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Drilling Lost wax castings.

2316 Views 9 Replies 7 Participants Last post by  adecoaches26point4
Hi Folks,

Can anyone recommend a technique for drilling into lost wax casting using wire gauge drill sizes.

Many thanks,

David
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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
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i was always tought to use spit as a lubrecant for small drills.

for brass i spin the drill as fast as possible. brass has a high machining speed anyway and to achieve that with a small bit takes allot of speed. i typically use about 30,000 rpm.

small castings are a pig to hold. sometimes just a good pair of pliers will be the only way to do it.

USE A GOOD QUALITY BIT. it will make your life sooooooo much easier! they are less likely to break. they last longer and they are quicker.

Peter
QUOTE (pedromorgan @ 2 Nov 2008, 14:42) <{POST_SNAPBACK}>i was always tought to use spit as a lubrecant for small drills.

for brass i spin the drill as fast as possible. brass has a high machining speed anyway and to achieve that with a small bit takes allot of speed. i typically use about 30,000 rpm.

small castings are a pig to hold. sometimes just a good pair of pliers will be the only way to do it.

USE A GOOD QUALITY BIT. it will make your life sooooooo much easier! they are less likely to break. they last longer and they are quicker.

Peter

***Spit is adequate for a pin vice.... at higher speeds, a proper lubricnt will help much more.
cant add much to the advice already given but sometimes it helps if any sprue is left on until drilling is finished as it gives a pin vice or larger something to hold onto without damaging the casting .
QUOTE (pedromorgan @ 2 Nov 2008, 10:04) <{POST_SNAPBACK}>you learn something new evry day!

Peter

I accidentally sneezed all over a job I was doing.....went rather well after that.......didn't need any glue either....
I only use new drill bits for drilling lost wax castings, better still if I can obtain Titanium Nitride coated ones for the size I need.
Paul M.
2
QUOTE (alastairq @ 2 Nov 2008, 19:41) <{POST_SNAPBACK}>I accidentally sneezed all over a job I was doing.....went rather well after that.......didn't need any glue either....

goodness! I trust this was not a commission then
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2
Many thanks for the advise folks

Weinert castings seem to be of a much harder material than my older parts, but are not a problem now


Thanks again!

David
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