't matter. It's times like these that I wished that I had a small bench top lathe. Turning the 2mm dia. spray bar was a bit of a challenge on my 14 x 40 lathe, but in the end I got there. I also made the inlet manifold.







I'm on the home stretch now, I only have to make the exhaust manifold, some sort of stand, fuel tank and hook up the electrics.

Paul.

 

[gus]

In the far distance,I hear an engine running soon.

Now upgrading the Rotary Table which had a 71 t worm wheel to 60 t gear(ex-USA) so that I could graduate the 360 degree table. With this done , other prepps required before cutting cam.

 

[Swifty]

Anyone that thinks retirement will give them plenty of time to do the things they like, is in for a big surprise. After being retired for 11 years now (no I'm not that old, I did retire at 51) I still have trouble finding enough machining time. I have just spent the last couple of days on things other than machining.

Despite this, I did have time to get in the workshop this evening and ponder how to determine which end on the neodymium magnet is the south pole, the one needed to trigger the Hall effect sensor. After googling about it, the best way was to use a compass to find out, the north arm of a compass will point to the south end of the magnet. For anyone interested, here is one site showing how to do it.https://www.kjmagnetics.com/blog.asp?p=which-pole-is-north

Further reading on the hall sensors appears to show that the pole on the magnet is not so critical so long as the sensor can be turned around to activate the correct side. This make the idea of mounting the sensor in a non permanent way ideal.

Paul.

 

[gus]

Anyone that thinks retirement will give them plenty of time to do the things they like, is in for a bid surprise. After being retired for 11 years now (no I'm not that old, I did retire at 51) I still have trouble finding enough machining time. I have just spent the last couple of days on things other than machining.

Despite this, I did have time to get in the workshop this evening and ponder how to determine which end on the neodymium magnet is the south pole, the one needed to trigger the Hall effect sensor. After googling about it, the best way was to use a compass to find out, the north arm of a compass will point to the south end of the magnet. For anyone interested, here is one site showing how to do it.https://www.kjmagnetics.com/blog.asp?p=which-pole-is-north

Further reading on the hall sensors appears to show that the pole on the magnet is not so critical so long as the sensor can be turned around to activate the correct side. This make the idea of mounting the sensor in a non permanent way ideal.

Paul.

Thanks for timely info. Will follow your post on magnet and pole effect.
Still taking my sweet time upgrading the R/table. Engraving cutters coming in next week to graduate the table disc and Knob dial. Did think of marking on the lathe but graduating and calibration a big problem. Fishing was great last weekend but we had great time recalling past fishing trips over beer and lunch.

 

[Swifty]

It's strange, but the closer that I get to finishing this engine, the less time I have to work on it. I managed to make some supports for the engine this morning, they will eventually be fastened to a piece of timber.



Paul.

 

[gus]

Engine is another Paul Swifty's Masterpiece .th_wav

I am having the same problem,slowing down but taking my sweet time. Hand Wheel graduated and number stamped. Numbers 1-----6 done good with a jig to hold stamp and job and alignment with eyeball. Messed the first piece with too hard hammer blows. This time two blows 4'' high gave me the depth. Could never stamp straight and tidy in Trade School. SW Monsoon blowing outside and fishing will be bad this weekend.:wall:

Take care in the machineshop. Gus tripped over some flexible cord and if not for the skating and judo training I could have knocked the back of my head on the shoe locker and gone. Was able to spun around in time to land on my hands. Will improve housekeeping with personal safety in mind.

 

[Swifty]

Take care Gus, I caught my toe on a garden hose last week, it was the leg with bad arthritis in the knee, it sure hurt. This cold weather that we are having is really playing up with my joints, I seem to have arthritis in every one of them, the only way to get relief in this cold weather is to visit the local hot springs for a few hours.

I managed to get some tubing for the crankcase breather, now I have to make a bender for it.

Paul.

 

[Swifty]

Another day, another short bit of work done. I made an adapter with 2 drive pins to fit my battery drill, and I added a piece to the flywheel with 2 corresponding holes so I can crank it over.



I also made a start on the fuel tank, a piece of 38mm dia tube, I turned up a couple of ends for it, they had a short location on the inside dia, After cleaning the tube with some emery, I dipped each end into the flux bottle to make sure it was coated. I then put the end plates on and smeared a little bit more flux on. Using a gentle flame with the Mapp torch, I brought it to the correct temp to melt the silver solder and worked my way around the end, being sure that the solder followed the heat. I found in the past that if I had the torch on full it was too much heat and hard to control. Of course, I drilled a hole where the filler cap will go before soldering, this saves having the ends blow off as it heats up. A soak for about 60 minutes in a citric acid bath cleaned up all the excess flux inside and outside. Citric acid is a great way to clean things.



Paul.

 

[doubletop]

Swifty

Its looking good!!

You may want to think about how you are going to get the starter dog to disengage. If you have the starting problems I had and Brian described well on his thread you find that once the engine fires it wants to go off faster than the speed of your drill but it can't decouple and the drill then becomes a brake and the engine stops. What you end up with is a few farts and then nothing. Take a look at my thread and the helio starter with sprag clutch.

Pete

 

[Swifty]

Will check it out Pete, I may have to go to the helix type starter that I made for the Rupnow hit and miss. The holes in the mating part are 0.5 mm bigger than the pins, if anything, it will let me turn over the motor for bedding in the valves.

Paul.

 

[johnny1320]

Why not just add a one-way bearing to the starter shaft with the drive pins. It's a beautiful engine you've got there.

 

[Swifty]

I've often thought about using one way bearings (sprag bearings). When I make a multi cylinder engine, I will use a permanent starter motor with sprag bearing.

Paul.

 

[AussieJimG]

For what it is worth Paul, I have used a driving dog with a release ramp like the one in the photo because I thought I needed it. The problem here was that when turning the engine over trying to adjust the carby, every time it fired it kicked the starting drill off and the engine would stop.

So I dispensed with the ramps (which were a pain to cut anyway) and now I am using the simple version shown in the flywheel. It works fine and disengages without any problems.

I know that others use the Sprag clutch idea but I am not sure how accurate the alignment needs to be between the starting drill and the crankshaft.

Jim

 

[Swifty]

Hi Jim, your ramp starter is virtually identical to my Rupnow one.

Paul.

 

[Swifty]

"That's funny, I don't recall seeing that on the drawings" I decided to add a bit extra to the crankcase, a dipstick hole. I turned up a 12mm dia x 32mm long piece of aluminium with a M6 hole, I then quickly drew up the modification in CAD to see what angle was best and also where to machine the hole. I then set the crankcase cover up in the vice at 30 deg and used a 10mm cutter to rough it out followed by a 12mm cutter. A bit of 2 part epoxy was used to glue the piece in, I used the excess epoxy to build up around the part on the inside. The dipstick was made easily from a bit of brass and some 3mm silver steel for the stick part, it may be hard to see on the photo, but there is a small groove in the stick at the full level.





Paul.