Build your own Oval Chuck

[Paul Rohrbacher]

Up to now, the only Oval Chuck available is Vicmarc VOD chucks at a killer price tag. I have a working design of an Oval Chuck that uses Cogs and Chain to generate the Oval shape. The chuck is balanced and has simplified methods to tighten both chains one and two.

Picture from left to right Pillow block with a counter weight just setting on top. Chain #1 that drives the Eccentric (the round component that chain #1 drives thru to Chain #2). Chain #2 drives the Divide by Two Cogs. Chain #2 drives the Hub that the woodturning chuck is mounted too. The size 40 chain and cogs are available at a farm supply store. In picture 2, the Oval Chuck Spindle is screwed directly onto the lathe headstock. The Oval Chuck can be mounted to any size lathe by the height adjustable mounts.

There is Metal Lathe work and some milling ( could be done with a drill press, hand saw and files). Material costs less that $200.00.

If there is any interest in building an Oval chuck, I will take more and better pictures.

 

[Karl Loeblein]

You are so right about Vicmarc’s price for the oval jig. Thats a very nice offer to show how this was made. Any thoughts on also doing a video of this device working?

 

[Emiliano Achaval]

Not sure if I follow Paul, you emailed me and asked me several times how to become a member here. You have been a member since 2013. Welcome back!!

 

[Paul Rohrbacher]

You are so right about Vicmarc’s price for the oval jig. Thats a very nice offer to show how this was made. Any thoughts on also doing a video of this device working?

I have never posted a video. The video will be made shortly and I will give it a try.

Please view Dale Larson's Ovalturning youtube video . Turning the wood on my chuck is exactly the same as Dale's process. also read Ovalturning by Johannes Volmer the internet.

My Oval Chuck design is simple no chain tensioners. Chain #1 is tightened thru turning an Eccentric. Chain #2 is tightened by turning the Offset Adjuster bar against the Eccentric bar. This won't make sense until I get the video made.

Remember chain doesn't stretch and it is impossible to get both chains equal tension all 360 degrees of rotation. Since the Talon chuck/bowl are exerting resistance against the entire Oval Chuck, the slight looseness and tightness as the chuck turns is irrelevant.

Remember, the chuck is balanced because for 1 turn of the lathe spindle, the Oval chuck turns 1/2 revolution. This allows adding balancing weights.

I turn mostly with gouges. since there is no center to an oval shape just a ling length equal to the difference length between the long and short axis.

All cutting is done not riding the bevel as the Point of Tranquility is in the center of a "X" which Dale explains nicely.

Oval turning is a challenge, much more than round turning. The quality of the cut is poor because the gouge bevel can't contact the turning wood, especially on the inside.

I hope others are also interested in building an Oval Chuck. You will require a Metal Lathe, Drill Press, saw, files and hopefully access to a small mill/drill. Material costs for the Aluminum bar stock, screws, bearings ,size 40 chain & cogs, and steel bar stock will be around $200. Try to find a local Steel Yard that sells the stock. You will be single point chasing threads, both male and female 1 1/4" X 8 TPI. or 1" x 8 TPI.

 

[Emiliano Achaval]

I have never posted a video. The video will be made shortly and I will give it a try.

Please view Dale Larson's Ovalturning youtube video . Turning the wood on my chuck is exactly the same as Dale's process. also read Ovalturning by Johannes Volmer the internet.

My Oval Chuck design is simple no chain tensioners. Chain #1 is tightened thru turning an Eccentric. Chain #2 is tightened by turning the Offset Adjuster bar against the Eccentric bar. This won't make sense until I get the video made.

Remember chain doesn't stretch and it is impossible to get both chains equal tension all 360 degrees of rotation. Since the Talon chuck/bowl are exerting resistance against the entire Oval Chuck, the slight looseness and tightness as the chuck turns is irrelevant.

Remember, the chuck is balanced because for 1 turn of the lathe spindle, the Oval chuck turns 1/2 revolution. This allows adding balancing weights.

