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Spot Weld Cutters Preference #1310402
Sat May 11 2019 07:17 PM
Sat May 11 2019 07:17 PM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
OK so you have your specially ground drill bit or a spot weld cutter. I've only used the first one with fairly good success. Certainly the objective is to not intentionally drill past the top panel and try not to disturb the bottom in order to separate the panel in question. So...is one better than the other or should I say its only as good as the individual operating the drill.
Seriously, is one better than the other or is there an occasion where both should be at ones disposal?

Last edited by Apache1; Sat May 11 2019 07:18 PM.

1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1310404
Sat May 11 2019 07:34 PM
Sat May 11 2019 07:34 PM
MNSmith  Offline
"Hey! I sound like Darth Vader!!
Joined: Oct 2005
Posts: 2,597
So Cal
I've used different methods as of late. My cowl panel was done with an old Snap-On center pilot drill bit spot weld cutter. Didn't bother me to weld up the center 1/8" hole on the panel that was staying. Comes in different diameters. As far as I'm concerned, easier to use than the center spring loaded awl type that Mac is selling these days.

When I did the wheel wells on the Suburban, so much metal was going to be fabbed and replaced by me, that I took a disc sander, sanded the spot welds until thin, then used a spot weld splitter ( a hard steel bar with a knife edge) and sheared off the rusty pieces.

I haven't used a drill bit to separate spot welds for a long time!

Re: Spot Weld Cutters Preference [Re: Apache1] #1310407
Sat May 11 2019 07:48 PM
Sat May 11 2019 07:48 PM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
A spot weld splitter...I need check them out for sure. I have used a pneumatic chisel on occasions for stubborn stuff. Although it will do some damage real quick! All of my bits have been used up and trying to decide if I should buy more or opt for cutter style.


1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1310419
Sat May 11 2019 10:52 PM
Sat May 11 2019 10:52 PM
5
52Carl  Offline
Master Gabster
Joined: Mar 2010
Posts: 7,966
Virginia
I have used a spotweld cutter before, but it dulled before I was half way done with a couple hundred spotwelds. I had an issue with getting the center to stay in the middle of the spotweld also.
I have been using a 3/16" drill bit since giving up on the spotweld cutter. The drill bit seemed to find the center of the spotwelds by itself. The 3/16" bit is plenty big to get all of the spotweld, and was just the right size to be able to get the bottom metal red hot for TIG welding the spotwelds back in. My old spotweld cutter made a huge hole, requiring too much welding, threatening warping of the panels.

Re: Spot Weld Cutters Preference [Re: Apache1] #1310427
Sat May 11 2019 11:45 PM
Sat May 11 2019 11:45 PM
B
Bill Trotter  Offline
Shop Shark
Joined: Jan 2018
Posts: 229
Iron River Mi.
I purchased a set of Blair spot weld cutters and had great results. They are a little pricey but the do work great. Bill

Re: Spot Weld Cutters Preference [Re: Apache1] #1310434
Sun May 12 2019 12:21 AM
Sun May 12 2019 12:21 AM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
Where did you find Blair cutters. Maybe one can ignore the investment if the results are favorable.:>)


1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1310443
Sun May 12 2019 01:42 AM
Sun May 12 2019 01:42 AM
B
Bill Trotter  Offline
Shop Shark
Joined: Jan 2018
Posts: 229
Iron River Mi.
Internet..type in Blair spot weld cutter. Also called rotabroach.

Last edited by Bill Trotter; Sun May 12 2019 01:48 AM.
Re: Spot Weld Cutters Preference [Re: Apache1] #1310450
Sun May 12 2019 02:14 AM
Sun May 12 2019 02:14 AM
L
LONGBOX55  Offline
Master Gabster
Joined: May 2006
Posts: 8,490
DANVILLE IL
I like the Rotabroach as well. I have a couple os set of them in assorted sizes, including an older set that was made by Hougen, which was the original manufacturer before Blair bought them out. Any welding supply store should carry them, too, plus I know that Snap-On sells them under their Blue Point name. Classic Industries also sells them.


Bill Burmeister
Re: Spot Weld Cutters Preference [Re: Apache1] #1310475
Sun May 12 2019 11:57 AM
Sun May 12 2019 11:57 AM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
Thanks fellows.


1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1310498
Sun May 12 2019 04:48 PM
Sun May 12 2019 04:48 PM
MNSmith  Offline
"Hey! I sound like Darth Vader!!
Joined: Oct 2005
Posts: 2,597
So Cal
Snap On has gotten cheap with their stuff. The older cutters are the Blair/Rotabroach style with a centering drill bit.

