What size screw extractor do you need?
What size screw extractor do you need?
Depends on the extent of stripping and remaining material. Probably the 2mm extractor is the only choice, but in the worst case you might need the 1.3 mm model. The screw core diameter is 1.25mm, so a smaller size than 1.25mm would be ideal. Drill sizes should be around 2.2mm and 1.5mm.
The screws still retain good material. The pump was worn out, causing the screws to become soft and requiring countersunk pozidriv fasteners. Since I didn’t have a Pozidriv bit, I used a PH1 bit which stripped the heads. I also discovered a left-handed 1mm drill bit that should remove the screw without harming the threads, yes?
For K22 screws the head measures 3.8mm and the slot width is 2.4mm. This places them in the compact screw category, meaning you should use an extractor sized between 2.5–3mm #1. Anything bigger won’t grip properly, and a smaller one will just turn. If the package includes the kit, select the 2.5mm or 3mm extractor bit—it’s the proper fit for K22.
Avoid the #8 size—it’s too big for a K22. Aim for 2.5–3mm, which usually matches a #1 or occasionally a #2 bit in most extractor kits. When purchasing a set, refer to the chart on the box: the slot width for K22 is just 2.4mm, so an #8 would spin freely. Choose the smaller #1 size with a 2.5–3mm range for better performance.
Opt for the #8 (2.3 mm) as it’s nearest to the 2.4 mm slot and will actually grip the head. #7 at 3 mm could be too broad and slide off, while #9 at 2 mm might not hold enough surface. #8 offers the best balance for a precise bite without forcing too much.