# Spherical Cutter



## Cedge (Jul 29, 2007)

I'm probably not alone in having built at least one "Ball Cutter" for my lathe. Truth being told, Ive made several in the past couple of years and each one gave me ideas of what I wanted in the "perfect version".  Below, you'll see my latest iteration of this fun tool. This one is unique, although it is solidly based in designs shared by John Moran's and Steve Bedair's web sites.  Both of these guys have been inspirational in my efforts to learn a bit about machining.

The swivel idea is abviously borrowed and somewhat modified, but there is where the similarity ends.  

The one shown below has several features I've added for my own convenience and fun.  

First of, the cutting head is interchangeable so I can swap cutters when the material demands it.  The second item is the tangential cutter or "diamond cutter" .  This basic idea was also borrowed from John's list of tools and modifications.  I simply changed the design a bit and adapted it to the ball cutter. If you've never used a tangential cutter, you have no idea what you are missing. 

I wanted the tool to be easily adjustable without having to take it apart so I added a small 8x32 tpi lead screw and carriage to make adjustment a snap. This little mechanism also holds the tool intact when things are lossened for movement.  The short version is I finally have the tool I want with the features I'd been wanting and its one sweet cutting little gadget. 

The second version is in the works which will cut concave contours with the same ease of control. I tried the dual use approach on earlier tools and  decided I could live with two tools, if the accuracy and user friendliness of both was improved.

Okay...I know... It's not a steam engine, but its one of the items here to help me build them....LOL.  In fact it's the exact tool I need to put the finishing touch on an engine that is way long overdue for its first test run.

Steve


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## Bogstandard (Jul 29, 2007)

Hi Steve, 
Lovely bit of work there, I like the way you have modified the original designs, the true sign of someone who knows what he wants.

John


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## rake60 (Jul 29, 2007)

Beautifully done!
That looks more like a wall hanger than a tool!


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## tattoomike68 (Jul 29, 2007)

Thats *way* nicer then my ball tracer. I used a peice of cardboard and popcicle stick.


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## Hal (Jul 29, 2007)

Steve 

Very nice work.  You need to engrave your name on it.

Hal


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## Cedge (Aug 2, 2007)

Sorry for the delay in responding... I get sidetracked sometimes, when real life encroaches on my fun.  Thanks for the kind words. I almost didn't post the little bugger but I finally figured the worst that could happen was that no one liked it or I'd get flamed for an off topic....LOL. 

Wall hanger?... we don' need no steekin wall hangers... it works or it walks around this shop...(grin).   Bottom line is I like my metal finished to a high shine and don't mind taking a few minutes extra to polish it out.  Funny, my wife also said I should sign and date the  little tool for my grandsons, if they get interested, or so that some future metal guy can ponder its past, just  as I ponder a few of the old items I have collected. 

Tin... Dude!!! .. popsicle sticks and cardboard?  Ok... I'll admit to being curious.  Care to share the technique you've developed?

Steve


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## BenPeake (May 20, 2010)

Just thought I'd revive this topic as there is an engine I would really like to make which requires a spherical surface both internally and externally (concave and convex) with an accurate fit. I was wondering if anyone has tried something like this or seen a tool that was designed to make cuts like this. I use a Myford ML7 if it helps. Any suggestions would be appreciated. Here is the engine I'd like to make:






And here are a series of pictures which describe the principle it employs:






Thanks in advance for any insight.


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## doubletop (May 20, 2010)

Steve

Nice job; even looks too good to use.

Pete


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## Cedge (May 20, 2010)

Thanks Pete

I need to remake it now that I'm using a slightly larger Lathe. I have used it enough it's not quite as shiny these days....LOL. 

Steve


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## GordTopps (May 20, 2010)

Lovely work Steve :bow:

Must have a go at this when i finally get my lathe, due at the end of this month (I hope)
at the mo it's on a _slow _ boat from China!

Also like the idea that you incorporated the use of the tangential toolholder.

