Articulated hollowing tools

Re: Articulated hollowing tools

Dick Coers

I made a multi link design from black pipe fittings and short sections of pipe. I reamed out the threads of the "T"s to accept 3/4" cold rolled steel bar, and machined the flanges on the the Ts so it would pivot nicely. I did put some Delrin washers between the Ts, along with a light coat of grease. Works like a charm. I made a base so I could offset the main pivot behind the center of the lathe. I thought it would pivot more easily if they never all lined up on center. The first one I made was really a proof of design. It worked so well, I never made a fancier one. That's my disclaimer because this thing is ugly!!!!

Re: Articulated hollowing tools

Dave Paine

I happen to be trying out an articulated hollowing tool design.

I have seen a number of designs. I am trying one which mounts to the quill via MT2 taper with a drawbar to keep the taper in place.

I have not tried this out yet. Still in the prototype phase so most of the components are wood. Easier to shape, drill etc.

A piece of 3/4in O1 drill rod as stand-in for hollowing tool.

For the prototype I am using an MT2 taper I made, which has 1in x 8 tpi thread. I turned an aluminium bushing to fit the thread which will be epoxied into the base.

A small bushing in the head piece for a 1/4in x 20 tpi set screw.

I am using thrust bearings in the rotating joints. Two ground washers and needle roller bearing. The design articulates easily - at least not under load.

Posting in case this helps you with your design.

Once I try this out I may make the base and head piece out of aluminium.

Re: Articulated hollowing tools *LINK*

Jim Evans

Captain Eddie has a fairly simple one that looks like I might try this.


Captain Eddie's Snake

Re: Articulated hollowing tools

David Walser

John -- As to which of the two designs is superior, I don't think either is. Trent's is more compact, which would be nice particularly for short bed lathes. However, the Monster design allows greater flexibility in setting the tool up. For example, you can use longer tool bars, if that's desirable. By extending the secondary tool rest over the far side of the lathe, you can have the tool bar come in at an extreme angle -- allowing greater access for undercutting a rim, perhaps.

When I use my Monster, I set the secondary support off the far side of the lathe. I like this because it keeps the articulating arm out of my way. I'm not sure I'd like Trent's design because it would keep the articulating arm between me and the turning.

In practice, I think you'd find the two designs are about equals.

Another design to consider is that of the Elbo Tool (which is now be made and marketed by Tim Yoder). The Elbo tool clamps onto the tailstock quill. This almost guarantees that the tool is cutting at center height and is a very secure way of mounting the tool to the lathe bed.

Re: Articulated hollowing tools

Ric Taylor

John, it seems to me that if one system had significant advantages over the other, then one would be in business and the other would not be. It boils down to personal preferences. I have not used the Bosch system but I have had the Monster system for quite a few years. I like the Monster's secondary tool support as it allows for very tiny adjustments (in conjunction with the adjustments of the tool rest) to insure that the cutting edge is on centerline. Also with the appropriate adapters the Monster can be used for a larger variety of boring bar diameters than the Bosch system. With the adapters that I have I can use bars from a bit less than 1/4" (for ornaments) to almost an inch (unusual but occasionally useful).

Re: Articulated hollowing tools

john lucas

Ric I agree with you. With my Homemade Jamieson system I can swing the secondary tool rest out to the side to help me reach into flat top vessels. I think that would be a good thing for the articulated arm as well, which rules out hooking it to the tailstock. If you built the support system correctly it should be centered height wise anyway.

It may be a while before I get around to building it since I'm having to drive to atlanta once a week to help take care of my Dad. It usually is a 4 hour drive but today took 5. What a mess. Why does everyone have to slow down to watch an accident in the other lane on the interstate. We drove 20 miles at about 10mph or less and there wasn't anything in our lane. The accident was in the southbound lane. What a pain.

Maybe I can get the articulated hollower designed while I'm down there and collect all the materials I need.

found this system this morning  *LINK*


http://www.harrisonspecialties.com/simple-hollowing-system-with-or-without-laser-for-woodturning/

copy of the Kobra system  *LINK*


http://s1002.photobucket.com/user/zydaco/library/The%20Shop/Articulated%20Arm%20Hollowing%20System?sort=3&page=1

Vicmarc system  *LINK*


http://www.vicmarc.com/default.asp?contentID=546

Re: Articulated hollowing tools

Peter Hyde

My experience with mine has been bad. The articulation has to be held perfectly square to the lathe bed and I mean perfect. So that means the bottom of the post support plate at the point of connection has to machined after the welding is done.

Any deviation from perfectly square means the cutter raises and lowers as the articulated arm is opened or closed. Maybe not a problem if you only hollow vessels with wide openings. But getting a 1/2" diameter hollowing tool into a 7/8" opening becomes a nightmare. Mine is not the only one that does this and other owners have also had to make serious alterations and rebuilds of their systems to get around this problem.

Postings on WoW will fill in details. Manufacturer is in denial.

Re: Articulated hollowing tools

John C Lucas

Peter. Which system did you have the problems. Seems like it would be a combination of the rear mount and the tool rest. Both would have to keep the tool centered and level

Re: Articulated hollowing tools

Dick Coers

My only experience is with my homemade articulation system, and a Jamieson. But I don't understand the statement that vertical precision is needed for it to work. I have several different hollowing bars, including an old system with a slotted disc bit holder on the end. When treading into tight openings, I have to raise and lower the system to thread either a straight bar, or that disc holder through the opening. It doesn't affect the cutting even a little bit. I did grind the disc holder into an oval to thread into even a tighter hole, but works just fine cutting 1/8" above or below center. I'd compare that to using a hand held hollower. Easily that much vertical movement inside the vessel and you don't even know where it's at.

