All Day Dan

My Feedback: (5)

This crankshaft has been knurled at the rear bearing position to extend it's usage after becoming loose. Now the knurling has failed. Is there any way to build up the area and have it refinished? I tried two plasma spray websites but got no response. Thank, Dan.

the pope

Could it be re-done ? Maybe centre punched around it in a few spots . This is from my non-machinist background so if theres other methods Im sure Im not aware of . What engine is it from . A one off job could get quite expensive as some shops have a min. fee unless u can phone a friend . I assume u can no longer buy a new one ? Can one get a special bearing sizes that allows for cases like this ? Again Im clueless just throwing ideas around . Cheers

Lifer

My Feedback: (1)

A brass sleeve attached with green loctite could be used.

Propworn

My Feedback: (3)

Whats it out of? Can you locate a new or good used one?

We repair shafts all the time but its not cheap. Usually requires removing some material then building it up with spray weld or chrome then grinding the finish size. An hour setup and grind. At least that maybe two to set up and add the filler material then an other hour to an hour and a half to finish grind to size. I don't know local shop prices but 3 more likely 4 hours labour. Not many shops will be interested in a small one off job like that.

Dennis

av8tor1977

My Feedback: (6)

I would be sorely tempted to braze over that area with bronze, then turn it back down to size on the lathe. I once did this to a cargo trailer axle that the bearing had seized on and ruined the axle. It was an emergency, roadside repair for a friend. (Obviously, in that case, I used a file to dress down the brazed area instead of a lathe.) Anyway, he never did replace that axle, and it ran just fine that way for many thousands of miles.

AV8TOR

av8tor1977

My Feedback: (6)

Looking closer at the pic, I am somewhat surprised that they were able to knurl it that well, AND that the knurling didn't hold up. That crank must be "soft". I stick by my "fix".....

AV8TOR

Truckracer

My Feedback: (19)

Yes, the Brison cranks were quite soft. If Loctite is used and Brison used Loctite, there's usually no problem. The crank pin is pressed in harded and steel.

av8tor1977

My Feedback: (6)

Hiya Truckracer. How have you been??

AV8TOR

Truckracer

My Feedback: (19)

Very well but spending much of my time in the Minnesota north woods refurbishing a lake cabin. Enjoyable project but it cuts into my flying time. How have you been?

All Day Dan

My Feedback: (5)

Thanks to everyone for the inputs. I am surprised at such a response for for a unique subject. I'm still trying to get replacements before I leap into these more expensive repairs. Dan.

av8tor1977

My Feedback: (6)

If you can't get it figured out reasonably, shoot me a "PM".

Truckracer- Ah, so you are still in the mountains. I'm jealous. I'm stuck here in the desert where it won't be cool enough to fly 'till Halloween! I am recovering from another big back operation. A week in the hospital, two weeks in acute care rehab, been home for two weeks now. PITA!!

AV8TOR

Truckracer

My Feedback: (19)

Get well soon av8tor!

No mountains here though there are some large hills. Lots of water though!

av8tor1977

My Feedback: (6)

Thanks! What do the temperatures run up there? Lots of rain?

AV8TOR

Truckracer

My Feedback: (19)

The highest temp I've seen when I've been here this summer is 89°. Normal temperatures seem to be in the mid to high 70s. It's very humid though that is something you don't experience where you're from. Temps in the mid to low 80s here feel like mid 90s in Iowa where I'm from. And Iowa is very humid. You have to feel high humidity to understand it's effects. It's miserable! But at least we can fly pretty much any day in the summer when the weathers is nice. I can't imagine the temperatures you experience in Arizona.

av8tor1977

My Feedback: (6)

I do understand humidity. I often spend time in Puerto Penasco, Sonora, Mexico on the Sea of Cortez. It runs close to 100 in the summer, with humidities from 60 to sometimes 100 per cent! That's miserable for sure, but 120 degrees is purely inhuman. One day in June my daughter and I had some errands we just had to run here in Tucson, and the car outside thermometer read between 118 and 120 the entire afternoon. It was over 100 degrees all night!!

AV8TOR

Jennifer Curtis

Turn the shaft on a lathe to make a
shallow notch. Form a piece of shim
stock or brass tubing into a slotted
cylinder to snugly fit into the bearing.
Spring the cylinder open enough to
slide it over the end of the shaft and
slide it down to the notch. If it won't
go into the bearing, chamfer the front
edge of the brass.

Jenny

karolh

That sounds quite ingenious to say the least.

av8tor1977

My Feedback: (6)

If I were going to go that route, I would turn down that whole, stepped up length of the shaft. Then I would heat shrink a non-slotted full length sleeve onto it, with Loctite as well.

AV8TOR

Jennifer Curtis

Yes that would be a very nice solution.
It would take a better machinist than me
to get a sleeve that long over the shaft
before the shaft heated and expanded
and the the sleeve cooled and shrunk.

Jenny

av8tor1977

My Feedback: (6)

I would put the crank in the freezer, and heat the sleeve with a torch. Then I would smear some Loctite on the crank, and put them together. The Loctite would kind of lubricate them going together, then harden and it would Never come apart. The hardest part of this fix would be making the sleeve to exact tolerances.

I would do the first fix I mentioned; braze it up and then turn it down to size.

AV8TOR

Propworn

My Feedback: (3)

Cranks are turned on centers. Look at both ends of the crank for them. If you have the ability to turn the crank down, make a liner the best way would be to press an oversize liner in place then turn it down to size.

Depending on the crank is there enough material to retain the strength when the material is removed? The liner can actually be thinner as the outside diameter is to be finish turned after installation.

Crank in deep freeze or better yet packed in dry ice. Liner heated in BBQ or oven for even controlled heat.

All Day Dan

My Feedback: (5)

A local machine shop I use has a supplier that can build up the knurled area somehow and machine it down to the necessary diameter. I'll keep you posted. Dan.

Propworn

My Feedback: (3)

What motor is it out of anyway?

Truckracer

My Feedback: (19)

Looks to be a Brison crank though Fox cranks are almost identical. Novel idea but my thinking is a good machine shop will charge as much or more to repair that crank than to make a new one. The crank pin appears to be in very good condition, and it could be reused. The cranks themselves are not hardened.

karolh

If Cyberwolf is listening in here hopefully he will chime in and give his opinion.