QUOTE (adecoaches26point4 @ 2 Nov 2008, 06:45)
<{POST_SNAPBACK}>Hi Folks,
Can anyone recommend a technique for drilling into lost wax casting using wire gauge drill sizes.
Many thanks,
David
*** Castings are much harder than brass wire/tube/sheet, so have new sharp bits.
* If you have access a drill stand will help a lot, with the casting held in a small vice or clamp.
* Have as much of the drill as possible in the chuck so the unsupported length is as short as possible.
* Start the hole with a scriber tip or similar and use gentle pressure until its bitten properly - otherwise it'll skate, wander off centre and or snap.
* Use Kerosene as a lubricant - anything similar will be OK. This is important as the last thing you want is a drill that gets too hot OR a drill that grabs and snaps off in the hole.
* drill with steady pressure in short bursts (3 to 5 secs) with the drill at reasonable speed
* pause for the same length of time then drill again...
* every two or 3 drilling steps clean away swarf and add more lubricant
....Take your time.
If its a larger hole make an accurate centre mark and punch a dot to start the drill in... start a couple of sizes of drill smaller and then clean, then re-drill with the correct size.
regards
Richard