How does a Captured Hollowing rig Work?

[Jim Ketron]

I will try to simplify this as best I can I have lettered the parts of the rig and I will describe what they are and do.
http://i20.photobucket.com/albums/b201/Jim_k/Hollowingrig2a.jpg
(A) Is called the boring bar it’s the part that holds the cutters that do the cutting most are made from 3/4" material but you can buy larger sizes for deep hollowing. The boring bar rests on the tool rest of the lathe, you should try to set the cutting edge at center of the turning or just slightly above. This part goes inside of the turning. Most use a drill bit to start the hole in the turning and drill it as far in as you can allowing enough thickness in the bottom of the turning to be able to dress it up while hollowing, this step saves a lot of time and makes hollowing a lot easier. Bellow is 2 pictures one is a hollow form I was working on and you can see how the cutting tool is on the tool rest and the orientation of how it looks, also there is a picture of 4 homemade bars this picture was taken after I shaped them the holes are not drilled in the ends yet or the set screws tapped to hold the cutters in the top of the tip end of the boring bar.
http://i20.photobucket.com/albums/b201/Jim_k/BEHollow.jpg
http://i20.photobucket.com/albums/b201/Jim_k/100_1471.jpg
(b) is the cutter there are many different types of cutters that you can use that are made for hollowing most use 3/16 or 1/4" Sq cutters.
You can also use scrapers; they are flat pieces of HSS steel and the come in a lot of different sizes and shapes.
Here is a few links of how they look.
http://www.packardwoodworks.com/Merc...borbrctrs-bent (http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=tools-borbrctrs-bent)

http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=tools-borbrctrs-strai

http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=packard&Produc t_Code=106412&Category_Code=tools-jamsn-hs-cuthold (http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=packard&Product_Code=106412&Category_Code=tools-jamsn-hs-cuthold)
(C) Is the arm for the laser, you mount a pointer laser and adjust it to where the dot of the laser is on the tip of the cutter or just off the cutter the thickness of what you want the piece to be. As you are making the cuts on the hollow form the pointer dot will tell you just how thick you are. If you have the laser pointer set 1/4" off the cutting edge of the cutter and the dot runs off the side as you are turning you will then know you have 1/4" wall thickness.
(D) Is called a Stabilizing Handle or as most call them the "D-bar" It does just what it is called, it stabilizes the boring bar and allows you to have great control of the cutting tool you can slide it back and forth and front to back as you are making the hollowing cuts. And greatly minimizes catches that’s why this system is so poplar it makes hollowing a breeze!
(E) Is called the Secondary tool support or as most call it the "back tool rest", it holds the "D-Bar" and keeps it from twisting and stabilizes the whole captured system so you can make cuts without strain from the tool twisting like a hand held hollowing tool would.
Hope this helps!

[Mark Pruitt]

Neat summary Jim! Earlier today I was browsing through what's "out there" in terms of hollowing rigs. I was at a gathering where someone was using a Kelton rig; frankly I think the Jamieson that you're showing is a better buy and I'll eventually spring for one after I buy my 3520B.

Something mystified me about the picture you posted with the homemade bars. They're sitting atop a table that looks like it has a slot in it, with a round thing protruding out of the slot that looks like it has "teeth" on it. I think I've seen one of those tables before. Isn't it used to hold turning projects?:D :D :D

[Bill Wyko]

I was just talking to mark about this technique. Are there any company's that sell a unit like that? Here's another one of those dumb questions. What advantage does this have over doing it by hand?

[Mark Pruitt]

Bill, Check out the links Jim posted. They should give that info. Here is another link as well:
http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=tools-jamsn-hs-packdeal

and another:
http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=tools-jamsn-hs

[Jim Ketron]

I was just talking to mark about this technique. Are there any company's that sell a unit like that? Here's another one of those dumb questions. What advantage does this have over doing it by hand?

Look again at section (E)

[Jim Ketron]

Neat summary Jim! Earlier today I was browsing through what's "out there" in terms of hollowing rigs. I was at a gathering where someone was using a Kelton rig; frankly I think the Jamieson that you're showing is a better buy and I'll eventually spring for one after I buy my 3520B.

Something mystified me about the picture you posted with the homemade bars. They're sitting atop a table that looks like it has a slot in it, with a round thing protruding out of the slot that looks like it has "teeth" on it. I think I've seen one of those tables before. Isn't it used to hold turning projects?:D :D :D

Thats what mine is used for ;)

[Bill Wyko]

Thanks for the info. I think we all can get alot of use from this post.:D

[Steve Schlumpf]

Jim, thanks for taking the time to explain your hollowing setup. I do have one 'ignorant' question - where do you stand when operating the rig?

