The aligning trick using putty and a needle is by itself worth watching the whole video even if one's not into cannon ball molds. Awesome video series. Thank you for sharing this.
Part of the success is learning why something didn't come out exactly as intended. Knowing that the adjustment of the ball turning toolpost is critical and having others comment explaining how to do that is great. If I needed another it would be perfect. Besides, there is no other way to get a ball that size without spending a lot of money. All this cost me was the price of the aluminum.
good stuff. liked it. To Every one always remember measure 100 times before each cut. not one time after 6 cuts. on the bright side, if they dont work for the cannon you have some good sinker molds. just mill a slot for an eye screw on one side.
It's a cool project. I would have milled the mold about .005" deeper than necessary to ensure the full radius was formed into the aluminum. Then fly cut the excess off of the surface until you can measure the exact diameter you needed for the mold. this way no oblong balls.
If you offset your radius cutting lathe gizmo in the other direction, you could us it to cut the half sphere directly into the mold block mounted in the lathe chuck and skip the custom cutter altogether. If I had to make these, I would first machine the parting faces flat, add locating pins by drilling/reaming through both stacked blocks, then machine them together so all sides are flush and square, and use a dial indicator to position them in a 4 jaw lathe chuck to machine the cavity.
Just a tip: Sometimes you're measuring diameters with the calliper points pointing in the axial direction. You should have the calliper points pointing alond the plane of the cross-section of the cylinder to make sure you're always taking the max diameter. I.e. the true diameter. It's impossible to be positioned wrong like this.
Chatter is caused by hitting the resonant frequency of the cutter or workpiece. It can usually be cured by either speeding up the feed, or slowing down the spindle speed. On the lathe, the work piece should always be as close to the chuck as possible.
Use your DRO and drill the alinement pin holes a given demention from the center of the ball cavity. That way you will have perfect alinement of the mold halves.
It is really tough drilling both halves with a large diameter ball end mill and get both separate pieces exactly aligned. So I bought a steel ball bearing the size I needed and just drilled both of the molds close with a ball end mill in both halves. Then I just put the exact sized steel ball bearing in the mould and clamped it in my mill and decked all the sides nice and flush, and at the same time drilled my alignment pin holes keeping the ball inside, makes for really hassle free very precision alignment 👍 but of course this method only works if you can find a steel ball and ball end mill bit the size that you need. The mold i needed just happened to be exactly 1.5"
He is facing them off first, and that should be the last step. Step 1: cut the ball mold inner halves. Step 2: cast 2 halves and use them to align the mold halves and assemble them. Most would use a steel ballbearing to align them. Step 3: drill and install the alignment pins. Step 4: face off the exterior faces. Step 5: cut the mold handle reliefs.
I am definitely not a pro-machinist, but I've got an idea for you. Make your ball turning attachment so that when the front end of the slide (part that changes the diameter of the ball) is flush with the outside of the base it holds the cutter tip exactly over the center of the pivot. Then when you slide the slide out, you can measure how far the "stick out" is and get the exact radius of the ball you want to cut. You would need a longer slide on the back to compensate for the extra in front.
Did you add the DRO to your Grizzly mill or buy it that way? If you added it do you have a video of that procedure? Great project. I am watching thinking of ways to adapt to making a large downrigger pancake lead. Doug
As you had a DRO on your mill, could you not have drilled two holes straight through each casting block a set distance away from the center of the casting holes (when you were making the round recesses, before you un-clamped the workpieces) to take some alignment pins? This would remove the need for an alignment ball all together. I think this is how I would have done this, but I'm no professional. Thanks for the upload!
When I was working as a CNC operator what they did for stamping dies is they would mill it to +0.005"(I believe that was the spec, you could probably get away with +0.010" for the mild), send it off for heat treating, then bring it back and finish it off. You might be experiencing problems that procedure was designed to counter. One thing that bugs me is the way you milled for the cutting edge, It looked as if there were some huge flats along the edge and the cut path was awfully crooked.
