Open Segment fixture (Manual)

Glenn McCarron

PRO Member
I wanted to build a Driskell type fixture but I also wanted to upgrade the basic design. My main goal was to keep the cost as low as possible as well.

The heart of the fixture is the index plate at the bottom. I elected to have a 16 inch diameter disc with index holes for 144, 120, 96, 60 & 48. I also had made a reference plate that also had the main index holes as well as a half way hole between each ring of holes. This enhancement will effectively double the capability of the index wheel. It will also provide the offset for every second row of segments.

I approached a fellow Guild member who had done some laser engraving for me on some trophies I had built. I gave him the basic information for my index wheel and he did the rest. And an awesome job he did at a very affordable price. It was made with 1/4 plexiglass.

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I also purchased a 1 x 8tpi bolt & nut as well as some T-track with bolts and two knobs. I purchased a 12 inch cast aluminum Lazy Susan.

My first step was to cut a MDF base and a 16 inch circle of MDF for the turntable. I drilled a 1 inch hole in the centre and then mounted it to a disc on my lathe. I had to put it on the outboard side as I can only turn 12 inches over the bed. I turned a dado that would allow the lazy susan to self centre on the bottom. After mounting I drilled a hole that allowed me to rotate the disc to reveal the screw holes to anchor the lazy susan to the base. I had also drilled a 1 3/4 hole in the base so the centre bolt had room to rotate.

I mounted the reference plate today as well.

Next session I will design the post to hold the T-track and anchor and support it.

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Glenn McCarron

PRO Member
I should also mention that my index wheel may sound a bit ambitious for me but it gives me room to grow. I also hope to do an open segment project but I would also like to experiment with doing closed segment projects on the jig as well. In the past I have had some alignment issues and I hope that this will help me keep things running straight.

As always comments and criticism is appreciated. I would like to hear from anyone that has tried closed segment on a jig. If you are not comfortable posting your comment you can start a conversation with just me.
 
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peter white

PRO Member
Hi Glenn Am keen to follow you how you do the closed segment rings.I am also having alignment issues with high number of segments gluing up perfect circles. I tried routing circles slightly smaller & clamping up as I posted some time back but a bit impracticable with large number of rings. I also have made a Driskell type jig which works well for open segments but haven't tried closed segment rings on it as yet.
 

pete marken

PRO Member
I have used the segment stomper on my last project "All American Trio". I found that the plastic shaft on the stomper could easily be deflected in one direction or the other causing inconsistent ring centering. This was especially true the taller the bowl got. I decided to modify the process by using an old air cylinder instead of a pop up sprinkler head. The cylinder has a stroke of 16". Since the air cylinder has a steel shaft there is no deflection at all. Operation is very simple. Open the ball valve to extend the cylinder shaft then close the valve. The air is only connected to the bottom of the cylinder, the top port is left open to exhaust as the cylinder extends. The bottom port has the air supply (maybe 3-5 psi). It also has a check/exhaust valve that will allow air to escape when weight is applied to the top of the shaft thus lowering the piece to the ring in the centering chuck. When the segments make contact with each other the weight is no longer pushing down the shaft and it stays where it is keeping the piece centered on the bottom ring. The bottom ring is held in place by a version of the Longsworth chuck. I also turn all my rings round before stacking.

Attached Files:
 

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Glenn McCarron

PRO Member
I have used the segment stomper on my last project "All American Trio". I found that the plastic shaft on the stomper could easily be deflected in one direction or the other causing inconsistent ring centering. This was especially true the taller the bowl got. I decided to modify the process by using an old air cylinder instead of a pop up sprinkler head. The cylinder has a stroke of 16". Since the air cylinder has a steel shaft there is no deflection at all. Operation is very simple. Open the ball valve to extend the cylinder shaft then close the valve. The air is only connected to the bottom of the cylinder, the top port is left open to exhaust as the cylinder extends. The bottom port has the air supply (maybe 3-5 psi). It also has a check/exhaust valve that will allow air to escape when weight is applied to the top of the shaft thus lowering the piece to the ring in the centering chuck. When the segments make contact with each other the weight is no longer pushing down the shaft and it stays where it is keeping the piece centered on the bottom ring. The bottom ring is held in place by a version of the Longsworth chuck. I also turn all my rings round before stacking.

Attached Files:
Great looking setup Pete, should be very accurate.
 

Glenn McCarron

PRO Member
Hi Glenn Am keen to follow you how you do the closed segment rings.I am also having alignment issues with high number of segments gluing up perfect circles. I tried routing circles slightly smaller & clamping up as I posted some time back but a bit impracticable with large number of rings. I also have made a Driskell type jig which works well for open segments but haven't tried closed segment rings on it as yet.

Peter the open segment projects should be no problem. The closed segment ones will be a bit of trial and error until it works out. Tom Lohman does some solid rings on his jig. It's on his Flora video. Have you tried any closed segment on a jig?
 
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Tom Lohman

Tom Lohman
Glenn,
Very clever with the doubling the segment count by having a half hole on your reference plate! That makes me say to myself why didn't I think of that. When you move to closed segment projects on your open segment jig you will find that alignment issues pop up, but it can work. I am getting better at it but if I let my guard down at all then issues pop up.

