Drilling through cast iron

[bb_gb]

I have been asked to bolt down a storm drain grate and I am trying to find a way to secure it without allowing bolt heads or plates to sit above the grate because vehicles may drive over it.

The standard cast iron grate that I need to use is 2" thick. Would this be unreasonable to drill through? Ideally I would like for there to be a 1/2" hole with a larger diameter hole at the top to be able to recess the head of the bolt.

This is not a typical work assignment for me, so I am trying to find someone who might be able to tell me whether or not this is reasonable before I go put it on some plans.

Any advice is appreciated

 

[MintJulep]

"Standard cast iron" really means nothing. Try to get an actual spec on the material.

Having said that:

Given a proper drill press, sharp bit and coolant-lubricant drilling cast iron is straight-forward.

If you need to counter-bore to recess the fastener head then a milling machine would be best.

This is not a job for a hand drill.

 

[SnTMan]

Or you could use a standard flat head fastener and standard countersink in your drill press. Agreed, not happily done with a hand drill, although a mag-drill would likely work as well, given someplace to stick it.

Few holes or lotta holes?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[EdStainless]

I have seen grates fastened down with clips so that there was no drilling.
This might be an option depending on the style of grate.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[racookpe1978]

Even the small "bump" of the head of a carriage head bolt would be inconsequential compared to the rough surfaces of most grates and drains for traffic.

But, yes, the flat head style will be flat, less of a problem than the countersink. The countersink "hole" around the bolt head will trap grit, dirt, mud, ice, de-ice compound, etc. = More corrosion and problems loosening the bolt next time the grate is pulled.

Spec a very large slot for the head.

 

[dhengr]

Bb_gb:
On most cast gratings, where are you going to drill a .5” or .625” round hole without removing at least 50% of that bar’s material section? Then, what are you going to bolt (or drill and tap) into with sufficient accuracy and precision to make your system work, at all four corners perfectly? I agree with EdStainless, and believe that most grating suppliers have several variations on these hold down clips which don’t req’r. such precision for installation.

 

[Tmoose]

"I have been asked to bolt down a storm drain grate "

One grate ?
For anti theft?
To reduce the clatter when vehicles drive over it at speed late at night, outside the mayor's house ?
Would anyone care if it was secured "forever", like no maintenance can be assured for a decade or so?

Depending upon the answers to the above questions, A few possible "solutions" , some costing less than 10 US bux, but requiring a few hours of someone's time, come to mind.

 

[arunmrao]

Theft of cast iron gratings is an universal problem. Depending on the level of security you need there are solutions available. Look for anti theft security bolts.
Have you checked Neenah Foundries website. You can get several clues.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[SnTMan]

I suspect the OP has moved on...

The problem with sloppy work is that the supply FAR EXCEEDS the demand