Ball Nose Cutters

Hi,

Trying to purchase 15mm (£40) ball nose milling cutters and 22mm (£70) or 78 can only find one site with these but they are very expensive and wouldn't justify the outlay for something you are only going to use occasionally. My biggest collet is 20mm, I was using these for making farming wheels for pipe benders. I am using them for cutting aluminium.

Thanks in advance for any information you may be able to provide me with.

Regards, Lynne.

For occasional use on Aluminium, you would probably get away with woodworker's Router Bits.

MichaelG.

May be worth having a good look at the Stock these people carry. They are local (walking distance) to me and they carry a vast range. Usual disclaimer. - http://www.drill-service.co.uk/Product.asp?Parent=100120300000&Tool=113

Regards.

Personally I wouldn't bother. Unless you have a large and rigid mill (and for reference that doesn't mean a Bridgeport) you'll find it difficult to get a good finish with a large ball mill.. One the cutter will be working over a long length, inviting chatter, and two the centre of the cutter isn't cutting, it's rubbing. Depending upon the shape of the wheels I'd turn them, or mill them, in steps and clean up the form with a file or similar. We're not talking precision shapes for a pipe bender. If you don't want to eyeball the shape it is simple enough to make a template from sheet steel.

Andrew

For grooving pulleys/roller just feed the side of an ordinary endmill into the work, then rotate it. That way you are left with a usable big endmill with a pristine end.

Or rough out and use a form tool on the lathe.

Neil

That's a good alternative.

Andrew

Even using the side of an end mill requires a decently rigid machine. Diameter of the wheel is limited by the length of the end mill too. If the wheel diameter is large enough to need a long series end mill a sidelock (Weldon) type in a holder would probably be more rigid.

I've used a similar technique on a large square column bench mill with R8 spindle a few years back. Keeping chatter under control proved difficult. I'm very glad there was only a short arc to do. I think I took several bites at it cutting first one side then the other before finishing off with a centralised cut.

Clive.

How about turning the recess in the quadrant by making a template with a 15mm recess in it and fixing it at centre height in place of your fixed steady. Now make a follower the same shape as your lathe tool fixed in the right hand position of your toolpost. This now limit your lathe tool position to that require. Mount the quadrant on your face plate. Should work but will be a be clunky.

Frank

Set the wheel on the Rotary table mounted vertically, use the boring head set to size to first drop down to ctr height and then rotate the work. If you advance the work in in several stages you won't be taking a lot off per cut and no need to buy 15 & 22mm cutters.

For teh 15mm you could probably do that on teh lathe with a form tool that is slightly smaller so you are not cutting over the whole width of teh tool, just offer up a bit of pipe to test the fit. I did this one a month or so ago from some scrap brass to bend 1/2" stainless

A 6mm button tool and a few offsets is another option with a bit of freehand knob twiddling to blend the final shape

If possible when using a ball nose cutter I tip the machine head over a few degrees to eliminate the rubbing when cutting on centre.

I have a good selection of ball nose cutters some new some used,all donated, When I was apprenticed I never saw or used one,years later I have found that they will chatter even on a large turret mill and they will break,first one that went was 1/2 inch and it surprised me how easily it broke,and long series ones are even more fragile,I think that they were used a lot when we had an aircraft industry on aluminium alloy and prototype work, I have found a use for them,should you need to turn a very accurate radius on the lathe ,place the ball nose cutter in the toolholder and use it as a turning tool, I have also collected a number of one inch bore horizontal form milling cutters which cut full rads, I made a tool holder too mount these cutters in the lathe and again use one of the teeth as a lathe form tool,these cutters were made very accurate ,there are also usually have about ten teeth to get blunt before sharpening the cutter.

Good hint Nigel, sounds like quite an interesting lot.

I do well believe the rigidity argument, when i used to side face aluminium to get a work piece square on a bridgeport turret mill i found you couldn't be too aggressive with the cut even on soft material like ally. When you think about it they aren't designed to take huge amounts off in one go, especially with really small sizes, doesn't matter if it's made of carbide if it gets too hot n dug in deep it'll either break or warp, you're better off using a horizontal for that kind of work.

Michael W

Edited By Michael Walters on 09/07/2016 22:27:59

> I have found that they will chatter even on a large turret mill

They seem to be more prone to chip welding on aluminium than normal cutters, I think the rake is less. The other day I machined a nice groove, but ran the cutter back along at the same setting and it picked up and spoilt the finish

Neil