Tapered ball mill

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Tapered ball mill

Postby Jerry In Maine » Mon Feb 12, 2018 9:33 pm

With regard to three dimensional component work; when is a tapered ball mill preferred over a typical "straight" ball mill?

Thanks!
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Re: Tapered ball mill

Postby IslaWW » Tue Feb 13, 2018 12:12 am

When your model does not have deep near vertical elements that the taper will mess up
When you want a stronger, longer bit that can cut faster
When 3 flutes will provide a better finish than 2
When you don't mind spending a lot more for the bit
There are more....
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Re: Tapered ball mill

Postby Jerry In Maine » Tue Feb 13, 2018 12:27 am

So I gather that you're not keen on them then... :wink:
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Re: Tapered ball mill

Postby Leo » Tue Feb 13, 2018 12:27 am

The KEY ingredient

A 1/32 straight ball nose bit will probably break. I 1/4" shank 1/32 ball nose tapered bit is VERY STRONG

MOST of the time, the 3D surface needs only the very tip of the ball nose - so all the stuff behind the tip (the taper part) doesn't really matter.

The taper ball nose can "easily" reach 1" but a straight 1/32 will reach maybe 1/4" if you are REALLY lucky.

Personally, I use tapered ball nose cutters a LOT. I have 1/32 - 1/16 - 1/8. I pay generally about $32-36 each ---- BUT - it gets better.

I did buy some Chinese Ball nose cutters. They were metric, but that does not matter at all, at all. They were a LOT less expensive and performed very well cutting brass. Wood should be really easy.

I posted my evaluation in here somewhere.

Yes I would definitely buy more of the Chinese bits.

And Yes I do use straight bits as needed.
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Re: Tapered ball mill

Postby IslaWW » Tue Feb 13, 2018 1:02 am

Jerry...
I would say the opposite, I use them almost exclusively. I would only select a straight ballnose for 2D work with radiused bottom.
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Re: Tapered ball mill

Postby martin54 » Tue Feb 13, 2018 1:52 am

As Gary & Leo have said there are a number of different reasons why people prefer to use a tapered ball nose instead of a straight ball nose, I use them for some of the reasons mentioned above, despite the extra cost the fact that they are stronger, less likely to break & you can machine much faster especially in the smaller sizes makes them worth the extra cost for me, I use them down to 0.5mm diameter for small detailed models but can still run them at a reasonable feedrate :lol: :lol:

Like Leo I also use straight ball nose bits for some work, as with any bit selection it comes down to what I believe to be the best bit for the work I am doing, probably not always right but it seems to work for me :lol: :lol: :lol:
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Re: Tapered ball mill

Postby dealguy11 » Sat Feb 17, 2018 2:35 pm

For 2d work I use straight ballnose bits. For 3d work at 1/16" and 1/8" diameter I use tapered bits exclusively. I use 1 degree tapered bits a lot and I have never had an issue where the taper of the bit has had any noticeable impact on the final product. You have to get very close to vertical for the 1 degree taper contact the side of the cut. If you're making precisely engineered components it's one thing, but if you're making artistic work it's very rarely an issue.

I also use the 1/8" tapered bit on moulding toolpaths when I'm making cabinet door profiles. Some of these profiles go very nearly vertical, and I have yet to see one where the taper has made any difference at all. The taper adds a lot of strength - I've made hundreds of doors with the same bit with no loss of quality.
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Re: Tapered ball mill

Postby scottp55 » Sat Feb 17, 2018 4:13 pm

Just a note on those Chinese TBN's Leo mentioned...1/8" shank, and only a .25mmR tip, and I've made 2 MASSIVE operator errors with them without them breaking:)
First I drove it into a solid Sugar Maple block full depth using an offset toolpath, and the toolpath was zeroed to the spoilboard, and I zeroed to top of material :oops:
THEN, in Walnut I zeroed to top of material, moved ZZ up and was cutting a few lines(not using a roughing toolpath), dropping the Z down in steps... and had a static "Burp" that lost all positions in a "Wolf" carving(the digger closest to the wolves) and it plunged and started carving .5" deep at 2IPS in X,Y,Z!...reset and then tried again and MISSED a decimal point :oops:
Amazed the bit survived all that and is still cutting beautifully.
Rugged little suckers :D
Just mentioning.
scott

Oh, static was my grounding wire inside hose had a connection come loose while I was cleaning behind machine...NOT a usual occurrence!
Attachments
9.2.17 CHINESE .25MM R TBN.jpg
CHINESE .125SHANK .75CEL .25MM RADIUS.jpg
10.17 Wolf Pair Chinese .25mmR TBN.jpg
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