Mill use for track support in rolling ball sculpture

[markstephens]

Hi,

I'm creating a RBS using wood, brass and glass marbles as the media. I'm pretty good at woodworking, but very new to machining.

My router table makes for a poor mill with the use of jigs and, as you can image, it's not very accurate or easy. The photo shows what I'm attempting. On the left is the raw stock, a brass pipe 1 5/8" diameter with 1/4" walls (also shown is a 1/8" rod used as track). I use a jig with a dremel to cut off a 1/4" circle. A jig on the router table mills the 1/8" holes in the ring (next photo clockwise). The ring is cut into 4ths, a small flat made on the each of these track supports and a hole drilled into, but not thru, the flat. Add some solder and you get to the picture on the bottom right.: a marble rolling of a track in dire need of a clean up!

Here are my assumptions based on reading a bunch of books:
- A mill with a rotary table (?) drills the 1/8" holes.
- An end mill cuts the flat on each track support
- A drill cuts the hole in the flat

Are these good assumptions?

Also, can a mill be used to cut the 1/4" rings from the pipe? (Don't want to buy a lathe... yet!)

Assuming the dremel has butchered out a ring. Can the mill surface this piece of uneven thickness?

How to hold (with accuracy) the track supports? Should I drill the holes (and make the flats) before cutting the ring in 4ths?

So... anyone want to convince me to buy a mill!?

thanks,

mark

 

[dlane]

RBS ? What dose it do

 

[Cobra]

Balls get elevated and roll down tracks to collect and be re-elevated.

 

[gonzo]

I would not bother to notch the ring, but make a jig to hold the rod in place for soldering.
The solder should be strong enough thus making the notch unnecessary.
Making the notches are time and effort consuming and your rbs will take a LOT of them.

 

[tincture500]

As you mentioned your best with wood. Why don't you opt to make the ring out of wood. Nice walnut and brass rod would look really sharp

 

[tincture500]

Couple hole saws would make you ring then cut them in half

 

[12bolts]

Yes a mill would do most of the work as you describe, apart from the ring cutting. But are you just looking at a mill for this job or do you see plans for more different miling in the future? Are you planning on going into full scale production of the RBS and needing mass production parts? More tools is always better, but a mill, and indexer for just this job is going to be pretty $pendy.
It appears you have a drill press? Although this could also be done with just a power drill and vise. A simple jig would enable you to get good consistent results quite easily.

Obviously this is just a quick sketch and the location of the various holes is just arbitary, but with correct layout you could have your jig clamped to the table, insert ring, (without a dowel pin) and drill the first hole. Move ring around and insert dowel pin, drill next hole. Pull pin, rotate ring, insert pin in next hole, drill new hole. Repeat. Once done drilling, remove jig from table, and by using the index pin you can file a small flat for your radial hole location. If you wanted to get really technical I suppose you could also put a hole in the edge of the jig and use that to drill your radial hole. Actually, if you did do that you could probably eliminate filing the flat.

If you are wanting to get consistent thickness of your rings you could make a 2nd jig with 2 holes.

1 is a through hole, neat fit on your tube. Clamp tube so it just projects proud of the surface and sand it flush. This will now be, (within reason), flat and perpendicular. Cut your ring slightly over length, drop it into the 2nd hole, (depth of which is your ring thickness), previously squared end down, and sand it flush.
Hole sawing your rings out of brass plate is another option but will require considerable clean up to get the finish you seem to be after.
It will be difficult to clamp the "dremel butchered" rings and mill them flat.

Cheers Phil

 

[markstephens]

I would not bother to notch the ring, but make a jig to hold the rod in place for soldering.
The solder should be strong enough thus making the notch unnecessary.
Making the notches are time and effort consuming and your rbs will take a LOT of them.

Gonzo, I did try this but there is not enough surface area to create a secure bond... even with filing flats on the track . Too easy to snap on handling and my design depends on being able to remove the track for cleaning, and polishing. With the notches, I can still snap the support from the track but it takes way more effort.

thanks for the reply!

mark

 

[markstephens]

As you mentioned your best with wood. Why don't you opt to make the ring out of wood. Nice walnut and brass rod would look really sharp

It would indeed! I'd need to epoxy the track to the wood and I'm not sure that would look so great.

thanks for the reply!
mark

 

[rwm]

Nice project! Please post more pics as you go.
I assume you used regular solder? Silver solder will give you a stronger joint. The soldering temp is higher and you will need to be careful not to deform your track but it is probably worth it for the durability. You may be able to get away without cutting any notches if you do that. Try a test piece.
12 bolts had some great suggestions above. I think the jigs would need to be made of steel, so you would have to have those machined. How many of these parts do you anticipate making? A small Sherline lathe and mill could handle brass parts at this scale nicely. This could all be done with a mill, and rotary table. To make the rings you could just cut off bands with a handsaw and then finish the ends with a rotary table on the mill.
Robert