[adecoaches26point4]

Hi Folks,

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

Many thanks,

David

 

[Richard Johnson]

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

 

[pedromorgan]

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

 

[Richard Johnson]

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.

 

[pedromorgan]

you learn something new evry day!

Peter

 

[rossi]

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 .

 

[alastairq]

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....

 

[bike2steam]

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.

 

[Lancashire Fusilier]

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

 

[adecoaches26point4]

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