Niander
New member
Hi i need to Drill and tap cast iron?
how does it compare with Drilling and taping steel?
softer isn't it?
any tips?
how does it compare with Drilling and taping steel?
softer isn't it?
any tips?
Drilling and tapping cast iron?
- Thread starter Niander
- Start date
Aja
Well-known member
That's paranoia setting in........
Donald
Donald
andy01842
Member
much dirtyer! and can have a very hard crust!
Thistle
Well-known member
I seem to remember doing this successfully with a hand drill (low speed!) and paraffin as a lubricant.
Niander
New member
[ QUOTE ]
That's paranoia setting in........
Donald
[/ QUOTE ] /forums/images/graemlins/laugh.gif
That's paranoia setting in........
Donald
[/ QUOTE ] /forums/images/graemlins/laugh.gif
DaveS
Well-known member
From my 1958 Higher Metalwork textbook...
Cast Iron:
No coolant is recommended for drilling, oil is recommended for tapping.
ISTR, but now cannot find confirmation, that the drill tip included angle should be reduced to about 100 deg, and that a low drilling speed and firm pressure were required.
Not sure about tapping, but seem to think that it will only work properly with fairly big holes / coarse threads (otherwise thread size gets too close to grain size).
Cast Iron:
No coolant is recommended for drilling, oil is recommended for tapping.
ISTR, but now cannot find confirmation, that the drill tip included angle should be reduced to about 100 deg, and that a low drilling speed and firm pressure were required.
Not sure about tapping, but seem to think that it will only work properly with fairly big holes / coarse threads (otherwise thread size gets too close to grain size).
nigelhudson
New member
It's not as consistent as steel - it can have inclusions and voids which can damage cutting tools. It's also abrasive and will wear tools faster than steel especially if you don't use a lubricant such as paraffin or a light oil.
The other difference to steel is that the swarf is powdery. When tapping make sure that you clear the tap every couple of threads - it's very easy to get it blocked with swarf and snap the tap in the workpiece (been there, done that!)
The other difference to steel is that the swarf is powdery. When tapping make sure that you clear the tap every couple of threads - it's very easy to get it blocked with swarf and snap the tap in the workpiece (been there, done that!)
VicS
Well-known member
Agreed. Drill dry but tap either dry or with soluble oil.
The standard drill point angle should be suitable.
The standard drill point angle should be suitable.
JKay
New member
bit like SWMBO then /forums/images/graemlins/blush.gif
cheers Joe
cheers Joe
VicS
Well-known member
[ QUOTE ]
softer isn't it?
[/ QUOTE ] No, not according to the figures I've got.
Scleroscope hardness: Mild steel 18-25, cast iron 25-45
softer isn't it?
[/ QUOTE ] No, not according to the figures I've got.
Scleroscope hardness: Mild steel 18-25, cast iron 25-45
Lakesailor
New member
Cliff might come along and tell you. But there again.............. /forums/images/graemlins/wink.gif
Andrew_Fanner
New member
Slower drilling speed, use at least one pilot drill which helps to clear the cuttings. When tapping use a tap lubricant and back off every turn or more often. Get the tapping drill size pretty exact.
What size are you tapping?
What size are you tapping?
fluffc
Member
It has a hard crust, which blunts drills quickly and needs quite a 'firm hand' to get through. Once you're through this, the 'core' is as others have described - feels softer but quite grainy swarf - clear out the drill / tap regularly.
Niander
New member
Probobly about 14 mm
FrankieJ
New member
Cast iron is generally easy to machine, but if a casting has been 'chill cooled' it can be as hard as glass and virtually un-machinable. This is unlikely to be the case in normal applications.
Drill it dry and at a slow speed (to prevent over heating the cutting tool) and use HSS. drills & taps.Lubricant may be used for tapping ( Trefolex is good) and compessed air is good for cooling when drilling.
I have used clean water to keep the drill cool when drilling large holes ( like 2 1/2. inch dia.) but it rusts very quickly.
Final tip~~ keep cutting tools sharp.
~~~ A lifetime in machining~~~
Drill it dry and at a slow speed (to prevent over heating the cutting tool) and use HSS. drills & taps.Lubricant may be used for tapping ( Trefolex is good) and compessed air is good for cooling when drilling.
I have used clean water to keep the drill cool when drilling large holes ( like 2 1/2. inch dia.) but it rusts very quickly.
Final tip~~ keep cutting tools sharp.
~~~ A lifetime in machining~~~
cliff
Active member
[ QUOTE ]
Cliff might come along and tell you. But there again.............. /forums/images/graemlins/wink.gif
[/ QUOTE ]Smart ass! Why does he need further advice - so far the advice offered seems reasonable to me however.....
I prefer to use straight flute carbide drills (not HSS) with lots of coolant for drilling, drill in a press drill - not by hand - to maintain medium pressure on the drill. Spiral taps, again carbide not HSS but as most folk will not have access to such tooling Ti coated HSS in a drill press, slow speed, lots of coolant or even compressed air (helps remove the waste and cool the bit at the same time) Keep running the bit out of the hole to cool and clean it, usual comments about pilot holes. For tapping HSS straight flute taps will do but use new ones that are shark and use planty of tapping fluid, backing the tap out every 1~2 turns. /forums/images/graemlins/grin.gif
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
Cliff might come along and tell you. But there again.............. /forums/images/graemlins/wink.gif
[/ QUOTE ]Smart ass! Why does he need further advice - so far the advice offered seems reasonable to me however.....
I prefer to use straight flute carbide drills (not HSS) with lots of coolant for drilling, drill in a press drill - not by hand - to maintain medium pressure on the drill. Spiral taps, again carbide not HSS but as most folk will not have access to such tooling Ti coated HSS in a drill press, slow speed, lots of coolant or even compressed air (helps remove the waste and cool the bit at the same time) Keep running the bit out of the hole to cool and clean it, usual comments about pilot holes. For tapping HSS straight flute taps will do but use new ones that are shark and use planty of tapping fluid, backing the tap out every 1~2 turns. /forums/images/graemlins/grin.gif
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sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
2Tizwoz
Well-known member
jleaworthy
New member
Ashamed to admit this, but when I had trouble getting sufficient pressure to keep the drill cutting whilst drilling the cast iron of my twin keels (later tapped 10mm to fit anodes) I ended up using a masonry drill in my 5kg SDS hand drill set to hammer mode - and it worked. Didn't do the drill bit a lot of good, though.
Heckler
Active member
its lovely to work with drilling and tapping, the carbon content keeps the tool steel happy and lubricated (simplistically)
huldah
Member
If using a masonry drill, I suggest you sharpen it with a diamond sharpener. Many have a poor cutting edge.
Philip
Philip
