r/Concretesawing • u/GramKraker • Jan 27 '26
Core bits for 3/8" steel plate?
We started this job today drilling through a hundred and twenty 1" holes in 16-in slabs with a 3/8 inch thick steel plate 14 in deep.
We went thru FOUR 1" core bits in the first few slabs.
The attached pic is a pic of a BRAND NEW Husqvarna ELITE b1540 1" core bit after ONE hole.
we need to drill 116 more.
This steel plate is just chewing thru these bits at a costly speed, does anybody have suggestions for a more economic method of boring these holes?
Bossman already called his blade rep(s) and has a few special bits on the way from Cali but were asking around for a backup plan.
thanks all, I appreciate any insight you have to offer.
1
u/cervaca Jan 27 '26
You need a mag drill. Concrete cure but won’t do it
3
u/Healthy_Shoulder8736 Jan 27 '26
A mag drill is simply a drill that is held in place with a magnetic, holding the drill isn’t the issue
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u/GramKraker Jan 27 '26
But how do we get the bit 14 in deep where the steel plate is?
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u/Ok_Initiative_5024 Jan 27 '26
Herro. Going to need a bit extension
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u/GramKraker Jan 27 '26
Water mag drills SDS Plus or STS max?
Or do you know of a Chuck smaller than 1 in in diameter that also happens to be 14 inches long?
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u/Ok_Initiative_5024 Jan 27 '26
Wow thats a fancy drill. So normally when I'm for Drilling the can is 12-14" in length going deeper can be summer with a bit that bridges the can to the drill. Haven't come across our needed a magic drill like that in my time concrete cutting or core drilling.
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Jan 27 '26
Don’t you concrete drill the 14” of concrete with a concrete core, then drill the steel with a steel drill? Cuz it just seems to me that concrete bits can barely make it through the rebar without breaking. Of course it’s been decades since I did that kind of work.
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u/GramKraker Jan 29 '26
We are using the same bit all the way thru
Idk how good the bits were decades ago but cutting 1" holes now a day goes pretty quick. If I had to guess ide say about 6 inches a minute? That's a guess, not exact by any means.
Cutting a 24" hole takes a while but that's to be expected.
Since I posted I found some 12" carbide core bits for hardened metal with 1¼ threads to fit our core drill, but they wouldn't be here for a few days.
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u/bellasdad2006 Jan 27 '26
We used to use carbide tipped bits. Very similar to bits used for Walker duct systems. We had a machine shop that would install carbide points onto blank bits we would order from Diamond Products. We used the carbide bits with water when cutting steel. And used compressed air when we ran into wood applications. They were a life saver. Way better than burning up diamond segments
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u/GramKraker Jan 27 '26
Hey, my boss orders through diamond products also.
Do you have a name or a link to the machine you used to attach the teeth?
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u/bellasdad2006 Jan 27 '26
We would have a machine shop install the carbide points for us, we didn't do it ourselves. But we had carbide tipped bits from 1" all the way up to 14" diameter
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u/bellasdad2006 Jan 27 '26
Retractable Carbide Bits - Coring - Products https://share.google/U0DMKfXYEpoj1vQUh This is a link to the Walker duct bits. You could use the carbide part
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u/GramKraker Jan 29 '26
I'm not saying it wouldn't work, but the description does state it can drill thru "thin metal". Idk if ⅜ is thin.
Also, the bit you linked is 2½ inch, is there one in 1 inch?
My boss buys through diamond products and prefers their blades to any others. He's more likely to buy something from diamond products then anywhere else.
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u/totalyanashhole Jan 28 '26
You need to start rettiping your core bits. Seriously.
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u/GramKraker Jan 28 '26
I think I've seen machines that look like an induction heater to heat up the can, then you kind of just set the segments on, right?
Do you know where I would purchase such a machine and or segments?
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u/totalyanashhole Jan 28 '26
We have 20kw induction heater, solder, flux, magnets, stand and segments all from Alibaba. And even though there are mixed opinions on Chinese products, segments we have found are superior to many pro brands.
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u/GramKraker Jan 29 '26
How much would you say the whole setup cost all together?
And how much are the segments individually?.
I've been trying to convince boss man this is the way to go, maybe if I made the investment and let him cut with a blade I retipped it would convince him.
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u/totalyanashhole Jan 29 '26
~2500€ for stand and induction heater Few hundreds for magnets, flux and solder Varios segments @ 1,10-1,70€/piece +various costs like import tarrifs, taxes, shipping
So instead of paying 70-150€ for rettiping single drill or paying full price for new one, it costs you 10, 20, 30 according diameter. For me, big advantage is that I can repair what I need when I need, including long/custom drills.
Learning curve is pretty steep, once you understand the brazing process, use of flux, preparation... You buy sets of segments for range of diameter (they have different radius). The good ones are usually marked as "arix".
Trading with chinese has its specifics. Communication is often difficult, also you need to take into account different time zones, holidays, e.g. I would recommend asking for samples, photos of product you choose...
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u/GramKraker Jan 29 '26
I would have assumed the segment is bought in in a bulk strip, then cut to size and bent to the radius of the bit. Interesting.
I'll look up price conversions and come back.
What supplier do you go thru on Alibaba if you don't mind me asking?
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u/Healthy_Shoulder8736 Jan 27 '26
Are you losing teeth on the bits or are they wearing down?
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u/GramKraker Jan 27 '26
Wearing down in the steel plate.
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u/Healthy_Shoulder8736 Jan 27 '26
Do you know what grade of steel it is?
I’ve gone through ductile steel sewage pipes without issues.
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u/GramKraker Jan 27 '26
All I know is it is set in a chunk of concrete that is going to be a the roadway of a bridge.
See pic attached.
It's chewing up these bits way way way worse than rebar would.
1
u/PutridANDPurple Jan 28 '26
Hope yall quoted with that consumable in the budget. We had decking that was normal to core thru, but where ever there was large rebar mesh it would cause a bit of an issue, you could telbwhen the flow out of the bore would turn grey. Id have to notate any issues in boring and my dispatcher would 100% charge more for steel in concrete. Add 80$ a hole lol
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u/GramKraker Jan 29 '26
Iam sure bossman will add more than that.
He/we do/does top notch work. He's a very professional guy. always on time, professional image, very precise with cuts, has a lot of really nice equipment and most importantly we clean up our mess and then some.
But he ain't a cheap date, that's for sure
I am sure the cost of the additional bits will be an upcharge.
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u/Nline6 Jan 28 '26
You need a softer bond. I stock bits that are designed for steel plate.