New frames: Square tubing VS. Machine cut plate???

Just wondering what the advantages/disadvantages were between building a fresh frame from say, 2"x4" square tubing OR having machine cut plates (sides) and then welding all the pieces up into a boxed frame.

A friend of mine has a fab shop with 2 water jets and a Lazer....and the place I work for just ordered a table plasma cutter. SO I could easily make the frame templates and have the pieces cut and then just weld them up.

From what I see, The pros for the tubing would be less labor and likely less cost.
And for the flat plate, you could get smoother lines, any shape you wanted really...and it would likely be structurally stronger.

Warping and twist will be the biggest factor in an four side plate frame. True, you can make it flow and bend in the direction you choose, but getting it there will be one thing, keeping it there when you apply the welding process can and will be tricky to say the least. Square or rectangular tube elevates most of these problems. If your looking at long graceful bends (like a 32 ford frame has) I can see where your coming from.There is a process that works really well for shorter bends and corners using square and rectangular stock. Go to You Tube and look up CMM Laser and they have various videos of metal fabrication. Look for the frame bending one. You don't so much bend the material as much as you remove the unwanted portion and then make your bend and weld it up. They are using factory settings and factory machines to do the job, but all you need is the example, and you can copy the way it's done by hand using what ever you have to work with as far as cutting out the waste. I did a test using the process and it works amazingly well. I used 'Bristol board' and drew the curve to actual size, then cut it out using regular sissors. Straighten out the cardboard pattern and lay it on the tubing, scribe the outline of your pattern and repeat on the other side making sure it's directly across from each other, otherwise your bend will come out cockeyed.This process isn't the answer to everything, but it sure has it's place. You can do a tight ninety or a long sweeping curve, that's up to you. Even a compound curve if you want to go through all that trouble. I'm sorry I can't just get the link on here for you, but it's there if you want to go and find it. (Hey Torchie where are you....I need your help with this link business again.) I manage to screw up the cut'n'paste stuff let alone move links around. Anyway, check it out, see if it will work for you.

I went back and found a couple of pictures. You can try 'How to Bend Tube Without a Bender' it's the same guys and same video if you can't find the other stuff which has a lot of examples and they are showcasing their equipment. We don't need the equipment, but the process' are pretty cool.

Why not use a mix. Using cut plate to attach rectangular tubing together is a good way to go. It makes for a more fluid look.

I'm not opposed to using the tubing, I just wanted to know the pros cons before I start my build. My rod will have fenders and a body anyway, so I'm looking mainly from a structural standpoint. I know the "fancy schmancy" chassis companies use the plate style and weld them in jigs. I just want whatever I build to be able to take power and abuse. I don't want something that won't handle anything over a 600lb small block making 300 horses. I want it to be able to handle a nasty gas motor or a 4BT Cummins turbo.

We've always used 2 x 3 or 2 x 4 rectangular tubing for our frames, but when my Son built the frame for his rpu he went a different route. He had a local steel supply shop brake up some steel plates into a C shape, and then he used those to build his frame. He boxed the C to add some strength. He was able to get the taper he wanted by having them bend them to a tapered shape for the front section.

It was a lot more work than just using rectangular tubing, but he did end up with a nicely shaped frame out of it.

Don

donsrods said:

We've always used 2 x 3 or 2 x 4 rectangular tubing for our frames, but when my Son built the frame for his rpu he went a different route. He had a local steel supply shop brake up some steel plates into a C shape, and then he used those to build his frame. He boxed the C to add some strength. He was able to get the taper he wanted by having them bend them to a tapered shape for the front section.

It was a lot more work than just using rectangular tubing, but he did end up with a nicely shaped frame out of it.

Click to expand...

That's a really fine looking frame, Don - using the C channel makes it look like a modified factory frame.
Here's one I made using a combination of box tubing for the center portion (2x2 stacked on 2x6) and the front and rear parts made from 1/8" side plates wrapped with 2"x1/4" flat bar. The front and rear frame horns are dovetailed to the main rails for strength. No fancy water jet table, I just torched the side plates from 1/8" sheet, clamped them together and ground the edges of each set of 4 plates to final shape, then cold bent the 1/4" flat bar around a pair of side plates, tacking as I went.

We build a lot of these type frames. The premade tube is much easier and faster to work with. We make the front rails on the CNC plasma and then weld it all together. Each front rail is about 4' long with 4 sides, so you have about 16' of weld to do, on each rail. Plus adding the tubes. Lots of welding, very hard to keep the rail from ending up all twisted and distorted.



Lots of tack welds and very small contiuos welds, then let it cool. Cool back to room temp, then weld somemore.
I tack weld about evey 2" then weld between the tacks, only several at a time in different places. Let it cool, then weld a few more and let it cool.

If want to get real creative, you could do the chain frame. 100 links all welded together to make a frame. You can figure about 80 hours of welding here.

That chain frame is sweet! Was is just flat plate, or an actual machinery chain?

It was all flat plate cut on the CNC Plasma. Then peices of tube cut, and then all welded together.

You guys have WAY too much energy and imagination for me ! Those are all very sweet.

Don

Here's a build thread with a fabbed frame.

http://www.hotrodders.com/forum/journal.php?action=view&journalid=39830&page=29&perpage=5&reverse=0

Sniper said:

I went back and found a couple of pictures. You can try 'How to Bend Tube Without a Bender' it's the same guys and same video if you can't find the other stuff which has a lot of examples and they are showcasing their equipment. We don't need the equipment, but the process' are pretty cool.

Click to expand...

Woah. I lover the second picture. Love the little notch in the cut line. How do I do that with a grinder with cutoff wheel ?!

choppinczech said:

Here's a build thread with a fabbed frame.

http://www.hotrodders.com/forum/journal.php?action=view&journalid=39830&page=29&perpage=5&reverse=0

Click to expand...

I was confused on this one until I realized their form had the newest page as page 1 and the oldest as page 54...Lol

Nice work on the stainless frame in the Chrysler though...[