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Hollowing Systems

trc65

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Started this hollow form without any thought of how large it was or how deep I'd have to go by hand. Used John Jordan 3/4" tool and it's about 9.5" deep. While I could probably go another inch deep by hand, got to say it wasn't exactly pleasurable hollowing it.

walnut form.jpeg

walnut form2.jpeg

Got me thinking about systems and looking at different ones. My lathe is a Rikon with 12.5" swing and 20" between centers. To me, a captured system just seems to be too big for my lathe, which led me to look at articulated systems like the elbo system that Tim Yoder sells. Simple enough looking system and rather than buy thinking about making one. Anybody make something similar? Any hints or lessons learned?

Any and all comments on hollowing systems welcome.
 
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Steve in VA

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Hey Tim - First off, great hollow form and I'd love to see some more pics of it! What type of wood is it? It reminds me of poplar when it's first cut.

We have the same tools and after doing a number of hollow forms I started down the path of looking at articulated arm systems myself. I evaluated them all and if I could buy one it would undoubtedly be Trent Bosch's system. That said, $400+ isn't in the cards right now so I decided to make one myself. I researched every system out there looking at how they attached to the lathe, how they moved, how tools were held, etc. There are several designs online and I look at those in depth as well. In the end, I took bits and pieces from each system and cobbled together what I thought was going to be a prototype to start from. I've been shocked by how well it works, without any further modifications. In fact, I've been using it so much I haven't even gotten around to putting a protective finish on it. I was initially most concerned about stability, so I designed it to attach in two places; on the tailstock via a bolt in my Jacob's chuck and plywood base that mounts to the bed ways. It's made with bearings between the wood arms which makes it very smooth, and getting it on or off the lathe takes less than three minutes.

I literally took it off the lathe a few hours ago after finishing my latest hollow form, but will put it back on and post some pictures for you tomorrow. Cost wise it was under $25, not counting the wood which I already had. I'm happy to chat over the phone as well if you want to know more after seeing the pictures. Stay tuned.
 

trc65

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Thanks Steve! For both the info and the pictures to come. Good to hear yours is working so well! I wasn't even thinking about wood arms, was planning to piece the whole thing together with scrap steel I've got sitting around from various farm implements (and dreading the drilling).

The form is walnut with the pith and a rotten section just off the center. I'd got about a 5 ft section of a log with the rotten section running the length. Plan on trying a series of different shapes all cut with the same orientation.

This one is about 9.5" diameter and just a little bit taller. Hollowed to about an inch thick so hopefully plenty of extra to tweak the shape a little when dry. I think it needs to have just a little longer neck. Sitting in a bag at shavings right now in the basement. Will be watching it closely to make sure it doesn't try to self destruct as it dries. I'm hoping it develops some interesting cracks from the pith. Originally was thinking about filling the anticipated cracks with malachite or turquoise, but now thinking about leaving them unfilled.

Here are a few more pictures of it.

IMG_4317.JPG IMG_4319.JPG

IMG_4322.JPG

IMG_4323.JPG

Here's a picture of the log it was cut from.

walnut3.jpeg
 

Nature Man

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Hey Tim - First off, great hollow form and I'd love to see some more pics of it! What type of wood is it? It reminds me of poplar when it's first cut.

We have the same tools and after doing a number of hollow forms I started down the path of looking at articulated arm systems myself. I evaluated them all and if I could buy one it would undoubtedly be Trent Bosch's system. That said, $400+ isn't in the cards right now so I decided to make one myself. I researched every system out there looking at how they attached to the lathe, how they moved, how tools were held, etc. There are several designs online and I look at those in depth as well. In the end, I took bits and pieces from each system and cobbled together what I thought was going to be a prototype to start from. I've been shocked by how well it works, without any further modifications. In fact, I've been using it so much I haven't even gotten around to putting a protective finish on it. I was initially most concerned about stability, so I designed it to attach in two places; on the tailstock via a bolt in my Jacob's chuck and plywood base that mounts to the bed ways. It's made with bearings between the wood arms which makes it very smooth, and getting it on or off the lathe takes less than three minutes.

