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Im stumped on how to ream out this tapered hole on my CNC lathe

Message 1 of 4
156 Views, 3 Replies

Im stumped on how to ream out this tapered hole on my CNC lathe

Not very highly experienced with CNC lathes but have a bit to do with a cnc router,


The part in the image is a cylinder, that has a 1/4" hole drilled in the centre with the first 45mm of it tapering up to 12mm. The solid plug adjacent to the cylinder is the model of the plug that would fit the hole. Know what I mean?


I have no idea on how to machine multiple parts with this taper bore? Would I look at having a tapered ream made up and fit it to my turret? Easy enough to drill out the 6.35mm hole its the taper I am unsure about. Would I use a very small boring bar? Fusion does not seem to have many operations for this, 

Message 2 of 4
in reply to: boyd.sofield

Off the shelf taper reamers won't match the taper you want

your taper is steeper than the 1:48 imperial or 1:50 metric taper pin reamers. 


you could use a boring bar like this Iscar solid carbide one 

You won't like the price though, probably over $100NZD

Also there is no good way currently of setting up those wee bars in fusions tool library


The other option is to make a D-bit reamer from some Drill rod.

a D-bit reamer is just a bit of round bar turned to the shape you want to ream and then half is milled/ground away.


You need to harden the drill rod after making the reamer.


the D-bit or other tapered reamers can be setup in fusion as a Form mill

Message 3 of 4
in reply to: boyd.sofield

If you're in North America, Micro-100 boring bars might just be the ticket for you:

Seth Madore
Customer Advocacy Manager - Manufacturing
Message 4 of 4
in reply to: boyd.sofield

Thankyou. Gee turning is not something I do a lot of. I found a small boring bar at 5.5mm its in the post from China. I have a 4 tool turret with a lot of room in front of the turret towards the rear of my lathe. Instead of mounting a boring bar onto my turret at 90deg, I am thinking about mounting it on a plate in front, which would I guess give me a turret with gang tooling as well. Make sense or a bad idea? Such a small part and I have a qty to make. I have a feeling I will be back here for some help with ops.

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