Good vudeo! Just a tip to speed you up. Start with your whole bar in the vise, figure out where your alignment pins will be in relationship to your cavity, leave a little for the saw to separate the blocks from the bar stock, drill all your holes at once just swapping out for the ball cutter. You can use the DRO or count turns. Cut your blocks off of the bar stock pin them together, back in the mill to clean up the edges and Mill your slots for the handles and you're done.
you could have just as easily carved the mold out on the lathe with an inside radius cutter. (same idea as the ball cutter just reversed) and put them in a 4 jaw chuck.
You need to get yourself an edge finder for your mill. Find the edge, zero out, move in by the radius of the finder, zero out agin, then move to your center measurement.
Nice effort, but I see it as a failed experiment - even if you made your cannon balls, you would have been happier having figured out a sure-fire way to produce spherical positive and negative molds. To save you the trouble, you could have bought a ball the size you want from the chinese, failing that you could produce a spherical artifact polishing machine (the sphere rotates on an axis orthogonal to the polishing head, which also rotates). The plunge cutter flexed, give it 2 cutting edges.
The aligning trick using putty and a needle is by itself worth watching the whole video even if one's not into cannon ball molds. Awesome video series. Thank you for sharing this.
Part of the success is learning why something didn't come out exactly as intended. Knowing that the adjustment of the ball turning toolpost is critical and having others comment explaining how to do that is great. If I needed another it would be perfect. Besides, there is no other way to get a ball that size without spending a lot of money. All this cost me was the price of the aluminum.
good stuff. liked it. To Every one always remember measure 100 times before each cut. not one time after 6 cuts. on the bright side, if they dont work for the cannon you have some good sinker molds. just mill a slot for an eye screw on one side.
It's a cool project. I would have milled the mold about .005" deeper than necessary to ensure the full radius was formed into the aluminum. Then fly cut the excess off of the surface until you can measure the exact diameter you needed for the mold. this way no oblong balls.
Thanks, I knew about keeping things close to the chuck, I'll keep the speed changes in mind next time.
If you offset your radius cutting lathe gizmo in the other direction, you could us it to cut the half sphere directly into the mold block mounted in the lathe chuck and skip the custom cutter altogether. If I had to make these, I would first machine the parting faces flat, add locating pins by drilling/reaming through both stacked blocks, then machine them together so all sides are flush and square, and use a dial indicator to position them in a 4 jaw lathe chuck to machine the cavity.
Nice job, thanks for the video.
Just a tip: Sometimes you're measuring diameters with the calliper points pointing in the axial direction. You should have the calliper points pointing alond the plane of the cross-section of the cylinder to make sure you're always taking the max diameter. I.e. the true diameter. It's impossible to be positioned wrong like this.
Chatter is caused by hitting the resonant frequency of the cutter or workpiece. It can usually be cured by either speeding up the feed, or slowing down the spindle speed. On the lathe, the work piece should always be as close to the chuck as possible.
I understand, makes sense. I guess I figured that with a 3/4 shank it would help lessen vibrations.
Really nice man. The cutting tool worked great!
Use your DRO and drill the alinement pin holes a given demention from the center of the ball cavity. That way you will have perfect alinement of the mold halves.
It is really tough drilling both halves with a large diameter ball end mill and get both separate pieces exactly aligned. So I bought a steel ball bearing the size I needed and just drilled both of the molds close with a ball end mill in both halves. Then I just put the exact sized steel ball bearing in the mould and clamped it in my mill and decked all the sides nice and flush, and at the same time drilled my alignment pin holes keeping the ball inside, makes for really hassle free very precision alignment 👍 but of course this method only works if you can find a steel ball and ball end mill bit the size that you need. The mold i needed just happened to be exactly 1.5"
He is facing them off first, and that should be the last step.
Step 1: cut the ball mold inner halves.
Step 2: cast 2 halves and use them to align the mold halves and assemble them.
