INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

What bolt thread to use for a bearing extraction drawbar tool.

What bolt thread to use for a bearing extraction drawbar tool.

(OP)
Hi all, I've finalised the design for a KTM motorcycle swingarm bearing extraction and installation tool. I need to know which is better to use as a drawbar, fine pitch or coarse pitch bolt. I will be using a grade 10.9 M16 bolt. The most important factor is resistance to thread stripping. My initial reseach on the web suggests that a coarse thread has the greater resistance to stripping. I realise that a fine pitch would offer more force for a given ammount of turn, but the resistance to thread stripping is more important in my design. Your thoughts and comments would be greatly appreciated.

Regards Richard

RE: What bolt thread to use for a bearing extraction drawbar tool.

Acme.

RE: What bolt thread to use for a bearing extraction drawbar tool.

richardmorgan1-

Your swingarm bearing OD should not have a huge interference fit, so the M16 x 1.5 thread should work OK. The gr. 10.9 bolt has a hardness of approx. Rc32, which should be fairly durable for this application. But if you want an even harder material then see if you can find a gr. 12.9 bolt, which is about Rc39 hardness. Personally, I would use the fine pitch thread since it would allow slightly more precision in the application of installation/extraction force on the bearing.

As long as your drawbar design has a sufficient engaged thread length and the threads have decent precision/fit, then the threads will likely fail due to surface galling long before they fail in root shear (or "strip out"). To minimize galling use hard materials for both of the threaded components, make sure the thread fits are precise, make sure the thread flanks have a polished surface and are free from burrs or raised material, and use some sort of DFL or anti-seize on the threads. It would also be helpful to make sure your drawbar tool is designed to maintain alignment between the jack screw axis and the bearing/bore axis, so that the jack screw is not subject to eccentric loading or bending.

Hope that helps.
Terry

RE: What bolt thread to use for a bearing extraction drawbar tool.

Fastenal stocks M16 PC 12.9 socket head cap screws.

RE: What bolt thread to use for a bearing extraction drawbar tool.

When I've used big bolts for bearing pullers in the past (in particular to remove bronze bushings from skid steer buckets and arms) I used coarse-thread ones available at the local hardware store. I lubed them thoroughly w/"high pressure" grease, also from the auto parts store. After replacing a full set of bushings the bolts were looking pretty ugly - but who cares, they were only $5.

RE: What bolt thread to use for a bearing extraction drawbar tool.

heheh...watched the first video - that bearing was a breeze to get out compared to the bushings on the skid steer. In that instance I used 1-1/4" * 7 TPI bolts, plus a 6' cheater bar in my hands with my pickup truck helping to hold the part in place. It was a long and sweaty job.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close