HBM Facing chuck. How does it work?

A

andypugh

Plastic

Joined

Mar 29, 2011

Location

Essex, UK

• Jan 9, 2020

• #1

My dad has had a little Kearns S-type Horizontal Boring Machine for pretty much as long as I can remember (so call it 50 years)

It is the facing-chuck model. You can twirl a handle at the back and the radial position of the tool slide changes. (And there is a power-feed for this axis too).

I have never quite worked out the mechanism that achieves this motion. Has anyone ever seen a picture or diagram?

It isn't the same as the stroke adjust on a shaper, as on a shaper the adjusting handle rotates when the machine is operating. On the Kearns the adjusting wheel is stationary except when the radius is being adjusted.

 

johnoder

Diamond

Joined

Jul 16, 2004

Location

Houston, TX USA

• Jan 9, 2020

• #2

Here is what it does

the facing

Click to expand...

Or in your neck of the woods, you might say surfacing

 

A

atex57

Stainless

Joined

Sep 6, 2006

Location

SW Wisconsin

• Jan 9, 2020

• #3

Hey Andy. Most facing head types have a finger that trips or turns the adjuster at each revolution of the head to get the radial feed.

Are you the same Andy from the Linuxcnc list?

Ed.

 

fciron

Stainless

Joined

Oct 14, 2009

Location

Louisville, KY, USA

• Jan 9, 2020

• #4

...and the same Andy from the Neracar group?

Small world. :-D

 

G

gregormarwick

Diamond

Joined

Feb 7, 2007

Location

Aberdeen, UK

• Jan 10, 2020

• #5

 

N

number 2

Hot Rolled

Joined

Aug 13, 2009

Location

Western Australia

• Jan 12, 2020

• #6

That is the second diagram of a facing head I have studied but both appear to operate the same. The important part as I see it is the differential. The drive comes off the spindle, to the differential, which drives the facing feed shaft on the spindle at the same rate, but as it rotating also it has no effect but to cancel it all out. However when you rotate the differential itself relative to it all, it has the effect of advancing or retracting the drive to the facing head at what ever rate is set by the feed gears. That facing slide is driven by a feed screw where as the ones I have used had a worm driving a rack on the slide.

 

G

Garwood

Diamond

Joined

Oct 10, 2009

Location

Oregon

• Jan 13, 2020

• #7

The facing head for my 4" Kuraki uses a special 50 taper holder installed in the quill. That holder has a rack on it that runs a gear inside the facing head. You can hand feed or power feed the slide using the quill feed. Just have to be careful not to push the quill through the front of the facing head (there's a sheetmetal cover there)

 

A

andypugh

Plastic

Joined

Mar 29, 2011

Location

Essex, UK

• Jan 15, 2020

• #8

Thanks for the picture.
(And sorry, all, for asking the same question again, but I am sure I could not find this thread when I looked a couple of days ago)
I think I might need to experiment with Meccano or something, I am not really seeing the details of what is keyed to what in the differential area.
But I suspect that the back bevel spins at twice the speed of the carrier, and the control shaft rotates the front bevel?

 

N

number 2

Hot Rolled

Joined

Aug 13, 2009

Location

Western Australia

• Jan 17, 2020

• #9

andypugh said:

Thanks for the picture.
(And sorry, all, for asking the same question again, but I am sure I could not find this thread when I looked a couple of days ago)
I think I might need to experiment with Meccano or something, I am not really seeing the details of what is keyed to what in the differential area.
But I suspect that the back bevel spins at twice the speed of the carrier, and the control shaft rotates the front bevel?

Click to expand...

The front or right hand bevel is keyed to the feed shaft, and in normal no feed conditions will be stationary, the left hand bevel drives all the time. When feeding the right hand bevel will turn advancing the the drives’ position so the feed shaft in the spindle advances also.

 

N

number 2

Hot Rolled

Joined

Aug 13, 2009

Location

Western Australia

• Jan 17, 2020

• #10

It’s an interesting spindle design and a little backwards to how you would expect. I recall Tyrone Shoelaces speaking of a Kearns borer which had unusual thermal growth of the spindle, which seeing how the left hand end is fixed by angular contact ball bearings and the right hand cylindrical bearings I can see why. Usually they would be the other way around, or both at the front and another set of cylindrical rollers at the back, in my limited experience with spindles.