[John Hart]

Nice explanation Jim. Good pics. I'm still doing it the old fashioned way but it's lookin like I'll be in the captured rig crowd next summer.

[Jim Ketron]

Jim, thanks for taking the time to explain your hollowing setup. I do have one 'ignorant' question - where do you stand when operating the rig?
The same place as you normaly do Steve.
I will be gathering with a few guys on here soon we will try to get some short video clips put together of us doing some hollow turning.;)

[Steve Schlumpf]

Jim - that would be great! Have thought about one of these setups - figure it has to be easier than what I have been doing! Plus, using the hand-held hollowing tools that I have, I am limited to about 5, maybe 6" in depth. Sure would like to be able to do something with more size to it. Looking forward to your video!

[Dario Octaviano]

Jim,

My hollowing rig is in order and I haven't done any hollowing yet.

Do you really use the bent bits? Seems like it is more cost efficient to have extra boring bars with different degree holes drilled on them and get the same result. Of course I may be mistaken. If there is an advantage to these bits, i would certainly would like to know.

BTW, I just learned from Mike that extra pre-drilled 3/4" double end boring bars can be had at ENCO for $8.08 each
http://www.use-enco.com/CGI/INSRIT?PMAKA=378-4014&PMPXNO=2889271&PARTPG=INLMK32
(from this thread http://www.sawmillcreek.org/showthread.php?t=49577 )

Your thoughts?

[Brian McInturff]

Jim,
How do you store yours when not in use. Do you completely disassemble or only as little as possible. Oh by the way. This was a great idea of posting it the way you did. I'm sure it will come in handy to many. I wish you had posted it back early last year when I was trying to understand what and how a captive system was. Brian

[Brian McInturff]

Dario,
The bent bits can come in handy on getting the different contours on the bottom and also for getting into the shoulders at the top. If you have the bent boring bar and then add the bent tip then I think you will get the idea of how they really help on the underside of the top of your HF.
Brian

[Jim Ketron]

Jim,

My hollowing rig is in order and I haven't done any hollowing yet.

Do you really use the bent bits? Seems like it is more cost efficient to have extra boring bars with different degree holes drilled on them and get the same result. Of course I may be mistaken. If there is an advantage to these bits, i would certainly would like to know.

BTW, I just learned from Mike that extra pre-drilled 3/4" double end boring bars can be had at ENCO for $8.08 each
http://www.use-enco.com/CGI/INSRIT?PMAKA=378-4014&PMPXNO=2889271&PARTPG=INLMK32
(from this thread http://www.sawmillcreek.org/showthread.php?t=49577 )

Your thoughts?

Yes I love those bent cutters! Dick Parr turned me onto them and they work great! you will find doing hollow forms sometimes some cutters/scrapers will work and sometimes they won't you will need an arsenal of different cutters and bars especially if you do a lot of different shapes. one of the hardest places to reach is just underneath the rim and to the corner on some forms like this.
http://i20.photobucket.com/albums/b201/Jim_k/HF.jpg
I have one boring bar that has a 3/8 hole at the end and one drilled at 45 and uses a straight and bent 3/8 rod that you can put a scraper and also a adjustable cutter that I use a lot, it is on the hollowing rig in the picture and it is similar to this one.
http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=packard&Product_Code=105805&Category_Code=tools-jamsn-hs-cuthold

[Jim Ketron]

Jim,
How do you store yours when not in use. Do you completely disassemble or only as little as possible. Oh by the way. This was a great idea of posting it the way you did. I'm sure it will come in handy to many. I wish you had posted it back early last year when I was trying to understand what and how a captive system was. Brian

Brian, all I do is take off the "D-Bar" Hang it on my wall and set the back rest in the floor, takes all of about 1 min to get it set up on the lathe. It takes more time setting up the laser than getting the rig on the lathe.

[Jon Shively]

Thank you for the explanation. I cannot even fathom doing that at this time and stage of the game. Also, might be something wrong with me, I don't have the inclination as the pens and kits of stuff are keeping me quite busy. But this is not a slam, beautiful work and an outstanding job of explaining. Just have so many other gravitational pulls on the wallet that I cannot even explore this to indepth at this time!

