Boring head capacity

Advert

New Replies

Report Bug

Help/FAQs

Boring head capacity

This topic has 12 replies, 8 voices, and was last updated 8 October 2018 at 20:51 by Bazyle.

Viewing 13 posts - 1 through 13 (of 13 total)

Author

Posts
7 October 2018 at 07:45 #374902
Reg Wortley
Participant
@regwortley
Hello,

Never having used a a boring head in the lathe I would like to understand the method for determining the maximum hole diameter that can be bored with either a 50mm or 75mm boring head.

Thank you

Reg
Advert

7 October 2018 at 07:45 #19104
Reg Wortley
Participant
@regwortley
Determining capacity
7 October 2018 at 07:56 #374903
JasonB
Moderator
@jasonb
On a lathe the size is more likely to be determined by the part and how you can set it up on the machine. Using the side hole to mount the tool you can swing quite a large radius but depth of the hole really depends on how close you can get the work and the head/spindle shape. On a mill the quill will often fit down a large hole so you can go deeper.
7 October 2018 at 09:23 #374910
SillyOldDuffer
Moderator
@sillyoldduffer
Forgive me if this is hijacking the thread, but does Reg mean a Boring Head mounted in the tailstock like this?

If so, is a boring head in the tail-stock advantageous? When I bore in the lathe, I clamp the boring bar directly to the tool-post and move the tool with the saddle. The boring-head is only used on my milling machine. Entirely possible I'm missing a trick due to inexperience. Comments welcome!

Dave
7 October 2018 at 09:43 #374913
John Haine
Participant
@johnhaine32865
Lathe or mill, surely irrelevant. Max diameter determined by max safe offset of the moving part in its dovetails. Personally I would not feel comfortable with it further than half the head diameter. Then you can add on the offset of the tool hole, or if you want a really big hole stick the tool out sideways in the transverse hole.
7 October 2018 at 09:48 #374915
Reg Wortley
Participant
@regwortley
Posted by SillyOldDuffer on 07/10/2018 09:23:30:

Forgive me if this is hijacking the thread, but does Reg mean a Boring Head mounted in the tailstock like this?

If so, is a boring head in the tail-stock advantageous? When I bore in the lathe, I clamp the boring bar directly to the tool-post and move the tool with the saddle. The boring-head is only used on my milling machine. Entirely possible I'm missing a trick due to inexperience. Comments welcome!

Dave

Hi Dave, I had envisioned the head in the 2mt in the headstock, I don’t have a milling machine so have to use the lathe for all things.
7 October 2018 at 10:05 #374916
Brian Wood
Participant
@brianwood45127
Hello Reg,

As Dave [ S.O.D] says, a boring bar in the saddle mounted tool holder has a much better capacity for boring any diameter hole within the capacity of the headstock mounting the job is fitted to. The boring head really comes into it's own on a milling machine where the job is bolted down to the table, but even then there is quite a lot of freedom in the size you can mill since you can put the cutting tool into a radial position in the head to sweep larger diameter holes.

The limitation in our machinery size then depends on the spindle torque that can be brought to bear at the necessarily slower spindle speed to suit the opening diameter. This is really the same as on the lathe, slower spindle speed for machining larger diameters in an effort to keep the surface speed at the tool tip within reasonable bounds.

Best wishes

Brian
7 October 2018 at 10:06 #374917
SillyOldDuffer
Moderator
@sillyoldduffer
Posted by NZreg on 07/10/2018 09:48:40:

Posted by SillyOldDuffer on 07/10/2018 09:23:30:

…

Hi Dave, I had envisioned the head in the 2mt in the headstock,

Ah with you now! Never thought of doing that, probably because I do have a milling machine. Good idea on a lathe. In that case, the maximum would be as John suggests – the point at which the boring bar starts misbehaving because the head can't hold it rigid at the tool point, even with light cuts.

Dave
7 October 2018 at 10:13 #374919
Journeyman
Participant
@journeyman
If you use a boring head in the 2MT headstock spindle taper it will need a draw-bar otherwise you may find it coming loose.

John
7 October 2018 at 10:31 #374921
JasonB
Moderator
@jasonb
Posted by John Haine on 07/10/2018 09:43:02:

Lathe or mill, surely irrelevant. Max diameter determined by max safe offset of the moving part in its dovetails. Personally I would not feel comfortable with it further than half the head diameter. Then you can add on the offset of the tool hole, or if you want a really big hole stick the tool out sideways in the transverse hole.

That does not make sense, first you say Max dia is determinded by the dovetails and then you say put the tool in the side to get a bigger dia which mean max dia is being determined by the tool.

Even if using the end holes the type of tooling can be used to gain more diameter where length is needed, look at these two same offset of the head but 1+" increase in diameter

A boring head in the lathe is handy when you have a part that is too tall to stand vertically in the mill or simply don't have a mill when the part is again too big to swing plus you get to use the lathes power feed for a nice smooth bore as not many small mills have power to Z.

Edited By JasonB on 07/10/2018 10:35:34
7 October 2018 at 10:47 #374925
David T
Participant
@davidt96864
Posted by JasonB on 07/10/2018 10:31:22:

A boring head in the lathe is handy when you have a part that is too tall to stand vertically in the mill or simply don't have a mill when the part is again too big to swing plus you get to use the lathes power feed for a nice smooth bore as not many small mills have power to Z.

+1. I recently used a boring head on the lathe to bore out this banjo, despite having a milling machine (jig borer, in fact!). The lathe's auto-feed made this job far easier than doing it on the mill.
7 October 2018 at 11:01 #374926
John Haine
Participant
@johnhaine32865
Posted by JasonB on 07/10/2018 10:31:22:

Posted by John Haine on 07/10/2018 09:43:02:

Lathe or mill, surely irrelevant. Max diameter determined by max safe offset of the moving part in its dovetails. Personally I would not feel comfortable with it further than half the head diameter. Then you can add on the offset of the tool hole, or if you want a really big hole stick the tool out sideways in the tr

That does not make sense, first you say Max dia is determinded by the dovetails and then you say put the tool in the side to get a bigger dia which mean max dia is being determined by the tool.

Even if using the end holes the type of tooling can be used to gain more diameter where length is needed, look at these two same offset of the head but 1+" increase in diameter

Edited By JasonB on 07/10/2018 10:35:34

Obviously the tool and its position affects the maximum diameter and with a long transverse tool it can be as big as you like in principle and given enough room on the lathe. But the limiting factor once you have decided where to place which tool, and given the size of your lathe, is how far out the movable part of the head can go without losing rigidity. For me that's about half the length of the dovetail, unless taking very light cuts..
8 October 2018 at 20:51 #375118
Bazyle
Participant
@bazyle
Imagine the set up in Jason's second picture say cutting 3 in dia. Now imagine that boring head set like that held in the tool holder on the topslide and cutting a 3 in round bar. See any problems with tool flex and chatter?
That is the equivalent geometry you are setting up. Just 'cos you can doesn't mean you should.
Author

Posts