Nemett Lynx 15 cc 4 Stroke I/C Petrol Engine

[Swifty]

I'm with you on the gambling Gus, I'm just not lucky, I lose my money every time. I don't mind playing a couple of dollars but that is where it ends.

Paul.

 

[gus]

Not a productive day. Friend called. And its ransom. He wants his fishing rod repaired soonest and that is tonite. If not,he will not fix my Bait Cast Reels now with him. Spent two precious hours to replace line guides and expoxy coat bindings. :wall:

For today,all that is done is the cut length of Cast Iron Bar for the liner. Band saw came in handy to cut C.I.Bar. :hDe:
I have two hours only to turn liner with a lunch appointment at 11:30am.

Will plan and write work instructions to turn liner.

 

[Brian Rupnow]

Gus--I share your regard for your fingers. Mine are old and arthritic, and one has been removed with an axe and then re-attached in the ancient past. However, I love them all dearly, and have no desire to part with any of them.--No propellers for this kid!!!----Brian

 

[gus]

Gus--I share your regard for your fingers. Mine are old and arthritic, and one has been removed with an axe and then re-attached in the ancient past. However, I love them all dearly, and have no desire to part with any of them.--No propellers for this kid!!!----Brian

Hi Brian,

Looks like we have a unanimous vote----------"No Props. We want our fingers
intact." My worries is ,in the process of trouble shooting the cause of engine problem and being deeply engrossed(will not rule out absent mindedness or just plain forgot we have a finger eating prop waiting"),we may lose our fingers or even hand. I have surplus off-cut C.I. Bars to cut flywheel. Or perhaps but a Brass Disc. (Not heard or seen posts from Canadian HP)

 

[gus]

OK. Got rid of all distractions. C.I. liner done. Took 4 solid hours. Being a big mini lathe and deeper cuts would stall motor.
O.D. is spot on. I.D. is 1/2 thou over. The parting off was scary. 4 hours of work could vanish in seconds.
I owe it Tin Falcon for recommending the Warner HSS Insert Boring Bar. No chatter.
CI bar was too big,had to reverse jaws to chuck and tail stock centre to secure job. DIY Fixed Steady mobilised to secure over hung bar for drilling and boring. Parting off was between life and death of completed liner.
Will work on Cylinder Jacket tomorrow. Now working on works instructions to turn jacket.

 

[gus]

Been a productive day. Started work at 8am, took tea/pee breaks and worked till 1:30pm to complete.
Stretched the chuck capacity,with reversed jaws to clamp aluminium bar. Cutting the grooves and fins was nail biting.
Tapmatic Tapping Fluid made life easier with good flow of swarfs.
Will make drilling jig to drill all holes.

 

[Swifty]

That's looking great Gus, I hope my cast iron arrives tomorrow so I can work on it. The only work I've done today is cut some material for the back cover of the crankcase.

Paul.

 

[gus]

Hi Paul,

Found an error.
Cylinder Jacket.
Bottom flange O.D. 55 mm and 6 off 4mm hole with PCD of 50 mm will place Socket Head Allen Screws sticking outside flange.
Corrected to 47 PCD. 48 may be best. Checked Best of ME front cover found fasteners well centred.

Will work on the outer-head tomorrow. See no errors for now.
Bought XL 12mm mill today. "Totem'' Carbide Mill made in India.Will work on crankcase this Friday. Having fun cutting the grooves and fins but scary.

 

[Swifty]

Hi Gus, I hate to be the bearer of bad news and upset your evening, but the bottom flange is 60mm dia, the same as the rest of the cylinder. The 55mm dia is to the bottom of the first few grooves at the top. My M4 screws have a head dia of 7mm, this would mean the screw heads would nearly fill up the step completely. You may be able to machine a bit more off the 40mm recess dia to give some clearance. If you use 48PCD for the holes, plus 7mm head dia, this will make the outside of the screw heads 55mm dia.the same as your flange. You may have to taper the last few fins in order to get a screw and hex key in. I did mention in an earlier post that all lines are drawn solid, this makes it very confusing.

Paul.