I turn mostly with gouges. since there is no center to an oval shape just a ling length equal to the difference length between the long and short axis.

All cutting is done not riding the bevel as the Point of Tranquility is in the center of a "X" which Dale explains nicely.

Oval turning is a challenge, much more than round turning. The quality of the cut is poor because the gouge bevel can't contact the turning wood, especially on the inside.

I hope others are also interested in building an Oval Chuck. You will require a Metal Lathe, Drill Press, saw, files and hopefully access to a small mill/drill. Material costs for the Aluminum bar stock, screws, bearings ,size 40 chain & cogs, and steel bar stock will be around $200. Try to find a local Steel Yard that sells the stock. You will be single point chasing threads, both male and female 1 1/4" X 8 TPI. or 1" x 8 TPI.

You can post a link to a YouTube video here. You won't be able to post a video. We have a size limit on all uploads. Looking forward to seeing your chuck in action! I believe there could be an interest in this, but definitely for a finished working product for me. I do not have the knowledge to build one.

 

[R Henrickson]

David Springett has published plans for an elliptical chuck -- made from wood! -- in his book Adventures in Woodturning. He also has an hour-long video on the chuck available on his website. He has a few short videos on Youtube

 

[Dennis Weiner]

Up to now, the only Oval Chuck available is Vicmarc VOD chucks at a killer price tag. I have a working design of an Oval Chuck that uses Cogs and Chain to generate the Oval shape. The chuck is balanced and has simplified methods to tighten both chains one and two.

Picture from left to right Pillow block with a counter weight just setting on top. Chain #1 that drives the Eccentric (the round component that chain #1 drives thru to Chain #2). Chain #2 drives the Divide by Two Cogs. Chain #2 drives the Hub that the woodturning chuck is mounted too. The size 40 chain and cogs are available at a farm supply store. In picture 2, the Oval Chuck Spindle is screwed directly onto the lathe headstock. The Oval Chuck can be mounted to any size lathe by the height adjustable mounts.

There is Metal Lathe work and some milling ( could be done with a drill press, hand saw and files). Material costs less that $200.00.

If there is any interest in building an Oval chuck, I will take more and better pictures.

I love your innovative spirt. I often build/reinvent accessories for my woodturning lathe. To teach others, like club members, these projects, I overtly use machines that are typically found in a woodworking shop to increase the likelihood of participation. There probably are a small group of woodturners that own or want to own machinist lathes and milling machines. However, if the components can be fabricated on woodturning shop equipment only, you may have more participation. 200 is reasonable but buying equipment? ….not so much for me.

 

[Paul Rohrbacher]

Question, why turn Oval projects? Most woodturning is done in a Round format. Segmented turning, carved turning are still basically Round. Oval woodturning offers a new dimension to the woodturning world. Dale Larson is using the Vicmarc VOD Oval chuck to make his famous Oval Bowls.

The modern Ovalturning venture starts with Johannes Volmer who invented a new way to turn oval using a balanced Oval Chuck. The traditional 600 year old Oval Chuck design was not balanced hence the old Oval Chucks were built in as part of the building. Johannes solved the Oval Chuck balance problem along with lubrication problems that plagued the old design.

Johannes wrote "Ovalturning" a PDF file that is a must read for anyone interested in Oval Turning. The key to a balanced chuck is for every 1 revolution of the driving lathe, the Oval form turns 1/2 revolution. Now, the Oval Chuck has a system of counterweights which effectively cancel out vibration.

The entire key to the Johannes version Oval chuck is reviled on page 17 in the PDF "Ovalturning". Johannes used Timing Belts and Timing Gears with belt tensioners and adjustable sliding weights. I used Size 40 Chain and Cogs. As chain doesn't stretch, a method of tightening two different chains together, became problem #1 to solve.

Design:
The first chain #1 drives two cogs, Cog #1 and Cog #2. Cogs 1 & 2 are the same size, each have 16 teeth but Cog #1 is fixed in place and doesn't turn. Chain #1 drives Cog #2. As Cog #2 Swings orbits the input Spindle, it doesn't change position (Just like the Moon doesn't change position as it orbits the Earth or the seats on a Ferris wheel stay level). To tighten Chain #1, Cog #2 is connected to Cog #3 thru an adjustable Eccentric.

