How to use a sprue reamer.

Anyone want to give tips and tricks to using a sprue reamer? I just got one and it was very expensive. I don't want to ruin my reamer or my mold.

Thanks
Hyrum

PS a youtube video would be awesome!

What Machine tool are you using ?

If a Brigdeport knee type mill. I usually lock the spindle and use the knee to drill. They can run themselves into the work piece ad break quite easy. Yes they are expensive, To clear the chips require alot of cranking so I usually rough out as much as I can by drilling in steps with serveral drills, here's where a little math helps out, but if you can't do the math just draw it out in CAD for your different drill sizes. These are usually measured in Taper per foot so you'll need to convert it to degrees. Roughing out is the key to saving your expensive tool and providing the best finish for you sprue.
I have used them in a lathe but requires a bit of skill and I wouldn't attempt it you a novice but you can polish in a lathe if it's easier or a round part.
Make sure you have the tool chucked as your most secure tool holder, These like to pull themseves out of even the best collets. The work piece has to be just as secure. If the tool starts to chatter- slow down, rough it out more use plenty of coolant. Sprue reamers are best used to resurface exisiting sprues and I would polish the sprue after machining even though it is drafted. I have used them in many machine tools but these are the basics for a toolroom. Trail and error can't get expensive quiikly expecially if it's your money!

i aint used one for a few years now as i have a wire eroder and clean up any damaged sprues using that.
But when we used to use them we had a rougher and a finisher for each size.
we would run the rougher in a machine nice and slow with plenty of tapping oil and with it gripped lightly in the chuch so if it did grab it would spin rather than break.
we then just used the finisher by hand held in a tap wrench again with tapping oil and as previously stated polish it afterwards.

Thanks guys! This will help a lot.