Tig brazing for shaft repair?

Hi folks.
I have a shaft I am trying to repair. The shaft is the upper shaft for
a Delta 20" wood cutting bandsaw. Some time during this machines life,
one of the upper bearings siezed up and the shaft spun in the inner
race and ground away at the shaft. A previous owner "fixed" the saw by
replacing the bearing, but did nothing to the shaft. the bearing area
in question is approximately 3/4" in diameter and the shaft is steel.
On a piece of scrap, I tried building up a section with multiple weld
beads axially along the shaft, I chucked this up in a lathe, and the
cut was horrible. I have decided that this won't work.
I was wondering if building it up with silicon bronze would be a better
method. I have put a few beads on my scrap piece but have yet to true
it up with the lathe.
any suggestions for this repair would be appretiated.
The welder is a Thermal Arc 185TSW, and I am an "enthusiastic amateur"
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Andy, maybe it would be worthwhile to reduce the diameter of the shaft to the next largest diameter, and use a different bearing?
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I will investigate this with my local bearing guy if someone talks me out of the tig-brazing idea.
The shaft has a fine thread on it and a matching nut to hold the bearing in place. It is beyond my current skills to replace this. Although as a last resort, I'll take a crack at it.
Thanks for responding Andy Ignoramus27636 wrote:
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Have you priced the replacement part? Delta tends to be really good about having parts for old machines, so mere age should not be a bar to getting a replacement (price could easily be, however, but it's generally worth checking before putting a lot of work into it).
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I spoke to Delta, and they are unable to supply a replacement shaft. Thanks, Andy Ecnerwal wrote:
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If I understand correctly the bearings are ball bearings and the shaft is no longer a press fit in the inner race. I won't try to talk you out af tig brazing as I think that would work just fine. However you might consider using a Locktite or GE retaining compound. They are suppose to work well for bearings. Your local bearing guy probably sell them.
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Dan: your understanding is correct. My bearing guy (FB Harris, Lynn, MA) had a Loctite product which will fill a gap of up to 0.020". my gap is 0.035, and there is no easy way to get the shaft concentric with the bearing while the goo sets up. He suggested a local place which will flame spray it for big money (his words). snipped-for-privacy@krl.org wrote:
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TIG brazing the shaft should work fine. Use aluminum bronze if you can find it.
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Ernie Leimkuhler
This sounds to me like a perfect excuse to purchase (or improvise) a toolpost grinder.
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Leo Lichtman
You are using cutting tools angled for bronze, 12-16 degrees for tool steel, or 8-14 for carbide?
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Stupendous Man
I think that you're on the right track with brazing. If it were me, since I don't have a TIG machine, I'd use oxy-acetylene and some hard surfacing brazing rod to build the shaft back up. If you don't have O/A, then your TIG machine will be the ticket. Post back and let us know how it goes. Also, pictures of before and after would be great!
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Ask your bearing guy about a repair sleeve. These are widely used in industry in any place where they can be fitted as they are far faster and cheaper than any welding, brazing, flame spray or other with machining.
andy wrote:
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I second that. As a 2nd yr toolmaking/precision machining student and an amateur(very) weldor, I think this is the way to go. its not something ridiculously industrial so the strength is not a factor really. you say you have a lathe? fantastic! turn down the shaft to fit the appropriate sleeve or machine a custom sleeve out of steel or brass round stock and either press-fit it into place or locktite if you machined it w/ a clearance. IMHO
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I made a mount for my Dremel , works like a charm for light grinding and polishing tasks . My set-up uses a small boring bar holder , and a bolt bent to parallel the sleeve that clamps the dremel tool .
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I have worked as an Industrial Mechanic (Millwright) for 33 years now.
The problem with Loctite is that there is no guarantee that it will harden with the bearing in correct alignment with the center of the shaft. The result on a saw would be MUCH vibration. Also, a press fit on the shaft equates to proper clearance inside the bearing. Lack of a press fit (such as when using Loctite) will allow the balls to rattle and result in premature bearing failure. - Regards Gordie
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The Nolalu Barn Owl
I'm too dumb to have any useful advice. So, I'll just help out by cheering you on from the sidelines!
snipped-for-privacy@krl.org wrote:
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Montego =E0=B9=80=E0=B8=82=E0=B8=B5=E0=B8=A2=E0=B8=99:
Have you ever check the quick sleeve?
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Thany you everyone for the suggestions. I went with the "build it up with bronze" approach. I will post some photos when the machining is finished.
Thanks, Andy andy wrote:
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Thanks for all the suggestions I received. My shaft repair was a success. I built up the scored area with silicon bronze (what I had handy) and turned it to the correct diameter on a lathe. In the photos you can see the damaged shoulder also. My brazing repair didnt work as planned here, but a turned spacer should take care of it.
thanks for looking, Andy Hall
http://metalworkandy wrote:
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