I could use some help on how to move forward to remove couple of bolts. I am currently out of ideas.

To give some context, I noticed that my scooter windshield was not exactly leveled and I thought to remove it and set it up again properly.

I had no problem removing the bottom two hex screws, but the ones above were stuck. So I bought one of these extractors you can see below:

Bolt Extractors

The problem is - I am unable to drill into the screw. It seems to be just too hard to penetrate.

I have attached some photos here, where you can also notice that the left screw one has some plastic stuff coming out, that makes me think somebody put some glue in the screw back in the time.

I am open to any suggestion to get this out. For the record, these are M6 x 30mm bolts.

Thank you!

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  • Why does the second photo appear to show that you were successful in drilling?
    – isherwood
    Jan 3 at 21:38
  • I have tried different drill sizes and they all seem to be able to scratch the surface of the bolt, but at a certain point it sounds like they stop being effective and get stuck
    – Vincenzo
    Jan 3 at 21:42
  • 2
    Get better drill bits. In particular, don't get ones listed only for wood. A nice new metal drill bit should go through steel like a knife through butter (well, cool butter, not melted butter).
    – Jon Custer
    Jan 3 at 22:28
  • 1
    start with a very small drill bit and work your way up
    – jsotola
    Jan 3 at 23:57
  • Scooter repair is not home improvement. There is a site for motor vehicles.
    – nobody
    Jan 4 at 1:14

2 Answers 2


A cobalt drill bit will work. A carbide bit would work faster, but the cobalt bit will be more forgiving against breakage.

Noting the 10.9 stamped on the bolt head, ASTM F568 specs the hardness of 10.9 grade bolts as ranging from 33 to 39 on the Rockwell C scale. For comparison, a cobalt drill bit has a hardness of about C65. A carbide bit has a hardness of about C75.

  • I have not tried cobalt drill bit - but the ones I tried (De Vault) are allegedly for metal as well. I will give it a try and see if that works!
    – Vincenzo
    Jan 3 at 23:47

Keep using larger drill bits until you've removed the entire screw head from the center out. Once the head is gone and you can get the windscreen off, you should be able to clamp a pair of vise grips on the shaft of the screw.

Or, maybe you could grind or file a slot across the head of the screw to accept a flat screwdriver blade? That approach might require sacrificing the chrome trim piece.

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