Drilling cast iron.

[Gary]

I need some help with my next project. I have a Clarke drill press with what is described as a wet table. The table is cast iron with no holes or slots.

To increases the use of the drill press I intend to build a work table, lets say 600mm by 350mm.

The question is this. What is the best way to drill the cast iron?

Yes I know a drill and bit would be a good start. But what I am really asking is whats the best type of drill bit for say an 8 to 10mm hole and would you recommend the use of any lubricant?

Thanks

Gary

 

[Jake]

It drills very easily - use a normal HSS jobber bit, and some light oil or white spirit or something. This may not be best practice, and someone may well give a better solution, but it works fine (even without any lubrication at all, in my lazy experience).

 

[Colin C]

One small bit to add is to start with a small bit and work up to the size you want.

 

[Gary]

Thanks Guys, unless anyone says otherwise I'll go with that.

Gary

 

[Nick W]

Just cover-up everything in the vicinity well, and clean-up afterwards well too (where's my command of the English language gone today? 8-[ ). Any machining operation on CI tends to get very messy.

 

[Gary]

Get what you're saying Nick. May be worth using the workmate outside the shop then?

Gary

 

[Nick W]

Gary,

Yes - if you want a rusty garden :shock: .
Seriously there's no need to go to those lengths, just have a good hoover up afterwards

 

[Scrit]

When I did metalwork at school decades ago the standard instruction was:

Cast iron - dry, just drill slowly and blow with air if possible as it gets hot
Maleable cast iron - soluable oil
Mild steel - tallow os soluable oil
Carbon steel, silver steel, etc - paraffin or mineral oil
Brass - dry
Aluminium - paraffin or soluable oil

By soluable oil I mean the (rape-based) vegetable oil mixed with water and designed for use as a lathe coolant.

Funny how you remember these things after more than three decades....

Scrit

 

[jasonB]

Grey cast iron can be worked dry as the graphite contained in it acts as a lubricant. As you work upto the larger size of bit reduce the speed and make sure you don't get a snatch as it breaks through.

Proper soluable oil is not not the same as diluted vegitable oil but it may well do the job if you dont want to buy a 5gal can of it, think mine will last a lifetime

Jason

 

[Hitch]

It will drill very easily with a sharp bit. As Jason said, it contains graphite which makes it a self lubricating, so no coolant will be needed.

Be carefull how you centre punch it though!

 

[omega1]

Hi

Instead of drilling the table could you not use 'T' slot nuts that are used to secure vices and other items to wet tables.
Just a suggestion so you wouldn't have to drill the table.

Cheers karl

 

[Project88]

Hello Gary,

I have a Clark metalworker drill press for which I have made an aux' table.

I attached mine to the cast iron table using some 'L' shaped oak blocks shaped rather like table top attaching buttons. These wrap around the edges of the cast iron table and clamp up with a screw down through the axu table into a tee nut in the oak. If I had figured out how to attach photo's I would attach one :?

For your info I drilled a matrix of 6.5mm holes in the aux table on 85mm centres and inserted more tee nuts from underneath. I can insert M6 studding into the tee nuts and clamp down just about any shape or size of work. This has worked well for me.

Cheers,
John.

 

[Gary]

John

I have sent you a pm about this let me know if it doesn't arrive.

Gary

 

[Bean]

Gary
All good advice so far,
Start small and build up in hole size, do not go up in 1/2mm's as the drill will snatch go up in 2 or 3 mm steps it is just easier to push the drill through that way.
I would not use any coolant, iron can and will get hot when you drill it, a squirt of coolant can and will chill the iron, you will find it very difficult to drill after that.
Put a piece of scrap wood underneath the table as it will help to prevent breakout when the drill breaks through.
The table may not be quality iron so expect a little difficulty in drilling, but it should not be that hard.

Bean

 

[Gary]

If I were to go the T slot nout route where can I buy them. No joy with Ebay.


Gary

 

[PowerTool]

Axminster do "T" track and nuts/bolts

Andrew

 

[Bean]

Gary
Measure the T slots the width and depth. If my mind serves me right there are 3 sizes. Armed with the dimensions of your T slots go to machine mart or any engineering supplier's ( loads in yellow pages) trade counter. They will stock them. RS also stock them as do cromwell tools and axminster. You can buy online from the 3 above.

As an alternative you can find some steel stock which fits into the bottom of the T slots, then drill and tap a hole for the screw/bolt to go through. Cheap and Cheerful solution.

Bean