LumberJocks

Segment Clamp V1.0

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Project by socrbent posted 02-27-2016 05:06 AM 855 views 4 times favorited 10 comments Add to Favorites Watch

My name is Gene and I’m a rookie segmenter. The purpose of this jig is to assist glue up of half rings for segmented turning. Getting a band clamp to fit my first segment ring didn’t work for me. I had purchased a variety of sizes clamps at the local big box. However none would fit my first ring. So I used slip glue method to assemble it in 2 halves them glued them together. I liked the idea of half rings, but wanted a way to make them under clamping pressure. Hence this first effort at a clamping jig that is adjustable for different sized rings and uses a lever to apply pressure . The jig was completed this evening, seems to work for a dry assembly, but has not yet proven itself under pressure :). Your suggestions for improvements or problems you foresee when I do a glue up are most welcome.
Photo 1 – Overhead view with half ring clamped
Photo 2 – Back side view – note the clamp is loose so the band is drooping
Photo 3 – Test of addition of mdf top board to hold assembly flat while glue dries
Photo 4 – End view showing rabbiting in top and bottom mdf pieces and the jig clamped in vise which helps hold jig while pushing on lever (real leverage) and access for flattening clamping shown in photo 3
Photo 5 – Bottom view showing attached block for clamping in vise
Photo 6 – Under the hood – showing clamping lever, pivot bolt, band slot and movable band anchor. This photo was taken prior to final assembly and doesn’t show the band attached to the lever with a screw

The jig works by adjusting the left side band anchor by releasing top pressure, sliding the band anchor block in the rabbits to set the the ring diameter from band slot on right. Tighten top pressure screws. Place the segments inside band. Dry test clamp with lever and wedge. Adjust as needed. Apply glue to segments. Tighten clamp with lever and wedge. Clean up glue squeeze out. Clamp on top board if needed to force half ring flat.

Wedge to hold clamp arm under pressure.

Wedge in place holding lever tight

When assembled the oak block on the left end of band sits in the rabbit and can be slid in slot to adjust for different diameter rings. The band is attached to the block by a screw. The oak block on right is glued in the rabbit and has a slot just wide enough to keep the band at the proper diameter for a half ring. Band slides through the slot and is attached to the lever.

This shows the mdf board used over lever with its rabbit.

While typing up this description, I’m beginning to think the jig maybe an overly complex solution to a simple problem. Guess I’ll find out as I use on my first segmented bowl.

-- socrbent Ohio





10 comments so far

View abie's profile

abie

818 posts in 3232 days


#1 posted 02-27-2016 03:27 PM

Great Idea
I Love the waay this site shows us how to accomplish just about anything.

-- Bruce. a mind is like a book it is only useful when open.

View drbyte's profile

drbyte

727 posts in 3523 days


#2 posted 02-27-2016 05:03 PM

You can gang as many small worm gear clamps together as needed! I make them from three inches up to 15 inches just by adding them together. I agree you need to keep the rings flat as possible but a press type jig would do that better. You are being very in-genius with your jig but I think it is a bit overly complex. Keep experimenting. Check out other segmenting solutions on this and other site and don’t give up! Segmented bowls are the greatest!

-- Dennis, WV

View drbyte's profile

drbyte

727 posts in 3523 days


#3 posted 02-27-2016 05:14 PM

Here are a couple pretty nice jigs to keep the rings flat: http://lumberjocks.com/projects/82119 and http://lumberjocks.com/projects/91866. Both are easy to make. I have one with one large all-thread in the center and a handwheel on top to put pressure on everything. It’s just a flat piece of counter-top laminte with all-thread up through it and a flat plate on top and large home-made handwheel on top. I also have one made with 4”x 4” pcs with 2 pcs 2” x 4” across the top and an old air cylinder mounted to the top. with about 15-20 pounds air put to it it really clamps down hard. It will take up to a 12” ring, I need to make it a little bigger. It works with bottoms and tops glued on whereas the one with all thread cannot be used with a bottom glued on. I can get you a pic or two if you’d like.

-- Dennis, WV

View drbyte's profile

drbyte

727 posts in 3523 days


#4 posted 02-27-2016 05:16 PM

I do like you half ring set-up, sometimes your ring just won’t go together exactly right and you need to run the two half rings through the table saw or sander and just take a whisper off so they will come together perfect and the half rings do facilitate that. I have a jig that holds a half ring and slides it through my table saw to use occasionally.

-- Dennis, WV

View socrbent's profile

socrbent

417 posts in 1730 days


#5 posted 02-27-2016 06:28 PM

Thanks guys.

Dennis – When I joined a couple of the worm gear clamps the worm gear assembly was distorting the circular shape. That is what lead me to try this jig. Thanks for the links and encouragement. In theory the way this jig works will force each half ring to be flat. I’ll know for sure after I’ve used it for a while.

This morning I easily glued up 2 half rings that look like they will mate perfectly. I did find that the wedge was distorting the separator triangle under pressure. So I’m in the process of adding some reinforcement. I’ll post photos when done.

-- socrbent Ohio

View branch's profile

branch

1107 posts in 2615 days


#6 posted 02-27-2016 08:46 PM

hi your jig looks very complicated but if it works for you that is great i do a little segment turning and i find the simplest way and fasted way to glue up rings
are with a rubber band if you put 2 or 3 bands on they ring it will pull the ring tight enough
and use a thin piece of timber to keep the rings in two half’s if you tap the ring flat with a mallet when you have the rubber bands on it will stay flat i make my rubber bands out of inner car tubes the are very strong and last a very long time i am not trying to put your jig down just saying what works for me
branch

View socrbent's profile

socrbent

417 posts in 1730 days


#7 posted 02-27-2016 10:39 PM

Branch – I looked at your projects and to say you do ‘a little segment turning’ seems to be an understatement – beautiful work! That makes me curious. What glue do you use, lots or sparingly, both faces or one?

-- socrbent Ohio

View socrbent's profile

socrbent

417 posts in 1730 days


#8 posted 02-27-2016 11:22 PM


This is the reinforcement I added today to support wedge



No gaps and same diameter when mating the the two half ring glue-ups.

-- socrbent Ohio

View Julian's profile

Julian

1034 posts in 2151 days


#9 posted 02-28-2016 12:10 AM

You can eliminate gluing half rings if you use the cutting sled designed by Jerry Bennett. Search youtube; Jerry Bennett woodworker. Cuts come out perfect the first time and no need for half rings.

-- Julian

View socrbent's profile

socrbent

417 posts in 1730 days


#10 posted 02-28-2016 04:00 AM

Julian,
Jerry’s sled is a great idea. I made one – http://lumberjocks.com/projects/220154. It does create excellent angles on the segments. I’m using the sled on this project. This jig is my attempt to make glue up of rings simpler. I will readily admit that my feeling that this jig helps may only be due to my lack of experience. Glueing up 4 rings with the jig today seemed better and simpler that the rub joint method and the problems I saw with the worm screw band clamps.

-- socrbent Ohio

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