Choosing T-shank jigsaw blades: material, length and cut

Start with the tool manual

Find the exact jigsaw model and check its permitted blade fitting. For example, Bosch’s GST 12V-70 manual specifies a single-lug T-shank. It also advises choosing a blade no longer than the cut requires and a narrow blade for tight curves. Those instructions belong to that model; check your own manual before transferring them to another saw.

Keep the manual open while reading blade specifications. The attachment, tool capacity and blade application must all agree. A retailer’s list of compatible brands cannot answer every one of those questions.

Separate total length from material thickness

Bosch lists its T 101 B wood blade as 100 mm long, with a recommended material thickness of 3–30 mm. One documented UK variant is the three-blade pack 2 608 630 557. The 100 mm figure is the overall blade length, not permission to cut 100 mm timber. This is why searching by length alone can produce the wrong shortlist.

Record both measurements when the manufacturer provides them. If a listing only supplies an overall length, look up the blade code in the manufacturer’s catalogue before deciding whether it covers your workpiece.

Choose the blade for the material and finish

Bosch’s wood-and-metal set contains separate blades for different jobs. Its T 101 B is an HCS blade for clean straight cuts in softwood and suitable woodworking materials; the T 118 A uses HSS and targets thin sheet metal. The set also includes narrower blades intended for curves. Sharing a shank does not make these roles interchangeable.

Write down whether the job needs a straight or curved cut, the workpiece material and thickness, and the required surface finish. Then compare the manufacturer’s description and thickness range against that short brief. Do not choose from a tooth-count or material abbreviation without checking the complete application.

Check the code inside a multipack

A set name can cover several blade types. Read the contents rather than assuming that every included blade suits the same material. For repeat orders, save the blade type as well as the pack part number: Bosch sells the same T 101 B type in several pack quantities. Count the useful blades for your task when comparing packs.