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thistle
05-13-2004, 10:52 AM
I was just using a Starret automatic center punch-

http://www.photobucket.com/albums/0903/mudskipper/broken/starret2.jpg

http://www.photobucket.com/albums/0903/mudskipper/broken/starret1.jpg
-and the tip broke off.

Cursing and jumping up and down has not fixed it yet.

Does anyone know if you can buy a replacement tip?

or am i going to have make a piece out of carbon steel and harden it.

[This message has been edited by thistle (edited 05-13-2004).]

krawdad13112
05-13-2004, 11:09 AM
Cursing and jumping up and down has always worked for me. Are you sure you are doing it right?

pgp001
05-13-2004, 11:40 AM
What size hammer did you hit it with ?

Paul Alciatore
05-13-2004, 11:50 AM
I have ordered direct from Starrett in the past and have found them very coperative and helpful. Except in the price category. You might be better off buying a new punch. I'd look for a General.

RE: Jumping up and down and cursing: You must properly synchronize the four letter words with the highest point of the jump. Works much better that way. Also helps if you are on the phone with the manufacturer at the time.

Paul A.

JCHannum
05-13-2004, 12:50 PM
Replacement tips are available. Part number PT02947, price $2.40 in my six year old price list.
That is for the 18A & 18AA punches, the 18B is P/N PT02948, price also $2.40.

omefford
05-13-2004, 01:42 PM
Hummm.. strange, mine broke in the same place last week. I was using it by hand with a light spring setting (no BFH involved). Upset didn't really describe my comments as it really gouged up work when it broke and went skating. I haven't started looking for a new tip yet, actually not sure if I will. I wonder if Starrett has a slight quality control issue.

rotate
05-13-2004, 02:06 PM
Call Starrett and e-mail the picture to them. I'm sure they'll send you a replacement part for free. The tip does wear with use, but it shouldn't break under normal use. This definitely falls under the "defective product" catagory.

Peter S
05-13-2004, 08:27 PM
Not the quite same problem, but I found that the Starret automatic punch tips are quite brittle - I tried using mine on some hot rolled mild steel - it didn't blunten, it chipped. I just resharpened it and won't try that again. (They sell new tips, I got a spare).

Actually, its years since I used my automatic punch, give me a hammer and a centre punch.

I reckon Starret makes their pin punches too hard also, the long series punches are extremely easy to break, whereas my old Millers Falls long punches seem to be much tougher.

[This message has been edited by Peter S (edited 05-13-2004).]

John Garner
05-13-2004, 09:12 PM
From what I've seen over the years, automatic center punch tips will often fracture if or when they are not fully threaded into the shank of the punch. The threaded TIP shanks don't hold up to impact loads very well, especially if there is even a hint of simultaneous side loading.

John

[This message has been edited by John Garner (edited 05-13-2004).]

AZSORT
05-13-2004, 09:16 PM
This reminds me. I've got apunch just like this one thst doesn't work unless I shake it first. I've taken it apart (any excuse to take something apart you know) and it looks OK to me. Anybody know the trick to this?

Sprocket
05-13-2004, 11:24 PM
After many years of use, I did the same thing. I think the replacement I got came from Enco, they were inexpensive as JCH says,so I got two and hid the spare around here somewhere....

just looked. Enco has them for $3.06

[This message has been edited by Sprocket (edited 05-13-2004).]

lunkenheimer
05-14-2004, 02:21 PM
Like John, the only times I have broken these is when the tip wasn't threaded in tight. Did it on a Starrett and also on a General....

jim davies
05-14-2004, 07:19 PM
Just recieved this part for an oooooold Starret automatic punch that the old man used in WW2 [the big one.] The part wasn't broken. Some little bugger [that would be me] lost it along with other desirable things playing dumb kid games.

thistle
10-01-2008, 03:31 AM
well this is an oldy, but anyway i had a stub of broken off tip i could not get out tried and tried, and chucked the punch in a drawer never too be seen again- i happened upon the punch today and picked it up and the broken tip fell out -
WTF-it unscrewed its self in the drawer after all this time .......maybe rolling back and forth all this time did it.

how weird , but hey tool saved !

oldtiffie
10-01-2008, 04:49 AM
I had one of those automatic punches - I gave up on it and put it in a drawer. I'd give it away but that would not endear me to the recipient. I guess I will just junk it.

