PDA

View Full Version : Apparently the tang does NOT drive the tool....



J Tiers
01-01-2010, 08:17 PM
I know, controversial subject.......

Views of the tang on an MT3 shank 1.187" reamer which apparently was at some point driven by the tang.....

http://img.photobucket.com/albums/0803/jstanley/tang1.jpg

http://img.photobucket.com/albums/0803/jstanley/tang2.jpg

Carld
01-01-2010, 08:24 PM
Yep, that's right, it will shear off many times if the taper slips. It don't look like the tapers were matching up well on your tool.

Stuff happens.

boslab
01-01-2010, 08:30 PM
Yep, that's right, it will shear off many times if the taper slips. It don't look like the tapers were matching up well on your tool.

Stuff happens.
Looking at the state of the taper on that it wasent too much of a suprise really? could do you some damage, and definatley chew your socket, soon it becomes everyday
get a better tool i think?
regards
mark

Machinist-Guide
01-01-2010, 08:46 PM
The tang doesn't drive the tool. From the looks of the first photo the taper is in pretty bad shape. The ruff finish on the tool prevented it from locking. The tool tried to spin and sheared off the tang.

Carld
01-01-2010, 08:56 PM
I think J Tiers knew what happened and why and was just having fun with us ;) .

J Tiers
01-01-2010, 09:56 PM
Well, I did clean up the dings on the taper with a burr file, but there were dings that were newer than the rusty old broken surface of the residual tang...... I don't know any more about the history or the order of events.... The taper might have got loose retracting the tool.

Someone seems to have thought it was a good idea to drive nails or wedge up a machine with the taper. The odd thing is the reamer is still sharp.

For sure if the taper is burred-up it is going to try to drive via the tang.

darryl
01-01-2010, 10:14 PM
Looks like it had a former alliance with a crescent wrench-

Mcgyver
01-01-2010, 10:18 PM
cripes, on a reamer? what, the hole it was being feed into was only .500"?

rockrat
01-01-2010, 10:20 PM
cripes, on a reamer? what, the hole it was being feed into was only .500"?

Yea, but the reamer was 1.000" :D


rock~

Jim Shaper
01-01-2010, 10:35 PM
The tang is only there to give you something to drift it out with that won't ding the taper.

Carld
01-01-2010, 10:46 PM
:eek: rockrat, you tryin' to start trouble :D ;)

Mcgyver
01-01-2010, 10:54 PM
Yea, but the reamer was 1.000" :D


rock~

reamer was bigger than 1", 1.1875 irrc

Paul Alciatore
01-01-2010, 11:59 PM
OK, I know I am going to get jumped on, but consider. The taper was driving it. The taper was in bad condition. The reamer jammed. The taper slipped and.....

the tang slammed into the socket with considerable force after the spindle continued to rotate a bit more. And the tang twisted and sheared off.

Now, would it have broke if the tang had been against the socket when the tool was first seated? Perhaps that would have provided enough extra drive to prevent the reamer from jamming.

All I am saying here is if we drive milling cutters with a single set screw against a flat on the shank (as in a mill holder), why is it so horrible to drive a tool with two flats on a tang?

And if the tang is not intended to drive the tool, why does the taper socket have a matching area that will attempt to drive it. This area is NOT necessary to allow tool extraction, nor is the more complicated geometry of a tang. A simple round (as in easily formed on a lathe) projection would allow tool extraction. I have added such features to Morse tapers that were tang-less and they work just fine.

I suggest that the shape of the tang strongly suggests that it was indeed intended to drive the tool. The fact that some break is of no more consequence than the fact that some drills and other cutters with straight shanks break when they jam. Tools just break if they are overstressed.

OK, I said it, now let the abuse begin.

Jim Shaper
01-02-2010, 12:27 AM
The driving of a weldon flat produces far more torque through a much thicker cross section than the tang on a morse taper.


