Hard spots in 11L14?
Wes
I was boring a .475 deep .624 dia hole in some 11L14 on my lathe.
Work was held in a 4 jaw chuck, boring tool was a boring bar for my Bridgeport's offset
boring head, one of those brazed carbide bars.
I noticed I'd start taking a cut and after a certain distance in, I'd start hearing
chatter. I removed the tool, double checked it was set it on centerline, and even gave
the cutting edge a light honing to touch it up. Didn't help any. I also looked for tool
rub as in insufficent relief.
Anyway, as I worked away, it became apparent my finishing cuts where not tracking the
amount of infeed. I was using a telescoping gage and mic to measure.
Getting near where I thought I should be at the right diameter, I tried the hex bushing
that I planned to press into the hole and it went in about 1/8". Now that is weird. Why
only that far?
On each pass, I had stopped the lathe, and retracted the carriage w/o backing off the
cross feed. That little scratch that can result isn't an issue since I'm pressing
something in.
I decided to dismount the work and use the bushing to check the back side and that was at
least 0.006" oversize.
The ways do not have detectable wear. This isn't a whooped lathe.
So what the heck happened? 11L14 generally cuts like butter and I've used a lot of the
stuff.
I've turned a shorter piece from the same round w/o issues using the same setup and I made
the same piece I was making tonight earlier.
For those that remember my recent post about screwing up a barrel plate by tapping the
wrong sized holes, this was the replacement.
Wes
Joseph Gwinn
Wes <ClutchAtL...@Gmail.com> wrote:
Was the heel of the boring tool skating on the side of the hole? It doesn't
take much. This has snuck up on me.
Joe Gwinn
Ed Huntress
"Wes" <ClutchAtL...@Gmail.com> wrote in message
news:npLyn.220507$rq1.2...@en-nntp-02.dc1.easynews.com...
Very possibly a hard inclusion, like a piece of HSS or carbide that got into
the melt.
I've related here before our experiences hitting a HSS tap, intact, in the
middle of a piece of steel bar. Unless the steel is arc-remelted, it can
happen.
--
Ed Huntress
Buerste
"Wes" <ClutchAtL...@Gmail.com> wrote in message
news:npLyn.220507$rq1.2...@en-nntp-02.dc1.easynews.com...
>
> I was boring a .475 deep .624 dia hole in some 11L14 on my lathe.
>
> Work was held in a 4 jaw chuck, boring tool was a boring bar for my
> Bridgeport's offset
> boring head, one of those brazed carbide bars.
>
> I noticed I'd start taking a cut and after a certain distance in, I'd
> start hearing
> chatter. I removed the tool, double checked it was set it on centerline,
> and even gave
> the cutting edge a light honing to touch it up. Didn't help any. I also
> looked for tool
> rub as in insufficent relief.
>
> Wes
I've run into more inclusions than I deserve, your turn!
spaco
relief) and see it anything is different.
I don't know what size insert you are using, but with a relief of
only 7° or so, the heel could easily be rubbing.
I have pretty much quit using carbides for boring for that reason.
Especially for small holes.
Pete Stanaitis
-----------------
Martin H. Eastburn
Or above - and not on the center line ?
Martin
Denis G.
> "Wes" <ClutchAtLycosDot...@Gmail.com> wrote in message
>
> - Show quoted text -
You can avoid them if you use Colgate and brush regularly.
Tim Wescott
No pictures?
My dad ruined a bandsaw blade on a ball bearing in the middle of some
angle iron, although I haven't personally run into such inclusions.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Ed Huntress
"Tim Wescott" <t...@seemywebsite.now> wrote in message
news:TuGdnewX_IwiaFbW...@web-ster.com...
There really was nothing much to see. We were milling a disk cut from the
bar, in a Bridgeport, and all hell broke loose when we hit it. If you looked
closely you could see the threads of the tap. Cutting across it with an
abrasive blade in a power hacksaw, we could see it in cross-section. But you
would have needed to etch it to get a good photo.
