DIY metal chassis & roll bars.

Why build your own — and what to build first

A scratch-built cage fits the body and chassis you actually own, not the average of everyone else's. It can be repaired at the bench the night before a run instead of waiting on a replacement part. And per dollar, tube stock is some of the cheapest performance there is: a cage that carries its loads through proper triangulation is stronger than a heavier one that doesn't, and you decide where every gram goes.

Do not make your first project a full 1/10 steel tuber. Start with brass — a rear cage, a bumper set, a pair of sliders. Brass cuts, files and bends easily, joins at the lowest temperatures, and lets you watch the filler flow and learn what a good joint looks like. Graduate to a steel or stainless 1/10 chassis once your practice joints on scrap hold. Note there is no single official RC standard for tube sizes or bend radii; the numbers in this guide are documented community practice plus full-size cage principles scaled down.

Safety first — read this before the torch comes out

The zinc trap is the big one. Much cheap brake-line tubing is galvanized — coated in zinc. Heat it with a torch and you get zinc-oxide fume, and breathing it causes metal fume fever: fever, chills and a metallic taste that typically show up 3 to 10 hours later and clear in a day or two, but are entirely avoidable. Strip any coating well back from the joints, ventilate hard, and wear a respirator when in doubt — or sidestep it entirely. The coil featured in this guide is 316L stainless steel specifically because it has no zinc coating to strip.

• Eyes: torch brazing calls for Shade 3–5 brazing glasses — welding shades are a different thing and far too dark to see the joint. Clear ANSI-rated safety glasses (plus a face shield) are for cutting and grinding only, never a substitute at the torch.
• Ventilation: braze outdoors or with local exhaust pulling fumes away at the source, and keep your head out of the plume. Flux fumes are respiratory hazards too — clean to bare metal near joints so there is less to burn off.
• Filler: some old silver fillers contain cadmium, whose fume is odorless and extremely toxic. Only buy filler explicitly labeled cadmium-free — the Safety-Silv 45 and 56 in this guide are.
• Burns and clothing: leather gloves, natural-fiber or flame-retardant clothing (synthetics melt to skin), no loose sleeves, leather footwear. Parts stay dangerous long after the flame is off and give little color warning at lower temperatures — pliers and tongs only, and park hot work on fire brick or steel.
• Quench bucket: a metal bucket of clean water at the bench. Quench small parts with tongs, face clear of the steam. Don't quench a steel joint whose hardness you need to keep.
• Fire: clear paper, rags, solvents and — especially — LiPo batteries away from the bench. Work on a fire-resistant surface, keep an ABC extinguisher in reach, and check behind and under the bench when you finish. Torch off and fuel closed when you walk away.
• Cutting and grinding: clamp small tube; never hand-hold it against a disc or drill. Gloves come OFF around rotating tools (entanglement) and go ON for handling sharp cut tube. Deburr every cut end.

Pick your metal

Four metals cover RC tube work, and they are not interchangeable. For the same size piece, aluminum is lightest (about a third of steel's weight), then mild steel and stainless are close, and brass is heaviest of all. In a cage, though, diameter, wall thickness and triangulation matter more than the strength number on a chart — and hollow tube gives most of solid rod's bending stiffness for far less weight.

Sizes that builders actually use. For 1/10 main structure: 3/16 inch (4.8mm) tube — hollow preferred for weight and scale looks — with 1/4 inch for main hoops on heavy trucks and 1/8 inch for mock-ups and light secondary bars. Secondary and detail work runs 5/32 inch, 4mm and 5mm. For 1/24 and 1/25, strict scale math off a real cage tube gives roughly 1.6–1.9mm, but builders go sturdier in practice: 2mm, 3mm (about 1/8 inch) and 3–4mm brass for main rails. The rule of thumb: tube for main structure, solid rod for short tight-bent pieces, tabs, and ends you will drill and tap.

