• Guest, Help us understand what we can do better in future. Click Here!

Over the top ball turning attachement

#1
My lathe only has 2 1/4" clearance between the cross slide and the center of the chuck, so a horizontal swivel base approach is not practical as far as I can tell. I drew up some plans for an over the top ball turner (same idea as https://littlemachineshop.com/products/product_view.php?ProductID=1970&category= ) and am now wondering what orientation the tool needs to be. I assume 90 deg clockwise (from normal) such that the cutting edge intercepts the oncoming metal as it turns into the tool at the top of the swing (am I making any sense here?). This affects how high the support arms need to be when using a standard carbide insert tool. Also affects where the tool holder hole needs to be positioned on the swing arm. Am I on track here?

Also, forgive me father but I am about to sin and go to MSM to source the materials I need.

Base - 1/2" X 2" X 6"
Supports - 1" X 1" X 5" (will suffice for both)
Swing - 1" X 3" X 3 1/2"

Anyone want to suggest an appropriate steel for this project?
 

kevin.decelles

Active Member
Premium Member
#4
I have some stock that may help you out, no idea what kind of metal it is though

Send me a pm if interested



Sent from my iPhone using Tapatalk
 
#8
A BIG BIG THANK YOU to member kevin.decelles. Kevin donated bar stock for my ball turning project. He even delivered it to my end of the city!!!!

I'm off to the races with this project now.

Stage 1 - The swing.

1.JPG

Lobbing off a 3" piece of 1" X 4" flat stock with my trusty PHS. Cut time was approx. 20 min.

I have discovered that the saw likes to walk all over the basement floor LOL. Looks like some sort of base is in order.


2.JPG

Milling the PHS cut square.

3.JPG

Next, I need to mill this piece into a horse shoe. A lot of metal to remove, 4.5 cubic inches worth.

I'm open to suggestions other wise it's going to be a LOT of back and forth with my mini mill, that piece is 1" thick.

Cut the two vertical lines with my PHS and mill the bottom horizontal line, might be an idea, I guess?
 
Last edited:

Dabbler

Well-Known Member
#9
You use your PHS to cut out as much as you can, even resorting to (horrors) using a hand hack saw to get out most of the extra material. Saves $$$ on milling cutters/inserts.
 

RobinHood

Active Member
Premium Member
#11
As PeterT mentions: drill the corners (i would even leave them round if at all possible to prevent stress risers). Make the holes big enough for the PHS saw blade and after cutting the bottom line, cut down both sides and voila. Leaves you a nice chunck of steel for future projects...
 

PeterT

Ultra Member
Premium Member
#12
Depending on that big hole size & your blade, you might be able to come in from either side of the hole & connect to the corner holes. Basically roughing out material so your end mill is reserved for cleaning up & finishing the opening to final dimension.
 

Attachments

#13
oooops…...

I was attempting to square up one end of a 1" X 4" X 7" piece like this

CRASH1.JPG

The end mill grabbed and stalled. The down feed on this mill is terrible.

CRASH2.JPG

Pulled the head over a good 4 degrees or more.

Now I have to re-tram it.

Won't attempt this sort of thing again.
 

Janger

(John)
Administrator
Premium Member
#14
Depending on that big hole size & your blade, you might be able to come in from either side of the hole & connect to the corner holes. Basically roughing out material so your end mill is reserved for cleaning up & finishing the opening to final dimension.
Chain drill along the bottom...
And get a vise that opens wider. I know money money money....
 

Janger

(John)
Administrator
Premium Member
#16
Ah. If you had a larger vise you could grip it like this and mill off the edge much easier and with more rigidity.

You could also just use your clamp down kit I see in the background and clamp the material to the table. Put a spacer in to avoid hitting the table.

For chain drilling drill a series of holes not touching in a line. Then redrill every second hole with a larger drill bit just big enough to remove the web of material left between holes. Eg drill 1/4” holes 5/16 apart and then drill every second hole with 9/32”.

@johnnielsen taught me this one... thanks John
 

Attachments

#17
I got it now. Keep the milled surface as close to the table as possible.

That piece of steel in you image looks just like the piece I have? 1" X 4" with a hole in the same location. Where did this stuff come from?
 

RobinHood

Active Member
Premium Member
#20
You could also just use your clamp down kit I see in the background and clamp the material to the table. Put a spacer in to avoid hitting the table.
X2

Also use a smaller diameter milling cutter (ie. 3/8” to 1/2” max) and employ step-over passes. That reduces the amount of power / rigidity required from the mill and works safer (albeit slower) for questionable set-ups (like stuff that sticks out a long way from its hold down).
Looks like you are trying to use about a 1”, two flute cutter. These require some serious power and rigidity. I rarely use anything bigger than a 3/4” endmill on my Bridgeport size milling machine in steel.