>
> My dad ruined a bandsaw blade on a ball bearing in the middle of some
> angle iron, although I haven't personally run into such inclusions.
I think they used to be more common than they are today. This all
happened...hmmm. 39 years ago, I think. Maybe they have better means of
sorting scrap?
--
Ed Huntress
Mark Rand
>I just had something weird happen.
Another (unlikely) possibility is, are you getting swarf/chips building up
beside the boring bar? I once had a problem caused by this. It sprung the
boring bar enough to reduce the depth of cut near the bottom of the hole.
Mark Rand
RTFM
Wes
>Was the heel of the boring tool skating on the side of the hole? It doesn't
>take much. This has snuck up on me.
It looks like at some point, likely before I started, since I did a touch up, I gave the
leading edge some negative rake by accident. In my mind, it all works out to fit the
condition. I *really* need to invest in some Circle Trigon small diameter boring bars
that use inserts.
Today at work was strange. One of the engineers bought a new 1 ton Dake arbor press. I
think it was made in USA but it might not be. He wanted a .501D by 1.00 dp hole in the
center of the ram.
First time I used the 4 jaw for the LeBlond at work, usually there I use a Buck 3 jaw true
set or collets.
After cutting 4 strips of bar stock to protect the ram from the curved jaws, I got my
first crack at centering square stock in a 4 jaw independent. It went okay, you rock the
indicator near where you think center is and remember the low reading. This was made a
bit more difficult since the only indicator I have at work is a 0.0001" .016" travel test
indicator. If I knew I was doing this today, I'd have bought one of my long travel
plunger indicators in with me from my home shop.
Anyway, got it all nice and squared up, center drilled it, drilled it, run a reamer into
it. All went fine and dandy using HSS tooling. I was a bit worried it might be fairly
hard but it sure seemed in HSS territory.
So next I take it over to the bridgeport. Use my center finder to find the edges of the
Kurt vise. I *wish* people would just leave the dro on. There is a button on the Sony
DRO to mute the display.
Now to drill a 1/4" hole so I can tap a 5/16 NC hole. The speed I use for the edgefinder
should be fine for a 1/4" drill. I am working my way down to center making nice looking
chips and all is well. Suddenly, I hear screeching and all progress stops. Pull the
drill and it is cooked. Okay, try another new one. DOA.
Try one more from my drilldex in case I have some crappy stuff. DOA.
I'm about .050" from breaking through into the .501" hole. This is p*ss*ng me off at this
point.
Head over to my tool box and find a 7/32 carbide drill I use to modify normal sockets to
accept 1/2" pin lock square drives. That punches right through. I also found a 1/4"
endmill that I am guilty of using in a drill chuck today since I just wanted to get this
ordeal over. No harm came to either.
So now I'm tapping this thing. Visions of a broken tap dance in my head and I really
don't want to break one. I go a bit and really don't like the forces I'm putting into it
and get another one from supply. That one cuts a bit easier but I can tell it doesn't
like what I'm asking it to do. Finally, I break through.
Now at this point I try to screw a 5/16-18 screw I pulled out of another arbor press when
I grabbed the tooling to use it to check fit. It will not screw in. It is the right
pitch. The tap I used was H3 or .0015" on the loose side. I head over to the bolt bin
and get another bolt, it fits fine, I champher the original fastener and it still doesn't
want to go on.
I compare it to my tap, perfect match. Go find a metric bolt near the size and it isn't
close so it isn't one of those deals.
Then there was the MCC I replaced in a CNC lathe, I didn't notice one contact was NC when
I expected NO, that took a while to figure out.
Some days you fight your way though.
Wes
Leon Fisk
Wes <ClutchAtL...@Gmail.com> wrote:
<snip>
> One of the engineers bought a new 1 ton Dake arbor press. I
>think it was made in USA but it might not be.
Should be be just a bit to your SW, Grand Haven, Michigan. See:
http://www.dakecorp.com/company.asp
The older presses were made there, take a look at the model
plate to see if that one was or not.
--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email