articulated arm/snake hollowing tools

[Les Dawson]

I need information about these type of tools. I have watched some you tube videos, looked for info in Google. It seems there are several good ones. I like the looks of the Monster, the Stabilizer, the Elbo, and the Simon Hope from UK.
I am thinking of making one, but not sure of all the requirements.
Any guidance/information as to goods/bad, do's and don'ts would be appreciated.

 

[hockenbery]

Les this is probably the wrong place. Technical means help,with the forum not technical woodturning.

The articulated systems all work but they don't do anything better than the Jamieson handle and back rest. If you ever plan to do really large forms those are all done with large Jamieson style system.
The sinner is a nice system too a clever modification of the Jamieson.

building a Jamieson style systems is a whole lot less complicated than building an articulated system.

The main advantage of articulated systems is smaller size for storage.
And possibly a faster set up although some articulated systems take a bit longer to set up than the Jamieson.
Switching hollowing bars is quite fast with the Jamieson. That is important - hollowing a typical form I swap between bars at least 5 times.

 

[Bill Boehme]

Thanks, Al. The thread has been moved to the Main forum.

I agree completely with Al about the benefits of the different types of hollowing rigs. The elbow type systems are good for small lathes or crowded quarters. Designing this type of rig is a significant design challenge because it needs to be flexible for freedom of movement and at the same time structurally rigid so that the knuckles don't allow out-of-plane flexing.

Building a Jamieson type hollowing system is indeed the easiest and least expensive way to go ... and Lyle Jamieson will even help you by giving you plans on building your own. If you can't fabricate all of the parts yourself, he will sell you any pieces of the system that you need.

 

[Richard Coers]

I find the articulating systems to be more flexible, especially when doing deep undercuts through small openings. With the captured systems, you have to move the rear support when you curve the cutter into a small opening and do the undercut. Biggest tip for building your own; you must be able to either install bearings, or have the capability to use a reamer and machine accurate holes. You can't just use a bolt in a drilled hole for the pivot.

 

[Raul McCai]

I need information about these type of tools.

I believe that most of the better articulated systems have some kind of bearing, but lots of guys have built 'em without.

The Trent Bosch one is pretty heavy

View: https://www.youtube.com/watch?v=RxWJAdWLn_Y



If you have a good drill press you can probably build a perfectly serviceable version of the Monster type. I'd use Stripper bolts ( AKA Shoulder Bolt) to make the hinge points. Stripper bolts are hardened and precision and come in very nicely controlled lengths. http://machinedesign.com/fasteners/basics-shoulder-screws
You will need some decent drill bits. Check out DrillsandCutters.com.
Start with a 1/4" drill and then drill 1/64" under-size and then drill with the size you want and you'll get better holes.

I'd make the arms out of 4140 steel bar stock. It's harder than cold or hot roll, but if you want to weld it, get A36 steel. 4140 requires pre-heating and ramping down from 600F or the welds all crack. A36 Steel welds like buttah. Free Machining steels tend not to weld well if at all. But they are free machining. And they cost a lot. Use a sulfur oil for cutting any steel. A great cutting oil is sold at any BORG under the Ridged brand name for cutting threads in plumber's pipe threading machines.
Check out metals Depot and Speedy Metals, prices can vary.

I am guessing you haven't seen the Kobra articulated system. It is very seductive.

Having built a slightly heavier version of the Kobra and having used it I can tell you that the Jamison system has it's appeal if for nothing else its direct simplicity. One thing my unit does (because it's big) that I've found useful is that it reaches around the tail stock so I can use it with the tail stock in place on the work. I don't think the Jamison system can do that. At bare minimum; you'd need a good metal lathe a drill press and a welder to build anything like the Kobra.

 

[Joe Greiner]

The articulated systems can achieve resistance to out-of-plane flexing with large diameter bearings. I attained the needed stiffness with tall hinges. Ball-bearing hinges work much better than ordinary door hinges. My quick and dirty experiment uses wood arms, attaches through the tailstock, and has interchangeable tool holders with torque resistance. The laser holder has since been improved.

 

[Mike Johnson]

One of my future projects is to use a short length of drive sprocket chain and weld a pin
on one end and a tool holder on the other end. The short length of chain would provide
the flexible pivot points to move the cutting tool in and out of the wood piece. The solid pin
welded on the far end would be held solid by the banjo at the proper height. The tool shaft
would move over the steady rest as designed.

