Choose a plan
What Premium unlocks
- Bolt schedule with no line limit - build a job sheet listing every fastener on the job with its pitch, tap drill, wrench size, grade, target preload and tightening torque on one line each. A free schedule holds 3 lines.
- Saved schedules, one per job, instead of the 1 a free plan keeps - named, stored in your browser, no account.
- Print the bolt schedule as a job sheet or save it as a PDF, and export it as CSV for a parts list or a work order.
- 8 printable shop charts - metric coarse, metric fine, UNC, UNF, pipe threads, a tap-drill reference covering all 228 sizes, and torque by grade for ISO 898-1 and SAE J429. Laid out for paper: black on white, column headers repeating at the top of every page, banded rows, no row split across a page break, and landscape where the sheet needs it. Print them or save them as a PDF.
- Selectable nut factor (K) - dry / as-received, zinc-plated, lightly oiled, and wax or anti-seize - in the bolt-torque calculator and on the bolt schedule's torque column, so the figure matches how the joint is actually assembled instead of the K = 0.20 default.
Weekly, yearly and lifetime plans are available.
Every thread size page stays free: all dimensions, the recommended tap drill and clearance hole, wrench sizes, and a torque estimate at the default K = 0.20 - plus the thread identifier, the tap-drill calculator, every guide, and a working bolt schedule of 3 lines you can build, save and read in full. Every figure printed on a chart is free to read on the size page it came from, and a sample of each sheet renders for everyone.
What stays free?
Every thread size page - all dimensions, the recommended tap drill and clearance hole, a torque estimate at the default K = 0.20 and wrench sizes - plus the thread identifier, the tap-drill calculator, every guide, and a working bolt schedule of 3 lines you can build, save and read in full. That's the whole reference plus a real sample of the artifact, no account needed.
What does Premium add?
Three things. First, the bolt schedule without its 3-line ceiling: a whole job on one sheet, a saved schedule per job instead of 1, printed or saved as a PDF, and exported as CSV. Second, the printable shop charts: 8 sheets that put the reference on paper - metric coarse, metric fine, UNC, UNF, pipe threads, a tap-drill chart covering all 228 sizes, and torque by grade for ISO 898-1 and SAE J429. Third, the nut-factor (K) selector in the bolt-torque calculator and on the schedule's torque column, so a plated, oiled or anti-seized joint gets its own figure instead of the dry default.
Why would I pay for a bolt schedule?
Because the sheet is the work product and a browser tab is not. A size page answers one question about one size; a rebuild has eight or ten sizes in it, each with its own tap drill, wrench and torque figure, and someone has to hold all of that at the bench. The schedule is that document - your line names, your quantities, your grades - printed or exported so it can go in the job folder. Every number on it is the same free number from the size pages, read from the same record, so a schedule line and a reference page can never disagree.
Why would I pay for a chart of numbers you give away?
Because paper is the format the web page can't be. A browser tab is no use with oily hands at the drill press, and printing a size page gives you one size. The sheets are built for print: black on white, column headers that repeat at the top of every page, no row split across a page break, a series heading never left stranded at the foot of a page, landscape where the columns need it, and banded rows so you don't read across the wrong line. The numbers stay free - every one of them - and a sample of each sheet renders for everyone, so you can judge the layout before you decide.
What about sizes the standards don't cover?
The charts and the bolt schedule both print not defined for those, with a footnote naming the standard that stops there. ISO 898-1 specifies property classes from M1.6 upwards, SAE J429 skips the numbered sizes and defines nothing above 1-1/2 in, and pipe threads are made up to a seal rather than tightened to a preload - so 71 of the 228 entries genuinely have no grade. A sheet that filled those cells with a computed number would be worse than no sheet.
Is the torque figure different in Premium?
No. The arithmetic isn't a secret either: torque scales linearly with K, so a lightly oiled joint at K = 0.18 is 0.90 × the free figure and anti-seize at K = 0.12 is 0.60 ×. Every free page prints the K it used and the T = K · F · d relationship it came from. Premium saves you doing that by hand on each row; it doesn't withhold anything you couldn't work out.
Are the numbers different in Premium?
No - the reference values are identical and free for everyone. Premium changes one assumption (the nut factor), removes a volume ceiling, and puts the tables and your job sheet on paper. It does not hide data, and no figure on a paid sheet is unreadable for free on the size page it came from.
How is my access stored?
Purchases are handled by RevenueCat and Stripe. An anonymous purchase id is kept in this browser so ThreadRef recognises your Premium on this device. Keep your receipt email for recovery.
I already subscribed on another browser or device - how do I get Premium here?
Head to Restore access and paste the access code shown on this Premium page (or from your receipt). Premium moves to this browser instantly.
Can I cancel?
Yes. Subscriptions renew automatically and can be cancelled anytime from the link in your receipt email. Lifetime is a one-time payment.
Lost your access code?
Your code is shown on this page whenever you're subscribed here, and it's in your purchase receipt email. If you can't find it, reply to your receipt email from the address you paid with - your subscription is tied to it and access can be recovered from there.
How do I get help?
Email [email protected] with what you were doing and which size or schedule it involved, and you will get a reply from a person.