Power Coupler Strip-Out

foxtrapper · Post by **foxtrapper** » Mon Sep 12, 2011 9:34 am

I'm kinda amazed at how well the shopsmith couplers do work. At first blush, you'd think they would shatter and fail almost as soon as you start the machine up. But, they don't. And they tend to work for years on end.

Couple of things I have observed or suspect about them and my own use.

Alignment should be darned important. If they have to play u-joint, things are going to wear. The more things are out of alignment, the more it would move, and the faster it should wear.

Lubrication might be helpful for preventing wear if things are moving. But, it could cause a lot more load on the splines. Not sure, never tried this.

Since you can fully seat the male parts into the shaft, do so. No, not bottoming them out. But not using half a spline when a full spline is available.

mountainbreeze · Post by **mountainbreeze** » Mon Sep 12, 2011 10:31 am

I too thought the SS coupler would easily break with normal use but then it occured to me that maybe it is designed to be the "weakest link" in the event of some type of failure/misuse in the SPT.

JPG · Post by **JPG** » Mon Sep 12, 2011 10:41 am

mountainbreeze wrote:I too thought the SS coupler would easily break with normal use but then it occured to me that maybe it is designed to be the "weakest link" in the event of some type of failure/misuse in the SPT.

I still use my 'weakest link' almost daily and it is almost a half century old.

It outlasted the control sheave and key!

But the coupler is not supposed to be lubricated every 10 operating hours!:o

More recent vintage couplers are made of a softer plastic.(you do not want anything rubbing against them while turning). Yes I now have a two piece coupler.

dusty · Post by **dusty** » Mon Sep 12, 2011 12:05 pm

I have recently had to replace two different couplers. Both came with the original equipment many, many years ago. However, like everything else either rubber or plastic, the Arizona sun and dry air do no good.

Now I do get full morning sun directly on my Mark V which does not help. If it was in the shade, I do believe it would be less of a factor.

There are times during the summer that the sun heats the headstock to a point where it is uncomfortable to touch.

JPG · Post by **JPG** » Mon Sep 12, 2011 12:13 pm

Window shades?????

charlese · Post by **charlese** » Tue Sep 13, 2011 4:54 pm

My favorite coupler is only 13 years old. it came with my first Shopsmith purchase - a Crafter's Station. I used it with my Mark V constantly, until getting the PowerPro and finding out the slight play worn into the coupler caused unlikeable noises from the headstock when using the bandsaw.

I now have a very snug fitting coupler marked for use with the bandsaw and I use the old one with the other SPTs.

randythewoodchuck · Post by **randythewoodchuck** » Wed Sep 14, 2011 9:21 am

When I originally posted my problem with stripping out the couplers I took the advice that I was perhaps out of alignment between the head and the SPTs. Being very careful to get the alignment correct solved the problem, but I increasingly had difficulty getting the alignment. While trying to figure out why I was having such a problem, about 3 months ago, I removed the Way Tube Tie Bar, dropping it on a concrete floor and breaking it. (Obviously, coordination is not my strong point.) When I put the replacement on, which Shopsmith quickly supplied, the alignment problem solved itself. Only thing I can figure is that the old Tie Bar had a fault in it of some sort, throwing the alignment off. This worked so well I am considering breaking a few more items so that I will be forced to replace them.

dusty · Post by **dusty** » Wed Sep 14, 2011 9:47 am

randythewoodchuck wrote:When I originally posted my problem with stripping out the couplers I took the advice that I was perhaps out of alignment between the head and the SPTs. Being very careful to get the alignment correct solved the problem, but I increasingly had difficulty getting the alignment. While trying to figure out why I was having such a problem, about 3 months ago, I removed the Way Tube Tie Bar, dropping it on a concrete floor and breaking it. (Obviously, coordination is not my strong point.) When I put the replacement on, which Shopsmith quickly supplied, the alignment problem solved itself. Only thing I can figure is that the old Tie Bar had a fault in it of some sort, throwing the alignment off. This worked so well I am considering breaking a few more items so that I will be forced to replace them.

I have no better prognosis to offer but I do doubt your suspicions about the tie bar being defective. It might not have been installed all the way onto the tubes but I doubt it was defective.

beeg · Post by **beeg** » Wed Sep 14, 2011 10:19 am

randythewoodchuck wrote: Being very careful to get the alignment correct solved the problem, but I increasingly had difficulty getting the alignment.

You should only have to do that alignment once. Sounds like maybe the tie bar wasn't tightened down correctly.

randythewoodchuck · Post by **randythewoodchuck** » Wed Sep 14, 2011 11:05 am

You may be correct, but I took it off, cleaned out the tube insert areas, and reassembled, and it was still out of alignment. When I took it off a second time I accidentally dropped it, or God was helping me fix my Shopsmith, whichever. All I know is that when I purchased it used it never sat on the lock shaft quite right. Now it does. So, whether it was not assembled correctly or it was a bit warped, the outcome was positive and for that I am thankful. It was worth all of the $25 or so that it cost me for a new one.

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