Here is the older Snap On cutters and the splitters.

Attached Files
spotweldcutter.jpg (74 downloads)
spotweldsplitter.jpg (73 downloads)
Re: Spot Weld Cutters Preference [Re: Apache1] #1310513
Sun May 12 2019 07:33 PM
Sun May 12 2019 07:33 PM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
I checked out Blairs website. More than likely will purchase a Spotweld cutter kit 49.05...reasonable. Splitters as well...maybe Harbor Freight?


1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1310541
Mon May 13 2019 12:56 AM
Mon May 13 2019 12:56 AM
F
Fox  Offline
Shop Shark
Joined: Apr 2002
Posts: 1,408
Breton, Alberta
I use a Blair as well and it performs very well. One thing I’ve learned is that the awl type end isn’t good enough to keep things in place on any spot weld cutter I’ve used. I now use a regular drill bit, just kiss the spot weld so it creates a crater for your awl to ride in and then spot weld cut away. It works so much better this way for me.



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Re: Spot Weld Cutters Preference [Re: Apache1] #1310558
Mon May 13 2019 02:15 AM
Mon May 13 2019 02:15 AM
5
52Carl  Offline
Master Gabster
Joined: Mar 2010
Posts: 7,966
Virginia
Great advice given of the better type of spotweld cutters.
I just hope that I stick to my guns about never buying another truck which requires the use of one. smile
We'll see.

Re: Spot Weld Cutters Preference [Re: Apache1] #1310564
Mon May 13 2019 03:15 AM
Mon May 13 2019 03:15 AM
MNSmith  Offline
"Hey! I sound like Darth Vader!!
Joined: Oct 2005
Posts: 2,597
So Cal
I saw somewhere that Eastwood also has the splitters.

https://www.google.com/search?q=spo...V3pBs4Q_AUIDygC&biw=1600&bih=757

Re: Spot Weld Cutters Preference [Re: Apache1] #1310595
Mon May 13 2019 01:43 PM
Mon May 13 2019 01:43 PM
M
MPandC  Offline
Shop Shark
Joined: Jul 2011
Posts: 610
Leonardtown, MD
In my experience the tool you use will largely be determined by which panel you are saving, what access you have to either side, and how well you and the tool work in harmony.

If you are facing the piece you wish to save, and the lower panel is essentially a throwaway, then simply use a drill bit the same size you would select for plug welds, and drill out the spot weld. When you place the new panel beneath and clamp it up, the hole you drilled in the top panel now serves as your plug weld hole.

If you are saving the lower panel, and throwing away the top, you can use whatever works best for you. There are many ways to accomplish the same thing, but if you are not proficient in using one method, try another. I think each method has it's faults, so pick the one that best suits the area you are working.

The holesaw type cutter typically cuts like any other holesaw does, and once the teeth start to cut a "channel", it is difficult to see how far along you are progressing. At the point the cutter reaches the second layer, which is where you would want to stop, if there were a bit of rust between the two panels and your cutter had enough speed, you would have a visual indicator in a wisp of "rust smoke" that is seen coming around the cutter. It is here that, even though some moderate speed is needed to produce this indicator, light pressure is also needed (better classified as "restraint") so that you don't go through too far and damage the second panel. In my case, I found myself going through too far, and would either need to repair the deep channel I just cut in the second layer, or would have to weld in a circle to repair the gaping hole I just left. Needless to say, I no longer use this method, and gave the cutters I did have to someone else that hopefully is having better luck with it than I did.

Some of the cutters have a spring loaded center punch, much like a machinists roto-bore. Even with an initial center punch used in the middle of the spot weld, These cutters have the misfortune of slipping off center, and many people will simply drill a 1/8" diameter hole, either partially or all the way thru, to prevent the cutter from walking about. I'll stop here and offer a generalized thought. If you have difficulty filling an 1/8" hole in a piece of sheet metal with your welder, you will likely have problems with the pilot drill method, and perhaps should try one of the other methods.

I think the Wivco cutters will work better than the hole saw type, in that they mimic an end mill, so the cutter is relatively flat on the bottom. This should give a less aggressive cut, a plus for people like me who may have a problem of leaning too hard on the cutter. The open flute design will also allow you to better see what is going on than the holesaw type, which obscures everything. It does use the pilot bit, so if that is not an issue (see above paragraph), then this is a good choice.


