northwest
Searching for the Holy Grail.........
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- 5,405
- Location
- Manchester UK
These are very useful tools, you can make unobtainable screws and bolts, you can not only cut hex heads but you can cut square and triangular holes too. The only downside is that they are really expensive, but you can make your own, you have a lathe right?
There are various designs floating about but because I was going to do this with someone else originally I bought the plans from Hemingway and that way there would be a clear guide and I could leave the other person to carry on on their own. I left it and forgot about it. A good few years later I have picked it back up as I really needed this for a job last week. Today being a holiday I decided to crack on and get this finished, how it was when I got back to it:
The thread for the cap, 20 x 0.5mm internal and external cut on a tiny Chinese model lathe some years ago:
This is the actual toolholder itself, it also holds the bearing pack.
Reamed the holder for the Broach itself, they are a standard 8mm diameter:
Bearing pack assembled and the hole drilled and tapped 4mm for the securing screw to hold the broach itself:
Holding the tool body in the Mill as it needs to be milled at one degree to make the offset:
This is the whole tool prior to assembly. The holder secures the body in a sliding fit with some adjustment as the tool needs to hit the hole square on and central to the hole you would br broaching.
Here is the tool ready for use and you can see the hole through the body allowing access to the broach retaining screw.
There are various designs floating about but because I was going to do this with someone else originally I bought the plans from Hemingway and that way there would be a clear guide and I could leave the other person to carry on on their own. I left it and forgot about it. A good few years later I have picked it back up as I really needed this for a job last week. Today being a holiday I decided to crack on and get this finished, how it was when I got back to it:
The thread for the cap, 20 x 0.5mm internal and external cut on a tiny Chinese model lathe some years ago:
This is the actual toolholder itself, it also holds the bearing pack.
Reamed the holder for the Broach itself, they are a standard 8mm diameter:
Bearing pack assembled and the hole drilled and tapped 4mm for the securing screw to hold the broach itself:
Holding the tool body in the Mill as it needs to be milled at one degree to make the offset:
This is the whole tool prior to assembly. The holder secures the body in a sliding fit with some adjustment as the tool needs to hit the hole square on and central to the hole you would br broaching.
Here is the tool ready for use and you can see the hole through the body allowing access to the broach retaining screw.