SEBO Screw F 3.9 x 21 (DIN 968) for ET-1 and ET-2 Power Heads

Power heads take more punishment than the machines they hang off, with the brush roll spinning inches away and every joint shaken constantly. The F 3.9 x 21 to DIN 968 is the long screw holding that housing together on SEBO's ET-1 and ET-2. DIN 968 describes a cross-recessed pan head tapping screw with a collar, meaning a built-in flange under the head that spreads the clamping load over a wider ring of plastic than a plain pan head manages.

That flange is the reason the standard is used here. On a component that vibrates continuously, a screw head bearing on a small area works its way into the moulding until the joint has play in it again. The collar keeps the pressure spread and the joint tight for far longer.

• Part number: 1020
• Fits: SEBO power heads ET-1 and ET-2
• Specification: F 3.9 x 21 to DIN 968
• Head and drive: cross-recessed pan head with collar
• Size: 3.9 mm diameter, 21 mm long
• Sold: each
• Shorter DIN 968 screw: part 1021 at 13 mm

At 21 mm it is noticeably deeper than the 13 mm DIN 968 screw used elsewhere on the same head, and the two are easy to confuse once they are out of the casing. Put the short one where the long one belongs and the joint is only half clamped, which turns up later as a creak, a gap along the seam, or a brush housing that no longer holds its alignment.

Replace one when the recess has rounded, when it no longer draws the casing halves together, or when the original was lost during a belt or brush roll service. Unplug the machine before opening a power head and keep the screws laid out in the order they came off, because lengths are mixed within a single casing.

Searches for a SEBO ET-1 housing screw, a SEBO ET-2 power head fastener or a DIN 968 3.9 x 21 replacement all point here. Genuine SEBO hardware supplied by an authorized dealer, with dispatch in 2-5 business days.