Spot welding

All topics related to mig welding, tig welding, spot welders, flame cutting, etc.
Post Reply
gamble
4 Star Member
4 Star Member
Posts: 950
Joined: Thu Jan 02, 2014 6:33 pm

Spot welding

Post by gamble »

Anyone here spot weld a lot? I picked up an el cheapo HF spot welder for the purpose of putting brackets on most of my pieces to hang them.

The electrodes are flat at the end and tent to leave a little divot in the metal. I remember using spot welders at work with a rounded electrode (and a lot more expensive) and they didn't leave an indent in the material. You think this would help using a rounded electrode? Not that anyone makes them, so I'd have to make my own :(
Torchmate 2x2 - Flashcut
Powermax 45 - Machine torch
Taig CNC Mill - Flashcut
Razorweld Distributor
Mtw fdu
3 Star Elite Contributing Member
3 Star Elite Contributing Member
Posts: 283
Joined: Sat Dec 20, 2014 3:12 am
Location: Barossa Valley, South Australia

Re: Spot welding

Post by Mtw fdu »

I use a spot welder every so often and it is supposed to leave a small divot in the metal.

If you can also see on where cars are spot welded together...there is always a mark it leaves.

I have my tips small (about 3mm) round and with some primer it covers them up quite nicely. You have to look very closely to see the mark it leaves sometimes.

Is there a problem with them being seen???

Mtw fdu.
Camcutcnc 4 x 4 plasma cutter with UC 100 Motion Controller
Powermax 45 with Machine Torch
Bobcad V27 and Mach 3
Proma THC
Now with Rotary Axis
Laser cross hairs
User avatar
acourtjester
6 Star Elite Contributing Member
6 Star Elite Contributing Member
Posts: 8183
Joined: Sat Jun 02, 2012 6:04 pm
Location: Pensacola, Fla

Re: Spot welding

Post by acourtjester »

The process of spot welding is to super heat the 2 metal parts to fuse them together. The clamping action of the tips is what makes the marks in the softened metal surface. I have not tried this but may be if you had a larger diameter tip on the side you don’t want to mark it would have a larger contact area there. This may not cause that surface to squash in as much only the back side with the smaller tip. Simple test flatten a small piece of copper pipe and put under the tip on the side of the metal you don’t want marked and spot weld it to see. One time should tell you if it works.
DIY 4X4 Plasma/Router Table
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
gamble
4 Star Member
4 Star Member
Posts: 950
Joined: Thu Jan 02, 2014 6:33 pm

Re: Spot welding

Post by gamble »

Mtw fdu wrote:I use a spot welder every so often and it is supposed to leave a small divot in the metal.

If you can also see on where cars are spot welded together...there is always a mark it leaves.

I have my tips small (about 3mm) round and with some primer it covers them up quite nicely. You have to look very closely to see the mark it leaves sometimes.

Is there a problem with them being seen???

Mtw fdu.
It's a huge problem seeing them. They are such an eye sore. Even when I grind them flush and paint over it you can still see grind marks.
acourtjester wrote:The process of spot welding is to super heat the 2 metal parts to fuse them together. The clamping action of the tips is what makes the marks in the softened metal surface. I have not tried this but may be if you had a larger diameter tip on the side you don’t want to mark it would have a larger contact area there. This may not cause that surface to squash in as much only the back side with the smaller tip. Simple test flatten a small piece of copper pipe and put under the tip on the side of the metal you don’t want marked and spot weld it to see. One time should tell you if it works.
Not a bad idea. I'll have to see if i can find two rounded pieces of copper to play with
Torchmate 2x2 - Flashcut
Powermax 45 - Machine torch
Taig CNC Mill - Flashcut
Razorweld Distributor
User avatar
acourtjester
6 Star Elite Contributing Member
6 Star Elite Contributing Member
Posts: 8183
Joined: Sat Jun 02, 2012 6:04 pm
Location: Pensacola, Fla

Re: Spot welding

Post by acourtjester »

Gamble you don't want to go too big on the top contact as it will change the concentration of the heat effected area.
DIY 4X4 Plasma/Router Table
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
Mtw fdu
3 Star Elite Contributing Member
3 Star Elite Contributing Member
Posts: 283
Joined: Sat Dec 20, 2014 3:12 am
Location: Barossa Valley, South Australia

Re: Spot welding

Post by Mtw fdu »

Here is a quick pic I took of the spot welds I have doe on my table.

You can see them because there is dust collected in them. Hope it shows how small they are.

Mtw fdu.

You currently do not have access to download this file.
To gain download access for DXF, SVG & other files Click Here

Camcutcnc 4 x 4 plasma cutter with UC 100 Motion Controller
Powermax 45 with Machine Torch
Bobcad V27 and Mach 3
Proma THC
Now with Rotary Axis
Laser cross hairs
motoguy
4 Star Elite Contributing Member
4 Star Elite Contributing Member
Posts: 1184
Joined: Tue Aug 25, 2015 12:05 pm
Location: Central MO, USA

Re: Spot welding

Post by motoguy »

Did the copper spacer/flattened tube on the front of the weld help with the visible mark?
Bulltear 6x12 w/ Proton Z axis & watertable
CommandCNC/Linux w/ Ohmic & HyT options
Hypertherm Powermax 85 w/ machine torch
Solidworks, Coreldraw X7, Inkscape, Sheetcam
plasma_burn
1.5 Star Member
1.5 Star Member
Posts: 45
Joined: Thu Jan 07, 2010 9:23 am

Re: Spot welding

Post by plasma_burn »

I have a similar problem, from another forum
http://www.practicalmachinist.com/vb/fa ... on-131924/

references a Miller spot welder manual that has different tips including a flat tip
http://www.millerwelds.com/pdf/spec_sheets/SW1-0.pdf

the guy on the other forum said the flat tip worked.
User avatar
tinspark
3.5 Star Elite Contributing Member
3.5 Star Elite Contributing Member
Posts: 722
Joined: Wed May 30, 2018 4:28 pm

Re: Spot welding

Post by tinspark »

Use a piece of aluminum (.063)on the side that you want to finish. (old tinners trick)!!
Typically the lower spot welder tongs will contact the non- finished side. Lay a small piece of aluminum on the top (finished) side and then spot weld as you normally would. A little bit of the aluminum may remain on the spot welded material, but you will notice the spot weld is convexed instead of concaved. This will pull the divot up instead of leaving a crater. Use an angle grinder to sand to flush. all of the aluminum as s\well as the raised base metal should be flat. Works great on stainless too.

Regards,
Doug,
4x4 GoTorch- expanded
Height Control/Advanced DesignEdge
Hypertherm 45XP-
Logan Lathe + myriads of other shop toys
**CAUTION**- "Does Not Play Well With Others" :)
cuttinparts
3 Star Elite Contributing Member
3 Star Elite Contributing Member
Posts: 412
Joined: Tue Sep 30, 2008 3:40 pm

Re: Spot welding

Post by cuttinparts »

tinspark wrote: Tue Aug 20, 2019 3:50 am Use a piece of aluminum (.063)on the side that you want to finish. (old tinners trick)!!
Typically the lower spot welder tongs will contact the non- finished side. Lay a small piece of aluminum on the top (finished) side and then spot weld as you normally would. A little bit of the aluminum may remain on the spot welded material, but you will notice the spot weld is convexed instead of concaved. This will pull the divot up instead of leaving a crater. Use an angle grinder to sand to flush. all of the aluminum as s\well as the raised base metal should be flat. Works great on stainless too.

Regards,
Great tip, gotta try that! Thanks :Like
Post Reply

Return to “Mig Welders, Tig Welders, Spot Welders”