Cutting & Welding a frame..Questions (1 Viewer)

[MANUCHAO]

Im thinking of cutting 5" of off this frame and welding it back together.

I got a millermatic 250 MIG welder and Im not so experienced at welding. I do know people that are welders (structural welding)

I know TIG welding would prob be best but I dont have access to that and gotta do with what I got....

What would be the best way to weld the frame back up and reinforce it where the cut and welds are ( e.i. scab plates, box that section of the frame ??) as Im trying to make it as stiff as it was to begin with.

This is for a project but want to get others opinions..

Thanks in advace...

 

[madinal]

Make the cut like a "Z." Do NOT cut it straight across. This give you more welding surface and carries original metal next to welds in all dimensions.

 

[fj40charles]

weld a fish plate on it.

 

[MANUCHAO]

A "Z" cut.. Im having a hard time picturing that.. drop half inch into the frame and then cut on a "Z" pattern the drop half inch straight down ?

What's a "fish plate"

Thanks for the replies and excuse the ignorance...

 

[MANUCHAO]

is this a fish plate ?

 

[fj40charles]

is this a fish plate ?

yes. I'd make it ends rounded and without any hard corners.

 

[MANUCHAO]

Thanks fj40Charles .....!!
I will make sure there are no sharp corners...!!

 

[Dynosoar]

After asking around and doing some "internet" research it seems 30deg is the magic number(see pic#1). Then covering the welded area with fish plates on all 4 sides (boxed frame). However, I was thinking it might even stronger of you do a "V" notch by doing 2 30deg cuts (see pic 2). then covering with fish plates. What do you think?


Dynosoar

 

[MANUCHAO]

I found the same on the angle cut but was not sure about the degree.
So 30° it is then...
Now the other challenge is the frame narrows where the cut will be made.. so I think in order to achieve the desire length I need to cut more and then add metal at a 30° from top to bottom and a xx° side to side so as to join the two sides....
Thanks for the info dude..

 

[zebrabeefj40]

The "V" notch would be a bad idea in that the point of the "V" is a stress riser. If a crack were to form it would likely start from the "V" point.

To the OP: Your 250 mig welder is more than enough to weld a frame; no TIG needed. I would recommend a skilled welder do the work if you are not comfortable with your welding skills in this application.

Good luck!

Nick

After asking around and doing some "internet" research it seems 30deg is the magic number(see pic#1). Then covering the welded area with fish plates on all 4 sides (boxed frame). However, I was thinking it might even stronger of you do a "V" notch by doing 2 30deg cuts (see pic 2). then covering with fish plates. What do you think?


Dynosoar

 

[MANUCHAO]

Given the shape of the frame narrow at the front wide at the back.. I think the 30° would be the easiest..
I think I'll have to cut more than 5" probably 12" then add to the frame until I get the right wheel base and match the frame up....

I think the most important thing is to not cut on a straight line (up n down) as someone already indicated not to do....

Thanks for all the great input everyone !!!!

 

[wadeclinton]

I'll chime in too. A 30 degree bevel is pretty much industry standard. You will also want to put a 1/8 90 degree face where the two plates meet. So your 30 degree bevels will end in a flat edge not a tapered edge.
After getting everything fitted weld the joint vertical up. It makes a stronger weld. Then fish plate the frame. We've done lots of frames this way.

 

[nat]

The "V" notch would be a bad idea in that the point of the "V" is a stress riser. If a crack were to form it would likely start from the "V" point.

To the OP: Your 250 mig welder is more than enough to weld a frame; no TIG needed. I would recommend a skilled welder do the work if you are not comfortable with your welding skills in this application.

Good luck!

Nick

this ^

 

[MANUCHAO]

Could you give more info on this ?
Pics......would be golden !!

Thanks......

You will also want to put a 1/8 90 degree face where the two plates meet. So your 30 degree bevels will end in a flat edge not a tapered edge.

 

[wadeclinton]

I'm working on it. Bear with me I'm outa town with only a mobile connection that is kinda crappy.

 

[wadeclinton]

Here is an example of the joint I mentioned in an earlier post. This one uses a backing plate.

 

[wadeclinton]

Here are some more examples. The flat edge I referenced earlier is called a root face. You want the root face 1/8" and the root gap to be equal to the size of rod you plan to weld with. So if using 1/8" 6010 for the root weld. The root gap would 1/8".

 

[wadeclinton]

This is the picture. It didn't load on previous post.

 

[MANUCHAO]

Thanks for the pics eh.
I actually used what post #16 shows but no backing plate..
I think with a fish plate it will be plenty strong....
I went ahead and used a 30° angle cut and a 30° bevel where the weld goes...
Im going to fish plate it now and hope it holds

I dont know how big or small of a fish plate to use.. (any ideas?)
The frame is 6"H x 2¼W".
At least those are the dimensions where I did my cutting and welding...
Im planning on using a 5" x 24" plate with welded donuts holes (bout 3 of them for added strength and round corners... )on the sides (in & out) and 1¾x 24" on the top & bottom

The frame is 3/16" thick so Im using the same thickness on the fish plate...

Manu !!

 

[wadeclinton]

5"x24" fish plates should be more than adequate. On the frames I've done we matched the length and height. For example 8" frame got a 8"x8" fish plate. I never did the holes in the plates but I suppose the extra welded surface cant hurt anything. I would just avoid having one of the holes directly over the weld joint in the frame. Also matching fish plate thickness to frame thickness makes welding it easier.