Model Engine Maker
Engines => Restoration of Model Engines => Topic started by: Bjorn_B on September 24, 2017, 03:11:46 PM
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Built a jet engine a few years back (GR180) and after a "mishap" it has been in parts (FOD damage to the compressor wheel)
A friend challenged me to bring it back to life, I have got two weeks... Need to run it for a demo on 6'th of October..
I need a new compressor and a new turbine wheel, new bearings.
A start was made on machining the turbine wheel blank, a hole must be drilled straight and to an exact dimension so first a jig is made to hold it in the lathe
(https://farm5.staticflickr.com/4411/37423699705_11be163f0b_z.jpg) (https://flic.kr/p/Z21f6P)20170924_121002 (https://flic.kr/p/Z21f6P) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Checking for size
(https://farm5.staticflickr.com/4345/37423702425_2a81fc7b75_z.jpg) (https://flic.kr/p/Z21fUH)20170924_121015 (https://flic.kr/p/Z21fUH) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Drilling holes for the clamp ring bolts
(https://farm5.staticflickr.com/4363/36612347873_9155d6a638_z.jpg) (https://flic.kr/p/XMiRt8)20170924_123432 (https://flic.kr/p/XMiRt8) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Tapping (M6)
(https://farm5.staticflickr.com/4405/37235017096_29ffe5d650_z.jpg) (https://flic.kr/p/YJkcko)20170924_124312 (https://flic.kr/p/YJkcko) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Ready for a really difficult job, drilling inconel is not easy!
(https://farm5.staticflickr.com/4361/37026453530_55d83b8d93_z.jpg) (https://flic.kr/p/YpUfDQ)20170924_132027 (https://flic.kr/p/YpUfDQ) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
I have found a D-bit tool ground from cobalt tool steel is the easiest way of doing this. I will do some boring work and perhaps internal grinding to bring it to size in next post. This is all for now..
(https://farm5.staticflickr.com/4368/36573672114_df7da0117c_z.jpg) (https://flic.kr/p/XHTCvG)20170924_143035 (https://flic.kr/p/XHTCvG) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
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Quite an impressive part - was the turbine wheel a casting from a master, or cast from a 3D printed mold?
:popcorn:
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I did not do the casting, it is from Jetmax (http://www.jetmax.ch/en/turbine_wheels.htm) I also got the inlet guide vane from there.
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Continued work on the turbine wheel today
Hole was in the end bored to size with a small carbide boring bar (lots of resharpening with a small diamond lap)
(https://farm5.staticflickr.com/4356/37454465535_da965de09f_z.jpg) (https://flic.kr/p/Z4HVHa)20170925_175856 (https://flic.kr/p/Z4HVHa) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Checking for size, getting close
(https://farm5.staticflickr.com/4331/37312680321_f8d0cfb9e5_z.jpg) (https://flic.kr/p/YRceUv)20170925_184543 (https://flic.kr/p/YRceUv) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Facing of the front side
(https://farm5.staticflickr.com/4349/36643502983_9cfbd83155_z.jpg) (https://flic.kr/p/XQ4wNc)20170925_192041 (https://flic.kr/p/XQ4wNc) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Turned around and facing of the other side
(https://farm5.staticflickr.com/4359/37283813712_981a924e2e_z.jpg) (https://flic.kr/p/YNDhSm)20170925_192640 (https://flic.kr/p/YNDhSm) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Old and new
(https://farm5.staticflickr.com/4461/36603768194_3a0d8309ea_z.jpg) (https://flic.kr/p/XLxT2C)20170925_192754 (https://flic.kr/p/XLxT2C) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
On shaft
(https://farm5.staticflickr.com/4377/37313552221_c23588ec98_z.jpg) (https://flic.kr/p/YRgH6g)20170925_192935 (https://flic.kr/p/YRgH6g) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Next up, compressor wheel machining.
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Sorry Bjorn but I can't see what is wrong with the old one in the picture - can you enlighten me please ?
I'm sure that balancing the compressor and turbine wheels are a extremely important considering how fast they spin - do this require special tool to do that dynamically or can you get away with static balancing on these small diameters ?
Best wishes
Per
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Damage was mostly to the compressor but I have ground away most of my balancing margin on the turbine wheel. Not much further balancing work is possible and the blade tips have struck the NGV. So it is a bit of an unknown right now and I'd better be safe then sorry with this.
Dynamical balancing is more or less a must. I'll come to that process later :popcorn:
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Very interesting to watch this one, well outside my knowledge range, neat stuff.
:popcorn:
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That's very interesting work you are doing here :popcorn: I'll be following too and hope the best you make the deadline.
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Thanks all!
Today compressor modification, this is a Schwitzer S200 series? wheel that needs a lot of work, it needs to be shortened at both ends as well as the whole backside needs to be re-machined. The diameter will also be taken down from about 80mm to 74mm.
