« previous next »
Pages: [1]   Go Down

Author Topic: drilling a grade 8 bolt.  (Read 1385 times)

0 Members and 3 Guests are viewing this topic.

Offline Gurp

  • I'm no.......
  • Master
  • *****
  • Posts: 2,111
  • Once was a...
drilling a grade 8 bolt.
« on: October 21, 2019, 08:58:08 AM »
I broke a grade 8 bolt in my shadow mointing the fender struts. It was my fault i was in a hurry starting to rain and I didnt run the tap all the way through... so far ive dulled 3 drill bits and 2 uni bits.

suggestions...
Logged
slow Progress 74 cb550.

Poor boy chop 73 CB500 chop

Future project 77 Cb750 Amen Savior

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,050
Re: drilling a grade 8 bolt.
« Reply #1 on: October 21, 2019, 09:05:21 AM »
Run the drills slower. Once you over speed it and dull the edge, it can't get better.
 Use a left hand bit if you can.
Logged
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline scottly

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 16,548
  • Humboldt, AZ
Re: drilling a grade 8 bolt.
« Reply #2 on: October 22, 2019, 08:58:17 PM »
Quote from: Gurp on October 21, 2019, 08:58:08 AM
I broke a grade 8 bolt in my shadow mointing the fender struts.
There is no such thing as a grade 8 bolt in the metric world. Do you mean a stock type Honda bolt with an "8" on the head? The 8 is a manufacturers mark, not a grade mark. ;)
Logged
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline 70CB750

  • Labor omnia vincit improbus.
  • Really Old Timer ...
  • *******
  • Posts: 14,817
  • Northern Virginia
Re: drilling a grade 8 bolt.
« Reply #3 on: October 23, 2019, 03:56:31 AM »
Get what they call cobalt bit at Home Depot or Lowes.
Logged
Prokop
_______________
Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline Gurp

  • I'm no.......
  • Master
  • *****
  • Posts: 2,111
  • Once was a...
Re: drilling a grade 8 bolt.
« Reply #4 on: November 01, 2019, 01:19:40 PM »
Quote from: scottly on October 22, 2019, 08:58:17 PM
Quote from: Gurp on October 21, 2019, 08:58:08 AM
I broke a grade 8 bolt in my shadow mointing the fender struts.
There is no such thing as a grade 8 bolt in the metric world. Do you mean a stock type Honda bolt with an "8" on the head? The 8 is a manufacturers mark, not a grade mark. ;)

I had bought the bolt at the hardware store.
Logged
slow Progress 74 cb550.

Poor boy chop 73 CB500 chop

Future project 77 Cb750 Amen Savior

Offline Gurp

  • I'm no.......
  • Master
  • *****
  • Posts: 2,111
  • Once was a...
Re: drilling a grade 8 bolt.
« Reply #5 on: November 01, 2019, 01:20:33 PM »
Thanks for all the suggestions I'll have to check Lowe's for one of those I haven't tried a left-handed bit yet I've been going slow and small but just haven't made a lot of ground against it I'm home for the weekend again so I'll try to give it a go
Logged
slow Progress 74 cb550.

Poor boy chop 73 CB500 chop

Future project 77 Cb750 Amen Savior

Offline Nicklopic

  • Hot Shot
  • ***
  • Posts: 338
  • New York
Re: drilling a grade 8 bolt.
« Reply #6 on: November 01, 2019, 02:40:04 PM »
its probably a little too late depending on how far you've drilled but did you try welding a nut to the broken bolt? that's my favorite and go to way whenever possible. even when broken flush or a little recessed, a little build up, then burn the nut to the build up. sometimes it takes a few tries but ive done it on a number of different fasteners.
Logged
80' CB650
Build Thread

Offline Tracksnblades1

  • My Son was a collegiate competition Trap, Skeet, and sporting Clay
  • Master
  • *****
  • Posts: 1,965
Re: drilling a grade 8 bolt.
« Reply #7 on: November 01, 2019, 03:12:07 PM »
What size bolt is it? Broken off in sliders (aluminum) ?
Logged
Age Quod Agis

Offline Don R

  • My Sandcast is a
  • Really Old Timer ...
  • *******
  • Posts: 20,408
  • Saver of unloved motorcycles.
Re: drilling a grade 8 bolt.
« Reply #8 on: November 01, 2019, 03:18:15 PM »
 I've done the weld trick Nick mentioned. It works, may require a few tries but the heat and grip works wonders.
Logged
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.

Offline Gurp

  • I'm no.......
  • Master
  • *****
  • Posts: 2,111
  • Once was a...
Re: drilling a grade 8 bolt.
« Reply #9 on: November 03, 2019, 04:07:33 PM »
It broke below flush so i couldnt do the weld trick to start.
its broke in the frame above the axle hole.
On my vt600. I'll have to take a pic when i get a chance
Logged
slow Progress 74 cb550.

Poor boy chop 73 CB500 chop

Future project 77 Cb750 Amen Savior

Offline demon78

  • Old Timer
  • ******
  • Posts: 2,816
  • After work to the "Wets"
Re: drilling a grade 8 bolt.
« Reply #10 on: November 03, 2019, 06:58:16 PM »
I would go after the Cobalt bit rather than the Titanium bit I have had much better luck to the point of replacing broken bits with Cobalt as S.O.P. 
Bill the demon.
Logged
Pages: [1]   Go Up
« previous next »