Can I drill holes in 3/4 inch steel at home?

[geeks]

I am in the midst of building an observatory at home. I have an adapter for my concrete pier that I was intending to put my telescope mount on however I believe that the holes already drilled in it are too close to the edge of my pier and I risk the concrete around the securing bolts (M10) cracking as they would be about 11-13mm from the edge of the concrete. I have room on the plate to drill some fresh mounting holes but that brings me to my next conundrum, how do I drill three M10 sized holes in 3/4 inch thick steel? I don't have a pillar drill (I do want one but alas this will have to wait) but I do have a decent mains powered drill, I have the right size bits and could step up from smaller to bigger holes as I drill it and I also have stepped drill bits too. Is this something I can diy with what I have or am I best just finding a local machine shop to drill them for me?

[ARHarh]

Keep the drill at right angles to the material this is the biggest mistake people make drilling holes, and why drilling on a pillar drill is easier. Next most common mistake is too fast a speed, then forcing the drill bit through the material.

Start with about 6mm hole, drop or 2 of oil, medium speed on the drill and let the drill bit cut do not put all your weight on the drill. next 8mm then 10mm, or 10.2mm. And clamp the part to something solid so when it catches it doesn't hurt so much.

[Griffith4ever]

20mm mild steel should be doable.

I'd start with something smaller like 6mm, then go to 8, then 10.

You want to drill very slowly, so careful with a mains power drill.

Cutting fluid like CT90 helps a lot.

I think, for 20mm, I'd want a magnetic pillar drill, personally. Perhaps you can hire one?

Random search: https://www.vevor.co.uk/magnetic-drill-c_11000/md4...

[zarlak]

Hire a mag drill:

https://brandonhirestation.com/tool-hire/drilling/...

[zarlak]

Perhaps you can hire one?

Random search: https://www.vevor.co.uk/magnetic-drill-c_11000/md4...

[/quote]


Beat me to it!

[21TonyK]

Local small engineering firm? I've got a guy on my local industrial estate who does simple things like that for a few quid.

[geeks]

Not sure a mag drill would work for me as the plate I am drilling into is only 8" in diameter. Here are some pics of what I need to drill. You can see the existing holes in there already and I can only guess the previous owner had a 10" diameter pier, mine will only be 8" in diameter as that is what I allowed for when I put the spec together. Changing to a 10" pier isn't an option now.

[Collectingbrass]

I would find a proper garage or workshop to take that to and pay them to do it. Holding it still while drilling will be a bugger and needs the right gear.

[goldar]

This is best handled with a pillar drill. You could potentially use a drill guide with a hand drill if that's all you have.

Edited by goldar on Friday 16th September 13:11

[dingg]

Alternatively get a strip of 4" wide brass made into a ring that is a tight fit slid over the top of the post.?

Or cut a section from 8"id brass pipe if you can locate some.

[R56Cooper]

Can't help with your question but an observatory sounds fascinating.

Any chance of a build thread?

[CubanPete]

Griffith4ever said:

20mm mild steel should be doable.

I'd start with something smaller like 6mm, then go to 8, then 10.

You want to drill very slowly, so careful with a mains power drill.

Cutting fluid like CT90 helps a lot.

I think, for 20mm, I'd want a magnetic pillar drill, personally. Perhaps you can hire one?

Random search: https://www.vevor.co.uk/magnetic-drill-c_11000/md4...

Probably only need to go to 8 to then tap to M10!

Hammer drills often have wobbly chucks!, sharp drills, bit of oil, 'peck' to remove swarf. I would maybe even start with something smaller, and not drill the whole way through with smaller drill to reduce risk of snapping. Should be more than doable.

[Griffith4ever]

1st thing to do is take it apart so you have the base disc on its own.

I could do that if you were near me on my pillar drill in short order.

Perhaps it's time to buy a pillar drill! :-) (well, drill press. Rare you need the whole stand)

[geeks]

Collectingbrass said:

I would find a proper garage or workshop to take that to and pay them to do it. Holding it still while drilling will be a bugger and needs the right gear.

I had assumed as much but there are plenty on PH who can be quite inventive to come up with ways of doing things like this, never hurts to ask first.

goldar said:

This is best handled with a pillar drill. You could potentially use a drill guide with a hand drill if that's all you have, but you won't be able to fit a 19mm bit in a hand drill chuck - the same applies with the pillar drill, you'll need a 'proper' one to be able to handle a 19mm drill bit.

Edited by goldar on Friday 16th September 12:54

Isn't M10 11mm?

dingg said:

Alternatively get a strip of 4" wide brass made into a ring that is a tight fit slid over the top of the post.?

Or cut a section from 8"id brass pipe if you can locate some.

Interesting idea I had considered using a brake disc mounted to the pier then mounting this to that but it starts to get a bit of a faff when all I need are a few extra holes (fnarr)

R56Cooper said:

Can't help with your question but an observatory sounds fascinating.

Any chance of a build thread?

Yes, one will be going up in a week or so

[Griffith4ever]

M10 bolt needs a 10mm hole. 11mm hole just means you won't have to be so crazy precise when lowering it onto all three bolts.

Not sure where Goldar's 19mm drill bit comes from? )edit - ahhh! he's edited it!)

Edited by Griffith4ever on Friday 16th September 13:20

Edited by Griffith4ever on Friday 16th September 13:20

[tendown]

You're worried about cracking the concrete with the fixings close to the edge, what kind are they?

Could you use resin to fix the m10 studs in and not crack the concrete?

[InitialDave]

I've drilled a 14mm hole about 30mm deep into steel with my normal rechargeable DeWalt drill, so I think you'll be fine. As others have said, decent drill bits, go up in size in stages, don't overdo it on rpm, and use a bit of cutting oil.

[hairy v]

R56Cooper said:

Can't help with your question but an observatory sounds fascinating.

Any chance of a build thread?

Yes please OP

[Roger Irrelevant]

Another vote for 'try to find somebody with the right kit and ask them', at least in the first instance. I'm quite fortunate in that there's a steel fabrication place in the next village that will do small jobs like this even though their real speciality is making big stuff like barns. Turn up with three bottle of Old Peculier and they'll drop everything for you!

[classicaholic]

Its a few minutes of a job on a decent pillar drill, if you were closer we could do it for you, the other option is to get a new plate made as a laser cut profile, plenty of people doing that on the web & ebay and it just arrives in the post!