I've always used a prick or centre punch and they have given me sterling service for years. I usually use round or square HSS stock. Sharpening takes just a minute. In the rare occasions that I "miss", it is really easy to "draw" the punch mark back to where I want it. I've always used a small ball-pein hammer that I've had for more years than I want to remember.

Unless there are compelling reasons to the contrary, I always mark out and centre-punch every hole I am going to drill. I can get mill accuracy on a pedestal drill that way - and a whole lot easier.

Centre-punching is an acquired skill - and a very valuable one.

Getting a 0.020" to 0.030" centre punch centred on a line or cross-lines within 0.002" is not only very visible but very easy - with patience and practice.

I also centre/prick punch any line that I have to file or grind (hand/pedestal grinder of surface grinder). "Getting (very) close" is easy to see.

Centre-punching is very handy with cutting on the band-saw, oxy/acet and plasma torches as well. I use it a lot in welding set-ups as those marks do not "disappear" under grinders or welding processes.

Some might find it hard to believe, but a spotting drill or a centre drill can or will move off-line on a mill.

Evan
10-01-2008, 10:36 AM
Automatic centre punches are the weapon of choice for car thieves. Nothing is quicker, easier and especially easily hidden for disintegrating a tempered glass side window.

interiorpainter
10-01-2008, 11:23 AM
Piece of plastic pipe, balloon, marble. 10cent slingshot!

J Tiers
10-01-2008, 08:52 PM
I have a "General" automatic punch. It was hardly hardened, and used to "get blunt" right away.*

So I hardened it, and did not draw the temper. It is just barely hard enough now....... I have not needed to grind it for a while......

Don't complain about the "too-hard" Starretts. At least you CAN draw the temper. The General one CAME with the temper permanently drawn...... Drawn in chalk apparently....

* Actually it might be good if it DID "get Blunt", I live in Missouri...........


BTW, the pictures of the punch are replaced with "your account is screwed up" messages........

alsinaj
10-01-2008, 10:26 PM
Can anyone explain to me what produces the "punch" in an automatic punch?
I have taken mine apart and pondered the parts, but I don't see how it works.

Paul Alciatore
10-02-2008, 12:42 AM
Can anyone explain to me what produces the "punch" in an automatic punch?
I have taken mine apart and pondered the parts, but I don't see how it works.

Quick answer, FM.

..............

As best as I can figure, there is enough friction between the spring loaded, moving "piston" and the outer barrel to hold it back until the spring pressure builds up. The piston sits off center for this to happen. When the spring pressure builds up, it releases.

As for General vs. Starrett, no contest. General does work, but you will have to resharpen it often. And the action is not as consistent. Starrett is very nice. I finally bought one and love it. I also have and use plain punches.

NickH
10-02-2008, 05:57 AM
Quick answer, FM.

..............

As best as I can figure, there is enough friction between the spring loaded, moving "piston" and the outer barrel to hold it back until the spring pressure builds up. The piston sits off center for this to happen. When the spring pressure builds up, it releases.

As for General vs. Starrett, no contest. General does work, but you will have to resharpen it often. And the action is not as consistent. Starrett is very nice. I finally bought one and love it. I also have and use plain punches.

It's the off-center bit that does it, part of the mechanism sit's on the edge of the off center hole until it's pulled on center at the end of travel, that releases the striker,
Nick

thistle
10-02-2008, 07:52 AM
sorry about the pictures , but its from 2004 , have to trawl through photobucket.
but its just a picture of a n automatic pucnh with a broken tip.
(which automatically fixed itself by unscrewing itself .
still have not figured that one out)

i use both types of punch , depends on the situation.

i like to scribe a box the size of the hole , if the drill wanders when starting , when it is still a v shaped depression , i can coach everyhting back on center , by hook an crook, or chisel and get everything straight again.

oldtiffie
10-02-2008, 08:45 AM
I start off with a prick punch - as by definition all my punches are.

Jim Hubbell
10-02-2008, 04:59 PM
I too have an auto-punch which requires " shakeing " in order to work. This came about after some inquisitive boys took it apart and lost a spring. I mentor at the local High School for the Nasa robotic competition and had a small kit of tools with me. They went on and did great last spring. Small price.


Jim