BoltHobber - a tool for tapping hobbed bolts

by enif Nov 17, 2013
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If I put the bolt through the spot where the tap goes, is it possible to get the hobbing closer to the head of the bolt? I need 15mm from the inside of the head.

Yes, this way you should be able to get the hobbing closer to the bolt head. It should go about 8mm closer, if you put the bolt head at the rear (note the asymmetry of the tap hole!). However, I am afraid that this way a normal sized tap will be too short for going through the bolt hole and still have the cutting part at the bolt position...

Now this one seems much more reliable :)


I've done this and add pictures later, but I really think you don't have to put other bearings, the 688ZZ are just best size for this tool, and you can get this in germany (good quality) and not really expensive


I like your setup. I as i know pretty much nothing about Openscad, i was trying to change the tap bearings from 688ZZ to 626ZZ 19 x 6 x 6. The tb dimensions i think is what i need to change. I can not figure out where to change this so i get the correct bearing size on the part.
How do i do this?
Thanks W

Hi W!

Glad you like my bolthobber :)

For using different bearings, you just need to add to the call of bolthobber() the parameters tb (=tap bearing) and bb (=bolt bearing) with the according new dimensions of the bearings. In your case this means to change the lines


at the end of the .scad file to



(and make sure that only these two lines are uncommented in the end section of the file).

Have a nice day! Heinz

PS: I will also upload the corresponding STL file, it's called bolthobber_base626ZZ_slide626ZZ.stl .

Thank you so much Heinz, That was really stumping me. i am printing them now. Can't wait to use it.