Automatic center punch - for steel? or wood/alum only?

[Joel_BC]

This type of center punch sounds like it has advantages over the standard one-piece type. But I'm not sure if it's made to punch a dimple in steel (bar, for instance), or just softer materials like wood, bronze, aluminum.

http://www.bosstoolsupply.com/index....OD&ProdID=3880

Can you tell me? Thanks.

[agmantoo]

That punch should at least make a prick type dimple in anything you are capable of drilling. If the dimple is not as big or deep as you want you can always use a standard punch in the small indentation made by the spring load punch and hammer a larger dimple more accurately. I find that my accuracy is much improved using the spring punch.

[Joel_BC]

Thanks. I've only used the old-fashioned ones in the past.

I get the sense from the description that there is some kind of multiplier effect with this automatic type - that the punch force at the point is greater than what you get from an old-fashioned one-piece punch and an ordinary hammer blow. Is this correct?

(I'm not discounting that you could hit an ordinary punch hard with, say, a two-pound hammer and get a lot of force at the tip.)

[agmantoo]

You can increase the pressure but you will not get the penetration of a conventional punch. One the other hand you can control the location better with the automatic punch. If you are trying to get a free hand precise center punched you can first use the automatic punch then observe how accurate you were. Then if necessary you can manually use the conventional punch and drift the hammered blow in the direction needed to get more precise. If I need a high level of accuracy I use a magnetic holder with a cross hair for positioning then I insert the punch designed for the magnetic holder and make the center punch dimple.

[Joel_BC]

Thanks for the info.

[foxtrapper]

I've got that one. It does not work on steel because it does not have a sharp tip. It only dimples soft stuff. And at that, it barely dimples it.

It has a coil spring inside that you compress by pushing down until it pops, slamming against the tip. The force isn't great, so the dimpling isn't great. Real easy to skid on the surface while compressing the spring, placing the dimple where one doesn't want it.

I always find myself going back to a standard prick punch and hammer. In fact I don't know if I could even find that spring loaded punch.

[farminghandyman]

the one I have I can mark steel with it, but it is more of a lay out tool, it marks things it does not replace a standard punch in steel, but if one carefully places the tip where one wants it and presses it will mark steel, so one can use a standard punch to increase the dimple,

on wood or softer metals it may be supplicant by its self, there are areas where it is a blessing and there are places where a standard one is just as convent,

it is just that one does not have to change position or have a second tool to make the mark and may improve accuracy, the point on mine automatic is a 30 degree point not a 60 degree as on a standard punch, I do not think the automatic's dimple is enough dimple to normally accurately start a drill bit on steel unless it is a very small bit, with out increasing it some, one can click it a few times to help the impression as well,

I keep mine in the wood shop and I think there is one or was in my screw driver bit box, that some times comes in handy for helping starting screws in things,

Down in the metal shop I have standard center punches and hammers,