Machining an accurate bore, 5mm diameter/ 30mm length

[vnks]

Hi all,

I'm having a hard time machining an accurate bore for my high-temperature Stirling power piston. I'm very new to machining, and mostly learning as I go, using a Taig Micro Lathe. I made some test pieces using a boring bar and a turning tool, which fit really well. However, the actual cylinder bore is much deeper, with a smaller diameter, and after grinding the boring bar down I ended up with a significant taper to the bore, which did not work. So, I got a 5mm reamer to use instead, but still end up with a taper in the bore, making it unusable. Is a reamer the way to do this, and I'm just not doing something right? Or is there another method that would work? The bore should be 5mm in diameter, all the way through a cylinder about 30mm long.

Thanks.

[Ian S C]

With a hand reamer the first part of it's length is tapered, OK if your hole is open ended, and you can take the reamer right through, a machine reamer is what you may need if it's a blind hole.
I can't picture a Stirling Engine with such a small bore but that long, my smallest has a power cylinder 3/8" bore X 5/8" long (the little beam engine in my gallery)
Ian S C

[vnks]

This is the reamer I have - http://www.ebay.com/itm/371234387700 , it does look tapered so maybe I should've faced off a bit more from the end. I'll try shortening the cylinder a bit to see if the taper is at the very end. It's this engine - http://www.machinistblog.com/downloads/ ... ing_60.pdf , on page 4 you can see the power cylinder with a 5mm bore, 27.5 mm long.

[Ian S C]

vnks, I think that is a machine reamer, and the only taper is the little chamfer at the tip, if you can, put the reamer right through the bore, keep turning the reamer to the right as it goes in, and on the way out(don't reverse turn the reamer).
Ian S C