The tang is also there to protect the bore from galling and scoring in the event the taper isn't seated tight enough. You need to be smart enough to realize that your taper has let go, and not continue to drive the tool without proper retention, and then you won't break tangs.

winchman
01-02-2010, 02:37 AM
It's REALLY hard to stop the machine in the 5 degrees of rotation between a slipping taper and a broken tang.

Jim Shaper
01-02-2010, 03:14 AM
Yeah, but it's really easy to let off on the feed or seat the taper properly from the get go.

Mark McGrath
01-02-2010, 05:21 AM
I think J Tiers knew what happened and why and was just having fun with us ;) .

Surely you don`t really think Jerry`s after a "discussion" do you Carl? :-)
Does he do that kind of thing? :-)

Mark.

Your Old Dog
01-02-2010, 06:54 AM
I have nothing in my shop that a tang has to fit in. No matter how I slip in a taper it never needs to be rotated to fit. The tang is used on my DP (for the un-initiated thats Drill Press but it's shorter to type DP :D ) to drive out the taper using the key.

Carld
01-02-2010, 08:34 AM
:rolleyes: ahh, wellll :D maybe ;)

None of my machines that take a MT have the slot for the tang. If they spin they spin.

I have twisted a tang in a radial drill press a time or two but never have twisted one off.

Mcgyver
01-02-2010, 09:27 AM
my monarchs tailstock barrel has two set screws that can be tightened against the tang....art they not to add to the torque resiting holding force?

Greg Menke
01-02-2010, 09:53 AM
I have a 1919 book on drilling, mostly from a production perspective. They mention twisted off tangs as a symptom of poor fit of the tapers; the worse the fit, the more of the cutting force goes into the tang until it breaks and the tool spins.

Greg

huntinguy
01-02-2010, 10:27 AM
:rolleyes: ahh, wellll :D maybe ;)

None of my machines that take a MT have the slot for the tang. If they spin they spin.

I have twisted a tang in a radial drill press a time or two but never have twisted one off.

Years ago an old guy showed me how to keep them from spinning. It was so simple.... Just apply a little 6011 to where the spindle and the drill taper meet. Must have run 100 holes with that core drill and not a slippage in the bunch.
:D

Carld
01-02-2010, 10:46 AM
What's 6011 :confused:

Peter N
01-02-2010, 11:00 AM
What's 6011 :confused:

http://www.sjdiscounttools.com/lewed031152.html

.

J Tiers
01-02-2010, 11:20 AM
Surely you don`t really think Jerry`s after a "discussion" do you Carl? :-)
Does he do that kind of thing? :-)

Mark.

Good start to the new year, mark......

I just thought it was interesting... got this reamer in a bunch of other MT3 stuff, and there it was....A a jen-you-wine twisted-off taper, exactly like Forrest has described.

Carld
01-02-2010, 01:01 PM
:eek: Oh, that 6011. Well I have been tempted to do that but I haven't done it yet. I did locktite a few in though and it worked for a while. I guess that was just as messy as welding them in.

Jim Shaper
01-02-2010, 03:03 PM
my monarchs tailstock barrel has two set screws that can be tightened against the tang....art they not to add to the torque resiting holding force?


Is that stock, or did someone add them?

My Voest has no tang in the 4MT tailstock, because if you retract the quill all the way the screw will bump the tool out for you.

Don Young
01-02-2010, 10:12 PM
I know, controversial subject.......

Views of the tang on an MT3 shank 1.187" reamer which apparently was at some point driven by the tang.....

http://img.photobucket.com/albums/0803/jstanley/tang1.jpg

http://img.photobucket.com/albums/0803/jstanley/tang2.jpg

I don't know if the tang drove the tool or not but it sure looks like it made a valiant effort to do so.

speedy
01-03-2010, 01:48 AM
I drunk too much

Mark McGrath
01-03-2010, 05:05 AM
Good start to the new year, mark.......

No worries,Jerry.:-)