CH3NO2
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Joined: March 2017
Posts: 455
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Post by CH3NO2 on Mar 1, 2019 13:01:09 GMT -5
I tried to harden one of the planet gears today. Unfortunately I was only able to get about 40ish RC hardness. I tried to upload some pics, but keep getting a 502 bad gateway error.... Don't know what that's about. I'll try again tomorrow.
Looks like I need some faster quench oil. I'm afraid to try water due to stress fracturing. Going to order some new quenchant....
Monty
Hi Monty, In addition to quenching, is carburizing an option? Tony
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Post by azwood on Mar 1, 2019 18:31:56 GMT -5
Years ago when I worked in a tooling shop some steels were air hardens and some oil hardens the 2379/D2 tool steel got to 60rws with air.
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monty
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Post by monty on Mar 1, 2019 20:00:57 GMT -5
Hi guys!
Yep, I could do all kinds of stuff if I have the gears made from high quality air hardening or other steel. I may wind up there. I'm trying to do this on the cheap...relatively. The planet gears are 1045, and are available off the shelf. It doesn't really need to be case hardened. It's a surface hardening steel. It will go to 60ish if quenched properly. The case doesn't go that deep, because it's so rate dependent. This makes it good for gears. Hard case, with a soft core for fatigue resistance. I just need to get a better quench oil. The stuff I have is probably at least a 20 second type oil. I need a 7-9 second with a fast initial quench and slow final after the martensite freeze to limit distortion. This followed by tempering at 300-400 F to reduce internal stress. I ordered some better stuff.
We shall see.
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monty
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Post by monty on Mar 8, 2019 22:20:22 GMT -5
The new quench oil is a big success. I have a video. Have to learn how to edit and post it.... For now some pics will have to suffice. I used heat treat ovens this time:
The parts were placed in nice little stainless cocoons....which were a PITA!!! I've ordered some larger ones...
SUCCESS!!!
More to follow.
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monty
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Post by monty on Apr 22, 2019 21:23:59 GMT -5
Been insanely busy at work. Unfortunately won't get a break until mid May. I did manage to cut some stock for the lapping fixture.
Squared it up and prepared it for the CNC mill.
Currently waiting on some other parts. Hope to make some progress this summer.
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monty
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Currently being spanked by mother nature.......
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Post by monty on May 8, 2019 20:01:37 GMT -5
Finally had a few moments after work to make some progress. Finish machined the lapping block fixture. I still need to make the shaft and bushing that guides the pinion and ring gear. But it's closer to being done than it was!
Decided that this needed to be done by CNC
Not everything though...
Nice when stuff fits.
Now all I need to do is make the center shaft. I will use the quill on the Bridgeport to move the pinion and ring up and down while spinning with polishing compound in the mesh. This should remove all the hobbing marks and correct the gear profiles. It will also give the proper surface finish so they will last at the ridiculous pitch line velocities this engine needs....Hopefully!
I also received the new compressor wheel. It looks to be much better as far as giving me room for the front bearing retainer and being matched to the engines projected mass flow. I can start working on finalizing the diffuser and rotating assembly. Should be able to start working on the rotating assembly in a week when work finally slows down a bit. Nice to see you guys have been making progress. Looking forward to Andy's run!!!
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Post by racket on May 8, 2019 21:11:16 GMT -5
Hi Monty
Nice bits :-)
I can only dream of having such quality workshop equipment to play with
Thats good news on the comp front , can't wait to see you getting back into your project .
Cheers John
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monty
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Post by monty on May 8, 2019 22:59:56 GMT -5
Hi Monty Nice bits :-) I can only dream of having such quality workshop equipment to play with Thats good news on the comp front , can't wait to see you getting back into your project . Cheers John John
The toys are fun, no doubt! I'm fortunate to work somewhere I have access to this stuff. I'm going to have to spend some time working on my personal workshop and tools at some point, because I'm going to need them. As well equipped as the workplace is....not going to cut it for the things I need to do moving forward. One of the projects that's had me distracted is my 5 axis mill. I have been working on retrofitting the controls on that thing....maybe I'll start an off topic thread. I also have to upgrade the electrical service to my shop, insulate my house and fix the HVAC, and there is this spring that has emerged in the middle of my driveway......going to be an eventful summer.
I'll post some more on the compressor in a week after work settles down. I'm really looking forward to getting back on this!! I have all these distractions.....some of them aren't so bad...
Monty
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monty
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Post by monty on May 18, 2019 13:59:05 GMT -5
Got a chance to start measuring out the new X841 compressor. Inducer throat area comes out around 6.87 sqin. Calculated ideal inlet angle is around 26 degrees. Here is a pic of the inducer with the calculated ideal inlet angle at max flow. I think it'll do the job!! Only downside is there is no extended tip on the exducer. Might actually work to my advantage, since I'm trying to keep the core as compact as possible. I only need a pressure ratio of 3.6 from the core compressor.
This week I should finally have some time to finish up the lapping fixture and make a new pinion gear. The last one got a nick on one of the teeth when I was cutting it out of the stainless pouch during heat treat. Hopefully I can also make some progress on the new core rotating assembly.
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Post by racket on May 19, 2019 0:44:20 GMT -5
Hi Monty
Does your X841 have a fairly large exducer angle , more radial than swept back ??
Cheers John
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monty
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Post by monty on May 19, 2019 9:40:45 GMT -5
Hi Monty Does your X841 have a fairly large exducer angle , more radial than swept back ?? Cheers John John,
Actually the new one has more sweep than the previous wheels. The KTS catalog lists it as 75 degrees. The 856 was listed at 60 degrees, and the 841 is obviously more swept. I can't figure out exactly how they are defining the trailing angle. I'll measure that later today.
Monty
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monty
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Currently being spanked by mother nature.......
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Post by monty on May 19, 2019 13:34:21 GMT -5
John,
I'm scratching my head....can't figure out how KTS defines trailing angle. Here is what I found:
KTS catalog has 60 degrees for this wheel:
And 75 degrees for this one.
Monty
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Post by racket on May 19, 2019 16:59:50 GMT -5
Hi Monty
LOL................you and me both.
When I've measured up all of my KTS wheels the angle at the exducer root is different to its tip at the shroud , its given me no end of trouble with trying to figure out the air exit angle heading towards the diffuser tips , so a generous vaneless space was the only option .
Cheers John
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Post by turboron on May 19, 2019 17:17:52 GMT -5
John/Monty, the advance centrifugal impellers I worked on 50 years ago had a varying exducer angle. The goal was to improve diffuser performance as I recall.
Thanks, Ron
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Post by racket on May 19, 2019 18:01:15 GMT -5
Hi Ron
Yep , theres undoubtedly very good reasons for the "twist" as well as the rake angle , theres some Papers on the rake but the twist seems to be less forthcoming , they're beautifully machined wheels , but frustrating to us DIY'ers trying to fathom out how best to accomodate them , I've taken the "easy" way out and made the vaneless space the full 15% , so for a 152mm exducer I'd play safe and work with an ~11-12mm gap between wheel and diffuser tip, we might lose a tad of efficiency from the extra distance but buy a bit more "flexibility" with our diffuser angle which might more than compensate ...................compromises :-(
Cheers John
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