Ball or Radius cutter

[raynerd]

on a forum, 10 people... 15 different ways!

[philf]

Hi Nick,

The difference I see in the design from the link is that it allows you to turn a much greater arc than would be possible with a symmetrically positioned insert.

As you say, there are many ways to accomplish the job. I keep looking at my boring head with a view to using it in a ball turner.

I haven't a clue why I feel a need to turn balls. The few I've needed have been made from softened ball bearings.
I have a Quorn tool and cutter grinder (which I inherited) which is covered in ball handles. I've removed some and replaced them with hex nuts as I find the ball handles, although looking nice, get in the way.

Cheers.

Phil.

[Divided he ad]

True, many designs based on the same idea.... Many designs based on others.


There is another thing I've noticed on the link supplied by Phil.

I'm not sure if it's an early attempt but that's not a ball shown in the last shot.... Close, but not a ball. (I made quite a few "acorns" when I first started to learn this!)  Just wondering how easy it is to set it up for accurate cutting?


Still.... interesting solution to the toolpost into arbour issue. So many cats to skin.....




Nick,

I pictured the mounting of these types of tip in a thread I had going ages ago....  http://madmodder.net/index.php?topic=319.msg901#msg901

It might help you if you read it first since I had to do exactly what you are now?  The tip mounting is about half way down the page.

You might need to remove some material from the toolpost too? Might be too chunky? You might be planning to?

 It might stop you getting close into the arbour? Assuming your cutting a ball on an arbour?
Of course that adjustment can be made later with little issues.


I'm looking at this and hoping it's not too much? I'm trying to help.
Tell me if it's annoying. I'd hate to be seen to be pushy. So hard to know when you've written too much?



That said I'm going to leave it at that.... Hope I've helped not hindered?




Ralph.

[MadNick]

Thanks Ralph,

Looks tricky - I have an index table here that may help, will let you know.

One thing about Mike's workshop solution - I cant see how you can cut convex curves with it.

I dont actually need to cut any balls as such, I just want to be able to cut a radius on the top of a pair of handlebar clamps - im looking forward to actually making something rather than making tools!

Nick

[Divided he ad]

Yes, I've been thinking about that too.... It would probably work once you pass the zero point and carry on pushing the toolpost forward towards the work piece?

But then you wouldn't have a lot to grip with the grub screws and the bottom leg of the tool post would be protruding quite a bit..... Always a chance of catching the chuck jaws   
(once you've got yours made, always try a dry run before turning the lathe on..... Learned that one the painful way!)


For what you describe this version should work very well. Won't be long now and you'll have some bespoke handlebar clamps 





Ralph.

[andyf]

.... One thing about Mike's workshop solution - I cant see how you can cut convex curves with it.

Looking at the last photo in the mikesworkshop link, I think that if the turret was rotated clockwise by a bit more than 90 degrees to bring what (in the photo) is the LH corner of the insert into play, it would cut concave curves into the side of barstock. The insert holder might need to be modified to allow that corner to project a bit more, and an alternative position for the handle to screw into would be needed.

Andy

[MadNick]

Andy,

I think you are right, it wouldnt take too much to adapt.

Ill try and get more done tomorrow.

Nick

[Fergus OMore]

Nick,
         I've been trying to follow the 'story' so far. My question is 'Do you have either a dividing head or a rotary table?' Or 'Do you have a boring head?' If you have one and want to do balls or convex cuts, you don't need to go to all this.

'Fergus'

[DaveH]

I have an answer:

Sometimes, there is more fun to be had in making it than using it.

There is also a sense of achievement in making it.

One can learn a lot by just making something.

And most important of all  …………. “He wants to”

Carry on Nick, and don't forget the pics

 
DaveH

[MadNick]

Thanks Dave,

Ive been busy today, mainly cutting out the slot in the centre of the turret.



Made a ballsup though and cut it a couple of mm too wide, should have paid more attention during maths at school.

Its not a biggie though and think i can use it to my advantage by taking up the the clearance with a couple of gib strips which would, in fact, add to the design.

As you have to work with what youve got I also thought of (i) remaking the toolpost from steel or (ii) making a toolpost from the ali I have left (this would mean having to make it from two parts). If I was going to do it the second way any does anyone have a suggestion for a good rigid design by bolting two pieces together in an L shape (I dont have the facility to weld ali).