 

[Ron Rutter]

Mike. Two or three section chain may not be too bad but overall i think you will find any chain unstable in the horizontal plane & hard to control. Ron.

 

[Mike Johnson]

Ron,

What would be the difference between the chain links and the articulated arms?
In essence the articulated arms are just longer chain links.
I have access to various sized chain links up to very large industrial type links.

 

[robo hippy]

The type of bearings used in the articulated arm type hollowing systems are called 'timpkin' or some thing like that. They are tapered, and they can be tightened down to take some of the flex out of the system. My experiences with the Monster system tell me that they are fine for small forms, not more than about 6 inches deep, and can go a bit deeper but not much. They work better for fine finish cuts than they do for heavy roughing. Just too much flex in the arms. I believe the Kobra was the most stable as the joints were a lot bigger in size. I do like that they take just finger tip pressure to move.

robo hippy

 

[Bill Boehme]

I believe that Timken became famous back in the early twentieth century because of their tapered roller bearings used in the auto industry. The name essentially became generic for any bearing of the same design. In aerospace, we basically used two bearing companies, Timken and Fafnir. I see now that Timken is the big fish in the pond and that Fafnir and several others are now a part of Timken.

I have the Steve Sinner boring bar hollowing system. It is the essence of simplicity and unlike the articulated arm tools it is able to do deeper hollowing than I would ever care to do. The tallest vase that I have done is about 17 inches and beyond that it's hard to hoist large logs onto the lathe. I don't even think about doing such stuff after getting a torn rotator cuff earlier in the year.

A good friend bought one of the articulated arm rigs for his Powermatic lathe. It was really nice but I think that the limit on depth was about 9 inches. Beyond that I think that vibration became a problem ... probably from flexing in the arm despite the fact that it was very solidly built. In reality there isn't much demand for large hollowforms.

 

[Raul McCai]

I attained the needed stiffness with tall hinges. Ball-bearing hinges work much better than ordinary door hinges.View attachment 21565

And those are commercial hinges too.

 

[Fred Belknap]

A good friend bought one of the articulated arm rigs for his Powermatic lathe. It was really nice but I think that the limit on depth was about 9 inches. Beyond that I think that vibration became a problem ... probably from flexing in the arm despite the fact that it was very solidly built. In reality there isn't much demand for large hollowforms.

I have the Monster hollowing system and at 9" you are pushing the limits hard. Sometimes you can put the end of the toolrest inside the hollow form and cheat a little. If you have an opening that large you need to finish the inside. It is a nice tool for smaller hollow forms.

 

[Hugh]

Bill Boehme.......Did you get the 1.25" diameter boring bar?
17" deep is good sized. I agree....anything much larger and the chunk of wood needed is too big for me.
It looks like it would be an easy hollowing system to build.
Thanks.
Hugh

 

[Bill Boehme]

Bill Boehme.......Did you get the 1.25" diameter boring bar?
17" deep is good sized. I agree....anything much larger and the chunk of wood needed is too big for me.
It looks like it would be an easy hollowing system to build.
Thanks.
Hugh

Hugh, I have the next size down which is 1⅛" and total length of 58". It has a maximum depth of 24" which seems like more than enough for my needs.

It isn't as simple to build your own as it might appear. The two bars need to be straight and close to perfectly parallel when they are welded together and then it is necessary to mill a small flat on top and bottom of the welded up bars. The surfaces on the trap also need to have a small flat on both bars so that the boring bar will slide in the trap smoothly without any wiggle room, but at the same time not bind at any point. I would guess that a large metal lathe is necessary to bore the cutter tool hole at the end. Everything else is pretty easy unless you want to make your own steady rest. I thought about doing that for a while and then decided on the Robust steady rest.

 

[Bill Blasic]

I can put any size bar on the Monster that I want, it all depends on how big the entry hole is going to be. Luckily for me if I'm going to make a tall hollow form that has to be deep I have the Pro-Rail Hollowing System from Alan Trout. I have adapters for the Monster 5/8" to 3/4", 5/8" to 1" and 5/8" to 1 1/4". In general I keep the Monster Articulating Rig on my Delta 46-460 and make hollow forms 3" to 7" using 5/16" tools (a small hole that you cannot put your pinkie into). When I bought my systems from Randy I had him make me receivers so I could use them on 12" lathes, 16" lathes and 20" lathes. If you are looking for an articulating hollowing system I recently had occasion to use the Elbo Toll which I had more or less dismissed years earlier. Originally made by Stan Townsend and now being manufactured by Tim Yoder this was a real surprise as to how well it is made and performs. It fills a gap now that the Monster unfortunately seems to be out of the business.

