Replies

1. 
   davcefai | Jul 26, 2009 08:06pm | #1

   How about two pieces of plywood each with a 3" hole. Bolt them together, sandwiching the ball. Clamp the lower one to the table and away you go. You will need 5" bolts.

2. 
   sapwood | Jul 27, 2009 03:57am | #2

   How thick is the wall of the ball? Are you sure that you can tap it?

3. 
   philip | Jul 27, 2009 05:29am | #3

   You could epoxy glue it to a piece of scrap wood or take something like one inch or more material and cut a hole on it so that the ball doesn't bottom out . Epoxy easily softens with heat.
   But I have the same question as Sapwood: sounds like you have a ball valve float? Philip Marcou

   
   

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   Edited 7/26/2009 10:32 pm by philip

1. 
   peteram | Jul 27, 2009 04:20pm | #6

   Don't know the thickness, but the ball is quite heavy and solid. I think it was part of a piece of statuary.

1. 
   philip | Jul 28, 2009 07:04am | #9

   "but the ball is quite heavy and solid".
   That will make it very easy then. Brass is easy to drill and tap . Just mark the hole and line it up , securing the ball by the quickest of those two suggestions I gave you, although I think the hole cut in a base is most secure. Use your left hand to steady it. Best to locate the hole with a centre drill but if you don't have that drill a small hole like 3/32nds or so to start the tap drill. I am assuming the hole to be tapped is not more than 1/2 inch or so. If you haven't much experience with brass then it is advisable to stone the cutting edges of the tap drill to prevent snatching. As you have said, it is a one off and not critically accurate-no need to go to town with all kinds of hold downs etc.Philip Marcou

2. 
   BrentD | Feb 01, 2010 05:01pm | #11

   clamp scrap wood to the drill press table and drill a large hole in it 1.5" or so. Leaving that clamped to the table, you can set the ball over the hole and it will automatically center under your drill press to drill the smaller hole to tap and thread. Were I you, I would file a very small flat spot where the tapping drill wants to start and then counter sink a dimple there to get the drill to bite and resist lateral travel when the drill tries to start the hole on a rounded surface.

   Depending on the size of the hole you are drilling you may be able to hold the ball by hand. If not clamp to the table with a similar piece of wood over the top of the ball.

   Be damn sure it is ain't a cannonball.....

   Brent

4. 
   Carya | Jul 27, 2009 06:13am | #4

   I would wrap a few elastic bands around it, put it between two wood blocks clamped to the table with V's cut in them, and use successively larger bits.

   Andy

5. 
   Jfrostjr | Jul 27, 2009 03:57pm | #5

   You could (I think) hold and steady the ball for drilling by "clamping" it in one of those wooden clamps with two screws. (I forget the proper name.) Cheap and reusable,

   Frosty

   "I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922

6. 
   dustymctevish | Jul 27, 2009 05:16pm | #7

   Clamping is the first concern; you need to hold it secure to the drill press table. This can be done preferably with a drill press table vise, anything else would be haphazardly, drilling metal is a lot different then drilling wood and it needs to be securely clamped. Harbor Freight sell a number of drill press vises, I bought one the other day for $14.00. Theses vises can be used in woodworking so isn’t not like a one off thing. Besides they’re cheaper then a visit to the E.R.
   Once you get it securely mounted file a small flat spot on the ball followed by a center punch to mark the location of the hole you want to drill. Use a good drill bit, sized for the tap, a table of drill bit sizes for the taps should be included in your tap and die set, if not this link should take you to one on the web :
   http://www.engineersedge.com/tap_drill_chart.htm
   Also you might want to add just a drop of 3 in 1 oil or something similar when drilling the hole and also when you tap the hole.

    

7. 
   mike4244 | Jul 28, 2009 04:08am | #8

   Make a vee block out of scrap wood. Cut a Vee with the angles of two legs forming 90° .Set the ball in the vee block.Usually clamps are not needed but if you want you can clamp it down. Cut another vee out of straight grain scrap. Bolt or screw the outside edges to the bottom vee block.If you center it on the ball then drill thru the top block    and thru the brass.Remove top block and tap.Be careful drilling,brass has a tendency to grab. Peck drill the brass, go in a bit then retract the bit.Do this often and you will be fine. If the brass is thin then it won't grab,might not tap either.Then use a sheet metal screw if possible.

   If the term vee block got you scratching your head, look it up on grizzly website.They are steel and used to hold round objects for drilling or milling. Anyways it gives you a clear picture if how it should be made.Very simple if you have a bandsaw,5 minute job at most.

   mike

8. 
   pek-r-wood | Jan 31, 2010 05:34pm | #10

   To the extent of your ability, measure the diameter of the sphere, and use the closest hole saw you have (erring on the small side if you have to) to hog out a hole in some scrap softwood. Saw through the middle of the hole on the tablesaw. This will give you more clamping contact surface, and thus more holding force, than v-blocks will. This would be for use in a vise, which I recommend.

   I think center drilling, to a diameter greater than the point on your tap drill, will be critical to your success. Unless you have the top dead center of the sphere precisely under the centerline of your drill press spindle, a twist drill, in my experience, is going to want to walk all over the place. Locating the work precisely enough under the spindle on a drill press would be a very difficult proposition.

1. 
   BrentD | Feb 01, 2010 05:47pm | #12

   double post

1. 
   user-64052 | Feb 01, 2010 06:28pm | #13

   just bring it to me and I will put it in the vacuum chuck and drill it

   ron