The stock itself, all live in our metal stock & tubing category: the 316L stainless brake-line coil, 3/16 inch x 25 ft — $46.52 landed for 1/10 work; K&S brass in tube ($29.98) and rod ($19.99) assortments for the small scales; a K&S aluminum tube assortment ($9.99) for rails and plates; and K&S music wire ($14.99) for pins, clips and spring details. K&S direct ships free on orders of $40 or more, and the four K&S items together come to $74.95 — they ship free as a bundle.

The starter kit — everything, priced

One of everything you need to go from raw stock to a finished, painted-or-polished cage, at verified landed prices to a US address (ZIP 83401). K&S items are counted at shelf price because the four together clear the $40 free-shipping threshold.

Two honest notes. The Dremel 3000 above is a used listing and the seller accepts no returns — it's priced accordingly, and the photos are worth a careful look before you buy. And the Harris kit is the expensive line on purpose: it is real 45%-silver alloy, one troy ounce lasts through many joints, and cheap low-temperature “brazing rods” are not a substitute for structural work. Every item is also a card in our tools category (stock lives under metal stock & tubing), where the live pages show current availability.

Joining: solder vs braze vs weld

The industry draws the line at 840°F: filler that melts below that is soldering; above it is brazing. Brazing filler flows into a tight joint by capillary action and the base metal never melts. Welding — MIG or TIG — melts the base metal itself. For RC tube work, silver brazing is the structural default, and here's why.

Safety-Silv 45 (45% silver, cadmium-free) starts melting at 1,225°F and is fully liquid at 1,370°F. That wide melting range is forgiving on joints that aren't perfect — aim for 0.003–0.006 inch of clearance. Safety-Silv 56 (56% silver) melts lower and narrower, 1,145–1,205°F, flows the most freely, and is the closest color match on stainless; it wants tighter joints, 0.001–0.003 inch. Either way, joint fit is everything: file or fishmouth (notch) the tube ends so they mate closely, because capillary action won't bridge a sloppy gap. Use white flux for steel, brass and copper; black flux for stainless — it dissolves the chromium-oxide layer and turns clear as it approaches temperature, which is your cue. Afterward, clean off all flux residue (quench and a wire brush) — left in place, it's corrosive.

Torch choice: propane's flame is hot on paper, but heat output against how fast the part conducts heat away is what matters, and propane only manages the smallest thin brass and copper joints. MAP-Pro is the standard recommendation — enough for small tube and steel under about 1/8 inch, including thin-wall 3/16 inch brake line, plus all brass. Oxy-fuel is for larger steel and fusion welding: more cost, more skill, more hazard, and unnecessary for a first build.

Soft solder (tin-based, under 840°F) is easy and reversible — and not structural. Its joints are much weaker than brazed ones and let go first in a rollover or at a link mount. Use it for mock-ups and light brass detail, and label it honestly if you do. MIG is the strength/speed/cost balance for steel-only work and TIG is cleanest with the most control on thin tube, but both are bigger commitments than a torch. And aluminum? Brazing it is a trap for beginners: its filler goes liquid around 1,065°F while 6061 starts melting around 1,080°F, the oxide layer survives far hotter still, and the metal gives no red glow before it slumps. Bolt aluminum, or TIG it later.

Why beginners start with brass and silver braze: the lowest working temperatures of any structural method, filler you can watch flow, and joints you can re-heat and reposition when — not if — the first ones are crooked.

Bending without kinks

A bend thins the outside wall and tries to wrinkle or kink the inside. Plan on a centerline radius of at least 3x the tube's diameter for hand or hot bending without a mandrel; proper former tooling can get down to 1–2x. The lever bender in the kit has 1/4, 5/16 and 3/8 inch grooves — note there's no dedicated 3/16 inch groove, so make your first 3/16 bends on scrap in the 1/4 inch groove and learn how your stock behaves before touching the real piece.

Springback is the metal relaxing partway back after the bend, so you overbend to compensate: stainless typically needs roughly 2–8 degrees extra, steel more than brass. Bend a test piece from the same batch and measure it before committing. To stop kinks, bend around a grooved former or a proper small bender, a little at a time. For hollow tube, the classic trick works: pack it tight with dry sand or salt, plug both ends, bend, then empty it — the fill supports the walls. A bending spring slipped over or inside hobby tube, or a close-fitting internal rod, does the same job on small brass. Springs alone often fail on tight 90-degree bends, so practice on scrap first.

