SKULD 666

[racket]

Hi Mark

LOL.....bit fancy ..........Yep, worth a try :-)

Cheers
John

[racket]

Hi Guys
A few more pics

Front cover , just need to drill the securing screw holes , they're position will depend on where the holes in the diffuser vanes are positioned so will have to wait until they're drilled ready for tapping ..............oh , and an O'ring grove around the OD , which can be done when I get the O'ring .



Inside of front cover , marking pen lines are used for checking profile accuracy at design clearance.



Diffuser in the process of machining



Diffuser mounted in chuck via an expendable boss that will be machined off when the shaft tunnel mounting face is machined, boss was machined when diffuser was mounted on faceplate .



Diffuser vane final shape



Cheers
John

[Johansson]

Sweeeet!

[pitciblackscotland]

Hi John,
Nice work. did you sand the inside of the front cover by hand?? .

Cheers,
Mark. -

[racket]

Hi Mark

A mixture of machining with a "shaped" tool and lotsa sanding, just a slow job as I had to remove the cover from the lathe chuck after each incremental adjustment to the profile to check against the comp wheels profile as it wasn't possible to engage the parts in the chuck as the comp snout is too long and it hit the chuck face before the comp was fully inserted into the cover, ........ I must of had it in and out of the chuck a hundred times :-( .............but she's pretty well spot on now :-)

The diffuser has been a lot easier to machine ................just a few more light cuts in the lathe and it'll be ready to remove from the chuck .

Cheers
John

Cheers
John

[racket]

Hi Guys

Finally got the camera out to take a few pics of progress.

Diffuser machined........



Front cover securing holes drilled for the 8mm X 1.25 mm X 35mm stainless button head screws , 18 screws should hold it onto the diffuser , I could have probably got away with 6mm screws but they looked a bit "small" on the 14 inch casting , even the 8mm ones are just big enough to look OK :-)



Next job is to make a "special tool" to mount the diffuser front face against so that I can machine the rear face and bore for the compressor/shaft .

Cheers
John

[Johansson]

Very nice finish!

Will the oil and fuel ports pass through the casing like with the 10/98?

[racket]

Hi Anders

LOL...........I haven't quite made up my mind yet , it'll probably depend on whether or not I can find enough space to fit the scavenge line , the fuel and pressure lube will go in the front so that I can mount them on the ancillary pad at the bottom of the front cover.

I had to mill out each diffuser channel as the slight warpage in the casting left unequal channel heights , it was a fairly quick job as there was less than a couple of millimetres in it at the worst case, just a skim out to even things up :-)

Cheers
John

[pitciblackscotland]

Hi John,
Hehehe i was going to ask you if you machine the channels in the mill. Did you use the rotary table and dividing plate to drill and tap the holes?.

Cheers,
Mark.

[racket]

Hi Mark

I tried using the rotary table to mark out and drill the holes, but , despite gluing the vanes onto the pattern in exactly the positions marked by the rotary table , there seems to have been enough "displacement" caused by the casting process that when I tried using the rotary table to drill the holes they weren't centered on the vanes , they wandered about a bit , and as I wanted to use 8mm screws in a vane only ~10-11mm wide , it left no choice but to centre punch a position on each individual vane at the correct radii( scribed when still in the lathe chuck) , and then drilled individually , they are only a millimetre one way or the other , and considering the holes are ~50mm apart, it only equates to an ~ half degree variation from the 20 degree theoretical division.

Once the diffuser holes were drilled ( 6.5mm dia) , I drilled a 1.5mm hole through the centre of the " #1 master hole" in the top of the outer cover in the centre of its "pad", and with the outer cover clamped to the diffuser so that the two holes were as concentric as possible , the outer cover was "back drilled" using the diffuser hole as a guide , the parts were seperated and the outer cover hole drilled to 8mm and with it in place over the 6.5mm hole the diffuser vane was tapped to 8 X 1.25mm .

With hole edges cleaned up, the parts were screwed together with a 35mm stainless button head screw , centralising the outer cover on the diffuser with a few bits of masking tape on a few diffuser vane "corners" , there being several thou of lateral movement to compensate for a hotter running diffuser.

Another 6.5mm hole was back drilled opposite the first one and similarly treated as the first one , with 2 screws in place the rest of the holes were drilled, tapped etc etc ....

Its looks pretty good with all 18 screws in place :-)

Cheers
John

[racket]

Hi Guys

A few more update pics .

Jig required to mount diffuser so that its rear side can be machined true to the compressor wheel rebate which is true to the rest of the diffuser both axially and radially.....a days worth of work machining it out of a >300mm diameter disc of roughly flame cut 25mm plate , the only material available :-(



Diffuser mounted and being machined , 3 X 6mm high tensile bolts holding diffuser onto jig .



Compressor wheel fitted to diffuser



Compressor wheel radial running gap



Compressor wheel within its housings




Cheers
John

[Johansson]

Ohh that is sexy!!!

[pitciblackscotland]

Hi John,
Nice - you are slowing get there. Ok 300mm x25mm diameter steel disc i got that on my shopping list, those 3 x6mm holes on the diffuser will they be plug up after machining??.

Cheers,
Mark..

[racket]

Hi Anders

LOL......I hope you like them with a bit of weight on , compressor with housings weighs in at ~10 kgs-22 lbs , hopefully the entire engine will be <50 kgs .

Cheers
John

[racket]

Hi Mark

Yep, the 3 X 6.5mm dia holes in the diffuser wall that the 6mm bolts go through will be tapped out for 8mm grub screws, I might use one of the holes for a pressure tap to measure static compressor discharge pressure so that I can compare it with total P2 to see what sort of pressure rise division there is between comp wheel and diffuser , it'll also help me determine if my diffuser throat area calculations were anywhere near the mark, or just a wild guess :-)

I'm still not happy about the amount of compressor wheel "overhang" and haven't decided on the shaft's air sealing yet , I'll give it time to sort out in my head before cutting more metal in case I do something dumb .

Cheers
John