Shopsmith Forums

Looking great Dusty! You are well on your way!

enyoc wrote:i think i'll design something like this next in sketchup (see video link below) - a ball turning jig for the lathe. Any interest in me recording how or doing a live session?

http://youtu.be/RsSRQwDlWFs?t=7m15s

or like this

http://youtu.be/tbvOb-tTNyc

Hi,

I have a few ideas on a jig to turn a ball but have not spent enough time developing them to even start drawing.

Turning a small ball, say 2" or so seems like a simple enough project but I'm interested in something with a capacity of 12". My thought was to turn half then flip end for end and do the second half. I'd also like to be able to leave an area in the middle where I could cut the ball in 1/2. Or perhaps a faceplate mount and turn a half circle???

I'd like to stick to using shopsmith lathe tools if possible, and as many shopsmith parts as possible in the design.

Is this sort of what you have in mind?

Ed

I'm going to add some general comments relevant to steady rests.
Since we may have several people working on this by now I just want to put out a few things that need to be looked at and commented on so the design can be proven in before the sawdust starts.

I also want to say this is not intended as a negative reproach to the design but what a early on design review should be like.

In fact the final design might be exactly as is.

First some general comments.

I have never had a real steady rest for my shopsmith until recent years. In a lot of cases you can do without one or jury rig one out of a "V" notched piece(s) of wood. Yea I know my age is showing, that is pretty much a thing of the past. When I got my lathe duplicator I added the capacity.

Then back this spring I made an adapter so I could take advantage of the steady rest in a different mode.

http://www.shopsmith.com/ownersite/item ... tem=555280

Details can be found here:

https://forum.shopsmith.com/viewtopic.php?t=12802

I did that because I had a project I was working on where I needed to turn some longer thin parts. This worked fine and I got the project done.

Independent of where shopsmith steady rest is used you have a range of between 3/16" and 3-1/2". So I have this range covered and if you have these same parts you do too.

Now for some thoughts.

Depending on the dia. of the wheels you will have a point where they touch and you can not go any smaller. In the design presented here you can then switch to the other end with smaller wheels (bearings?). Since I don't have the drawings up I can't tell you if you will have overlap or a missing size range. It is pretty critical to make sure you have overlap.

Depending on a lot of factors at some point the workpiece can support it self quite well at a given length and diameter. Shopsmith thinks this is about 3-1/2", and that sounds pretty good to me. This is for spindle turning of course. This means an opening of at least say 4" might be a good design point. So can we get the wheels open far enough to get around a 4" workpiece?

Another thing to look at is how close to the head stock can we get? How close to the chuck? and well yes how close to the carriage, tail stock, which side of the carriage do you want to mount this???? Yea, lots of questions. With the shopsmith carriage as wide as it is can be an issue, as can having a universal lathe tool rest mounted.

I've also seen designs where a stabilizer can be used for bowls, then of course it has to be much larger.

Does it need to open? I have seen a lot of designs where it is a one piece design. As was pointed out to me in one of earlier threads on the subject lee valley has a very simple looking design posted here.

http://www.leevalley.com/en/wood/page.a ... at=1,43455

I have similar wheels some where in the shop and have a few plans out of magazines/online sources and a few sketches of my own. In none of the ones I have seen in that collection open. It does look cool but is it needed? I have seen commercial ones that open BTW.

Will the design show be strong enough, rigid enough, do we want to use plywood (baltic/finish) or maybe hard maple???

I'd like to dig in on this but I don't have the time right now. I am open to discussions here if people want to look in to this in more detail.

Ed

reible wrote:Turning a small ball, say 2" or so seems like a simple enough project but I'm interested in something with a capacity of 12"

I think SS has a 16" swing, so it should be possible, but imagine the volume of unbalanced wood required for turning a 12" diameter ball...
V = (4/3)*pi*r^3 = 904.78 cubic inches or 0.523 cubic feet which in dried red oak would be over 20 lbs once turned to a sphere (http://www.wood-database.com/wood-artic ... d-weight/). Chucking up that much wood would be the bigger challenge to cutting the sphere IMHO (someone check my math!)

reible wrote:I'd like to stick to using shopsmith lathe tools if possible, and as many shopsmith parts as possible in the design

That's the beauty of designing your own, you can use whatever tools you want. My thought was baltic birch for the steadyrest, not sure about a radius device. For cutters I have some cobalt metal lathe tool blanks to employ.

reible wrote:Depending on the dia. of the wheels you will have a point where they touch and you can not go any smaller. In the design presented here you can then switch to the other end with smaller wheels (bearings?). Since I don't have the drawings up I can't tell you if you will have overlap or a missing size range. It is pretty critical to make sure you have overlap.