 

[Mark Wollschlager]

Bill,
Is Alan Trouts system ready yet?
His site says it is "nearing its first limited production run" which is close to what he told me at the AAW symposium.
It is a nice looking and well engineered rig.

 

[Richard Coers]

Cutter design also makes a huge difference with the articulated systems going deep. If you keep the rpm high and use a little scraper cutter, you can get chatter. But use a Munro cutter with slow rpm, and it works really well. I've gone more than 12" deep with my home-made articulated system.

 

[john lucas]

I have a homemade Jamieson style system made out of 3/4" bar. I can easily go 10" and have hollowed up to 14. Several things will improve your depth. One is the size of the cutter. I find the smaller cutter reduced the chatter. I use mostly 3/16 HSS bits or the #1 Hunter tool. Hollowing down hill with respect to the grain also reduces the chatter a lot. In other words instead of pulling the cutter straight to the side which is cutting across the grain try to pull it from the bottom toward the side at about 45 degrees. That cuts down hill and there is a noticeable difference in the ease of cut. Ridgidity of the whole system is of course a factor. Systems like the Jamieson and Sinner are solid bars. There isn't any flex anywhere, only chatter from the bars themselves flexing when you extend them at or beyond their limits. We had 1 1/4" solid bars when I took a class from Frank Sudol and there was absolutely no chatter at 14" deep at all. We easily thinned our vessels out to 2 or 3mm for that entire depth.

 

[Steve Worcester]

Ron,

What would be the difference between the chain links and the articulated arms?
In essence the articulated arms are just longer chain links.
I have access to various sized chain links up to very large industrial type links.

Chains generally have a side plates and roller to allow a sprocket. The distance between the rollers, that open area, which will allow for greater fl;ex at the rollers joints, is not present on articulated systems. You would have to have some way to clamp down the plates so they don't move and can be adjusted to the angle you need. One of the best examples of an articulated was Hugh McKays (1980/90?). There has to be a way to bind the links of the articulated arm.

Is it a matter of cost, or what is on the market won't solve your problems?
You could always make a system that adapts to a Rolly Munrow head, it has a few links I believe.

 

[Mike Johnson]

Steve,

I will do some research on the links. Thank You!

 

[Hugh]

Thanks for the detailed answer Bill. Good info.
I have been using a Stewart handle with 3/4" drill rod with a cutter. I can do about 12" deep or so in wet wood.
My problem is that my shoulder does not like to do much hollowing lately. If I could only talk it into calming down.
I have been looking at the captive systems and I like Lyle's and I think I really like Steve Sinner's. Both just seem so simple.
I remember watching Frank Sudol with the huge bar.........the man just seemed to have fun at it. Great stuff.
Thanks again Bill.
Hugh

 

[Hugh]

Bill Boehme - Takes me awhile to think of some of these questions.......hope you do not mind.

Why did you get the 1 1/8" bar over getting the extra weight and strength of the 1 1/4" bar......on the Steve Sinner hollowing set up?
Then the next question - Would you buy the same setup again?

I think I came up with these two question while I was trying to hollow out a 10" hollow vessel......using Stewart tools and home made tools. I am finding that my wrist and shoulder do not like to work on these sort of projects more than a couple of hours a day.
Thanks.
Hugh

 

[Bill Boehme]

Bill Boehme - Takes me awhile to think of some of these questions.......hope you do not mind.

Why did you get the 1 1/8" bar over getting the extra weight and strength of the 1 1/4" bar......on the Steve Sinner hollowing set up?
Then the next question - Would you buy the same setup again?

I think I came up with these two question while I was trying to hollow out a 10" hollow vessel......using Stewart tools and home made tools. I am finding that my wrist and shoulder do not like to work on these sort of projects more than a couple of hours a day.
Thanks.
Hugh

For the standard bed Robust, the one I got was the right size and even with the length of the 1.125" boring bars it is necessary for me to use the outboard rest to hold the gate. The extra length of the 1.25" bars would have been unwieldy and not really enough room to turn a 33" tall hollowform. Steve Sinner recommended going with the smaller size bar when I was debating in my mind about getting the larger bar.