[Dario Octaviano]

Thanks, I actually cannot picture as of yet how you guys reach and cut the further corners near the top (shoulder like area) especially on shapes like you just posted without making the hole bigger. It looks too far even for the swan neck to reach. :confused:

[Christopher K. Hartley]

Jim, I really appreciate it when you do these types of things. It makes it so easy to get the correct picture. Keep it up Coach!!:D :)

[Curt Fuller]

Jim, one more question. How is the boring bar held in the "D" handle. Does it thread in, or slide in and held with some type of set screw?

[Jim Ketron]

Jim, one more question. How is the boring bar held in the "D" handle. Does it thread in, or slide in and held with some type of set screw?
I used 2 set screws on mine, and I think this is how most of them are made.

[Gordon Seto]

Are you experiencing any vibration on the laser with this set up?
Thanks,
Gordon

[Jim Ketron]

Are you experiencing any vibration on the laser with this set up?
Thanks,
Gordon

I think most all at some point vibrates especially if you are being aggressive with your cuts. yes It does sometimes but not real bad, usually when it does I back off the cut a little and it smooths back out. I have thought numerous time of putting in a piece of pipe at a 45 degree angle just have not got around to it and I really don't have too much of a problem with it unless it's extremely hard wood I'm working with.
I know some are using the lasers and the laser holder from Monster Tools and they really like them! and are not having much problems with vibrations.

[Gordon Seto]

Thanks Jim,

I am on the fence on which system to get and wondering may be the design like Kelton rig that has the laser arm supported at two places better.
http://www.leevalley.com/images/item/woodworking/turning/53b0166s1.jpg
I am also considering this:
http://www.elbotool.com/index.html
Any thoughts?
I don't plan to do massive HF.

Gordon

[Jim Ketron]

I have no clue about the elbowtool never seen one used. But I don't think I would like to stick something Sq. into a round hole There are times my round bar hits the sides of the opening and I think this could cause more damage than a round bar would.
As for the Kelton system yes the laser mount looks good and stable. The thing I don't like about that system is that it uses solid bar with a cutter ground on it. Like I said I like to have many different cutters for certain situations that are hard to reach. I know a lot of people use that system I'm sure it does a fine job but I don't think it would fit the type of hollow form turning that I do. If I had that system I think I would use the Jordan Hollowing Bars on it.

[Keith Burns]

Jim, great tutorial.:)

[Gordon Seto]

Jim,

Appreciate your inputs. Very informative.

Gordon

[Tom Sherman]

Hey Andy, what would ya think of making this one a sticky in the tutorials. Could answer a lot of questions for folks looking for this info.

[Keith Burns]

Jim, I thought I might add this photo of another secondary tool rest. Made from wood with 3/8" rod embedded/epoxyed for the d-handle to ride on.

[John Miliunas]

Fantastic rundown on the captured system, Jim! I'm still looking and trying to figure out the best way to work with my current Vega lathe to do something like that. Basically, one which wouldn't take half a day to setup just to do an hf! :) :cool:

[Ed Scolforo]

Thanks for the instruction, Jim. It will help when I finally give it a try. I bought Don Pencil's Scorpion set which I think has pretty much all the tips and cutters you mention. I figure that I should get a feel for doing it freehand before going with a captured system, as some have advised.
Ed

[Jim Ketron]

Thanks Keith for your Pics, If anyone can help with this thread Join in!
Maybe this can go into the archives and it can be very helpful to someone wanting to get started in Hollow Turning.

I will add a picture of the Steady Rest that I use. when doing large HF's or longer HF's or vases this piece of equipment is a necessary tool also!
I suggest making one with at lest 2 wheels some don't like a 4 wheel rest but I do.(note) the top bar will get in the way of the laser on this type of steady but its not bad to work around.
I'm going to modify mine with a removable top portion that is able
to offset to one side then I will be able to flip it on either side of the steady as needed.

http://i20.photobucket.com/albums/b201/Jim_k/Steadyrest2.jpg

[Brian McInturff]

This is the system I ordered a couple of weeks ago for the Stubby. Once it arrives I'll post actual pictures. Never used a captive system but thought this one was one of the best. It came down to 4 different systems Jamieson, Monstor, Vermec, and the Clark. Isettle on the Clark after doing my research. Not that it's any better just that I think it will work well with the Stubby.
http://www.theokspindoctor.com/graphics/hollowtr.jpg

Brian