Annealing brass: bending work-hardens brass until it cracks. Heat just the bend zone — a practical anneal is around 750–800°F for a few seconds; a faint glow near 950°F risks over-softening and zinc loss. Brass doesn't need quenching to stay soft; air-cool it, or quench only to handle it sooner. Re-anneal between repeated tight bends. Steel brake line is the opposite: bend it cold with the bender and don't anneal it — you'd throw away its strength. Stainless annealing is a furnace process, not a torch trick.

Design it like a cage, not a jungle gym

• Triangulate everything. A triangle is inherently stable; a rectangle racks sideways and folds. Make tubes the legs of triangles and add diagonals across the roof, the sides and any big open panel.
• Gusset the nodes. Small sheet or tube gussets at corners, bends and high-load joints buy a lot of strength for almost no weight.
• Land tubes at nodes, not mid-span. Shock and link loads should flow through diagonals into the opposite side and the lower rails. A lone shock tower bends like a flagpole.
• Mounting tabs belong at nodes too. Braze steel or brass tabs where tubes meet for body, shock and link mounts; double-shear (a tab each side of the bolt) beats single-shear. Drill after joining, and use a sleeve or shoulder bolt so hardware doesn't crush the tube.
• Decide link and shock geometry before you close the cage in. The cage must not block link travel, shock travel, or battery and transmission removal.
• Build on a jig. A flat plate, rails clamped parallel and square, everything tack-brazed first, wheelbase and symmetry checked, then finish-braze alternating sides so heat doesn't pull the structure out of true.
• Keep the weight low. A metal cage raises the center of gravity fast, and a crawler lives or dies by CG: heavy tube low (sliders, lower rails), light tube high, battery low between the rails. Our weight balance guide covers the theory.

Watch & learn

Six videos worth your evening, linked — watch the technique, then come back here for the shopping list:

• Cheapest way to start brazing for RC — Brazing 101 (Harley Designs): a budget-first walkthrough of getting set up to silver-braze your own RC bumpers and tube work.
• Beginner's Guide to Brazing — RC4WD C2X Rear Cage (Scale Builders Guild): brazing fundamentals applied to a real project, a rear cage for an RC4WD C2X.
• Mikes RC World Presents How to Braze (Mikes RC World): a MAPP-gas torch and Harris silver filler, start to finish, with the safety basics covered.
• How I build my custom crawler tube chassis (Harley Designs): one builder's method for laying out a custom tuber chassis from solid rod with downloadable templates.
• Crawler Tube Chassis — In Depth How-to (Harley Designs): the long version — a full tube chassis build, and how different construction approaches compare.
• Flawless Tube Bends for RC Projects with the $39 HD Bender! (Harley Designs): getting clean, repeatable bends in 3/16 inch tubing with an inexpensive bender.

Your first build, in order

1. Practice joints on scrap brass. Cut, fishmouth, flux, braze, quench, break them apart on purpose. Learn what a flowed joint looks like before it counts.
2. Practice bends. Spring-bender curves and lever-bender corners on offcuts; measure the springback of your actual stock.
3. Build a simple two-hoop rear cage on a jig. Clamp it square, tack everything, check symmetry, then finish-braze alternating sides.
4. Test-fit on the truck. Check link and shock travel, battery access, and body fit before final finishing.
5. Finish. Clean every trace of flux, deburr, then paint steel or polish brass. Stainless just needs the flux gone and a wipe down.

From there, the path is a front bumper and sliders, then a full cage, then a complete tube chassis. Each one uses the same $452.58 kit — the torch and tools are a one-time buy, and after that a cage costs you tube and an ounce of silver at a time.

A quick note on links

Some links on this page are affiliate links. If you buy through them, the retailer may pay us a commission at no extra cost to you — it keeps the lights on and the deal verification going. Prices were verified Oct 13, 2026; the live deal pages always show the current verified total. RC Crawlers Seek currently tracks 3,545 hand-verified deals.