To independently tighten Chain #2 which is driving Cogs #3 and #4, the bar the Eccentric is mounted to is free to swivel and be tightened when Chain #2 is tight.

Chucking: Cog #4 is driving the Hub. The Hub has the 1" x 8 tip or 1 1/4" x 8 tpi chuck driving Spindle that the Talon Chuck is screwed to.

Divide by two:
The Hub and Talon chuck are orbiting at the lathe's rpm The initial 1 to 1 cog ratio of Fixed position Cog #1 to Cog #2 and Cog #2 is connected to Cog #3 thru the Eccentric, results in the three Cogs remaining in a fixed relative position. (see discussion about the Moon and Ferris wheel above). To divide the Talon's forward lathe speed by two ( 2), Cog #3 (12 tooth) is driving in CW to Cog #4 at 1/2 lathe speed subtracted as it rotates forward CCW at 1/2 lathe speed.

Weights: Now add the counter weights to the Oval Chuck so with no power applied, the Oval chuck would remain in any position (Static Balance).

If this makes sense to the readers and the readers want to see drawings and the chuck operating, let me know: paul.rohrbacher@aol.com or call 319-465-6369.

Costs estimated : aluminum $5/lb., Cogs $10 + each cog, #40 Chain $15, Bearings 5 to 6 bearings $10 ea. screws $10 So you are up in the $200 material cost range. You will need a metal Lathe, Drill Press, tooling and some skid operating a metal lathe. A Mill/Drill would help but it isn't necessary.

If you respond to this Posting also be sure to send a Email with your questions.

 

[Bill Boehme]

It would be preferable to keep all questions, answers, and comments online in this thread. Otherwise, there would be a loss of continuity for many people who are following this thread but aren't posting comments. Additionally, You may find yourself repeatedly answering the same questions. There's no need for someone to email you to say that they have posted in this thread since you will receive an alert. Posting your email address and phone number in a forum post or social media puts you at risk of getting spam emails. I am moving this thread to the Tutorials and Tips forum which is a more appropriate location.

 

[hughie]

I have never posted a video. The video will be made shortly and I will give it a try.

Please view Dale Larson's Ovalturning youtube video . Turning the wood on my chuck is exactly the same as Dale's process. also read Ovalturning by Johannes Volmer the internet.

My Oval Chuck design is simple no chain tensioners. Chain #1 is tightened thru turning an Eccentric. Chain #2 is tightened by turning the Offset Adjuster bar against the Eccentric bar. This won't make sense until I get the video made.

Remember chain doesn't stretch and it is impossible to get both chains equal tension all 360 degrees of rotation. Since the Talon chuck/bowl are exerting resistance against the entire Oval Chuck, the slight looseness and tightness as the chuck turns is irrelevant.

Remember, the chuck is balanced because for 1 turn of the lathe spindle, the Oval chuck turns 1/2 revolution. This allows adding balancing weights.

I turn mostly with gouges. since there is no center to an oval shape just a ling length equal to the difference length between the long and short axis.

All cutting is done not riding the bevel as the Point of Tranquility is in the center of a "X" which Dale explains nicely.

Oval turning is a challenge, much more than round turning. The quality of the cut is poor because the gouge bevel can't contact the turning wood, especially on the inside.

I hope others are also interested in building an Oval Chuck. You will require a Metal Lathe, Drill Press, saw, files and hopefully access to a small mill/drill. Material costs for the Aluminum bar stock, screws, bearings ,size 40 chain & cogs, and steel bar stock will be around $200. Try to find a local Steel Yard that sells the stock. You will be single point chasing threads, both male and female 1 1/4" X 8 TPI. or 1" x 8 TPI.

I would be interested in your design have often thought about building one. Vicmarc, yeah I looked at that, very pricey