First a fixture to be made, axle driven between centres, M6 thread at the end and 7mm main diameter to fit the compressor wheel
(https://farm5.staticflickr.com/4387/37334768181_a1947d1a26_z.jpg) (https://flic.kr/p/YT9rRF)20170926_184416 (https://flic.kr/p/YT9rRF) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Time to start..
(https://farm5.staticflickr.com/4458/23483686788_2d866734a4_z.jpg) (https://flic.kr/p/BMb2Vw)20170926_190736 (https://flic.kr/p/BMb2Vw) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
After rough machining the backside, the tip diameter is adjusted
(https://farm5.staticflickr.com/4450/36666093873_8981afacc1_z.jpg) (https://flic.kr/p/XS4jhi)20170926_192246 (https://flic.kr/p/XS4jhi) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Remaining boss is adjusted to diameter
(https://farm5.staticflickr.com/4457/23484140118_1685afa9ca_z.jpg) (https://flic.kr/p/BMdmFy)20170926_193124 (https://flic.kr/p/BMdmFy) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Another, clamp type fixture is needed for further machining, it still needs shortening of both bosses (old and new)
(https://farm5.staticflickr.com/4499/37305821062_ae1d9b69ba_z.jpg) (https://flic.kr/p/YQA5Tq)20170926_193414 (https://flic.kr/p/YQA5Tq) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Old and new
(https://farm5.staticflickr.com/4387/37288477356_005dde49d3_z.jpg) (https://flic.kr/p/YP4cd1)20170926_193422 (https://flic.kr/p/YP4cd1) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Perhaps tomorrow..
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Hi Bjorn, great to see those 3-D impellers on such a small machine. No tricks missed in the search for performance.
I am another following along your amazing project.
MJM460
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Thanks for your comments! Input/feedback is always nice
The compressor wheel is actually from a ordinary turbo compressor (can/could be bought as a spare part) In this turbine it needs "some" modification, diameter is reduced to lower pressure ratio down somewhat I guess (keeps combustion/exhaust temps down a bit as it would overload the turbine wheel otherwise).
A bit of a golden rule is to have somewhat matched diameters of turbine wheel and compressor wheel in these contraptions.
Length of the complete rotating assembly also needs to be as short as possible to keep critical rpm higher than max rpm. So it needs to be machined both ends as well.
I'll finish the compressor wheel tonight if I can find my old fixture. :thinking:
/B
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Ok, a bit more done today
This is the compressor getting it's snout cut short
(https://farm5.staticflickr.com/4508/37307421956_6b60742c4e_z.jpg) (https://flic.kr/p/YQJhM3)20170927_183357 (https://flic.kr/p/YQJhM3) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Done!
(https://farm5.staticflickr.com/4418/36685074143_e64312462b_z.jpg) (https://flic.kr/p/XTJAsk)20170927_183750 (https://flic.kr/p/XTJAsk) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Bored out the alu "backplate" to accept the compressor wheel turned nose in
(https://farm5.staticflickr.com/4470/37325162592_b32f0677b6_z.jpg) (https://flic.kr/p/YSids5)20170927_185805 (https://flic.kr/p/YSids5) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Then a backwards turning job (carefully)
(https://farm5.staticflickr.com/4455/23503849668_c86510ef37_z.jpg) (https://flic.kr/p/BNXnDo)20170927_191740 (https://flic.kr/p/BNXnDo) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Done
(https://farm5.staticflickr.com/4452/36646151424_ed505f7dfb_z.jpg) (https://flic.kr/p/XQi75Y)20170927_191852 (https://flic.kr/p/XQi75Y) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
Now, this thing needs to be balanced..
(https://farm5.staticflickr.com/4439/37325802172_9a1240c309_z.jpg) (https://flic.kr/p/YSmuzj)20170927_193031 (https://flic.kr/p/YSmuzj) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
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Just a quick post today, printed a new balancing rig and got the computer with program working. It's been a few years since I did this so it took a while (runs windows XP, says something about the timespan here).
(https://farm5.staticflickr.com/4379/37410365331_d4bf37c8b7_z.jpg) (https://flic.kr/p/YZPUfP)20170930_160815 (https://flic.kr/p/YZPUfP) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
(https://farm5.staticflickr.com/4421/37362590416_b8bcd1a21b_z.jpg) (https://flic.kr/p/YVB3ro)20170930_162540 (https://flic.kr/p/YVB3ro) by Bjorn Bursell (https://www.flickr.com/photos/139032632@N06/), on Flickr
It is all set up for work now, but I'll have to get some modelling clay first. It is used to ge a imbalance reference/test weight and then used to get an idea of where to grind. See if I can find any tomorrow..
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Looking good, Bjorn :ThumbsUp: :ThumbsUp: :ThumbsUp:
Would you please share some more details about the balancing process and the equipment you're using for this? This is very interesting stuff.
Thanks
Plani
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Sadly, I did not make my deadline. Messed up one of the bearings instead :wallbang:, these are not the cheapest thing on earth so I had no additional spares. This project is on hold for now and I'm back working on the GHT geared and retracting topslide instead...