Gethenet
Member
The kit calls for a 7mm bit, however I believe the tube is smaller. I say this only because it didn't fit on my mandrel.
am I missing something?
am I missing something?
.50 caliber kit
- Thread starter Gethenet
- Start date
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If it's the PSI PK50CAL kit, it is a standard 7 mm tube. So unless yours was packed with the wrong tube, it should fit a standard A mandrel. If you have a set of digital calipers, you can check the tube to verify its size.
wyone
Member
I am thinking glue in the tube as well. I have done that, more times than I want to admit. 
Gethenet
Member
I did, however I cleaned it out. I did notice after I drilled the hole ( with a brand new 7mm bit fresh from pack) that when I glued tube in....it seemed to look " smaller" than hole
sbell111
Member
It could also be a burr on the edge of the tube from milling.
eranox
Member
Likely, your bit wasn't quite centered in the chuck, or your tailstock wasn't in perfect alignment with the headstock if you drill on the lathe. I've messed one or both up plenty of times, which results in the hole being just a bit oversized. Fortunately the .50 cal kit is pretty forgiving; I just fill the gap with thick CA and drive on.
Another possibility is that you may not be clearing out your shavings quite as often as you should. When that happens, the shavings can cake up inside the flutes of the drill bit and scrape away a bit more material from the the hole.
sbell111
Member
One thing that you can do is take a fresh tube from another kit and slide it onto the mandrel. If it goes on easy, then it's something wrong with the tube/blank that you were turning such as glue in the tube or a burr on the brass. If the tube dsoesn't slide on easily, then there is something amiss with your mandrel such as a bit of glue buildup or a small amount of damage (perhaps from a burr on another tube) that is hanging up the tube. I'm not above hitting my spinning mandrel with a bit of sandpaper to fix such issues.