Regards
Gordy


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## Lew Hartswick (May 20, 2010)

BenPeake  said:
			
		

> Just thought I'd revive this topic as there is an engine I would really like to make which requires a spherical surface both internally and externally (concave and convex) with an accurate fit. I was wondering if anyone has tried something like this or seen a tool that was designed to make cuts like this. I use a Myford ML7 if it helps.



The internal hemispheres are no problem but the other internal parts do look to be
a bit of a challenge. Internal hemispheres just require a "boring bar" type of holder 
with the cutter at a 45 deg angle to the bar and sticking out in front. I've done 
a few for an "artist" to make some parts. They can even be recessed from the face
a short distance.
  ...lew...


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## BillTodd (May 20, 2010)

Ben,

Please keep us informed of your progress with this model . 

I've wanted to build a physical model of the Tower Spherical ever since I animated it for Doug.

Regards,

Bill Todd

http://homepage.ntlworld.com/bill_todd/animations/TowerSpherical%204.avi





			
				BenPeake  said:
			
		

> Just thought I'd revive this topic as there is an engine I would really like to make which requires a spherical surface both internally and externally (concave and convex) with an accurate fit. I was wondering if anyone has tried something like this or seen a tool that was designed to make cuts like this. I use a Myford ML7 if it helps. Any suggestions would be appreciated. Here is the engine I'd like to make:
> 
> 
> <snip>
> ...


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## djc (May 20, 2010)

BenPeake  said:
			
		

> ...there is an engine I would really like to make which requires a spherical surface both internally and externally (concave and convex) with an accurate fit. I was wondering if anyone has tried something like this or seen a tool that was designed to make cuts like this.



Have a look at http://bbs.homeshopmachinist.net/showthread.php?t=27210 specifically the YouTube movie on page 1 and the photos on page 2 of the thread.

A lot easier on a milling machine, but you can use a lathe as a milling machine...

If you ask nicely, someone will be along to do the maths for you (relating angle of boring head, and radius of flycutter to diameter of sphere).


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## New_Guy (May 20, 2010)

looking good i love the tangent tool just trying to wrap my head around that adjustment you have on there ??? great work Thm:

Ben i really like that engine Thm:


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## RichD (May 20, 2010)

Cedge,
Nice work again!

I have the Steve Bedair version and often wished it had your features.

I did add a swivel-locking feature to mine so I could use it for simple straight machining if needed.

Thanx for sharing that,
Rich


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## BenPeake (May 21, 2010)

Thanks for your suggestions! I think I have a solution for cutting the parts from the info you've provided - it's amazing how clever some of the ideas people come up with are! I am in Denmark on holidays for another month and a half, so I wont be around my workshop to start for a while. When I do start I will be sure to post some pictures of my progress. Sorry to have high-jacked your thread Cedge - I love your cutter, and will be making one similar.


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## walnotr (May 21, 2010)

Is there a drawing of this spherical cutter any where? Would the designer be willing to upload one in the uploads section? It really is an excellent looking piece of work.

Thanks

Steve C.


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## Cedge (May 21, 2010)

Steve
I'd be happy to post drawings.... if there were any....(grin). Like so many of my projects, it began with a rough pencil sketch, a few mental notes of where I thought things should be and then away I went. The basic design is from Steve Bedair's concept. I opened a slot on one side of the body to expose the cutter bar. The lead screw is a 10-32 threaded rod with a threaded brass "carrier" on it. A stud soldered in the side of the carrier nut is long enough to reach through the slot and mate with a hole in the side of the tool bar, making it move when I turn the little thumb wheel.

Note.... I've pretty much abandoned the Diamond cutter idea and opted to go back to using HSS cutters. The HSS tools allow me to do convex and concave curves.... and with a bit of care.... even the odd concave hemisperical cuts as well.  You basically lose the concave option using the diamond cutter due to lack of reach.

Steve


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## lugnut (May 22, 2010)

Steve, your ball turning tool is the best one I've seen as yet. I like the way you have made it easy to adjust. Is there any chance you would disassemble it and take some more photos of the parts and post them. Not that we would copy it, but just get a better understanding of it's workings. ;D
Thanks
Mel


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