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Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 12:23 pm
by dphoto1
Hello All, I was wondering if I am missing some spacers or something on my jointer. When I mount it and tighten the accessory lock the jointer will slide down and break the coupler when running. It looks like a 3/8 spacer would fix the problem but I cannot find any on the Shopsmith website. I know I could probably fashion a couple spacers but wanted to see if there was something already available. Any help is appreciated.
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 12:49 pm
by edma194
The locking handle has two bolts that extend as you rotate it. The square heads on those bolts push against the mounting tubes to lock it in place. If the bolts are not threaded into the handle the same distance then only one side puts full pressure against a tube and an accessory can easily slip.
To check this, remove the handle by loosening it until you can remove it, then rotate each bolt until it protrudes the same distance from the handle. I try to get the bottom of the bolt head flush with the side of the locking handle on each side. Now when you tighten the handle you'll apply equal pressure from the bolts on both sides.
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 1:01 pm
by chapmanruss
The mounting posts for your jointer should be an eccentric post with an offset near the middle. IIRC all Model 620 Jointers and on made starting in 1954 have eccentric mounting posts. The posts should be installed with the eccentric offset resting on the mounting holes of the Mark V and the Jointer set on the top of the posts. Align the Jointer's hub to the lower aux. shaft hub on the Mark V and tighten the set screws. The eccentric should always rest on the Mark V's mounting holes. This information is in the owners manual under setup.
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 1:20 pm
by dphoto1
That's probably part of my problem. The posts are not eccentric.
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 2:10 pm
by dusty
dphoto1 wrote: Thu Nov 05, 2020 1:20 pm
That's probably part of my problem. The posts are not eccentric.
If the posts being used are not eccentric you would most likely have an alignment problem (the hubs would not align) but that would not cause a slipping issue. You would be able to lock the jointer at various heights but would not be able to align the hubs laterally. This one is used on my jointer.
- Short Eccentric
- Eccentric_Short.jpg (57.16 KiB) Viewed 1475 times
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 3:23 pm
by DLB
edma194 wrote: Thu Nov 05, 2020 12:49 pm
The locking handle has two bolts that extend as you rotate it. The square heads on those bolts push against the mounting tubes to lock it in place. If the bolts are not threaded into the handle the same distance then only one side puts full pressure against a tube and an accessory can easily slip.
To check this, remove the handle by loosening it until you can remove it, then rotate each bolt until it protrudes the same distance from the handle. I try to get the bottom of the bolt head flush with the side of the locking handle on each side. Now when you tighten the handle you'll apply equal pressure from the bolts on both sides.
There are some Headrest castings where this may not work. An alternative check is that the handle portion of the locking handle should not be in contact with the Headrest at either end when in the locked position. As long as there is some clearance at each end, the lock should work. If the handle portion is in contact with the Headrest on one end, you're only getting a fraction of the locking effectiveness.
- David
Re: Jointer Slipping down and breaking coupler
Posted: Thu Nov 05, 2020 3:29 pm
by edma194
DLB wrote: Thu Nov 05, 2020 3:23 pm
There are some Headrest castings where this may not work. An alternative check is that the handle portion of the locking handle should not be in contact with the Headrest at either end when in the locked position. As long as there is some clearance at each end, the lock should work. If the handle portion is in contact with the Headrest on one end, you're only getting a fraction of the locking effectiveness.
- David
Yes, you'll see a problem if one side of the handle is up against the casting when you tighten it.
Re: Jointer Slipping down and breaking coupler
Posted: Fri Nov 06, 2020 12:55 pm
by chapmanruss
I would recommend changing to the Jointer Eccentric Mounting Tubes P/N 5020809. Having the Jointer, which is very heavy, resting on the eccentric offset would eliminate the chance of slipping down even if the lock doesn't completely hold it. Do check to see that both sides of the lock put pressure on the mounting tubes as others have indicated.
Re: Jointer Slipping down and breaking coupler
Posted: Fri Nov 06, 2020 7:49 pm
by DLB
I agree with Russ, there are multiple reasons the eccentrics are needed for the Jointer. They'll hold the weight while you tighten the SPT lock handle. They maintain alignment in both directions from one installation to the next. And because the Idler shaft that drives it is in an eccentric bushing for tension adjustment, it's unlikely that you will get good shaft alignment without them as stated above. Straight tubes can sometimes be used for SPTs driven on the upper shaft, but not so much the lower.
- David
Re: Jointer Slipping down and breaking coupler
Posted: Sat Nov 07, 2020 6:19 am
by dusty
DLB wrote: Fri Nov 06, 2020 7:49 pm
I agree with Russ, there are multiple reasons the eccentrics are needed for the Jointer. They'll hold the weight while you tighten the SPT lock handle. They maintain alignment in both directions from one installation to the next. And because the Idler shaft that drives it is in an eccentric bushing for tension adjustment, it's unlikely that you will get good shaft alignment without them as stated above.
Straight tubes can sometimes be used for SPTs driven on the upper shaft, but not so much the lower.
- David
I agree that proper orientation (both vertical and lateral) of the hubs is unlikely without using eccentric tubes BUT I don't understand your differentiation between the two drive shafts. If one aligns vertically with a given SPT I would think the other would too.