Triumph 500 twin

[John Roberts]

Thanks Mike and Ron. I am enjoying this build from design through to making parts. The thought process especially. By the end of this project I should be a better machinist. Hopefully!

[John Roberts]

If any of you who have been following my build and wandered what has happened to it. The answer is I am having my summer break from being in the workshop. However since the weather has not been great I have got withdrawal symptoms!
I decided to draw up and make a coupler  that can be fitted to a SDS drill with dogs that locate into disc on the end of the crank.
Inside there is a one way bearing so that  the driven end can rotate at engine speed before the dogs are disengaged. This coupler will gain access my removing a cover on the left hand side case.

The main incentive to make this assembly is also to power up my Bentley BR2 with a collet attachment that fits inside the engine nose as seen on photo.
Last year it fired up and pulled the workmate it was mounted on over, smashing the maple propeller to smithereens! The engine is not at a stage that it will run simply by turning it over my hand. Hopefully the  drill I have will supply the enough torque to drive the Rotary so that I can hear and see it running again.

If not I will remake the propeller after the Triumph engine is finished. Work will resume in the Autumn.

John.

[Admiral_dk]

Great to see that none of those projects are forgotten 

Sorry about the Prop - but at least the Engine survived 

Per

[John Roberts]

Now I have had a summer break from being in the workshop, it is time to continue with this project. I decided to tackle the crankshaft which is an assembly of 7 parts.
2 shafts.                   silver steel
2 webs.                    ground gauge plate
1 big end journal       silver steel
crank centre              mild steel
fly wheel                   cast iron.

The two shafts are screwed into the webs and will be loctited  with high strength bond. The big end is also screwed one end and loctited and pinned the other. Also pinned and bonded onto the centre part.  Finally the crank counter- balance fly wheel is a tight push fit and will be screwed with 3 M5 C/sunk screws.
Photos show progress so far.
This engine will not have an oil pump but I will be fitting an oil nipple one end of the crank which can be used the prime the big ends before starting.


 

[Admiral_dk]

Great to see you back on this build John 

Very fine work on the Crank Assembly 

Per             

[John Roberts]

Thanks Per.
 Here's another photo showing the machining of the counter weights in the fly wheel. Pure guess work. I will try and balance the whole assembly after the con rods and pistons are made.

[Roger B]

That's an interesting design with the flywheel in the middle    I guess that was normal British bike practice 

Excellent machining 

[John Roberts]

Many thanks Roger.
The crankshaft is now finished after drilling internal oil ways, key ways and cutting threads. I fitted an oil nipple at one end so that engine can be primed prior to starting. I made a dog clutch as can be seen in photos.
I remade the cover with logo re- engraved (3D) in the correct place. Also I made a small alteration to the primary cover  profile as I was not completely happy with the shape.
Think I will make the con rods next.

[BillTodd]

Beautiful .

My brother has a full sized one on a stand under his bench

[jcge]

That looks tremendous John, and a clever addition of the oiler nipple too.
Regards
John

[mikemill]

John

Your work on the engine is a Triumph in the real sense of the word. Have you thought how to make the exhaust pipes?

Mike

[John Roberts]

Hi Mike. Thanks for your kind words. I have bought the copper tubing which on my engine as I recall is 14mm. There are benders available for that size but I have not been told the curve radius. If need be I will make one. On this engine the exhaust pipe will be a two into one. That's a long road before I get to that stage!

[John Roberts]

Currently machining 3 Con-rods (1 spare) The sequence of ops was
 Face both sides,
Drill tap 4ba and spot face for big end bolts.  Profile ends
Saw and face ends. Assemble
 Drill, Pocket and bore Big and small ends.
Mount blank on fixture plate with dowels and screws.
3D Rough tool path using 6mm x 1mm rad end mill.
Semi rough out groove with 6mm ball nose
Finish toolpath  6mm  ball nose
Finish small end fillet 4 mm ball nose.
 Finish profile around the outside.  6mm end mill

The below photos give an idea what is involved.
The last photo is con-rod as it came off the mill next to a full size con- rod.

When all three are completed I will bore out small ends for bronze bushes. Drill some oil ways then start on the shells.

[John Roberts]

This photo shows what it looked like after 3D roughing toolpath.

[John Roberts]

Con-rods and bearings finished and assembled onto crankshaft.
The big end shells were first drilled under size,then cut using slitting saw leaving one side just over half diameter. Both cut faces milled, then lead soldered together. Back on the lathe to bore hole to same dia as crank journal. Turn out side  to fit internal con-rod dimensions. Part off and  heat to separate  into two halves. Final assembly needed a tiny amount removing using adjustable reamer to obtain a perfect fit.
The small end was machined out and bronze bush pressed in.
As there is no  oil pump on this engine, big ends get lubricated to start with via the oil nipple. I have drilled 4 holes for oil access in the rods which hopefully will receive oil from mist. I small amount of oil will get picked up by the fly wheel and thrown around. If too much gets thrown up.  I have threaded the bottom of each con- rod so that a (2.5 mm) rod can be screwed in which will if needed can act as an oil paddle throwing oil up inline with the centre of the rod.  That's my plan!