I ordered a 4-20mm step drill with a titanium coating on Aliexpress. Vastar brand. Came fairly quickly. I ordered it on 11/11/2019, it came on 11/26/2019 for only 165 rubles. You can order 3 sizes: 4-12mm, 4-20mm, 4-32mm. Suitable for deburring holes, filling holes, making holes more eleptic. Can be used on metal, aluminium, brass, wood. The drilling pitch for my case is 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 20mm. The drill is convenient because it is not necessary to change drills for different drilling diameters. All holes can be drilled with one cone drill. The only negative is for drilling in metal, before drilling, you need to make a dent with a punch or drill less than 4 mm., Then drilling can be easy and simple. I like this tool. I recommend this tool to everyone.
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