@Fergus, thanks for your comments. I do have a boring head and would be interested to learn how to use that to do this job. I did find a website last night where someone made a radius cutter to go on the boring bar but the pictures werent clear enough for me to see how to do it.

Nick

[DaveH]

Nick,

Coming along nicely,

Nothing wrong with making a few design changes whilst making it.

 
DaveH

[Fergus OMore]

Made a ballsup though and cut it a couple of mm too wide, should have paid more attention during maths at school.
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There's another question. sorry but there is! Were you using an end mill to do the slot? If you were- don't blame your maths! You should have used a slot drill
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@Fergus, thanks for your comments. I do have a boring head and would be interested to learn how to use that to do this job. I did find a website last night where someone made a radius cutter to go on the boring bar but the pictures werent clear enough for me to see how to do it.
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All you need is to is to use a boring bar but take care to have a cutter which cuts on the outside of the curve to do a convex cut and an inside one to do the concave stuff.

One of the big mistakes is forget that you are making a single tooth cutter which follows the shape of a hole saw and that the flanks of the tooth/bit must follow the circle- and give clearance.

Often the best way to see what you are doing is to draw the job out on paper at full scale.

Really, it is dead simple- the second time!

Good Luck

[Divided he ad]

Nick,
Just my thoughts on it.

If you remake the toolpost I'd use the steel personally.
Could lose the job and other stuff if the thread/material gives way!? Ali isn't the strongest material to thread into.

The forces on the cutting tip can be quite considerable...  Everytime the cutter contacts it pulls down on it a little... Over time it may work loose?
I made my round tipped cutter from steel screwed together. That worked fine. (but cutting force only 1mm off the edge of the post. Not like 6-8mm on the diamond tips)  I'm just not too sure on ali holding up?





Fergus,  Doesn't it take a bit of heavy lifting and a fiddly set up to use a dividing head/rotary table to cut a sphere? I'm sure I've seen it shown in pictures on another forum and I know I'd have had the ball made in the time it took to lift/fit and set the job up in the dividing head.
I'll gladly watch a video of it if you have or know of one? Always wondered about the exact procedure for doing it with one of them?  Every little bit of knowledge helps you make something else 




Ralph.

[Fergus OMore]

Fergus,  Doesn't it take a bit of heavy lifting and a fiddly set up to use a dividing head/rotary table to cut a sphere? I'm sure I've seen it shown in pictures on another forum and I know I'd have had the ball made in the time it took to lift/fit and set the job up in the dividing head.
I'll gladly watch a video of it if you have or know of one? Always wondered about the exact procedure for doing it with one of them?  Every little bit of knowledge helps you make something else 




Ralph.

I'm all of 81+ and lifting things is an out of question thing! Consequently, I have a small dividing head( a George Thomas, from a Hemingway casting), a Vertex BSO which takes Myford collets and ER32 and a Myford set of chucks and a small GHT boring head- made from scrap,  which goes onto the Myford and the mill/drill. There is nothing BIG. I have a bigger rotary table( somewhere)
Actually, the even tinier rotary table on the homemade Quorn will do a hell of a lot of things.

But, and this is important- Chaddock used a file which he softened and re-tempered and did all his ball handles.

All in the books

Cheers

[MadNick]

Thanks fellas,

Will keep you posted on how I proceed

Nick

[MadNick]

Evening,

This afternoon's progress.

My neighbour came up trumps with a brass piano hinge of the ideal width for my shims -



I fitted them to the sides of the toolpost by way of self tapping screws. I originally tried to use an M3 tap with some tiny countersunk crosshead screws but for some reason I just couldnt get the screws started after tapping out the holes - I believe my M3 tap to be just too worn. You have to work with what you have so I used the self tappers and ground them flush -



A quick dressing with some emery paper and wayhey, the shims werent brass at all but brass-coloured. Too late to do anything about it now as those shims are going nowhere.

The next job was to find the centreline on the toolpost -



I milled out a shoulder and then drilled/tapped three M6 grub screws -



Tomorrow is what I believe to be the tricky bit, milling out the recess for the tool. Got to get it right or the whole toolpost becomes scrap...

