How to fill a hole in sheet metal | Austin-Healey Bugeye Sprite Project

Our Bugeye Sprite’s body was just full of holes. Holes drilled for a fire extinguisher and a Panhard bar, holes drilled for an MSD ignition and a tachometer.

We had lots of holes.

As we’re putting this one back on the street, we needed to fill those holes.

The smaller ones could just be fill welded. This technique involves picking up an edge of a hole and adding in some wire. From there, you carefully fill the entire hole.

[8 Tips for Welding Like a Pro]

You need to bump up your wire speed a bit to fill, but you don’t want to get your heat so high that you melt the metal. This task is easy for an experienced welder but takes time to learn.

The best way to learn it is to drill holes in a piece of scrap metal and keep working until you master the task. Vary the sizes of those holes, too.

You are looking for a smooth liquid fill that is easy to grind down afterward.

 

To fill the larger holes, we first cut metal plates out of sheet metal–same thickness, of course–and then butt welded into place.

[How to repair a hole left from a roll bar install | Austin-Healey Bugeye Sprite Project]

After a day or two of filling holes–yes, there were that many–we turned the car on its side to fill the ones hiding below.

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nocones
nocones PowerDork
10/3/22 1:17 p.m.

One great trick for making small patch panels like this is masking tape.

Here you can just see the outline of the rectangle I'm prepping to fill. 

Masking tape over the hole and then razor blade it out as accurately as possible.   Then since it's masking tape you can just stick it to scrap metal like a sticker.  If I want to leave a gap and the shape is complicated I give the masking taped part a light shot with spray paint, peel off the tape and then bandsaw cut INSIDE the lines.  The Paint won't lift like masking tape will as the metal heats.  For simpler shapes you can get away with just using the masking tape. 

 

The masking tape is also great if there is contour to the part.  If your dealing with rusty metal before you cut it out, cover it in masking tape.  Then scribe your cutlines through the tape.  The masking tape is your pattern and when you try to force it flat it will tell you if you have a compound curve your dealing with.  You can cut the maksing tape to flatten it and it shows you where to shrink, or anywhere the tape bunches you know you need to stretch.  If the masking tape lays flat nicely you just have a simple curve and you can use whatever means to bend it.   

David S. Wallens
David S. Wallens Editorial Director
10/12/22 12:50 p.m.

In reply to nocones :

Good tip. Thank you for sharing the details. 

Tim Suddard
Tim Suddard Publisher
10/13/22 1:14 p.m.

In reply to nocones :

Yes, great tip.Never thought of that one.

03Panther
03Panther PowerDork
10/13/22 10:08 p.m.

In reply to nocones :

That is great stuff!!! If I ever get to a few of my way back burner projects, that'll save me some money

wspohn
wspohn SuperDork
10/14/22 3:09 p.m.

When building a race car (or returning one to the street) one must deal with uneeded holes in the firewall one way or the other - either plug them by welding or installing rubber plugs or wedling them up (or in the case of my TVR, glassing them up).

I took another route on another race car of mine, a vintage MG.  I simply sheathed the firewall and heater shelf area with lightweight sheet alluminum.

Your way is better assuming that you have the ability to weld (or a weder that works for beer).

 

Kendall Frederick
Kendall Frederick New Reader
10/14/22 9:04 p.m.

In reply to nocones :

Wray Schelin has a good video on making flexible patterns like this with masking tape:

https://www.youtube.com/watch?v=y-JQgPm4_7s

 

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