Jet JBOS-5 rebuild

[Troy Gamm]

I have wanted a nice spindle sander for quite some time and kept my eye out for used any used JBOS sanders. One finally popped up a couple of days ago. When I went to see it, it seems like it is one of the older units based on the serial numbers (different user manual than the newer ones) and the sticker states it is a Taiwan built machine. The motor runs fine but it has a bit of a runout you can feel with a spindle mounted in it. I ended up offering the guy $150 for it and he took it so I own it now for better or worse.

One of the reasons I went ahead with it is because short of needing a new motor, I could have it rebuilt (or do it myself) and end up with a pretty nice machine for less than the price of new ones.

I know the oscillation mechanism runs in an oil bath but I am guessing the bearings are shot at the least and it may need a new transmission slider (~$50 for the transmission). Has anyone on here ever rebuilt one of these machines? I have an inexpensive WEN I bought to get me by until I can get this one rebuilt.

I have also read a few posts (all newer) where guys have had issues with the new spindles being out of round. I plan on picking up a 3" spindle directly from Jet and keep sending it back until the send me one that is true. Has anyone purchased the 3" for one of these?

[Edward Weber]

I bought a 3" one, but it didn't come directly from JET.
Mine runs true as it can, no problems.

How bad of a wobble? Is it the spindle or the rubber drum that's the causing the issue?

[Robert Hayward]

When I had a JBOS-5 it had a significant wobble on the spindles with rubber drums. It was the rubber drums that were out of round. Some more than others.

[Dave VanDewerker]

All three of my rubber drums are out of round, probably just going to make my own replacements.

[Steve Jenkins]

Don’t mean to hijack but I have a Jet 9” oscillating spindle sander and found a big puddle of oil under it. I haven’t dug into it yet but any suggestions?

[Troy Gamm]

I bought a 3" one, but it didn't come directly from JET.
Mine runs true as it can, no problems.

How bad of a wobble? Is it the spindle or the rubber drum that's the causing the issue?

The wobble is bad enough that you can't push enough to get rid of the chatter. I do suspect the rubber drum is out but i also think there is some runout between the transmission (part that moves up and down and holds the bearings for the spindle) and the part it runs up and down in. When it is running, you can see a shift in the spindle at the top of the oscillation as it starts back down.

I called an authorized Jet service facility this morning I have used for other tools and they said to bring it in and they will figure it out. I have wanted one of these for too long but am frustrated by Jet's lack of quality control on the rubber drums.

[Troy Gamm]

I decided to do a little investigating on my own before I took it to the Jet approved service center. Not sure I have completely solved the issue but I do think I have found some contributing problems.

The first issue is that I have some play between the transmission (A in my Photo below) and the housing (B). There is .01" of movement right where the transmission meets the housing when using applying pressure at the top of the drum. I removed a few parts (Table and spindle dust shield) so I could do some measurements.

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Not sure what the acceptable amount of play is for these parts but I still plan on taking it to the service center for them to determine if this is excessive. I do believe this sander has had quite a bit of use so it wouldn't surprise me to find these parts are a little worn.

The drum spindle itself has a .008" runout and with the drum on it is .015" just rotating it by hand.

That being said, the second issue I found is what I think introduces wobble and exacerbates the play in the spindle. The hole in the large washer on the top of my 2" spindle doesn't allow it to center on the threads and since it is pretty heavy, any amount of off-center will cause the top of the drum to exert enough on the top of the spindle and induce a wobble (.03") when it is running.
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I have a hard time understanding how Jet sells this spindle ($160) with a washer that has such a large hole in it. It seems it would be pretty easy to ship it with a washer with a hole the same diameter as the threaded rod. I am going to 3d print an insert that will center the washer on the spindle. I will post pics of it when I get it done in the next day or so.

[Troy Gamm]

I went ahead and printed up a centering washer that inserts into the large washed to keep it centered on the threaded rod. It ended up working out pretty well, so much so that I can live with the runout in the oscillating parts until I can get it into the service center. It is so much smoother. I ended up ordering a 3" spindle assembly from Jet yesterday. If it has the same washer issue, I will print up a centering washer for it as well.

Not sure if others could use this but if you can, I can provide the stl file for those who have access to a 3d printer. Just let me know.

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