I have a Robust outboard tool support on my Oneway lathe and am interested in getting a hollowing system to use in it. Lacking outboard ways I have no place to mount my Clark pivot plate so I visited my friend/mentor Tom Dunne today to try out his Trent Bosch hollowing system. In the past he had said he liked it but when I showed up he was using his old Stewart handheld hollower and said he had stopped using the Bosch setup and thought it was out of adjustment. I found the links were a bit loose so we loosened the two grub screws at each arm joint, lubed the joints, tightened up the large bolts and retightened the grub screws. This took almost all the play out of the mechanism and my small scale test convinced me to place an order. It's a nice design and less cumbersome to set up than the Clark so I suspect it will be the hollowing system of choice except for deep work. Anyway, if anyone out there has found their Bosch stabilizer chattering because the links are loose, there is a cure.
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Tightening up Bosch stabilizer
- Thread starter Kevin Jenness
- Start date
Have noticed over time that the arms on my Bosch stabilizer have been getting a slight bit of play in them. Was thinking about doing maintenance on it but never got around to it. Thanks for the motivation.
One suggestion - Contact Trent and ask what adjustments might eliminate the play. I can't imagine that anything would wear sufficiently to cause a problem like you describe. I've taken classes from Trent at his shop in Colorado. All his Robust lathes are equipped with Stabilizers and Visualizers. Since they get a lot of use and probably abuse from inexperienced turners, I would gues they would show wear and tear. They don't. I know there are some tricks to getting at least one setscrew tightened down so it doesn't come loose. Maybe that's the problem. It's not an obvious setscrew.
I might get in touch to see if he recommends lubing the bushings, otherwise the problem seems to be solved. I didn't see any wear on the arm surfaces but I'll bet it could develop over time if they were left loose. It would probably be a good idea to put some loctite on those grub screws. It may well be that they weren't tight enough and the large bolts backed out a bit over time.
We have a Hope hollowing system at the club which has more play in the arms than Tom's Bosch rig. I will take a look at it tomorrow to see if it can be adjusted similarly.
Last edited:
Had mine for 4 or 5 years and love it.
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A common trick for dealing with setscrews that tend to work loose is to install a second setscrew on top of the first one. It might be necessary to get shorter setscrews. It would be a very good idea to do something to remind you that there are two setscrews. DAMHIKT
Here's what Trent had to say (only 12 hours after my query)
Thanks for reaching out. It is unusual, but it does happen that joints can loosen up. When we make and assemble it here we tighten them, like you said, with a little bit of friction and then we use loctite on the two set screws that hold those bolts in place. We tighten them evenly, making sure it still has a little bit of friction with a slight drag.
When tightening the large bolt, it could be overtightened and make the joints not move easily at all - to avoid that just snug them down, continuing to feel the movement of the joint as you do so.
I have been using the same Stabilizer's in my shop for almost 10 years and have not had them come loose, however it does come up every once and awhile with our customers. As you noticed it is easy to fix. My guess is that it is likely due to excess vibration. When I am turning I try and take very controlled cuts at a depth of cut that the tool can handle, so I have very little vibration. But I think that some people take heavier, less controlled cuts sort of stabbing at the material which puts a little bit more torque on the joints, and loosens them over time. I'm glad you reached out because I am always happy to help customers solve any issues that might come up.
As for lubrication, we grease the bearings here, and the initial greasing should last a good long time. However if you do take it apart, there is nothing wrong with adding a little bit of fresh, multi-purpose grease to the bearings.
Thanks for reaching out. It is unusual, but it does happen that joints can loosen up. When we make and assemble it here we tighten them, like you said, with a little bit of friction and then we use loctite on the two set screws that hold those bolts in place. We tighten them evenly, making sure it still has a little bit of friction with a slight drag.
When tightening the large bolt, it could be overtightened and make the joints not move easily at all - to avoid that just snug them down, continuing to feel the movement of the joint as you do so.
I have been using the same Stabilizer's in my shop for almost 10 years and have not had them come loose, however it does come up every once and awhile with our customers. As you noticed it is easy to fix. My guess is that it is likely due to excess vibration. When I am turning I try and take very controlled cuts at a depth of cut that the tool can handle, so I have very little vibration. But I think that some people take heavier, less controlled cuts sort of stabbing at the material which puts a little bit more torque on the joints, and loosens them over time. I'm glad you reached out because I am always happy to help customers solve any issues that might come up.
As for lubrication, we grease the bearings here, and the initial greasing should last a good long time. However if you do take it apart, there is nothing wrong with adding a little bit of fresh, multi-purpose grease to the bearings.