[img]http://www.tonsoftools.com/images/Wvth25000.jpg[/img]


The blair cutter is available in either the spring loaded version or the pilot bit version, I think these are a more aggressive cut than the wivco, especially since the cutting surface is extremely narrow, so it may be more likely to pose the cut through problems I described initially.



[IMG]http://cdn3.volusion.com/uo9gz.acro2/v/vspfiles/photos/13224-2.jpg?1470814969[/IMG]



A rounded burr grinder is also a good method which should somewhat limit the damage to the (throwaway) panel to just slightly larger than that of a spot weld cutter. The downside is that these also come with little tiny slivers of metal that are a pain when you get them in your skin, so it would be advantageous to address these with a vacuum cleaner/foxtail and dust pan on occasion to keep the issue at bay. A pair of work gloves come in handy as well. Keep some duct tape handy to pull out the slivers that sneak by.


[img]http://static.wixstatic.com/media/7...jpg_srz_500_500_75_22_0.5_1.2_75_png_srz[/img]



The last method I'll discuss is the one that I use because I don't play nice with the holesaw type. I tend to inflict enough damage that I'll need to fix hole saw size holes through the save panel, or at least deep grooves. I use a 3" cutoff wheel with a 1/16" thick cutoff disc and use the tool to grind away the spot weld. I find for myself, it offers a less obstructed view of any of the methods listed, and with the proper speed (fast), will give you an indicator in the discoloration of the top layer (blue or darkened) usually before you have even broken into the second layer. Basically the metal is heating up and as it starts to get thin, it heats up more quickly and shows this via a color change to blue. The color change back to bright silver will indicate you have reached the second layer, and act as a guide where to not grind anymore (the bright area) and where to grind, the blue/dark circle surround it. The disadvantages with this method, are the top panel is basically useless now, you will need good eye protection (more so than the holesaw type cutters), and due to the grinding particulate, will need to use a respirator/mask to prevent you from hocking up black globs shortly afterward. I usually get a 3M or equivalent paint respirator, as the typical dust masks only serve to fog up your safety glasses, and as is evident upon the removal of the dust mask, they don't work all that well. A paint style respirator exhales to the sides, away from your safety glasses, and typically conforms to your face much better.


Grind pattern visible:


[img]http://i5.photobucket.com/albums/y167/rmccartney/1955%20Chevy%20Wagon%20Restoration/HPIM5779.jpg[/img]


Or better yet, the video instructional method....

https://www.youtube.com/watch?v=nb49MgRPzvY&t=2s


That should give a brief view of both the good, the bad, the ugly with most of the methods, now it will be up to you to figure out which one works best for you and best for the situation at hand

Last edited by MPandC; Mon May 13 2019 04:30 PM.
Re: Spot Weld Cutters Preference [Re: Apache1] #1310648
Tue May 14 2019 01:29 AM
Tue May 14 2019 01:29 AM
5
52Carl  Offline
Master Gabster
Joined: Mar 2010
Posts: 7,966
Virginia
Great post, Robert!
You provided the ultimate correct answer to the question.
One should use any and all methods available which work best for them, and for the specific application presented to them.
The best part is that you thoroughly covered all of the methods and how each one applies to each scenario.
Carl

Last edited by 52Carl; Wed May 15 2019 02:05 AM.
Re: Spot Weld Cutters Preference [Re: Apache1] #1310675
Tue May 14 2019 11:19 AM
Tue May 14 2019 11:19 AM
A
Apache1  Offline OP
Shop Shark
Joined: Dec 2018
Posts: 297
Whitwell, TN
Yeah, I second that...GREAT POST!

Very informative videos as well.


1959 Apache 3100 Fleetside SWB Resto-Mod







Re: Spot Weld Cutters Preference [Re: Apache1] #1313579
Sat Jun 08 2019 01:51 AM
Sat Jun 08 2019 01:51 AM
T
Truckrolet  Offline
Shop Shark
Joined: Feb 2011
Posts: 974
Wa
Being a machinist helps. And knowing how to hand grind a drill also helps. I have bought special spot weld drills, and cutters in the past. The best thing I found was to hand grind a cobalt drill I forget the diameter, just measure the diameter of the spot weld for that, anyway I grind it to a very flat angle. I'm thinking something like a 170 degree included angle.
If that, even when using the store bought spot weld drills I still always center punch and use a center drill to make a start spot, then your drill isn't dancing all over the place.
Its not a perfect deal so using an air chisel and hammer and chisel is sometimes necessary to help separate the panels..


Ret, Machinist , Industrial Engine
Engine specialist
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