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Old 27th September 2011, 07:22 PM   #41
Matt BH is offline Matt BH  United Kingdom
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Was going to ask if you had a drawing

Is the allen key passing right through the conical nut and into a hex hole in the shaft?

The drawing looks like there is a slot in the nut, is there?

Maybe a good sharp crack on the end will free it, dont want to damage the other bearing though.

Cheers Matt.
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Old 27th September 2011, 07:22 PM   #42
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your overestimating . requires some tubing some skill in sealing , barium getters and easily weldable wire .

also a array of stuff like a spot welder vacuum pump and RF bombardner . but thats about it

rf bombardner and a spot welder aint that hard at all there are plenty of vids on youtube of 17 year olds glowing nuts and bolts red hot whit 500 watts of power

a nice spot welder is 100 bucks worth of scrap iron a microwave transformer and some heavy guage wire

next thing you do is you make a tube whit a thin fillament wind a spiral grid ant start plotting . also called a hell glower 2700 degrees fillament .

or make a paste of the aka lines i posted earlier barium strontium and calcium put it on and it will emit at 800-900 degrees .
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Old 27th September 2011, 07:40 PM   #43
Matt BH is offline Matt BH  United Kingdom
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Sorry more questions Smoking Amp.

Does it spin clock wise looking at the drawing ie rotating left to right? If so I would say almost definately it is left hand threaded. Some heat should free it, stainless expands quite a bit with heat unless it is some other alloy like Inconel or Hastelloy.

Also it looks like a tapered ball race. I guess the large threaded part is to pre-load the bearing which will be critical to the life of the bearing.
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Old 27th September 2011, 11:19 PM   #44
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re: Matt B.H.

The rotor spins clockwise looking at the bottom open bearing end. The conical nut protrudes downward into a plastic cup filled with oil soaked felt washers ($73 to change the cup for an oil change). The conical nut probably wicks oil up into the bearing during operation. The friction of the felt on the conical nut would tend to loosen a conventional right handed thread if it were loose. This is why I suspect it's a left hand thread. The "notches" in the drawing are probably just a drawing artifact to show how a felt washer surrounds the conical nut.

The plastic cup (white outline on the drawing) is totally filled with stacked felt washers, each with a hole in it to allow the conical nut to penetrate down in. Nothing is visible on the conical nut in the way of a notch, smooth all around. The Allen wrench appears to be mating only with the conical nut. They likely have a bearing puller tool to remove the bearing once the nut is off. I've seen it in the kit of parts for the bigger turbos, but those have a different bearing setup. (the manual with bearing change info is available online for the larger TPU170. I guess I should go look at it closer to see if they used a left hand thread there, but it would depend on the rotation direction there which I don't know.)

By the way, the top end of the turbo has holes in the rotor to insert a special tool to lock it in place. I just put some appropriate sized drills in to lock it. In retrospec, I should have examined these immediately to see if there were any obvious signs of torque applied. This might have given away the thread handedness. Too late now though, but I don't see any obvious marks anyway.

I would like to be sure of the handedness of the thread before using heat on the nut, since I might end up tightening it up further if I get it wrong. I tried both directions without heat up to the failure point of the Allen wrench to no avail already.
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Last edited by smoking-amp; 27th September 2011 at 11:25 PM.
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Old 28th September 2011, 01:58 AM   #45
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I read thru the TPU170 bearing change info and it IS a left hand thread there.
TPU170 info attached. I'll try heating the nut next and removing it correctly now.
Attached Images
File Type: gif TPU170_1.gif (84.4 KB, 74 views)
File Type: gif TPU170_2.gif (37.5 KB, 72 views)
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Old 28th September 2011, 02:28 PM   #46
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Quote:
Originally Posted by franzm View Post
The easiest way to "make" a vacuum tube: Take a bifilament car bulb with convenient geometry. Distroy one of the filaments (the lower power one). The result is a very basic direct heated triode (good enough for school demos).
Great idea. Can you post a picture of a suitable car bulb with the
right geometry?
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Old 28th September 2011, 08:53 PM   #47
Matt BH is offline Matt BH  United Kingdom
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Glad you found out Smoking Amp. Hopefully you can get it off, maybe a 1/4in socket type 2mm key will help. I guess making some kind of puller will be next.

Cheers Matt.
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Old 28th September 2011, 08:58 PM   #48
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WooHoo!!! I got the conical nut off finally. I went over to Northern Tool and picked out some Allen wrenches with a lifetime guarantee, Bondhus Protanium. Tried it on the conical nut and twisted CW (left hand thread) an obscene amount until I heard a loud crack. I looked in expecting to see a cracked wrench, but the nut had popped off!!

Now the darn inner bearing race won't come off. It does have a mm roughly of clearance to get a micro pulley puller on or I need some miniature hardened crow bars. The next adventure begins! Heat will probably help for this.

Interestingly the conical nut does not have a flat end on it where it contacted the inner bearing race, but rather a slightly concave surface. Maybe they used this like a lock nut, tightening up on the threads as it gets torqued up. No sign of Loc-tite on the threads.

Photos attached of the conical nut and of one of my earlier attempts with an ordinary high carbon steel Allen wrench.
Attached Images
File Type: jpg WooHoo.jpg (14.4 KB, 47 views)
File Type: jpg twisted.jpg (14.0 KB, 46 views)
File Type: jpg inner_race.jpg (20.0 KB, 45 views)
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Last edited by smoking-amp; 28th September 2011 at 09:14 PM.
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Old 28th September 2011, 09:07 PM   #49
Matt BH is offline Matt BH  United Kingdom
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great news.

The Bondhus keys are great aren't they. I aquired a set of metric and imperial ones at my last job. The smaller ones can be almost bent in half and they just spring back!

An old flat screwdriver could be heated to cherry red and the end hammered over to form a sort of small pry bar. Polish it a bit so its shiny then heat back up to a straw colour and quench in water with a bit of oil and washing liquid. Should be hard but not brittle then.

Good luck.
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Old 28th September 2011, 09:37 PM   #50
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My thoughts exactly! I'll try heat first with just a needlenose, but I'm expecting to have to fabricate some tool(s). That 2 mm Bondhus wrench is still straight! I would have twisted the ordinary ones clear off with the force it took. Maybe I can just grind the ends down to make pry bars from the earlier bent up Allens.
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