Thread: Oval turning device

Always good to make your own suff!
Vicmarc and Nova already have such devices on the market>

Looks good, Ad. I haven't completely digested the drive train, but it seems you've made a rocking headstock as used in a Rose Engine. Likely more orderly behaviour than the sliding contraptions used in devices like that of the Old Schwamb Mill, or even a cam on a Rose Engine. (Google capitalised terms in quotes for clarification.)

The sketch shows the drive belt at the highest speed on the motor. How fast do you actually run it? I see you have about 2:1 reduction for the final speed on the faceplate.

Joe

Thanks Joe for looking!!
For this design,I had a couple of points in my mind, point 1) a 90 degrees turn (anticlockwise) of the faceplate, and a movement in the same time to the left, creates a quarter of the oval.
point 2) try to make the construction as simple as possible, so with less as possible parts.
And at last I have to make it in my own workshop, so a lot of handwork.
The device is lathe driven, the electromotor of my lathe is frequency controled, which is a avantage, so I can run with every speed.
Studied also before I started with my design,the Bollinger device,the Rose engine as well as the Vicmarc.
My device is only suitable for small objects, like low profile objects.

Ad

Originally Posted by Ad de Crom

My device is only suitable for small objects, like low profile objects

I'm glad you're aware of that. When I first spotted your post I wrote a long-winded reply about counter-balancing, inertial forces, rah, rah, rah... and then deleted it 'cos it all sounded like I was trying to put a damper on your party. I tried again... and deleted that, too. I decided it's better to refrain from comment than to make a (seemingly) negative post.

I seriously doubt you'll be able to run it at anything higher than ultra low RPM and keep your underwear clean but I'm curious to see the end result if/when you go ahead and build it.

(Might require yet another redesign of my Rose Engine project if I decide to pinch your idea... )

Originally Posted by Skew ChiDAMN!!

I'm glad you're aware of that. When I first spotted your post I wrote a long-winded reply about counter-balancing, inertial forces, rah, rah, rah... and then deleted it 'cos it all sounded like I was trying to put a damper on your party. I tried again... and deleted that, too. I decided it's better to refrain from comment than to make a (seemingly) negative post.

I seriously doubt you'll be able to run it at anything higher than ultra low RPM and keep your underwear clean but I'm curious to see the end result if/when you go ahead and build it.

(Might require yet another redesign of my Rose Engine project if I decide to pinch your idea... )

Thanks a lot for your comments, I appreciate that, it's always better to tell me what you think than keeping yourself quiet.
But I'm afraid about nothing, so I keep for sure my underwear clean.(LOL)
As you know, every new design has his problems, so is not 100%, but you have to start with something you believe in, and there are for sure always down the road some problems which I have to fix lateron.
For example the Bollinger device tooks almost 12 years, before they got this device properly running. With this in the back of my head I'm full of confidence. Again a lot of thanks for your attention.
Never try something new, you will never know.

Ad

Thanks for the heads-up about Bollinger, Ad. I was either unaware about him, or I'd forgotten.

The Old Schwamb Mill is extensively covered in "Lathes and Turning Techniques; The Best of Fine Woodworking," Taunton Press, 1991, ISBN 1-56158-021-X. The original article was in FWW May 1986. I have a Post-It stickied relating to an episode of Nawm's New Yankee Workshop shown here on HGTV 3 Dec 1998. HGTV has reruns, so the original NYW show would have been quite a bit previous. The sticky indicates I'd estimated the speed at about 100 rpm; might have been slower of course. The article is silent on the exact speed; only states "considerably under 1,000 rpm."

Joe

Hi Joe, thanks for pointing me on the Old Schwamb Mill. So I took a look to this Mill, looked to the small video's, and saw the working principle of the device. I had this principle already in a file on my computer, but wasn't aware that I would see this principle on the site of this Mill.
It looks to me like a museum, very interesting!

Ad

Righto, Ad. It seems it's still open, as an operating and producing museum: http://www.oldschwambmill.org/

One thing to be wary of in devices like this: As the workpiece rotates past the tool rest, the angle of tangency is vertical only in a narrow band near the equator. According to my crude analysis, and pretty much substantiated in the article, most of the cuts are by scraping and "rubbing the bevel" would be nigh impossible or dicey at best.

I hope it doesn't take you 12 years to build it. Please post WIP pics as the project advances.

Joe

Joe, for sure I will post work in progress pictures. Have now to work out production drawings.
Well I'm now 67, so I haven't that much time, learning that trick is quite a challenge, but in the same time a lot of fun, anyway I hope so.

Cheers. Ad

Started yesterday after figuring out the needed counterweight for the rocking headstock with the production of parts for this device.
Finished the next parts, chainwheel 44t, faceplate with bearings, spindle rocking headstock complete with bearings. Used parts of a bike like the chainwheel 44t, cut off bearing parts of the crankaxle. The spindle for the rocking headstock exsist of a steel tube 20mm and the cut off parts of the crankaxle. Had to spend some time to get the bearings fit on the 20mm tube.
By doing it all with my bare hands, it's a time consuming job, but also a fun job, it will keep me busy for several weeks.

Thanks for looking. Ad

Finished several parts of the Oval turning device, under which, the crankaxle drive, and the almost completed frame.
The picture of the frame shows the spindle for the rocking headstock.
The frame is made of hardwood, in this case pretty hard meranti.
The work on the device goes slowly, a lot of handwork, especially a time consuming job making fit the rollerbearings.
But step by step I'm driving into the right direction.
Thanks for looking.
Ad

well done ad de

Yayyy! I wish I could make progress at your rate, Ad. The Shed Code of Practise requires at least 3 unfinished projects. Perhaps I've taken it too much to heart.

Joe