What a Tubular Chassis Actually Costs

People budget for tube and then get surprised by everything else.

I'm not going to quote material prices. Steel moves week to week, your market isn't my market, and an article full of dollars-per-foot is misinformation inside two years. What's durable is the quantities, the categories, and the ratios between them — those hold up, and they're what you need to build an estimate you can trust.

So: get quotes on the list below. The point of this article is making sure nothing on it surprises you in week three.

Tube: how much you'll actually use

Rough starting figures, before waste:

• A basic 4-point cage: 25–40 feet of primary tube — a main hoop, two rear stays, a harness bar.
• A full 6- or 8-point cage: 80–140 feet, depending on how much bracing the rulebook mandates and how big the car is.
• A complete spaceframe chassis: 200–400 feet across several sizes.
• A set of equal-length headers: 20–30 feet of thin-wall, and you'll use more than the geometry suggests.

Then add waste, and add more than feels reasonable. Saw cut-off, notching allowance, bend scrap, and the stick you ruin working out springback on a new heat. I'd budget 15% on a first build and 10% once you know what you're doing. Headers are worse — call it 25%, because short convoluted primaries generate offcuts that are too short to be anything.

Order from developed lengths, not chord lengths. A bent member consumes the arc, and if you order against centerline distances you'll be short across the whole frame by a consistent amount.

The categories people forget

This is the actual content of the article. In rough order of how often they get left out of a budget:

Dies. A bend die for a new tube size is a significant single purchase, often a meaningful fraction of what the bender cost. If your design uses two tube diameters that both need bending, that's two dies. This is the one that most often blows a budget, and it's why "design around the dies you own" is financial advice as much as engineering advice.

Hole saws. Consumable, and faster than you'd think. One saw does a number of notches that depends entirely on your feed, speed and lubrication discipline — abuse them and you'll buy several per cage. They're individually cheap and collectively not.

Abrasives. Cut-off wheels, flap discs, grinding discs, deburring. On a cage this is a genuinely substantial line item and it's invisible because you buy it ten at a time.

Shielding gas. Cylinder rental or purchase, plus refills. TIG on a whole cage will go through more argon than you expect, especially if you're purging anything.

Filler. Wire or rod. Minor on its own, but part of the picture.

Tungsten. Consumable if you're learning. Every dip into the puddle is a regrind.

Plate. Mounting plates, gussets, tabs, brackets. It adds up to more area than you'd guess, and rulebook-specified plate thickness isn't cheap stock.

The jig. Material for a table and fixtures, or the cost of a modular table. Produces no visible progress and is not optional. See building a chassis jig.

Measuring tools. A long quality square, a digital angle finder, calipers, a decent level or a laser. If you're checking wall thickness yourself, an ultrasonic gauge.

Finishing. Degreaser, etch primer, paint or powder coating. Powder coating a cage is an outside service and it's not a small invoice.

Certification fees, if your series requires an SFI or equivalent inspection. Plus recertification at interval, which is a recurring cost people don't plan for.

PPE. A good helmet, gloves, a respirator for grinding. Please don't economise here.

The ratio that matters

Here's the useful heuristic, and it surprises people the first time: on a first cage, the tube is frequently less than half the total spend.

If you've never done this before, take your tube quote and double it to get a realistic materials-and-consumables figure. If you also need a die, or a notcher, or a table, add those separately on top — they're capital, not consumables, and they'll serve the next project too.

Where that ratio improves is build number two. The dies, the notcher, the table, the tools and most of the measuring kit are already paid for. The second cage can genuinely cost half of the first, which is worth knowing if you're deciding whether to buy tooling or send the work out.

Where design software changes the arithmetic

I'd rather be specific than oversell this, so: two places.

It cuts waste, because developed lengths computed per member are more accurate than lengths worked out by hand, and because a nesting-aware cut list gets more parts out of each stick. On a 300-foot chassis a few percent is real money.

And it prevents the expensive mistake, which is the big one. Discovering at the design stage that a member needs a die you don't own costs nothing. Discovering it after the steel is delivered costs a die or a redesign. Discovering a clearance problem after the frame is welded costs a cut-and-reweld, and that's the scenario where the hours lost dwarf every material line on this page.

What it won't do is make the steel cheaper or the argon last longer. Budget for those properly.