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Post by jetjeff on Sept 13, 2016 16:18:13 GMT -5
I must say, when the impingment air is removed from the intake, it moves quite a bit of air.
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Post by smithy1 on Sept 13, 2016 18:21:03 GMT -5
Hi All, I replaced the bearings with the new ones, still seems like a binding issue, not sure what to do next. The new ones spin a tad easier than the old ones, but no where near GRW bearings. I must have some issue going on with the bearings not being in the same plane. The new bearings are 28x12x8 and have ceramic balls, but there is no cage, they are full compliment. They do have a metal shield (where the rubber seal would normally go). Supposedly the shields are removable. I'm stumped. Jeff Hi Jeff, Do you know what sort of "pre-load" you have on the bearings?? If they're "full compliment" bearings they may/would normally be "angular contact" type bearings and require a fair amount of pre-load to operate correctly. I'd be pulling the shield off too so you have a free flow of lube mist going through them... Cheers, Smithy.
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dieselguy86
Veteran Member
Joined: September 2014
Posts: 186
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Post by dieselguy86 on Sept 13, 2016 18:37:46 GMT -5
Ive pressed bearings in before that had too much interference fit and it made the bearings stiff. The tight fit actually compresses the outer race, i bet if you shaved off .002" it would free right up. I know you were worried about the clearence when the shaft tunnel warms up, but the bearings will expand some also.
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Post by jetjeff on Sept 13, 2016 23:57:07 GMT -5
Hi All,
In rechecking the turbine to shroud clearance, it's more like .010" to . 015". The total engine weight came out at 6.10 lbs, just over 1 lb lighter than my old build, even though it's slightly bigger. I guess not too bad for an engine that's 6 7/8" diameter at it's widest point.
Jeff
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Post by Johansson on Sept 14, 2016 0:23:37 GMT -5
Hi All, I replaced the bearings with the new ones, still seems like a binding issue, not sure what to do next. The new ones spin a tad easier than the old ones, but no where near GRW bearings. I must have some issue going on with the bearings not being in the same plane. The new bearings are 28x12x8 and have ceramic balls, but there is no cage, they are full compliment. They do have a metal shield (where the rubber seal would normally go). Supposedly the shields are removable. I'm stumped. Jeff Sounds like an alignment issue to me, do the bearings spin freely one by one without the rotor in place?
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Post by jetjeff on Sept 14, 2016 2:27:10 GMT -5
Hi Anders,
Yes they do. When I had the engine apart, I reduced the interfereance fit of the I.D. to .0005" and .0015" on the O.D. When reinstalling the rear bearing it dropped onto the shaft after heating with no force at all.
Jeff
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Post by Johansson on Sept 14, 2016 4:44:56 GMT -5
Were the shaft tunnel bearing seats cut in one pass in the lathe or did you flip the tunnel around to cut the second one? If so there is probably not 100% perfect alignment of the two bearing seats.
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Post by jetjeff on Sept 15, 2016 4:59:37 GMT -5
Hi Anders,
The shaft tunnel was flipped. I removed the metal shields from both bearings, they are not full compliment, they do have a cage for the balls.
Jeff
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Post by jetjeff on Sept 17, 2016 2:22:45 GMT -5
Hi All,
The bearings I used are from Boca Bearings, part # SMR6001C-YZZ/C3 (12x28x8). I stated the rated RPM in the 30K range, that was incorrect, they are good for 41K, 250 degrees C. The metal shields are removable, but not easily.
Jeff
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Post by jetjeff on Sept 17, 2016 13:11:08 GMT -5
Hi All,
Quick question on the propane delivery for testing. Is the valve that's on the top of a 20lb propane cylinder sensitive enough to try running with just the tank valve, or do I need a valve that delivers more precise flow?
Jeff
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Post by racket on Sept 17, 2016 17:21:31 GMT -5
Hi Jeff
It should be OK , but generally a quick action ball valve in the line is a wise safety precaution for those emergency shutdowns where screwing in a valve wastes seconds .
Cheers John
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Post by smithy1 on Sept 18, 2016 22:03:42 GMT -5
Hi Jeff It should be OK , but generally a quick action ball valve in the line is a wise safety precaution for those emergency shutdowns where screwing in a valve wastes seconds . Cheers John +1 on that....a couple of seconds is a loooong time when you're spinning at ~100,000rpm.. Cheers, Smithy.
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Post by jetjeff on Sept 19, 2016 0:12:48 GMT -5
Hi John / Smithy,
Thanks. On the topic of propane, I had to remove a rubber disc inside the quick attach fitting for the tank. They switched to a different style filling valve a few years back, in the U.S. This rubber disc prevents large amounts of gas from escaping.
Jeff
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Post by smithy1 on Sept 19, 2016 2:53:04 GMT -5
Hi John / Smithy, Thanks. On the topic of propane, I had to remove a rubber disc inside the quick attach fitting for the tank. They switched to a different style filling valve a few years back, in the U.S. This rubber disc prevents large amounts of gas from escaping. Jeff We usually do away with the regulator and just make our own fittings to allow the correct amount through....the regulator does just that....regulate. Cheers, Smithy
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Post by racket on Sept 19, 2016 15:45:44 GMT -5
Hi Jeff
Yeh , those modified tanks in the US have given us DIY turbine builders grief for years , guys had problems with their engines only to find out it was the propane tank :-(
Some switched to fork lift propane tanks that didn't have the mods .
Cheers John
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