Sandeep Sawant has programmed wire-cut EDM and built tooling at Accurate Industries in Pune since 1980. The tap, fit and weight charts on AlwaysReach are the lookups that shop already uses. Sameer Sawant puts each one on the page that answers that question. A chart is not given a second address.
Tap drills
A metric cut tap starts from major diameter minus pitch, then the nearest stock drill. That is about 75% thread engagement. For M8 × 1.25 the sum is 6.75 mm, and the drill issued in the shop is 6.8 mm. The working page is the M8 tap drill calculator. Why the number is rounded, and why a roll tap wants a larger hole, is the M8 note. Clearance holes are listed on the same calculator and are not tap drills.
UNC, UNF, UNEF, BSW and BSF use the published drill for that designation, not a metric guess. The tap drill chart is the full list. A tap maker's chart wins when the material is stainless, a blind hole is short, or the tap is a form tap.
ISO fits
Hole and shaft limits come from ISO 286. The letter is the fundamental deviation. The number is the IT grade. A 20 mm H7 hole is a table lookup at that diameter, which is why 20mm H7 has its own page and the H7 tolerance calculator covers the rest of the classes. The band changes with the size range. A number copied from a 20 mm chart onto an 80 mm hole is the wrong band.
The pages say what the code means in the toolroom: a location fit, a press, a running fit. They are not a substitute for the current standard or for the tolerance block on the drawing.
Metal weight
Plate, bar and tube weight uses a published density. Mild steel on this site is 7850 kg/m³, which is 7.85 g/cm³. That figure is on the steel weight calculator. Stainless, aluminium, copper, brass, bronze, titanium and cast iron each have their own density and their own page. A mill certificate overrides the chart when the grade is specified.
A STEP, STP, IGES or IGS file is different. The STEP file weight calculator reads the solid in the browser, takes its volume, and multiplies by the density you pick. Hide a part and it drops out of the mass. A mesh file is an estimate of that mesh. The file stays on the device.
What is checked, and what is not
- Tap drills and clearance holes are checked against the shop chart before a size page is added.
- ISO limits are checked against the size band, not against a single remembered number.
- Densities are the figures the shop uses for quoting. They are not a laboratory assay.
- CAD mass depends on the file. An open solid or a missing body will not weigh like the drawing.
These are shop references. They are not a sign-off, a mill certificate, or a calibration record.
When a number is wrong
Send the page address, the size, and the figure you expected through the feedback form, or email sawant@accurate.industries. Name the standard or the tap maker if you have it. The calculator page is corrected. A second URL is not opened for the same lookup.
Wire-cut stock and spark gap are not in these charts. That practice is written up as spark gap and skim stock.