"Fat Boy" 12/118 thrust engine

[racket]

Yeh , gotta have a lathe , it doesn't have to be fancy , my old flat belt drive unit was worn out when I purchased it 40 years ago , and because it was too big and heavy to move around when I changed house I cut 3 feet off the bed length , got rid of the heavy cast iron drip tray and all the thread cutting gear , she's "bare bones" , but it has a nice big 14" swing even though the bed length now limits me to shafts of ~20 inches , but turbines need flanges and round things not long things , so a short "fat" lathe is all you need

[azwood]

Yeah i have a mate who wants to sell an old belt driven lath with a milling attachment and tooling might need to buy that

Jul 28, 2018 23:04:10 GMT -5 racket said:

Yeh , gotta have a lathe , it doesn't have to be fancy , my old flat belt drive unit was worn out when I purchased it 40 years ago , and because it was too big and heavy to move around when I changed house I cut 3 feet off the bed length , got rid of the heavy cast iron drip tray and all the thread cutting gear , she's "bare bones" , but it has a nice big 14" swing even though the bed length now limits me to shafts of ~20 inches , but turbines need flanges and round things not long things , so a short "fat" lathe is all you need

[racket]

LOL, if I can make my engines on my old bit of crap , you'll be OK

[azwood]

Jul 29, 2018 2:42:17 GMT -5 racket said:

LOL, if I can make my engines on my old bit of crap , you'll be OK

Ive had a bit of time on mills and lathes i was in press tooling for a few years just need to remember all the tricks i atuly miss doing that stuff.

[turboron]

azwood, I have two lathes. A 10" Atlas(Sears) and a 13" Lebron. The Altas belonged to my wife's grandfather and has quite a bit of tooling. I paid $500 US for the 13" LeBron. The point of this note is that old lathes are cheap and readily available. My real expense is all the claptrap you need for a DIY gas turbine. In other words, pumps, fittings etc.


Thanks, Ron

[azwood]

Yeah cool i will definitely get one

Jul 29, 2018 7:17:24 GMT -5 turboron said:

azwood, I have two lathes. A 10" Atlas(Sears) and a 13" Lebron. The Altas belonged to my wife's grandfather and has quite a bit of tooling. I paid $500 US for the 13" LeBron. The point of this note is that old lathes are cheap and readily available. My real expense is all the claptrap you need for a DIY gas turbine. In other words, pumps, fittings etc.


Thanks, Ron

[racket]

Hi Guys

Freepower shroud/mount coming together , weight is 2.9 kgs






Now to mount everything together and check clearances and concentricity of the wheel

Cheers
John

[racket]

Hi Guys

Took the engine out for a test run this morning and despite the mods it still didn't get to self sustain :-(

It was a frustrating session , often the first spoolup doesn't succeed so I switch off and let the heat soak back into the bearing tunnel and shaft to aid in reducing drag for the second attempt which is generally successful , but there wasn't a second attempt , something went wrong with the electrics supplying the toggle switch that activates the relay that activates the starter solenoid, its wired into the ignition circuit somehow and the ignition was playing up , its been on the test stand for ~14 years and originally was used for the two shaft kart before that and hasn't given any trouble to now .

Maybe the new heavy duty starter solenoid has overloaded something , so will rewire/replace as necessary ..............bugger .

So back to the freepower/gearbox :-)

Cheers
John

[turboron]

John, sometimes in our world the thorns seem more plentiful than the roses.

Thanks, Ron

[racket]

Hi Ron

Yep , its winter here so plenty of thorns , maybe I'll see the roses in the Spring :-)

I've replaced the ignition toggle switch , ignition operation is nice and positive now , so no problems there , and it doesn't appear that theres any other wiring taken from that circuit , but on attempting to activate the starter I still have the same problem ..............very strange ...........more digging around required this afternoon, ............I'll recharge the battery in the meanwhile .

Cheers
John

[racket]

Hi Ron

It was the battery :-(

After a recharge everything worked as it should , but I'll swap the starter solenoid over to one of the bigger batteries , the new heavy duty solenoid is a 24 V one and maybe the discharged battery simply didn't supply enough power to operate it , more fiddling tomorrow.

On a brighter note , I assembled the freepower bits onto the gearbox and everything looked OK until I tried to turn the wheel , it rotated half a turn before locking up :-( ...........bugger I thought, whats wrong now , but found I hadn't given enough axial depth to the shrouds rebate where the labyrinth seal goes , and because Allison wheels are cast , they don't run "true" , they can "wobble" a bit , the laby seal being machined runs true though .

I had a similar problem with my turbine bike , things were OK when wheeled forward but when pushed backwards the helical gearing pulled the freepower wheel into contact with the rebate , again it was a slightly "wobbly" freepower wheel that was the culprit.

When I assembled things this afternoon there was just enough depth where I assembled it but once turned a tad it locked, so I disassembled things and fitted the assembly to the jig in the lath and skimmed out another 1.5mm - 0.060" axial depth to provide some extra running clearance , whilst I was at it I skimmed the bore of the shroud and found it was only a few thou out , pretty good considering its a welded up piece .

I'll reassemble things tomorrow and check again , but its looking promising :-)

Cheers
John

[turboron]

John, behind every thorn there is another rose. We hope.

Thanks, Ron

[racket]

Hi Guys

A coupla pics of the assembly getting its final machining, its running fairly true which is a relief , the extra work machining the leg extremities to provide indexing/locating positions paid off.



Aaron , you only need an old crappy lathe like this to make turbine engines :-)



The mounting jig was made from a length of 110 mm bar , nice and solid so it can be securely tightened in the chuck and able to cope with the overhang of the freepower assembly



Cheers
John

[hurdman]

John,
Here's a picture of my 1932 Pratt & Whitney.  I use it nearly everyday.
Hurdman

[racket]

Now thats a substantial lathe..........nice :-)