Most would use a steel ballbearing to align them.
Step 3: drill and install the alignment pins.
Step 4: face off the exterior faces.
Step 5: cut the mold handle reliefs.
the best machining videos on youtube!
I am definitely not a pro-machinist, but I've got an idea for you. Make your ball turning attachment so that when the front end of the slide (part that changes the diameter of the ball) is flush with the outside of the base it holds the cutter tip exactly over the center of the pivot. Then when you slide the slide out, you can measure how far the "stick out" is and get the exact radius of the ball you want to cut. You would need a longer slide on the back to compensate for the extra in front.
Did you add the DRO to your Grizzly mill or buy it that way? If you added it do you have a video of that procedure? Great project. I am watching thinking of ways to adapt to making a large downrigger pancake lead. Doug
+Douglas Thompson I added it a number of years ago. It is this one. www.shumatech.com/web/
That actually worked when I made my buckshot mold, but I didn't take the time to make these blocks exactly the same.
As you had a DRO on your mill, could you not have drilled two holes straight through each casting block a set distance away from the center of the casting holes (when you were making the round recesses, before you un-clamped the workpieces) to take some alignment pins? This would remove the need for an alignment ball all together. I think this is how I would have done this, but I'm no professional. Thanks for the upload!
When I was working as a CNC operator what they did for stamping dies is they would mill it to +0.005"(I believe that was the spec, you could probably get away with +0.010" for the mild), send it off for heat treating, then bring it back and finish it off. You might be experiencing problems that procedure was designed to counter. One thing that bugs me is the way you milled for the cutting edge, It looked as if there were some huge flats along the edge and the cut path was awfully crooked.
Great job.
Good vudeo! Just a tip to speed you up. Start with your whole bar in the vise, figure out where your alignment pins will be in relationship to your cavity, leave a little for the saw to separate the blocks from the bar stock, drill all your holes at once just swapping out for the ball cutter. You can use the DRO or count turns. Cut your blocks off of the bar stock pin them together, back in the mill to clean up the edges and Mill your slots for the handles and you're done.
Thanks!
Edge finder works in the same concept as that needle, except it wont fly off and it's accurate.
once again great job
Nice videos BTW. I wanted to tell you this, but ran out of room on my last post. Good work :)
What he wants to say is that you have to clamp youre tools or workingpiece closser. This will give a lot of fibrations.
Greetz Chris
Very good point.
why do you let your tool hang out so wide?
I learned a lot
Awesome project... why do you say 600/1000 instead of 6/10?
+Jimmy Louis Don't even remember now. Where in the video was it?
+Jimmy Louis Oh, I found it. Just a brain fart, I never caught that even in review. That as an obvious flub wasn't it.
you could have just as easily carved the mold out on the lathe with an inside radius cutter. (same idea as the ball cutter just reversed) and put them in a 4 jaw chuck.
if i had a 3/4 ball end mill in my tool box i would have just settled for 3/4 cannonballs
Just touch your tool off on x and y then move in your distance plus the tool radius.
You need to get yourself an edge finder for your mill. Find the edge, zero out, move in by the radius of the finder, zero out agin, then move to your center measurement.
Cont.
Granted, I probably couldn't do that well on a mill anyway.
Nice effort, but I see it as a failed experiment - even if you made your cannon balls, you would have been happier having figured out a sure-fire way to produce spherical positive and negative molds. To save you the trouble, you could have bought a ball the size you want from the chinese, failing that you could produce a spherical artifact polishing machine (the sphere rotates on an axis orthogonal to the polishing head, which also rotates). The plunge cutter flexed, give it 2 cutting edges.
why you draw your tools out so far? better?^^
I'm not sure what you mean.
using the digital caliper to scribe? not a good idea
yea try to polish chatter marks o.o''
C right job will Ci
Please please please do not use your calipers for scribing ever again, buy a vernier height guage and a slip set !!