Nick

[Divided he ad]

Nice save Nick 


Just a note before you machine... Best to turn a point in the chuck first and re-check that line... I made my first one to the tail stock height as Steve Bedair said (IIRC) It was approx 0.20mm too low. Subsequently leaving a pip on all I machined!

Worth the extra time to check.



Fergus,
 I'm aware that much is in books.... Sadly I do not own many of the books out there. Some, but not many. Hence my questions.
Fair comment on the smaller lighter machinery.... I'm a mere 37 and much of it is too damn heavy now!





Ralph.

 
 

[rleete]

Easiest way for me was to mount it in the lathe, and drill the hole with the chuck.  Since I was using a 1/4" round bit, that ensures it is perfectly on center.

[MadNick]

Thanks for the responses

Last night I came to a simpler conclusion in mounting the cutting tool.

Rather than bolting up the tip in the picture, I could use my 8x8 carbide toolholder, mounting it on the upright part by cutting a slot/drilling a hole and securing with a couple of grub screws.

This would allow me to swap out tips and save a lot of aggravation/time in forming the toolpost.

Hopefully will get a chance to do some more work on this later.

Nick

[ksor]

>> MadNick

I think you have to protect your balls - the ones in the bearing of cause - I think small chips will find a way to obstruct a nice smooth turning.

I did one much like yours - http://kelds.weebly.com/kuglevaeligrktoslashj.html - see the 6. 7. 8. picture the balls are hiden behind a skirt - just like a scotchman would do 

But try it out - if it's a problem - you can turn a ring on the lathe and solde it in place to protect the balls.

You HAVE to use brass to protect against scratches - again look what I did - it was a bit tricky to mill it but it can be done.

You can make Google to translate my website !

[MadNick]

Thanks Ksor,

Thanks for the reminder about the skirt and I will keep my eyes open for some strips of brass.

I didnt need to use a translator for your site as the pictures speak for themselves - beautifully made tool

Nick

[ksor]

Thx !

[Fergus OMore]

Fergus,
 I'm aware that much is in books.... Sadly I do not own many of the books out there. Some, but not many. Hence my questions.
Fair comment on the smaller lighter machinery.... I'm a mere 37 and much of it is too damn heavy now!





Ralph.

Books? well, one of my better books is free on the net. I have  Advanced Machine Tool Work by A H Smith.

Bit ancient in places but a lot answers many of the questions posed here.

Elsewhere, is the great Holtzapffel books on Turning and Manual Manipulation.  Absolutely spell binding stuff and if you want to turn the Eiffell Tower or the Taj Mahal or lesser things- it's Holzapffel. Even more dated but I might have some fancy books- but none can keep up with this set.

You sort of read them, put a modern odd bit of know-how to them and really wonder what is really new.

Regards

Fergus o'Dooodah

[MadNick]

Afternoon,

A quick update.

I got the cutting tip mounted on the toolpost and did a few test cuts. A couple of observations -

1. Im not sure my bearing idea is adding to the tool - perhaps a taper roller would have been better suited as its designed to manage radial force. I have to ask myself why no-one else needed to use a thrust bearing in their design like I have - it feels like a lot of force is pushing the cutting tool back and up.

2. It may be to do with 1. but reading the chips tells me that something isnt quite right. Im not getting the nice curly swarf (even on ali) and it looks like the metal is being torn rather than cut. Im certain my tool height is correct and am starting to think the cutting tip isnt right for this application.

Back to the drawing board. I started to get despondent and then remembered that James Dyson made something like 2000+ prototypes for his first bagless vacuum cleaner...

Nick

[Fergus OMore]

Ah, Nick, Fergus a Doo Dahl calling!

I have a set of bearings in my Clarkson Radius Attachment. However, there are none in my Quorn head and none in my George Thomas ( geared) rotary table. Well, we do do thingies!

So you have a pressure in a vertical mode which is fouling the pivot bearing( recall my somewhat rude remarks about these things- well, a lot of did) It's all to do with Pythagorus and 101 and another one in Euclid's Fairy Tales about angles.  That's my theory, anyway.

So now you get rid of these bloody awful carbide tips and make some nice sharp hss ones which have a 5 degree front edge rather than negative or at best 3 degree positive front rake. They might work

I know, I know!!!!  Say no more!

Fergus of the Whatsits