• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)

What size of spot weld drill bit


Jedi Trainee
I am on to the body work of my frame off and need to pick up a spot weld drill bit. When I went to eastwood, it never occured to me that they came in different sizes. So what size is the best for the spot welds on a TR6? 8mm, 10mm, 3/8, 1/2, other?



Darth Vader
I am not a millimeter guy, but 3/8's bit works fine for me. Plenty wide enough to span dimpled welds. Get a couple, they are easily dulled.

Remember, you are only going through the top piece of sheet metal with the spot weld drill bit. Hopefully the piece you are replacing.

I found that when removing an old panel, a cutoff wheel and grinder took care of most of the welds, making the spot weld drill bit a little used, but when needed a handy tool.


Country flag
When I was removing welded panels on my TR3 resto, I found that just using a regular 3/16" drill bit in the middle of the spot weld worked better then any specialty spot welding drills. I played around with different style drills, and finally settled on 3/16" cobalts that have a 135 deg. split point. Try differnet sizes, to see what works best for you. Then get several of that size in cobalt. Cobalts always have the 135 deg. split point. The split point centers much better then the standard chisel point, and cobalts last much longer then high speed. Sometimes the 3/16" size (or whatever size you found to work) isn't quite large enough in diameter to free the weld, but once all of the welds in a section are drilled, the stubborn ones can usually be finished off with a thin chisel between the panels. If you're careful with the drilling, the grinding afterward is minimal.
Similar threads
Thread starter Title Forum Replies Date
J TR2/3/3A What size speedi-sleeve needed for pinion seal on a TR3? Triumph 6
B Exhaust Pipe Size Austin Healey 23
Geo Hahn TR6 TR6 Oil Line Thread Size Triumph 1
Healey Nut TR6 Headlight size Triumph 47
MadRiver TR6 Emissions Hose/Tubing Size? Triumph 2
JPSmit Not quite an LBC - but the size might be close :) Restoration & Tools 3
B TR4/4A Oil Drain plug size Triumph 14
P TR6 What make and size tire was on the TR6 when it left the factory? Triumph 7
69MGC MGC What size tires will fit nicely MG 2
M TR5/TR250 Compatible Modern Tire Size Triumph 5
J Nut size for BJ8 center console trim piece Austin Healey 8
PAUL161 T-Series MGT Exhaust Stud Thread Size MG 2
AngliaGT '74 Midget - Heater Box Bolt Size? Spridgets 8
T TR2/3/3A Can someone confirm size and thread count on fuel line tube nuts [brass fittings]? Triumph 15
D TR4/4A SU HS6 throttle spindle size Triumph 19
C Size or matching screw on cap for Trafalgar bottle? Austin Healey 0
Bayless What size fuel line for '67 Sprite? Spridgets 2
S Bugeye Radiator Tank Plug Size? Spridgets 24
Jim_Stevens TR2/3/3A Rear bumper bolts size/thread? Triumph 3
K Abington Allocation Plate size? Austin Healey 1
R TR4/4A Door mirror base size Triumph 2
D TR2/3/3A tr3 temp guage capillary tube thread size Triumph 3
S TR2/3/3A Pixel primmer size Triumph 18
F TR2/3/3A Spare Tire Size Triumph 11
C Size of axle bearing nut Austin Healey 11
GeorgeC Steering wheel nut size? Spridgets 3
ckeithjordan TR2/3/3A Trim Hole Size Triumph 3
M TR4/4A Triumph TR4/4A Steering Column spline size Triumph 1
KVH TR4/4A Belt Size for TR4A Triumph 4
P TR2/3/3A Recomended enclosed car hauler size? Triumph 8
vette Tire Size and Improving Rear Brake Drums Austin Healey 17
55modified Radiator sensor thread type size needed for bn1 Austin Healey 12
jfarris For Sale New TR3 Rod Bearings Big End Std Size Triumph Classifieds 0
George Zeck Wheel Stud Size? Spridgets 10
Jim_Gruber Size Matters Spridgets 3
2billydavies TR2/3/3A belt size for TR3a? Triumph 13
Rut TR4/4A steering shaft/nut thread size Triumph 5
S T-Series screw size MG 0
D Battery Tray Size Austin Healey 1
C Need to order correct size Austin Healey 4
M 948 Pulley Nut Size Spridgets 1
aero3113 Gauge size Austin Healey 7
tomshobby Spitfire head size of damper pulley bolt on 78 Spit? Triumph 2
wkilleffer MGB 1974 MGB convertible top anchor bar size MG 4
GeorgeC BN1 bolt size Austin Healey 0
D TR4/4A Trans replacement front oil seal not same size as original Triumph 2
HealeyPassion Tri-carb intake manifold balance tube size Austin Healey 10
D Series II E-Type tire size Jaguar 9
jfarris TR2/3/3A Vacuum Advance Thread Size Triumph 9
K TR2/3/3A Temperature sensor size where it fits in the housing? Triumph 4

Similar threads