Nose cone - ball turner (1st attempt)

[Divided He ad]

Well here is the first attempt to make what I think is the right part? feel free to tell me otherwise. I wouldn't know if there are exact standards that should be adhered to. I just made what I think looks right! ;D

Ralph.

( be kind.... I know it's not perfect!! : )

[ame]http://www.youtube.com/watch?v=s_KRElCauTM[/ame]

Hi everyone,

How do you use a ball turner to cut more of a nose cone type shape? I built a ball cutter similar to the Bedair website over the weekend, but have not had a chance to try it out yet. I need to cut an ogive type shape and now am wondering if anyone can steer me in the right direction.

Thanks
Walt

Fellas, I'm still not getting my head around this one.

It seems to me that no matter where you move the axis, or what the radius is, the cutter is still going to describe an arc of a circle. Nose cones are more parabolas or elliptical unless I am confused about what is meant by a nose cone. I can't see how you get a ball turner to make a parabola or an ellipse.

The axis does need to move, but it needs to move along the axis, not perpendicular to it. Now if you could somehow engage the power feed and cause the pivot to be synced while moving the center of rotation from one ellipse focus to the next, you get an ellipse or segment thereof. Think of it as a taper turning attachment connected to a ball turner in some nefarious way. Some sort of cam connecting the power feed motion to the rotation of the ball turner would allow you to modify the nose cone shape. Better yet, a tracer attachment makes more sense. Alternatively, perhaps a talented operator could freehand the ball turner well enough while the power feed was engaged.

I did draw some examples in Rhino3D of what happens if you simply move the center of the turning tool and increase the radius. It cuts a torus, which may or may not be helpful. Assuming you don't dip into the flat spot on the end, I guess you can make a useful shape, but still doesn't seem like a nose cone shape to me.

OTOH, this is all in my head and I may be completely confused! LOL

Cheers,

BW

 

[Powder keg]

Great stuff Ralph!!! I'll have to mount a camera on my lathe now. You can get some good video that way.

Wes

 

[Bernd]

Very nice job. It's starting to make me want to build one of those ball turning tools.

Just a question; how hard would it be to make several so they look alike in size? I know the OD would need to be the same and the same goes for length.

Bernd

 

[Divided He ad]

Bernd, firstly... build one!!! secondly, thank you ;D

Thirdly, it would be pretty easy I think! Once the tool is set to the required arc and you have locked the saddle, you just don't move it until all the required parts are made.
The arbour stays in the chuck and the 'pre-tapped and length adjusted blanks are screwed on.. polish them all after the cuts are completed. Why you would want multiple I don't know? I don't know what to do with this one... I only made it to take on the challenge! ;D

Ralph.

Very nice job. It's starting to make me want to build one of those ball turning tools.

Just a question; how hard would it be to make several so they look alike in size? I know the OD would need to be the same and the same goes for length.

Bernd

 

[wdp67]

Thats 100% what it was I was asking!! Awesome video, now can you kind of explain it a little please??

I assume you have it set up to cut a bigger arc than the diameter, and how did you determine where to put the tool to start out? Did you have to move the tool while you where cutting or was it in the same place for the whole job.

Sorry for all the questions, but I messed around all last night and had no luck, cut lots of ball shapes but no nosecone shape.

Thanks again for your help!!

Walt

 

[AllThumbs]

That part is more commonly called a spinner! Very nice.

E

 

[Divided He ad]

Hi Walt, I was expecting this ;D

It's late so I'll try to Write this well and correctly before my face hits the keyboard!! :big: (seriously... it's nearly 2am! spent 8 times what it took me to make the cone editing and uploading the vid!!!)

So here goes, I'm afraid it's a little Heath Robinson right now but it should get you on the right track... as I said it was my first go!

1/ I set the arc a lot larger than I would to make the ball. then test rotated it from the back of the work piece toward the front (see the vid... when the tool is in the forward facing position it's near the chuck end)

2/ I wound the tool back so that when it was rotated it just contacted the front.

3/ start her up and start cutting, moving the tool inward in small steps (in the vid I wasn't quite in the correct position so you will see me correct it, you may need to do this too?... but only on the first if your making many?)

4/ the cone shape should start to form as in the vid, if it does not then you either have the tool too far from the chuck end of the work piece or the arc is too small ( I will try to work out a measurement setting for the dia of work piece and the tool setting tomorrow)

I have been using this tool for over a year and made a huge quantity of items for myself and customers, it will all become easier if you make lots of bits and experiment ;D


I hope this helps? I'll put some better thought on it tomorrow morning when I can think!


Ralph.

Ha! no spelling mistakes either... can't be that tired eh!?

