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Post by pitciblackscotland on Apr 30, 2015 12:26:47 GMT -5
Hi John, Yes you got that right just the way i like it Did you need to weld those 19x25mm flats or was the bolts enough to hold them in place Cheers, Mark.
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Post by racket on Apr 30, 2015 17:06:33 GMT -5
Hi Mark
Nope , just the clamping force holding things in place, I can't machine that tough alloy at high rpm anyway , it tends to "skid" on the surface when taking fine finishing cuts , its the only alloy I've come across that will blunt cutting tool bits.
Cheers John
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Post by racket on May 1, 2015 19:42:52 GMT -5
Hi Guys Couple of pics of the shaft tunnel , most of the important stuff now done , just need to make up a couple of fittings for oil in/out and drill/tap the necessary threaded holes for the securing screws . Those angled lube holes to the brass bushes turned out easier than expected , even the crescent oil groove went off OK , but I did have some stuff ups with the lube gallery to the back of the thrust washer , I really shouldn't have done it late in the day , nothing a bit of "liquid metal" won't fix ..........kinda usual when making prototypes . Cheers John
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Post by pitciblackscotland on May 2, 2015 3:48:29 GMT -5
Hi John, ok have a couple of questions see pics. Cheers, Mark.
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Post by racket on May 2, 2015 5:58:12 GMT -5
Hi Mark
Yep , scavenge outlet in first pic .
Small hole is oil supply to thrust bearing and big hole is drain back from thrust bearing oil slinger area
Cheers John
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Post by racket on May 22, 2015 20:04:21 GMT -5
Hi Guys Bit of work been done this week on the NGV , the 18 vanes have been made , slow job milling the Inconel 600 1/8" thick flat . I've run into some "problems" positioning the vanes into their usual positions as per previous engine builds due to the steeper angle , >30 degrees vs <20 degrees for the lower flow engines , to get a reasonable length of "nozzle" between vanes they take up considerably more radial distance than previously so some compromises will be necessary ...........LOL, I work that out when I come to it Cheers John
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Post by pitciblackscotland on May 23, 2015 18:33:23 GMT -5
Hi John, so you machine the vanes at 30 degrees by tilting the cutting head on the milling machine or the jig in the vice Cheers, Mark.
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Post by racket on May 23, 2015 19:37:36 GMT -5
Hi Mark
LOL.............the simple way , I have the strip of metal at the required angle and mill horizontally along it , the jig positions and holds the strip for easy repeatability , just clamp it in the vice jaws at the angle you want :-)
I mill the slope , remove strip , cut off vane at required length with angle grinder , slip strip back into jig after cleaning up cut end , clamp down and start cutting , generally in 0.4mm depth cuts , so several passes required to get the required amount removed
Cheers John
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Post by racket on Jul 11, 2015 19:59:09 GMT -5
Hi Guys Bit of an update. Front and rear walls of NGV machined up . Front wall fitted to mill to have the 18 vane position steps milled Close up of steps and the clear contact with angles marked so that step provides a nice square flat surface for the cutoff saw to cut the vane slots from . Front of front wall showing mount for shaft tunnel , and the rear wall with stub. Bleed air holes for cooling turbine wheel hub and to provide "fresh air" to the seal area to prevent combustion products from passing across the seal. Bugger of a job , small drill , low angle , several millimetre long holes, done with a small electric hand drill And a few pics of the intended cutoff saw jig ( still to be finished), and how things will be mounted etc, once everything is in position, its an "easy" job, the mounting boss allows the NGV wall to be simply "clocked" around to the next "step", the central holding bolt tightened and the cut made. Cheers John
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Post by pitciblackscotland on Jul 12, 2015 3:17:07 GMT -5
Hi John. Looking good My thinking was that you would use a slitting saw on the mill to cut the vane slots? I find the cutoff saw won't make straight cuts, are you using 314 or 316 stainless steel? Cheers, Mark.
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Post by racket on Jul 12, 2015 18:05:47 GMT -5
Hi Mark
LOL, ....... they'll be precision ground slots ;-)
The walls are in 304 stainless.
A slotting saw setup would be ideal , but I don't have one, but I do have a cutoff saw , theres also the need to hold the wall firmly whilst machining , unfortunately theres not many spots to hold it firmly in a chuck , it took me 4 passes on each of those small steps.............a couple of hours work to do the 18 , the cutoff saw is fast .
Even with a slotting saw cut there'd still be a need for some "massaging" of the vane to get the throat just right .
FM-1 , the 9/94 and the 10/98 all had slots cut using the cutoff saw .................heh heh , call me a traditionalist :-)
I'll post some pics of the finished job .
Cheers John
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Post by racket on Jul 13, 2015 0:46:06 GMT -5
Hi Mark Finished machining the slots today And an "action" shot Just finished cutting Other side Cleaned up and some vanes slipped in to check "tightness" , the vanes will need just the faintest touch on the grinder for them to slip right home , unfortunately the cutting disc gets a tad worn on the sides which reduces the slot width near the bottom . Cheers John
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Post by pitciblackscotland on Jul 13, 2015 1:14:17 GMT -5
Hi John, Very clever Now i can see what you mean yes this way looks a lot easy to cut the vane slots. Cheers, Mark.
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Post by Johansson on Jul 13, 2015 1:16:01 GMT -5
Very nice work John! I used a slot cutting disc on the JU-01 NGV vane slots but it was a problem to get them deep enough with the small diameter disc I used, I think I will try your idea on the new engine. Cheers! /Anders
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Post by racket on Jul 13, 2015 4:06:05 GMT -5
Hi Mark Anders
Yep , its a fairly quick job once things are setup , only ~15 seconds to do each actual cut , pretty quick considering its stainless, even though I take it fairly gentle with the cutting force, preferring to take a few seconds longer so that the disc doesn't "wander" , but its imperative to have that "flat" step for the disc to start cutting from, if it starts straight , it keeps going straight .
The disc I used for the cut was only a 3mm thick one , the vanes are 3.2mm-1/8" inco 600 , fortunately after ratting around amongst some old worn out discs I found a 1/8" thick one that I then used to do a final "trim to size" width cut with, it seems all the replacement cutoff discs I've used are 3mm width , but the machine came with a 1/8" wide one for some reason , lucky I kept the "half diameter" worn out remains, a few seconds to run it in and out of the cut ,first to one side, then the other, using the play in the arms pivot point to get a few thou more width .
For the 9/94 and 10/98 engines I used 3mm thick RAX material for the vanes, so no problems using the standard cutoff disc to make the slots with , but I had to start using the Inco 600 for this engine , I think I originally used the same material for FM-1 and I purchased the cutoff saw to do its NGV .
I'm happy with the outcome :-)
The NGV vanes will need the small full thickness section at the outlet tip cut back so that the vane projects a tad further towards the turb wheel , by adjusting this cutback I can adjust the throat width to get exactly what I want ...............LOL, thats the theory anyway , I'll start finding out tomorrow .
Cheers John
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