Small shaft repair options?

[calgaryguy]

I've got a shaft out of a 6x48 sander belt idler thats abnormally worn on one bearing location. I just picked this sander up at an auction and was going thru it and noticed the idler pulley bearings were noisy.
Shaft is ~12" long, and slightly larger than 1/2" dia.

There are identical bearings at each end of this shaft with an id that is a slightly loose press fit. I initially thought the shoulder shown in the last two pics was machined and that the wrong bearing had been installed at some point. Nope, the shaft spun for so long in the bearing that it wore a new shoulder.

The two options I can think of to repair this is
1) machine the 'shoulder area' shown in the pics down to the next smaller ID bearing. I've already procured a bearing whose other dimensions are identical to the original except the ID is slightly smaller than the worn area.
2) build up the shoulder area via tig/mig and then machine down to match the OD of the shaft.

Any other options Im not thinking of?

 

[Darren]

I'd probably mig it and machine it back down, but sleeving it will ensure no warping. easy fix either way, assuming you have a lathe.

 

[calgaryguy]

So my neighbour has a craftex CX709 lathe and is the welder. "Hey Buddy!" Same gent has the Bridgeport Series II NC machine that I posted about months back.

His (the neighbour who welds) concern wasnt warping the shaft, but losing the 'temper' in it from tig/mig heat. I wouldnt have thought steel for a medium duty shaft like this application would be hardened beyond whatever alloying process was used to make the steel in the first place - admittedly I'm a complete noob when it comes to metallurgy. I am a little surprised that the bearing managed to wear the shaft as much as it did without showing any serious signs of wear on its ID (and it wasnt seized).

 

[Darren]

I highly doubt its hardened, it doesn't need to be. It's not normally a wear surface. It looks like the idler wheel shaft.

 

[calgaryguy]

It looks like the idler wheel shaft.

Thats exactly what it is.

 

[Darren]

Thats exactly what it is.

Weld er up, machine to standard size. Not an issue.

 

[calgaryguy]

I happened across some threads on the vintagemachinery.org forums for this exact delta/rockwell sander model. Seems this shaft getting f***ed is pretty normal. Seems the 'fix' is to buy some 15mm drill rod and just make a new shaft. Ends get machined down to 1/2" and then threaded for 1/2"-20

 

[Darren]

thats always an option as well.

 

[ShawnR]

I did as @dfloen suggested this week in a project I have been working on. Plans kept changing as I progressed and I ended up welding in a lot of "build up", and then turning down. Having not done much of this, I was quite happy with the result.

 

[calgaryguy]

thats always an option as well.

I'm thinking this would be a great exercise for me on the lathe - machining a whole new shaft and some single point threading. Drill rod is cheap so I can make plenty of f-ups as I progress.

 

[PeterT]

if you didn't want heat involved you could clean up the worn surface in lathe, machine a ring with snug/slight interference fit on ID, attach with Loctite retainer, turn the (slightly oversize) ring OD to whatever the bearing ID needs. Minimum diameter of ring dictated by threads.

The overall shaft looks like its slips in something, or is that just the way it came out? You could probably machine a better one in about as much time, but that presumes the mid section diameter is just nominal. Plus maybe look like you have opposite threads on either end? OK, maybe a few more minutes LOL

 

[calgaryguy]

if you didn't want heat involved you could clean up the worn surface in lathe, machine a ring with snug/slight interference fit on ID, attach with Loctite retainer, turn the (slightly oversize) ring OD to whatever the bearing ID needs. Minimum diameter of ring dictated by threads.

The overall shaft looks like its slips in something, or is that just the way it came out? You could probably machine a better one in about as much time, but that presumes the mid section diameter is just nominal. Plus maybe look like you have opposite threads on either end? OK, maybe a few more minutes LOL

Here's the tool schematic, part 8 is the shaft in the pics.

So the two drums slip fit on the shaft and two spacers are added, one at each end of the shaft. The two nuts thread on at each end of the shaft until it draws the bearings, spacers and drums together tightly to rotate with the rotation of the shaft - does that make sense?

 

[calgaryguy]

Anyone know where I can buy "Ground Drill Rod" in Calgary? I've brought drill rod at places like Greggs Distributing before, but the posts over on vintagemachinery.org forums spec 15mm *ground* drill rod

 

[YYCHM]

Here's the tool schematic, part 8 is the shaft in the pics.

So the two drums slip fit on the shaft and two spacers are added, one at each end of the shaft. The two nuts thread on at each end of the shaft until it draws the bearings, spacers and drums together tightly to rotate with the rotation of the shaft - does that make sense?

No schematic?

 

[calgaryguy]

No schematic?

Missed it on the first try, thanks for the heads up!

 

[YYCHM]

Anyone know where I can buy "Ground Drill Rod" in Calgary? I've brought drill rod at places like Greggs Distributing before, but the posts over on vintagemachinery.org forums spec 15mm *ground* drill rod

MSM

 

[calgaryguy]

MSM

Who is MSM. I googled 'MSM Calgary' and was a little surprised at the results...

"Metal SuperMarkets" Got it. Duh.

 

[PeterT]

KBC has good selection of OH & AH & flat shipping, imperial & metric. Shipping might be a week though FOB BC.
Wouldn't surprise me if it landed less cost all in. Metal prices seem all over the map these days, maybe supply hangover issues.
You mention 15mm, are the threads metric?

 

[calgaryguy]

KBC has good selection of OH & AH & flat shipping, imperial & metric. Shipping might be a week though FOB BC.
Wouldn't surprise me if it landed less cost all in. Metal prices seem all over the map these days, maybe supply hangover issues.
You mention 15mm, are the threads metric?

I believe the threads are 1/2-20 based on the forum posts at OWWM.org (vintage machinery forum site) but I'd need to verify. And yeah, odd that the shaft is 15mm but standard threads. All teh fasteners on this sander are imperial/standard.

EDIT:

Granted those calipers are cheapies, but they've been moderately accurate to date.

 

[DPittman]

Well I think welding it up and then machining it down would be best if not a whole new shaft. Many many years ago I repaired a larger shaft with the exact same cause of wear and I did not have a welder or a lathe or much anything other than hand files an acetylene torch and a belt sander. So I brazed up the worn area and then filed and sanded the brazing down to a very nice finish. I believe the machine ran for many more years with that fix.