Yes my thought was bearings, they could get really tight in the same plane, but if you needed tighter, you could offset the wheels by placing each wheel assembly in a separate plane - move one set to the green and add the red slot when you make yours to move the top wheel set:

for offsetting closer together, one of the bottom wheel assemblies could be reversed in the same plane and the top moved to the new slot.

reible wrote:Depending on a lot of factors at some point the workpiece can support it self quite well at a given length and diameter. Shopsmith thinks this is about 3-1/2", and that sounds pretty good to me. This is for spindle turning of course. This means an opening of at least say 4" might be a good design point. So can we get the wheels open far enough to get around a 4" workpiece?

As drawn, the opening has a 12" diameter - it's no slouch ]Another thing to look at is how close to the head stock can we get? How close to the chuck? and well yes how close to the carriage, tail stock, which side of the carriage do you want to mount this???? Yea, lots of questions. With the shopsmith carriage as wide as it is can be an issue, as can having a universal lathe tool rest mounted.[/QUOTE]
as drawn it relies on attaching to the way tubes, so it would have to be modified, or might not be possible to use, directly above the carriage. By being able to mount the arms on either the leading or trailing plane, you could get it as close as you dare to the head and tail stocks. You could also swing the lathe tool rest to be directly adjacent, or for that matter build two and bridge really thin pieces like goblet stems.

reible wrote:Does it need to open? I have seen a lot of designs where it is a one piece design. As was pointed out to me in one of earlier threads on the subject lee valley has a very simple looking design posted here.

Opening might be convenient or maybe it's an unnecessary overdesign, but it looks cool and this was the design challenge that got me to draw it in the first place, so if i build one, it will open

reible wrote:Will the design show be strong enough, rigid enough, do we want to use plywood (baltic/finish) or maybe hard maple???

I imagined baltic birch as I drew it, it looks beefy and i like to design towards the overbuilt side of the spectrum. I think a plexiglas one would be cool too.

reible wrote:I'd like to dig in on this but I don't have the time right now. I am open to discussions here if people want to look in to this in more detail.

Nice start! Thanks for taking the time to think about it.

enyoc wrote:I think SS has a 16" swing, so it should be possible, but imagine the volume of unbalanced wood required for turning a 12" diameter ball...
V = (4/3)*pi*r^3 = 904.78 cubic inches or 0.523 cubic feet which in dried red oak would be over 20 lbs once turned to a sphere (http://www.wood-database.com/wood-articles/average-dried-weight/). Chucking up that much wood would be the bigger challenge to cutting the sphere IMHO (someone check my math!)


That's the beauty of designing your own, you can use whatever tools you want. My thought was baltic birch for the steadyrest, not sure about a radius device. For cutters I have some cobalt metal lathe tool blanks to employ.

It's all good!

enyoc wrote:I think SS has a 16" swing, so it should be possible, but imagine the volume of unbalanced wood required for turning a 12" diameter ball...
V = (4/3)*pi*r^3 = 904.78 cubic inches or 0.523 cubic feet which in dried red oak would be over 20 lbs once turned to a sphere (http://www.wood-database.com/wood-articles/average-dried-weight/). Chucking up that much wood would be the bigger challenge to cutting the sphere IMHO (someone check my math!)


That's the beauty of designing your own, you can use whatever tools you want. My thought was baltic birch for the steadyrest, not sure about a radius device. For cutters I have some cobalt metal lathe tool blanks to employ.

I think most people would go with a hollow ball once over 6" or so and certain the projects I envision with 10" - 12" would be glue ups and hollow inside. So weight should not be an issue. If you need to turn solid objects like the 12 oak ball I'd seriously be looking for a more capable lathe.

Anyway it sounds like you have a path you hope to follow and it is not the same one that I am on.

Ed

cut list (list? how about diagram.)



all will fit on 36" x 36" piece of ply

not shown is the piece of wood below the ways, it's a nominal 2x4 size, but i would use a hardwood

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