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Trepan tool?
- Thread starter celsoari
- Start date
- Joined
- Nov 12, 2017
- Messages
- 391
Aha...same writers, different site! Different avatar for me, but the boy's look and my attitude are similar...
There are commercial trepan cutters, they use an insert almost like a parting tool but sides have concave and convex radii. They really are more a parting tool than drill. Good toolholders also have some adjustment in respect to the final diameter clearance, but limited. The adjustment is clearance for underside of tool. And economy is not one of the advertised features!
If pressed to make one, I'd bore and turn an alloy bar such as 4100 series into the correct side clearance, cut away a 60 or 80% portion and silver braze a carbide tip in place; just like a cemented tool.
For larger sizes; it's not necessary to produce the entire tube, just sufficient cutter support. Offsetting in a four jaw, or mounting on a face place will do. Provide a small center pin to make measuring accurate.
Another way, which I've employed is making a holder for small HSS or cemented carbide bits; like a flycutter but oriented axially to the shank. If depths will be shallow, a couple set screws will do. Just remember to support underside that will fit into radius being cut. That support is fine being helical formed, where support is needed most and tapering away to the outside.
The single biggest issue is chip ejection; again just like a parting tool. That means running forward rotation but inverted cutter can be more stable.
Seeing things you've built, tells me you can handle this easily.
Post questions/ PM me here or you-know-where.net if you like.
Except for why he like to sit in a chair that way. We have NO clue!
There are commercial trepan cutters, they use an insert almost like a parting tool but sides have concave and convex radii. They really are more a parting tool than drill. Good toolholders also have some adjustment in respect to the final diameter clearance, but limited. The adjustment is clearance for underside of tool. And economy is not one of the advertised features!
If pressed to make one, I'd bore and turn an alloy bar such as 4100 series into the correct side clearance, cut away a 60 or 80% portion and silver braze a carbide tip in place; just like a cemented tool.
For larger sizes; it's not necessary to produce the entire tube, just sufficient cutter support. Offsetting in a four jaw, or mounting on a face place will do. Provide a small center pin to make measuring accurate.
Another way, which I've employed is making a holder for small HSS or cemented carbide bits; like a flycutter but oriented axially to the shank. If depths will be shallow, a couple set screws will do. Just remember to support underside that will fit into radius being cut. That support is fine being helical formed, where support is needed most and tapering away to the outside.
The single biggest issue is chip ejection; again just like a parting tool. That means running forward rotation but inverted cutter can be more stable.
Seeing things you've built, tells me you can handle this easily.
Post questions/ PM me here or you-know-where.net if you like.
Except for why he like to sit in a chair that way. We have NO clue!
Last edited:
- Joined
- Nov 15, 2016
- Messages
- 943
Go hard and go big? userwl2850 -Trepanning YouTube - YouTube