Thanks for sharing!



I wanted to build a Driskell type fixture but I also wanted to upgrade the basic design. My main goal was to keep the cost as low as possible as well.

The heart of the fixture is the index plate at the bottom. I elected to have a 16 inch diameter disc with index holes for 144, 120, 96, 60 & 48. I also had made a reference plate that also had the main index holes as well as a half way hole between each ring of holes. This enhancement will effectively double the capability of the index wheel. It will also provide the offset for every second row of segments.

I approached a fellow Guild member who had done some laser engraving for me on some trophies I had built. I gave him the basic information for my index wheel and he did the rest. And an awesome job he did at a very affordable price. It was made with 1/4 plexiglass.

View attachment 2305 View attachment 2306 View attachment 2307
I also purchased a 1 x 8tpi bolt & nut as well as some T-track with bolts and two knobs. I purchased a 12 inch cast aluminum Lazy Susan.

My first step was to cut a MDF base and a 16 inch circle of MDF for the turntable. I drilled a 1 inch hole in the centre and then mounted it to a disc on my lathe. I had to put it on the outboard side as I can only turn 12 inches over the bed. I turned a dado that would allow the lazy susan to self centre on the bottom. After mounting I drilled a hole that allowed me to rotate the disc to reveal the screw holes to anchor the lazy susan to the base. I had also drilled a 1 3/4 hole in the base so the centre bolt had room to rotate.

I mounted the reference plate today as well.

Next session I will design the post to hold the T-track and anchor and support it.

View attachment 2297 View attachment 2298 View attachment 2299 View attachment 2300 View attachment 2301 View attachment 2302 View attachment 2303
I should also mention that my index wheel may sound a bit ambitious for me but it gives me room to grow. I also hope to do an open segment project but I would also like to experiment with doing closed segment projects on the jig as well. In the past I have had some alignment issues and I hope that this will help me keep things running straight.

As always comments and criticism is appreciated. I would like to hear from anyone that has tried closed segment on a jig. If you are not comfortable posting your comment you can start a conversation with just me.
 

Glenn McCarron

PRO Member
Just built the post and tracks today. I added some slats to the edges to help guide the platform that I don't have made yet. I will not secure the post until the platform is built so as to ensure the metal guide comes to the exact centre of the bolt.

IMG_2488.JPG IMG_2489.JPG IMG_2491.JPG
 

Glenn McCarron

PRO Member
Glenn,
Very clever with the doubling the segment count by having a half hole on your reference plate! That makes me say to myself why didn't I think of that. When you move to closed segment projects on your open segment jig you will find that alignment issues pop up, but it can work. I am getting better at it but if I let my guard down at all then issues pop up.

Thanks for sharing!
Thank you Tom for your comments. I certainly look forward to trying the process of doing closed segments on an open segment jig. My last bowl was a 60 segment ring so the next I think I will try the 96 before moving on up to 144. I've been having problems finalizing a new design. I'm trying to come up with a design that is not a flower but they just seem to keep sprouting out that way.
 

Bob Beaupre

Administrator
Staff member
Looking good Glenn.

You might want to think about using a face plate instead of a chuck. less movement with the face plate and if you need to do a job in between you chuck is still avaible
 

Glenn McCarron

PRO Member
Looking good Glenn.

You might want to think about using a face plate instead of a chuck. less movement with the face plate and if you need to do a job in between you chuck is still avaible

Good point Bob. I will mount a waste block on my faceplate, mark centre on the lathe then attach it to the jig to plan the platform placement. Will probably save a few inches in height as well.
 

Glenn McCarron

PRO Member
Today I finished up my new Driskell jig. I added the movable platform, the angle aluminum and a enclosure that supports the post.

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I used a small clamp from my old William Smith jig that will act as the stopper for the desired radius. I will probably pick up another small piece of T-track and a knob to make an easier movable stopper.

I also took Bob Beaupre's advise and used a faceplate instead of the chuck.

Now the hard part starts. I need to finalize a new design and get to work.
 

Malcolm Douglas

PRO Member
IMG_0200.JPG I have built an index disc with just an mdf disc and printer indexing cable. You can make index discs for as many positions as you want. The one shown in the picture is for 120 open segments, that is 240 positions using every other position on each row. The diamond vase I posted last week was made with this. The only drawback with this is that discs vary in size for different counts but that is easily accommodated by moving the locking clamp. The cost is only the cost of the printer toothed cable and the mdf or ply. Malcolm.
 

Glenn McCarron

PRO Member
View attachment 2347 I have built an index disc with just an mdf disc and printer indexing cable. You can make index discs for as many positions as you want. The one shown in the picture is for 120 open segments, that is 240 positions using every other position on each row. The diamond vase I posted last week was made with this. The only drawback with this is that discs vary in size for different counts but that is easily accommodated by moving the locking clamp. The cost is only the cost of the printer toothed cable and the mdf or ply. Malcolm.
Malcolm can you elaborate on the "printer indexing cable". A google search is coming up blank. I'm curious.
 
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