Author Topic: Ball Turner for 7X12 Lathe  (Read 5308 times)

Offline 75Plus

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Ball Turner for 7X12 Lathe
« on: April 01, 2010, 12:28:00 PM »
 :proj:  :med: :med:

I am contemplating making this ball turner for my Seig 7X12 lathe. I thought I would put the design up for a critique before I put tool bits to metal. The material is aluminum and steel for the axle. The planned dimensions are, 2.5" OD X 1.25" tall. By making the slot for the tool holder only .375" deep I can reduce the overall height the maximum ball size will be just under 2 inches. Final loading adjustments will be made by using shim washers placed on the axle. Have I missed anything?

Top and bottom views of the rotating part.





Top and bottom views of the lower, base, part and the axle.







Tell me what you think.

Joe


Offline No1_sonuk

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Re: Ball Turner for 7X12 Lathe
« Reply #1 on: April 01, 2010, 01:00:05 PM »
I assume it's meant to fit in place of the compound.  Interesting idea.  :thumbup:

However, is the "keyway" part of the axle necessary?  It'll be a pain to machine the slot in the rotor, and may not be needed.

You'll also probably need a countersink/counterbore in the rotor for the screw head.

Offline 75Plus

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Re: Ball Turner for 7X12 Lathe
« Reply #2 on: April 01, 2010, 01:57:39 PM »
Actually the keyway  will be simple. While the rotor is in the mill to cut the slot for the tool holder it will be centered on the "Y" axis. It will be a simple matter to flip it over and cut the keyway. It is my intention to use a flat head screw to join the parts. I have a unit that is similar in design to this that does not have the keyway and it tends to loosen with use.

Replacing the compound with the turner is the easiest way to get larger ball sizes. Of course you could drill and tap the cross slide behind the compound to mount it but then you would have a rather large obstruction to deal with when using it.
Joe
« Last Edit: April 01, 2010, 02:15:22 PM by 75Plus »

Offline Divided he ad

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Re: Ball Turner for 7X12 Lathe
« Reply #3 on: April 01, 2010, 02:31:41 PM »
Hi Joe,

Looks interesting and a little "fun" to machine but I couldn't tell you the results you'll get? Suck 'em and see I say! You'll either end up with a functional tool and a lot of experience or just the latter.... Either way I'd follow my design through to find out  :smart:  :)

I made one of these for a 7x12 and it works very well.... Never had any issues from the new owner  :thumbup:


There is a project log of it on here if you want to see it? I had issued with keeping the swarf out of the areas that mattered, there are quite a few designs out there to get around that one too.



Have fun  :dremel:




Ralph.
I know what I know and need to know more!!!

Offline 75Plus

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Re: Ball Turner for 7X12 Lathe
« Reply #4 on: April 03, 2010, 09:13:52 PM »
I looked at the BT that I had and found that I could modify it to the design I was contemplating. Everything worked as I had hoped and the converted unit works very well. I did not take as many pictures as I should have but I will try to explain how I got the parts to fit.

The first operation was to mill the keyway in the turret. Once I had it centered it was a simple matter to mill the slot. I opted to make the keyway .100" deep so as to have room for fitting the axle length. Next came the axle.

When I made the axle I left it long so I would have extra material to clamp in the mill vise. Although it was not in my original plan I found that I could assemble all the pieces on the axle without removing it from the mill. I started by making key .060". I then assembled the parts and, using a feeler gauge I found that the axle was about .020" too long. I pulled the base and turret back off and set the "Z" axis to remove about .015". My plan was to get very close then use a shim or shims to bring it to a snug fit. Imagine my surprise when, after reassembling the unit, I found that I had about 6 to 8 pounds of drag with the center bolt tight. This was just a bit more than I wanted. I remembered reading in Ralph's thread that he has lapped the turret and base for a smooth operation so I gave that a try. I did not have any lapping compound handy but I did have some rubbing compound used on automobile paint. I decided to try that and it worked very well. The turret now turns smoothly with approx. 3 to 4 pounds of drag. I am unable to find any looseness and, turning some hard stainless, there was chatter. Guess you can tell that I am very happy with the result.

Here are some pictures of what I did. BTW the turret had two holes to provide access to the mounting screws similar to the one Ralph made. I found the hole size was just right for a 1/4-28 thread and I had a couple of 1/4- 28 X 3/16" set screws so swarf getting inside will not be a problem.








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Re: Ball Turner for 7X12 Lathe
« Reply #5 on: April 04, 2010, 10:55:20 AM »
Nice work Joe, following a re-design through to see if it works is usually fun... Sometimes not so much  ::)

But on  this occasion it sounds like it's a winner    :nrocks:




Now.... Let's see what you can make with it    :thumbup:  :dremel:





Ralph.
I know what I know and need to know more!!!

Offline 75Plus

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Re: Ball Turner for 7X12 Lathe
« Reply #6 on: April 04, 2010, 11:53:54 AM »
I am unable to find any looseness and, turning some hard stainless, there was chatter. Guess you can tell that I am very happy with the result.

That should have read "There was NO chatter" :borg: :borg:

Ralph, I got several ideas from your thread while making the BT and I intend to study your BT Tutorial as I put it to work. It's posts like yours that keep me motivated. Thanks.

Joe

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Re: Ball Turner for 7X12 Lathe
« Reply #7 on: April 04, 2010, 07:07:06 PM »
No chatter is certainly better  :thumbup:  the old typo's rearing their heads :lol:


Quote
It's posts like yours that keep me motivated. Thanks.


Your posts, my posts and all the others get us all thinking about differing designs and on crazy tangents that just might work! That's the fun of this palce   :mmr:
I think it's the forum in general....  I've had my share of weeks off recently, been back on posting a bit more than I was, made a few videos and it's cheered me up no end and I've been in the 'shop the last 3 days   :dremel:  :) 

Didn't come in last night till gone 02:30!!  (Not something to do every night mind.)

Quote
I intend to study your BT Tutorial as I put it to work.
Good stuff, take what you can from the videos... Then let your imagination run riot  :ddb:   :thumbup:






Ralph.


I know what I know and need to know more!!!