I literally took it off the lathe a few hours ago after finishing my latest hollow form, but will put it back on and post some pictures for you tomorrow. Cost wise it was under $25, not counting the wood which I already had. I'm happy to chat over the phone as well if you want to know more after seeing the pictures. Stay tuned.
Anxious to see pics! Chuck
 

Steve in VA

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Looks great Tim and I now I see the walnut colors! Good luck with the drying process, especially after investing the time to hollow that big boy out!

Here are some pics of what I came up with. In this first pic, you can see the main block I used to connect to the base, the Jacobs chuck, and the first arm. It's 2" thick maple. The bolt that inserts into the chuck is tightened down with big washers and epoxied into place. On the headstock side you can see where I had to cut a notch in order to through bolt the first arm. I wanted full access to this in case I needed to loosen or tighten that bolt in the future. This block is screwed and glued in from the bottom plywood base that sits on the bed ways.

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Steve in VA

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Next, the arms are attached to each other using bearings I got off Amazon. They were only about $12 for 10 of them and are inset into the plywood middle arms. A washer sits between the bearing and the arm to ensure metal to metal contact for a very smooth operation yet the bolts are tightened down very well. There is no vertical play at all; only horizontal with no effort to move them side to side. I can get you the exact bearings I used if you can't tell from the pic I took of some extras, but they have 12mm diameter holes which is critical to match with the bolts you use to eliminate any slop. The outside diameter is also important so that it matches up exactly with a forstner bit.

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Steve in VA

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To mount the tools, I used a metal insert then drilled and tapped it for two grub screws. The metal insert extends into the maple handle for extra security and is epoxied in.

20210625_065053.jpg
 

Steve in VA

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And here are three pics showing the range of motion you can get. Obviously you'll need to modify the arm lengths to suit your lathe. Once the tool is mounted in, just adjust your headstock & tool rest to best position the piece and ensure the rest is under the straight part of the tool vs. the curved neck. The plywood base is also bolted to a 3/4" piece of plywood that fits underneath the bed ways. Big flat washers and a lock washer ensure it's extremely tight and not going anywhere. The two mounting points lock everything in and make for a very stable platform.

We're on the road today headed to West VA to pick up our son from a Scout camp, but I can get you any details, dimensions, etc. tomorrow and again am very happy to chat on the phone if this is something you want to do or just talk through the details.

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Nature Man

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And here are three pics showing the range of motion you can get. Obviously you'll need to modify the arm lengths to suit your lathe. Once the tool is mounted in, just adjust your headstock & tool rest to best position the piece and ensure the rest is under the straight part of the tool vs. the curved neck. The plywood base is also bolted to a 3/4" piece of plywood that fits underneath the bed ways. Big flat washers and a lock washer ensure it's extremely tight and not going anywhere. The two mounting points lock everything in and make for a very stable platform.

We're on the road today headed to West VA to pick up our son from a Scout camp, but I can get you any details, dimensions, etc. tomorrow and again am very happy to chat on the phone if this is something you want to do or just talk through the details.

View attachment 211574

View attachment 211575

View attachment 211576
Would it be possible for you to video how this works in practice? I’m having a hard time making the mental leap on just how it all comes together. Thanks! Chuck
 

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Tim,

Beautiful hollow form. I also use John Jordan's hollowing tools and like them very much. As for hollowing, I started off with a pre-owned Monster set up, its an articulated system. When I moved up to my larger lathe I couldn't find a taller base so I sold the Monster and bought Trent Bosch's hollowing system. I love it, very little time needed to set up (after the first initial set up that is). I had considered the Elbo from Tim Yoder. My only issue with the Elbo is it needs to have the tailstock in place. A tailstock can take up a lot of space and reduce your 20" between centers by quite a bit. Something like Trent Bosch's system or any other that doesn't need the tailstock can be set up at the end of the lathe, giving you more hollowing depth. The benefit of either the Elbo or Bosch setups is that you can use them on any size lathe, so if you ever upgrade or go over to a buddy's shop and want to do some hollowing, you'll be able to take your setup. The monster I had previously had a base that mounted to the ways of the lathe. I had a 16" lathe, that mean I could only use it on a 16" lathe. Lots of options and if you're creative like Steve, making your own is a good option as well.

