Boring hole was easier with 4 jaw chuck as opposed to mill, why?

[Firstgear]

I was watching this video on setting up a 4 jaw chuck. https://video.search.yahoo.com/vide...&sigb=133a00kgo&sigt=10lp1f294&sigi=12j0tto4s

The person that made the video stated that it would be more accurate to put the hole in this block with the lathe than the mill. Since I believe he put the small hole in the block while in the mill I would have thought that it would have been easier to put the hole in while it was setup in the mill.

I am missing something, can someone help me understand? I would have used the mill.

 

[Firstgear]

He said he wants to put a 1-3/8” blind hole. I get that he probably doesn’t have a drill that size, I know I don’t. Is he going to use a boring bar that he can set to that dimension? If he is, why couldn’t he have done that with the mill? I am missing something.....help!

 

[P. Waller]

Yes you are missing something.

Lathes are excellent for round work by their very nature, far simpler and designed for this sort of work then doing round work with a milling machine.

 

[Asm109]

Depends on your tooling.
In the lathe you can make a flat bottomed blind hole with ease.

In the lathe, a boring head will give you greatest control on diameter, but you need a very expensive boring/facing head to get the flat bottom.
Alternatively, you could put the part on a rotary table and use an endmill to cut the flat bottom.

 

[tech610]

I was watching this video on setting up a 4 jaw chuck. https://video.search.yahoo.com/video/play;_ylt=A2KLfSB8u1NcrcgAHmXBGOd_;_ylu=X3oDMTEyMmhuZzg0BGNvbG8DYmYxBHBvcwMxBHZ0aWQDQTA1NDdfMQRzZWMDc2M-?p=why+would+you+use+a+4+jaw+chuck+i+stead+of+a+3+jaw+chuck&back=https://search.yahoo.com/search?p=why+would+you+use+a+4+jaw+chuck+i+stead+of+a+3+jaw+chuck&ei=UTF-8&turl=http://ts2.mm.bing.net/th?id=OVP.jHU7GGtj21tqClxVsDFCogEsDh&pid=15.1&w=144&h=77&c=7&rurl=https://www.youtube.com/watch?v=pxs3POSVn9I&tit=4+Jaw+chuck+centering&l=432&vid=352874815bb9d63c25e0a82bbfdc8d7d&sigr=11bsqh1aa&sigb=133a00kgo&sigt=10lp1f294&sigi=12j0tto4s

The person that made the video stated that it would be more accurate to put the hole in this block with the lathe than the mill. Since I believe he put the small hole in the block while in the mill I would have thought that it would have been easier to put the hole in while it was setup in the mill.

I am missing something, can someone help me understand? I would have used the mill.

I would bore it in the mill, right after drilling a hole. That kind of setup in a 4 jaw will be unbalanced.

 

[homebrewed]

In the lathe, a boring head will give you greatest control on diameter, but you need a very expensive boring/facing head to get the flat bottom.

Did you inadvertently indicate 'lathe' instead of 'mill' in your next-to-last sentence? Owning a standard boring head, I can see how it would be difficult to get a flat bottom with it in the mill.

 

[Firstgear]

I would bore it in the mill, right after drilling a hole. That kind of setup in a 4 jaw will be unbalanced.

But isn’t that the point of a four jaw chuck? The ability to put odd shaped parts in it for holes?

 

[JimDawson]

Either way works. Both machines will bore a hole, it just depends on what you're working on, what tooling you have, and what you feel is the best way to bore the hole. If the part was already set up in the mill I would probably just do it in the mill. I wouldn't take the part out of the mill to bore a hole in the lathe, then put it back in the mill to do additional work.

 

[P. Waller]

I would bore it in the mill, right after drilling a hole. That kind of setup in a 4 jaw will be unbalanced.

I bore square and rectangular parts for several days every 2 months or so, mostly bearing bores with internal retaining ring grooves, you would be surprised at how fast an unbalanced lathe spindle will run.


I also make large cams once or twice per year, 5" diameter solid 1045 hot rolled solid bars 91" long.
The machine does not shake or vibrate at 250 RPMs/325 FPM cutting speed, you will find that a boring head with a large off set in a mill spindle will cause it to dance around a bit more.
On the rare occasion when turning a large heavy part or using a boring bar far out of balance install counter weights on the chuck or boring head until the vibration disappears, this is easily done.

 

[Asm109]

Did you inadvertently indicate 'lathe' instead of 'mill' in your next-to-last sentence? Owning a standard boring head, I can see how it would be difficult to get a flat bottom with it in the mill.

Yes I did. I meant to type mill.