 

[gus]

Hi Gus, I hate to be the bearer of bad news and upset your evening, but the bottom flange is 60mm dia, the same as the rest of the cylinder. The 55mm dia is to the bottom of the first few grooves at the top. My M4 screws have a head dia of 7mm, this would mean the screw heads would nearly fill up the step completely. You may be able to machine a bit more off the 40mm recess dia to give some clearance. If you use 48PCD for the holes, plus 7mm head dia, this will make the outside of the screw heads 55mm dia.the same as your flange. You may have to taper the last few fins in order to get a screw and hex key in. I did mention in an earlier post that all lines are drawn solid, this makes it very confusing.

Paul.

Will use studs and nuts and a yarn to spin later. ( To spin a yarn is Boy Scout language--------story to tell). No wonder the drilling jig shown in Best of M.E. was as wide as the crankcase top. OK . No problem. My drill jig will be made to 60 mm O.D.
The Outer-Head looks tricky to cut. Will cut the blank Head and work out details.
Am happy with good progress and work pieces. No rejects so far.

 

[Brian Rupnow]

Gus--You are doing nice work. I am watching. Don't feel bad. I am currently modeling the Jaguar from Malcolm Stride's drawings, and I find his drawings confusing to read.----Brian

 

[Jasonb]

Gus you won't be able to turn the nuts. M4 nuts are 7mm A/F and you only have 3.5mm clearance between the cylinder and centre of the hole

 

[Brian Rupnow]

Gus--Can you do this to save your cylinder??---Brian

 

[Jasonb]

Or just skim down the 40mm dia waist by 1mm then you can fit the intended socket head screws.

Can't see how that ring will fit over the flange Brian ?

 

[Brian Rupnow]

Or just skim down the 40mm dia waist by 1mm then you can fit the intended socket head screws.

Can't see how that ring will fit over the flange Brian ?

Split ring

 

[mu38&Bg#]

Consider a smaller screw. 6 M4 screws is excessive. Model aircraft engines use 4 M4 in displacements up to 2.2ci making considerably more power than this engine.

Greg

 

[Niels Abildgaard]

The latest Citroen 2 Cv engines had 74 mm bore cylinders that was kept together with crankcase by three m8 (m10?) tie rods.
It is probably more than sufficient for put-putting model engines to have four cylinderbolts (not to short please) or tie rods that are one tenths of the cylinder diameter.

 

[gus]

Thanks for helping. Was nearly unforgivable goof and so many friends to the rescue. Long live ''HMEM''.
About to move on to the machine the Outer-Head which is mind boggling. Took the issues to bed. However I did get some sleep.

Lesson learnt.Read plans and ask questions. Guess I am improving. ''Measure twice before cutting.drilling.turning etc etc.''

 

[gus]

OK .Took 3 1/2 hours to cut Outer-Head Blank. Cutting fins is scary. The O/H has some very difficult details to drill,mill,counter-bore etc.
Even more difficult for Gus w/o DRO. There will be at least three----five drilling jigs to make in order to get holes right. I am worried with the details on the holes for the valves. W/o DRO this will be tough and so back to WW-1 Workshop Technology.

Malcom's work instructions are very useful.Best to follow 100%. Cutting a spigot to chuck raw blank was a very good idea but to play
safe,I had tail stock centre snugged on to ensure blank does not fall out especially cutting fins which foul and cause job to fly out.
Parting-off was very scary. Saw out the last 1/2 inch.
Had to use the Height Gage to mark outer-head thickness. Note Gus's poor man's surface plate.

I am a nut on buy tools ahead of time. To drill and counterbore the valve ports made easy with spotting drills to spot on hole. Bought 2mm end mills ages ago. Use same to cut Outer head fins. Was nail biting.
See fotos. Since I have no DROs drill stops sure helped ensure required Couterbore depth.

5:30pm.
Made drilling jig to drill Outer-Head. WW-1 Technology still in use.

 

[Jasonb]

Gus I measured the heads on some M4 cap head screws last night and they were just under 7mm so you may just be able to use them without having to resort to other methods to hold the cylinder on. As you have not drilled the holes yet I would move them out to to a 47.5mm PCD which will place them in the middle of the flange and give the screw heads a bit of clearance to the 40mm waist.

Drawings show the head at 28.75, not whats on your height gauge.