Damon
 

Barb

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Beautiful hollow form! I don't really have anything to add as far as making your own setup. I used to have the Simple Hollowing System that mounted to the ways of the lathe and I ended up selling it to get the Trent Bosch system. Like Damon said, it's much easier to set up and portable if you need it to be. I use Trent's 5/8" hollowing tools with it and I don't regret the change at all.
 

trc65

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@Steve in VA
Thanks for the pictures and explanation! Nice looking system you've put together, simple construction that works. With my shorter bed, I couldn't use the attachment system you used, I'd probably weld up an extension like the elbo system sells. Happy to hear though that your wooden system works well, will definitely save a lot of time vs machining metal arms.
@Woodworking Vet @Barb
Thanks for the discussion on the systems. The Bosch system would be ideal for my lathe, but $400 (for the 3/4")is just too much for me right now. I know I could make a system like Steve's fairly quickly, but I keep thinking about the Bosch, and how I could make one....

I will probably make a "elbo" type system in the short term, but I'm definitely going to spend some time looking through my steel piles an thinking how I could make a Bosch type system.....

Thanks again everyone for the info, think I've got a plan solidifying in my mind.
 

Steve in VA

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Would it be possible for you to video how this works in practice? I’m having a hard time making the mental leap on just how it all comes together. Thanks! Chuck

Hey Chuck, I'm not opposed to taking a short video but I've never been able to upload a video to the site. Let's see if this helps by showing it with the tool installed. Imagine the hollow form in the chuck. The tool rest supports the front as normal. The tool is held by the articulated arm and the whole system /arms pivot very easily on the bearings in any direction to allow you to manipulate it. Hope this helps.

20210626_103155.jpg
 
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Nature Man

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Hey Chuck, I'm not opposed to taking a short video but I've never been able to upload a video to the site. Let's see if this helps by showing it with the tool installed. Imagine the hollow form in the chuck. The tool rest supports the front as normal. The tool is held by the articulated arm and the whole system /arms pivot very easily on the bearings in any direction to allow you to manipulate it. Hope this helps.

View attachment 211679
Got it! This photo really helped make sense of it! Thanks! Chuck
 

TimR

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Great job and very pleasing to the eye! Look forward to seeing that curly grain pop. Kudos on keeping the inclusion...
 

Tony

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Hey Chuck, I'm not opposed to taking a short video but I've never been able to upload a video to the site. Let's see if this helps by showing it with the tool installed. Imagine the hollow form in the chuck. The tool rest supports the front as normal. The tool is held by the articulated arm and the whole system /arms pivot very easily on the bearings in any direction to allow you to manipulate it. Hope this helps.

View attachment 211679
Steve, you have to upload the video to YouTube, then you can post it here.
 

Sprung

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Nice hollowform.

Might not work in your circumstances, depending on the stand your lathe is on, but here's what I did to be able to use a captured system with my Jet 1221VS.

L.jpg
 

trc65

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Thanks for the picture Matt. That's definitely an option to consider, although I've never built a stand for my lathe. Ever since I got it, it has resided on my Roubo style workbench. Really need to get a stand built for it, and now when I do, will definitely make it long enough so that a captured system like yours is possible.
 

Steve in VA

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So now you all have me venturing down the slippery slope of putting content on YouTube! Here's a quick look at the articulated arm I built in use:

 

Nature Man

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So now you all have me venturing down the slippery slope of putting content on YouTube! Here's a quick look at the articulated arm I built in use:

Excellent video! Really brought home the operation of your invention! Thanks! Chuck
 
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