melted/broken power coupler

[jsburger]

The interesting thing about this discussion is the fast that the bandsaw hub got hot. It could be that the water pump bearing on the bandsaw drive wheel got contaminated somewhere and got hot. That would be a very rare occurrence however. I have never seen one of those bearings go bad but there is always a first time. My bandsaw is mounted on the power stand and not driven by a coupler so I have no problems and this time of year is when our woodworking club is making Toys for Tots stuff and I use my bandsaw a lot. I have a suspicion but I will refrain for now and wait to see where this discussion goes.
Bill V

I thought he said only the coupler end got hot not the band saw hub/shaft.

None of this makes any sense. Sounds like a TROLL or someone that bought non SS 3D printed couplers.

SS couplers just do not fail as we all know.

[hfmann]

In the Troubleshooting section of the bandsaw manual, the first problem listed is "Drive shaft heats up...." First possible cause is "lower bearings worn" with "replace lower bearings (factory job)" as the solution. Some years ago I had SS do a factory refurbishment for what reason I don't remember.

I discounted this cause as the shaft itself wasn't hot. Just the end of the coupler, and I assume the hub inside the coupler. After both failures, I had to pry the coupler off the bandsaw hub.

Under this listed problem, other possible causes include "hub improperly aligned" and "... hub slips drive shaft." For reasons stated earlier, I don't believe either these is to blame.

Interesting....

[beeg]

My thoughts on the power coupler is that it serves two purposes. #1 The transfer of rotational power from the headstock to the SPT. #2 That it is an expendable item. Meaning that if something happens (a jam), that the coupler is designed to break before the headstock is damaged.

[hfmann]

Wow - never been accused of being a Troll before.

But I agree - this just doesn't make sense to me.

These couplers I got directly from SS just about a week ago.

Will let you all know what SS says after I talk with them tomorrow.

hal

[rpd]

Wow - never been accused of being a Troll before.

But I agree - this just doesn't make sense to me.

These couplers I got directly from SS just about a week ago.

Will let you all know what SS says after I talk with them tomorrow.

hal

Hal. having taken note of your join date, previous posting history, and long experience with Shopsmiths, I certainly didn't take you to be a Troll.

So the two, recently purchased couplers have both overheated or failed at the same point when the old coupler did not. That would seem to rule out alignment issues.

The new couplers do appear to be made of a different material, opaque and bright white like PVC, unlike the old ones (that lasted forever) that had a bit of translucency and a slightly yellow tint.

We know that Shopsmith has been have problems finding suppliers to make some parts. One might suspect a new supplier shipping a batch couplers that are not up to the task, especially when coping with the higher HP of the Power Pro motor.

It will be interesting to see what Customer Service has to say.

[JPG]

. . .

It will be interesting to see what Customer Service has to say.

I do hope that an answer does not include an invitation to talk to an engineer about this!

















Yes I am.

[hfmann]

Update:

Just talked with cust service. At first she wanted to "set an appointment" to talk with someone. That was going to cost me $19.99 for 15 minutes. She said the power couplers had been the same for 35 years. I explained the original I had was translucent and these new ones were hard white plastic material. Obviously not the same as my original. I don't know when they actually changed.

From my order history she saw that these were under warranty, so is having someone call me back today at 12:30. I emailed pictures which she is forwarding to the person who will call me back.

for reference, here's pix of the original coupler used throughout the years for jointer and bandsaw. We think I got my Shopsmith Mark V in 1985 and have upgraded it (table, powerhead, lift assist, etc.) many times since.

Stay tuned,

hal

[dusty]

The couplers (old and new) are identical fit and form...but...they are not identical otherwise. I don't know what it is that causes this but they are not the same color. My guess would be the formula for the plastic. Are these from a mold or are they extrusions?

[jsburger]

Wow - never been accused of being a Troll before.

But I agree - this just doesn't make sense to me.

These couplers I got directly from SS just about a week ago.

Will let you all know what SS says after I talk with them tomorrow.

hal

I apologies, that was not fair. But again none of this makes sense unless SS changed something or got a batch that are not to spec.

[hfmann]

Update:

Just off the phone with Jim McCann, head engineer at Shopsmith. He's been there since 1979.

We spent some time going through the possibilities, but ruled them all out. Prior to our discussion he reviewed the manufacturer's sheets for the batch my couplers came from. He was looking to see if they used the correct material and confirmed they had (at least as reported by the manufacturer.)

He said the usual culprits are misaligned hubs and bandsaw hub set screw not securely tightened on the flat of the drive shaft. We ruled those out in this case.

Bottom line, it is a mystery to him. He's sending replacements along with a prepaid FedEx label to return the failed parts. He's going to examine them to see if he can figure it out.

Jim seems like a nice man, thoughtful of the problem, and respectful of my experience. He said to let him know if I experienced any problems with the replacement couplers.

Earlier this morning I took at look at reviews for this product on the SS site. Several reported their hubs worked fine on everything except the bandsaw where they broke. One person reported it broke right away. Another reported it broke but said his hubs were not aligned properly.

I did find an original translucent used Shopsmith brand coupler on ebay and ordered that.

that's it for now.

thanks for all your input and comments. This is a great community and I always find quick help.

thanks,

hal