As far as articulation design, I'm a firm believer in more links to the system. It gives you more flexibility and they pivot more freely than long links.

Re: Articulated vs Captured

Stuart Johnson

I have the Monster Articulated system and other than the laser like it very well. The laser holder is fairly thin, hard to adjust and prone to move. It doesn’t seem solid and any cutting vibration is magnified causing the dot to bounce around. This might all be operator induced error.

I spent the last couple hours re-viewing Lyle Jamieson’s YouTube videos showing him using his captured system with the D handle. Of course like any pro with a lot of practice he makes it look easy. The laser seems to be very stout as compared to the Monster and looks to be very stable. After using the Monster and watching Lyle I don’t see where there is an advantage using an articulated system over a captured bar system. All of the articulated ones appear to basically be alike in allowing controlled movement. I haven’t compared the captured systems to see if there is a great deal of difference.

What is your system of choice? Any suggestions on how to beef up the Monster laser or if you use it do you have the same bouncing issue?

BTW, if you haven’t watched Lyle’s videos you are really missing out. He shows not just how to make a cut but explains why it works.

Re: Articulated vs Captured

john lucas

Stuart I used square aluminum rod to make my laser support for my Jameison style bar. It was from an article in American Woodturner. Simple to build and works pretty well. I do have a minor problem with it wanting to rotate because I used round bar for the riser portion and screw to lock the round bar in place. I think my system needs a more solid lock for the riser bar. The top square bar seems to work fine. Some have suggested filling the bar with spray foam to make it more rigid but I've never done that.

I have 2 problems with my solid bar system. One is the secondary tool rest is quite large out of necessity to give you the flexibility to cut different shapes. I swing it forward sometimes to give me a little more room but sometimes it's still not enough and I end up changing bent bar cutters more often than I would like to get into these flat top kind of shapes.

The other problem is just storage. It takes up a huge chunk of wall space. I've been wanting to build a beefier bar similar to Steve Sinner's system. It takes up less space. Then I would build the articulated system that should store in a drawer somewhere. I think a properly designed system would reach into just as many or more shapes. I'll probably build a prototype out of wood to play with lenghts of each leg and to make sure it does what I want it to do.

Re: Articulated vs Captured

Dick Coers

Lyle and I have discussed it before, but I prefer the articulated for small opening, large flat diameter vessels. Vessels where you have a wide undercut (southwest style). Lyle does those, but you have to loosen and move the back support, then move it back when you get back to the deeper sections. Also with the type of hollowing bar I use, I actually have to thread the cutter through the opening. It will not fit straight in. So I have to rotate it way over to one side, then rotate it back over to the opposite side once the cutter is inside the opening. Not enough travel room with the captured support.

Re: Articulated vs Captured

dick hines

All the joints always looked like pinch points to me. I have never use one of them so, I am just saying.

One of the brilliant design features of the Kobra

Dick Coers

One hand on the hollowing bar, another on the handle out the back. You really get the leverage.

Re: Articulated hollowing tools

john lucas

I had a real nice conversation with Lyle Jamieson this afternoon. Very enlightening and informative. I don't have the bent tool holders that he sells and he thinks that might solve my problem with reaching into the upper outside corners of the hollow forms. I will probably build one to see. He is always helpful.

As Dick Hines mentioned I was also a little concerned about pinch point on articulated systems. I suspect you would hold the main bar up to point but when your hollowing to the full depth of the bar where do you put your hands.

One of the reasons I picked the Jamieson style system early on is there aren't any moving parts. Nothing to wear out. I just need to get back to hollowing and see what I think. I might borrow a Monster system from a friend and see what i think.

I do like the Kobra system a lot and have played with it. It is an excellent tool but from what I hear it takes a year or more to get one. I also worry about replacement parts on all of the articulated systems. these are all built by small shops and who knows how long they will stay in business.

Re: Articulated hollowing tools

Russel

All parts including bearings you can find at McMaster-Carr

Re: Articulated hollowing tools *LINK*

Peter Hyde

I made reference to my posts on WoW.

I suggest anyone interested in building/buying an articulated system go read the discussion. Keep in mind that until I started raising issues with this particular tool most owners kept quiet about it's problems.

I think for a tool costing $500 there should be no need for owner modifications or other tweaks and if there were any problems then the tool should be replaced and future models updated to eliminate those problems. Sadly neither has happened.


More here

Re: Articulated hollowing tools

Ric Taylor

John, before I purchased my Monster system I had the Elbo tool which hooks on the the tailstock quill. There is no problem doing undercuts and reaching in to flat top vessels. You just move the tailstock up closer to the work to give yourself some "slack" and you push the articulated arms out to the side, allowing you to come in from the side and easily undercut, especially with a goose-neck cutting bar. It works the same way with the Monster tool.

You do need to be able to make adjustments, making sure the cutter is on centerline, because if you change the diameter of the cutting bar, then you need to adjust the height of the cutter. I usually begin my project with a small boring bar and change up to a thicker bar as I get deeper. Each time I have to adjust the height.

Re: found this system this morning

Ric Taylor

The Harrison system certainly does have an attractive price but I don't know how sturdy it is. The components appear to be less beefy than other systems. It could easily be upgraded from the laser system to a video system.

Re: Articulated hollowing tools

Ric Taylor

John, pinching is not an issue. Remember that you are moving everything very slowly, just a fraction of an inch at a time. Nothing is going to get pinched while you are hollowing. The only possibility of getting pinched is when you are setting up, that's when things are moving around, but it has never been an issue for me.

Link doesn't help if you are not a member

Dick Coers

and I'm not a member..........