Ordering North American Stainless Round Bars: A484 Tolerances and Lengths

Which tolerance and which length do I write on a North American Stainless round bar order? The surface condition you name first — peeled, cold drawn, or precision ground — decides both the ASTM A484 tolerance table your bars fall under and the standard length that shows up on the dock. Get that order backwards and the rest of the quote is guesswork.

The length line causes more saw-side rework than the tolerance class ever does. Peeled and cold drawn bars both get called "12 ft," but they do not arrive at the same length, and that gap quietly changes how many parts you cut from every bar. Here is the sequence that keeps a precision-turning job on schedule, from the first RFQ to the morning the truck backs in.

What Goes on the First RFQ

The first line that matters is not the grade — it is the condition. Write "peeled, 1.000 in diameter, 303 stainless, precision ground, 12 ft" and the mill has enough to price it. Write "303 stainless round bar, 1.000 in" and you have asked for a product the mill quotes from its loosest shelf stock, which is not what a Swiss-type lathe or a bar-fed CNC wants to see. Alloy, diameter, surface condition, tolerance class, length — in that order. Condition sits ahead of tolerance because peeled, cold drawn, and precision ground each carry their own default length and their own starting tolerance, and those defaults do not swap.

Leaving condition blank costs you a full queue cycle. The RFQ comes back for a family of bar you cannot feed, and by the time you correct it you are behind the shop that sent a complete inquiry. A same-day follow-up call — literally asking the desk to read back whether the quote says "precision ground" or "cold drawn" — catches the mix-up before the mill schedules the heat. That call takes four minutes. Fixing it after the steel is rolled takes two weeks.

Choosing the A484 Tolerance Before You Quote

North American Stainless quotes dimensional tolerances per ASTM A484, with tighter tolerances on precision-ground bars and ISO tolerances available on request. Read that as a table with rows, not one number stamped on every bar. A484 sets the permitted deviation for a given diameter and condition. Precision grinding then removes the outer skin — the oxidation and decarburized layer peeling or cold drawing can leave behind — and lets the grinder hold a band tighter than the standard table on the same diameter. ISO bands sit somewhere else again and only exist if you type the ISO callout onto the order. Say nothing and you get the loosest default the mill applies to that condition.

That is where split orders go wrong. Name a class on the first PO and skip it on the second, and the two lots can land in adjacent but different A484 rows. Shafts that ran fine through the first batch of bushings bind on the second, and the tolerance chart says both lots are legal. Settle the class inside the first day or two, while the mill is still pricing the job, because a class change after the quote moves price and lead time together.

On a metallurgist's bench the reason ground bars hold tighter is simple: the drawing and grinding sequence centers the bar and strips the surface variability, so the finished diameter reflects the steel under the skin rather than the skin itself. You pay for that in cost per foot and in the mill's grinding capacity, which is why it is worth naming only when the part needs it.

What Length Shows Up If You Ask for Nothing

Default length is set by condition. Peeled bars come at 12 ft ± 1 ft, so a bundle can run anywhere from 11 ft to 13 ft. Cold drawn bars come at 12 ft +2 in / −0 in, meaning none are short of 12 ft but some stretch to 12 ft 2 in. Those windows look small on a quote and turn into real money on the saw floor.

Run the number. If your part is a 9 in slug, a 13 ft peeled bar yields 17 pieces with a 3 in stub; an 11 ft bar yields 14 with a 6 in stub. That is three extra parts and a shorter remnant on one bar, across a whole bundle. Cold drawn gives 16 pieces at 12 ft and still 16 at 12 ft 2 in, because the extra two inches will not buy a 17th cut — so the tight window buys consistency, not yield. Pick the condition with your cut length and remnant strategy already on paper.

By the end of the first week you should know whether your bar feeder or magazine can swallow a 13 ft bar. A machine with a 12 ft magazine that receives a 13 ft peeled bar cannot use it without cutting it down first, and the cut-down offcut is scrap. If your feeder tops out at 12 ft, cold drawn's +2 in / −0 in window is the safer assumption, or you order a fixed length.

Getting Bars Longer Than 12 Feet

The mill can supply special lengths up to 20 ft, and the same capability line says those come with other tolerances. Treat that as one move with two variables, not a length swap. Ask for a 16 ft or 20 ft bar and you have also signed up for a different tolerance band, so the ground finish you assumed from the earlier quote may not carry over.

Declare the length and the tolerance together on the inquiry. Ask for 20 ft alone and the mill supplies a legal 20 ft bar to whatever tolerance travels with that length; if that band is looser than the precision ground your process assumed, you find out at the saw, not at the quote. Handling changes too — a 20 ft bar of 1 in 303 weighs roughly two and a half times a 12 ft bar, so check your rack, your feeder, and your freight before you commit.

Raise this about two weeks in, when you are laying out the saw plan and nesting bars against the cut list. Once the nesting is set around 12 ft stock, switching to 20 ft reopens the remnant math and the bundle count, and it is cheaper to decide before the PO than after.

Checking Bars on Arrival

The check happens the morning the truck arrives, before anything goes to the saw. Tape the length against the class you wrote. Peeled should measure inside 11 ft to 13 ft; cold drawn should measure 12 ft to 12 ft 2 in and never short. Log the measured range of the whole bundle, not one bar, because the peeled ± 1 ft window is a per-bar allowance — one 12 ft bar sitting in a stack of 11 ft bars tells you nothing about what you can nest.

If you paid for precision ground, look at the finish. Ground bars carry a fine, even pattern from the grinding wheel; peeled bars show a coarser turned surface. A bright bar with no grinding pattern that arrived on a precision ground PO is worth a phone call before the first cut.

Then match the paperwork to the PO. The A484 class on the mill certification has to be the class you named, not the mill's default. A cert can be perfect and the bar still unusable — one half a thousandth over your bushing clearance will not press onto the arbor, whatever the paperwork says.

When the Ground Bars Miss the Callout

Re-measure at shop temperature with a calibrated micrometer before you blame the mill. Steel grows about 6.5 millionths of an inch per inch per degree Fahrenheit, so a 1 in bar measured warm off a summer truck can read a few tenths over a bar checked at 68°F. Set the bar, the gage, and the part on the bench for twenty minutes and measure again before anyone calls the mill.

Then re-read the PO to confirm which A484 class you actually named. If the order said tighter tolerances on precision-ground bars but never named a class, the loose default is technically correct and the miss is on the order, not the bar. A callout you never wrote cannot be enforced, which is why the class belongs on the RFQ and not in a phone call after the steel is cut.

If you did name a class and the bars sit outside it, stop before the saw and call the mill. The drift usually shows up three months later, on the second order of the same part — first lot fits, second lot binds, and neither cert looks wrong until you compare the two A484 rows and see you named the class on one PO and left it off the other.

The habit that prevents the whole cycle: measure length and finish on the dock against the exact class you wrote, and accept that tighter-than-A484 and ISO tolerances only exist if you asked for them on the order. Once the first bar is in the saw, you are negotiating about cut steel, not about a bar.