Arcol blog Just another RepRap weblog

29Apr/12Off

Hobbed bar, hyena v1.0

This is my take of a new hobbed bolt replacement :)

I call it the hyena, because hyenas have the strongest jaw of all mammals.
All teeth are cut individually:

Here is a comparison photo with one of my hobbed bolts:

The brass one is the new version:)
You mount it with a M8 nylock nut, so the width of your extruder does not matter.

Key advantage over the old version

  • It's machined from straight, round brass stock. Regular bolts often have large tolerances and are not entirely straight. The hyena is guaranteed to be straight.
  • Each tooth is individually machines, so there is no "orphan tooth". An orphan tooth is an incompletely cut tooth that occurs during hobbed bolt production with a tap, because the teeth of the tap do not match the diameter of the bolt while cutting. This is a problems because it's the spot where filament begins to slip. It tends to bite a small piece of plastic off the filament as it does not reach deep enough to grip. The next (normal) tooth continues eating into the filament, resulting a complete filament strip, and no printing. The hyena prevents this by making sure every tooth grips by the same amount.

Installing on a Wade style extruder

Some pictures, from the top:

Also when opened (please note the washers around the bearings!):

(Also take note the really useful and special M8 nut. It will be the subject of an another announcement:)

Im a technical guy, any drawings?

Here it is:

Enough talk, I want one!

Comments (4) Trackbacks (1)
  1. Hiya,

    The hyena is great, and looks like a good replacement for the hobbed bolt in my extruder due to my non-standard spacing. I do have a question though – is the grip on the nyloc nut up to the job? I’m worried that it might come unscrewed in a situation that requires/generates a high torque.

  2. Hi Laurence,

    Thy nylock M8 nut is more then enough, if it isn’t, then usually you have some other problems.

    I also worried in the beginning, it may not be enough, thats why I “developed” a simple but handy M8 nut with M3 grubscrew on the side.
    It is adjustable, and it can support as many torque as you want.
    Here is more info about the bolt:
    http://wiki.arcol.hu/arcol-hu-m8-nut

    It turned out since, then nylock M8 nut is enough for the job, and that nut is really usefull on the other end of the hyena (see the above wiki page for pictures). So all the two is on sale now, you can purchase them on my shop (http://arcol.hu).

    The hyena does come with a nylock M8 nut by default.

  3. Thanks for the reply,

    I’ve ordered both they hyena and the nut with grubscrew. I’ll post a blog link here once I’ve got the parts fitted.

    Thanks!

  4. Are hyenas and micro-hyenas suitable for 1.75mm filament? Thanks.

Trackbacks are disabled.