Yes, I would do it again. A member of my club who bought a Robust a couple years after I did came over to my shop to try out my rig and he really liked it. I believe that he bought one, but I'm not positive about that.

One tip that I have to make the bar glide really smoothly was that I used silicon carbide sandpaper to smooth the top and bottom of the bar as well as the gate ... Starting with about 400 grit and going to 1500 grit and then using metal polish to make it glass smooth. I then apply Johnsons Paste Wax every time that I use the rig and the thing is glass smooth. I think that Steve recommended waxing the surfaces, but the extra effort paid off in reducing friction to almost nothing.

 

[john lucas]

I just use an old candle and rub the mating surfaces of my tool rest and captured bar rest. It makes things slide like you greased it.

 

[Hugh]

Bill.....Thanks.
If I think of anything else.......you will hear about it.
Merry Christmas.
Hugh

 

[Peter Kaup]

With larger / deeper vessels don’t you need to steady rest?
What rest do you recommend?
I’ve looked at the Spin Doctor out of Oklahoma and it appears to be quite well made and very heavy duty.

 

[John Turpin]

they can be tightened down to take some of the flex out of the system. My experiences with the Monster system tell me that they are fine for small forms, not more than about 6 inches deep, and can go a bit deeper but not much.

Tim Yoder (ELBO tool) has developed a line of tool rests for the ELBO that extend inside the mouth of hollow forms. This gives additional support for deep dives. I picked one up at SWAT, but haven't used it yet.

http://www.wtwtim.com/elbotooltoolrests.htm

 

[Bill Boehme]

With larger / deeper vessels don’t you need to steady rest?
What rest do you recommend?
I’ve looked at the Spin Doctor out of Oklahoma and it appears to be quite well made and very heavy duty.

It depends somewhat on wall thickness and shape. The primary purpose is to dampen vibration by lightly contacting the wood, but taking lighter cuts and reducing speed also can reduce vibration. Applying any more than light pressure can actually cause vibration.

 

[John Torchick]

Bill, good info. I'm far, far from an experienced turner. My philosophy is to take a bit more time in turning. I would rather take a few extra minutes with light cuts to prevent vibration and watch for things that lead to catches.

 

[Paul Sook]

I also use the Tim Yoder, Elbo tool and love it. It works great. I have gone up to 12” deep with no problems. I have the carbide tip which I believe is made by Hunter and works really well.

 

[Don Wattenhofer]

I made my own articulated arm twice the first one had bolts holding the joints with a brass washer between but it still would bind up. The second try I used small thrust bearings
that could be adjusted for a snug fit and still moved smoothly. The arm is now residing in a drawer and instead I tapered the end of a 1" drill rod and bored the end to accept a wood cut head, which works so fast it seams like you are always emptying the chips. The woodcut head cuts like a gouge and has a brass piece on top to limit the depth of cut. The drill rod is 24" long and I have a heavy pipe set screwed on to extend it for an overall length of about 4 feet, which makes it good for up to 16" deep cuts.

 

[Dennis Weiner]

I made my own articulated arm twice the first one had bolts holding the joints with a brass washer between but it still would bind up. The second try I used small thrust bearings
that could be adjusted for a snug fit and still moved smoothly. The arm is now residing in a drawer and instead I tapered the end of a 1" drill rod and bored the end to accept a wood cut head, which works so fast it seams like you are always emptying the chips. The woodcut head cuts like a gouge and has a brass piece on top to limit the depth of cut. The drill rod is 24" long and I have a heavy pipe set screwed on to extend it for an overall length of about 4 feet, which makes it good for up to 16" deep cuts.

Good job. What size thrust bearings? I would love to see pictures of your assemblies, if you can.

 

[Don Wattenhofer]

Good job. What size thrust bearings? I would love to see pictures of your assemblies, if you can.

The bearings I used are F10-18M which have an outer diameter of 18 MM an inner diameter of 10MM and a thickness of 5.5MM. The joints each use 2 bearings 2 O rings ( for seals) and 1 3/8" bolt and self locking nut. For any further info please PM me.