P.S. here's a few of my customers pieces... just to show you where experiments get you.... all in stainless ;D

 

[wdp67]

Thanks a lot for the help, I really appreciate it!! I will let you know how it goes, heading out to the shop right now!

Walt

 

[tattoomike68]

Well here is the first attempt to make what I think is the right part? feel free to tell me otherwise. I wouldn't know if there are exact standards that should be adhered to. I just made what I think looks right! ;D

Ralph.

( be kind.... I know it's not perfect!! : )

[ame]http://www.youtube.com/watch?v=s_KRElCauTM[/ame]

Its perfect , we machinist strive to be artist and craftman. I like the music, we used to lock the doors and work saturdays and listen to celtic on NPR radio. It was quite peaceful to work to.

 

[mklotz]

The proper name for this shape is "ogive". It is formed from arcs of a circle which is why it's possible to turn it with a ball turner. The center of rotation of the ball turner must be placed off the central axis of the of the ogive.

An excellent treatment of the mathematics of the ogive is available here...

http://www.geocities.com/rocketguy_101/ogive/OgiveNoseCones.htm

 

[BobWarfield]

Ah so, said the blind man!

The ogive diagrams make it all clear: big radius (bigger than diameter of workpiece), center of radius on far side of spindle axis, convex ball cutting.

Thanks!

BW

 

[Divided He ad]

Can't wait to see your results Walt, your question is the only reason I tried this one out

Thanks Mike, and glad you like the tune

Marv... that makes my head hurt! ??? ( but is going to be read in little bits!)

BW, I think your thanks are to Marv? but I shall say no problem either way! ;D (Am I to understand that you understand the stuff Marv linked to?... if so... Wow!)


Ralph.

 

[mklotz]

Ralph,

Now you know what I'm talking about when I use the phrase "shop math". It looks complex at first glance but it's just simple algebra and trigonometry. Stick with it and all will become clear.

For those who haven't yet built a ball turner, the OGIVE program on my page will produce an incremental cutting schedule (similar to the operation of BALLCUT) suitable for non-critical-dimension ogives.

 

[Divided He ad]

Thanks Marv.... I failed maffs (as we call it here!!) couldn't get my head around algebra!! and to be honest haven't used trig etc for so long it's all but gone!! ??? (I've been fixing cars... don't use many sums for most of that.... just a hammer ;D )

I'll persevere though. Some day I'm going to have to make something that requires it ?!?

Ralph.

P.S...... holy @#*% Marv... just looked at your web site and read your little bio' ... no wonder you know your math!! ;D

 

[wdp67]

Well I tried it again last night after watching your video, and I had some success!!

I got family stuff happening today, so tommorw I will try to get some pictures posted. Thanks again for all the help, could not have done it without you!!!

Walt

 

[BobWarfield]

BW, I think your thanks are to Marv? but I shall say no problem either way! ;D (Am I to understand that you understand the stuff Marv linked to?... if so... Wow!)


Ralph.

That math I can still do, LOL. I'm sure Marv goes past my pain zone though! It wasn't the math that got me there, it was the diagrams showing the radius in relation to the workpiece and curve.

Incidentally, those equations, an Excel spreadsheet, and just a little effort and you could get the results Marv's program outputs on depth of cut for each position. Or, with a little more effort and cleverness, that Excel spreadsheet could generate the g-code to do it on a CNC automagically.

Cheers,

BW

 

[Divided He ad]

No problem Walt, was glad I could achieve what I thought I could! ;D
Waiting to see your pics, will make sure I check tomorrow

BW, Even if I could do all that with the spread sheets etc (which I have never tried!) I sure know I could not afford the cnc equipment!

Question: Do all you fellas who 'cnc' still get the same satisfaction from creating a program and seeing it run as you would if you used your head and hands to manually power the machine into creating a similar part? ( I know the advantages of precision and awkward part creation, but still....?)

Just wondering, Ralph.

 

[bentprop]

Nice job,Ralph.But i hope those spinners are not going on a flying aeroplane.
With that point you can split someone's head in two ;D.Looks great,though.
Did you use aluminium or steel?
That ball turner is definitely going on my "to do" list.

 

[Divided He ad]

Hello Mr Bentprop (didn't leave a name!) Thank you, and no my spinner has no home at all, it was just to help out Walt (wdp67)
I listed the materials in the credits... no one ever stays till the end!! ;D

Bright mild steel.

The website for the plans is also listed in the credits!


Ralph.

 

[Bogstandard]

Ralph,

This post is getting better and better.

I am sure a few of the members on here always wanted to make a ball turner, but had really no idea for the correct use or what they can achieve with one.

Now we are all learning how it is done, and model engines will benefit from it all.

I must admit, my ball turner very rarely gets used, I tend just to hack things out with a graver and files, but that will all be changing soon.

Well done.

John