How to drill "clean" holes in a '50s chain guard

[spinman]

Ratsters,

I'd like to drill 1/2" or larger holes along the straight surface of my '50s Higgins chain guard. Kind of like the holes around the shroud of a .50 cal machine gun.

I plan on putting a piece of wood underneath the guard so it's nice an firm when I go in with the drill press.

I'm just worried that the drill bit will deform the sheet metal either on the way in or out.

Is there any special drill bit or trick of the trade that'll make this go easier?

I know that with wood, the Forstner bit does a real clean job of making holes, but i don't know if there's anything like that for steel.

Thx

Spin

 

[Rodland]

Place a piece of wood on top and bottom, then clamp it together. Drill through. Should give a clean hole.

 

[socal_jack]

I usually use a metal hole punch like at the following link, good for soft sheet steel like on chainguards, just need to drill a smaller pilot hole.

http://www.eastwoodco.com/jump.jsp?itemID=1454&itemType=PRODUCT

 

[MikeS]

Another clean way to cut holes in thin sheet metal is to use the Jancy Slugger sheetmetal cutters. They work great and can be finished off using a flaring die for strength if you have access to a press..
http://www.vansantent.com/sheet_metal_cutters.htm
http://www.vansantent.com/sheet_metal_machines/flare_tools.htm

 

[sensor]

these work great......(there are cheaper ones just dont know the links)
http://www.autobodytoolmart.com/pm-1173 ... 11090.aspx
or you could always use these....(they work good but youll have burrs on the backside.......)
https://www.autobodytoolmart.com/p-10254-12687.aspx

 

[spinman]

Fantastic!

Thanks for all the great advice.

Spin

 

[lofrontier]

step drills make nice clean holes in sheet metal
http://www.harborfreight.com/cpi/ctaf/d ... mber=44460

I like those dimple dies though.

 

[spinman]

I'm a puncin' fool now!

Thanks to "socal jack" I bought one of thoose little british punches. So far, it's working great.

Did about 15 holes and got 25 to go! Will post pics when done.

Spin

 

[spinman]

Here's the finished product.

 

[tomb]

looks GREAT!!!

 

[Rodland]

You don good. 8)

 

[sensor]

cool....now just need a shot of it on a bike! :wink:

 

[spinman]

I've got the frame, rims, tires, and guard. The seat is enroute from England. The fork is on back order.

I'll shoot some pics when the seat arrives.

Spin