Tool Info Needed

[Model A Bill]

What is the tool called that you use to drill a hole in metal to do a but weld onto a backing strip that doesn't require you to file off the back side like a drill bit would ?? Or is there such a tool or am I dreaming again ? Where could I buy them ? Again thanks in advance.

[James(Western Canada)]

Bill: Are you referring to a spot weld cutter??

http://www.blairequipment.com/Spotwe...d_Cutters.html





.....or a whitney (type punch)??

http://roperwhitney.com/punching/2-45.cfm

[Roger J.]

I've used the ones below quite a bit. Only leaves a small hole in the panel beneath.
http://www.wivco.com/spot_eze.htm

[Model A Bill]

It is not used for a spot weld. I want to make a hole in the top panel to attach a butt plate under it. If I use a regular drill bit isn't the under side of the top metal have to be filed smooth to make a tight fit to the second panel ??

[steve.murphy]

What if you put a scrap piece of metal underneath temporarily so it fits tight with clamps or whatever and drill through both, so the burr is in the disposable piece.

[larry mullen]

Bill
Would a tapered step drill work for you ?
larry Mullen

[RedBeard66]

they make a reverse counter boring bit that attaches to a shaft that you stick through a hole and can de bur but I'm guessing you don't have back side access to attache the counter bore to the shaft

http://www.browntool.com/Default.asp...ProductID=2133

[dmc1]

There is a twist drill with a small centre point, the cutting edges curve upward and down again to cut at the periphery. Something like the brad-point twist drill used to cut a clean -walled hole in wood. I've only heard it called a sheetmetal drill. Cuts a thin disc as it finishes the hole, which usually has to be removed from the drill point.

I don't know if you can buy these or have to regrind a twist drill. You would probably get good information on the Homeshopmachinist group.