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T

Toneyz

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Is it me or when you have used a drill bit (especially metal) they are blunt same with hole cutters.
 
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ipf

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It depends on the standards of both the bits and the metal.
Certainly, bit standards aren't what they used to be, though....as with most other things, production costs leading to degradation.
 

Megawatt

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Is it me or when you have used a drill bit (especially metal) they are blunt same with hole cutters.
Anthony are you using oil to keep the drill bits cool while you drill. They will last a lot longer, but a lot of the cheap drill bits and hole cutters aren’t worth buying
 
T

Toneyz

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It depends on the standards of both the bits and the metal.
Certainly, bit standards aren't what they used to be, though....as with most other things, production costs leading to degradation.
Usually dis.boards trunking etc. but had to drill mild steel you could see it drilling with the swarth coming off then nothing.
 

Andy78

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As above, the quality of the drill bit is key. If they are blunt after first use then they are quite clearly garbage.
Presto jobber bits used to be the standard all purpose bits of good quality when I worked for a firm.

My daily set is a Milwaukee set which are lasting nicely and by no means expensive

I also find cobalt mix bits have a good life for metal use, Armeg do a thin wall cobalt mix hole cutter which is a decent product.
 

freddo

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For holes >20mm in metal enclosures I mostly use a hydraulic punch set. For quick conduit size holes the Armeg acceler8 holesaws are great, we were using them on stainless steel enclosures last weekend and they worked fine. Smaller holes I just use a cheap set of HSS bits that come in a case with about 10 of each size. I have a little grinding tool thing that is connected to a drill to sharpen the blunt ones.

I also have a set of DeWalt drill bits for very special occasions, they seem to drill all types of metal with no problem, the larger bits have a tip of a smaller size to automatically drill a pilot hole before the full size hole.
 
For holes >20mm in metal enclosures I mostly use a hydraulic punch set. For quick conduit size holes the Armeg acceler8 holesaws are great, we were using them on stainless steel enclosures last weekend and they worked fine. Smaller holes I just use a cheap set of HSS bits that come in a case with about 10 of each size. I have a little grinding tool thing that is connected to a drill to sharpen the blunt ones.

I also have a set of DeWalt drill bits for very special occasions, they seem to drill all types of metal with no problem, the larger bits have a tip of a smaller size to automatically drill a pilot hole before the full size hole.
Have noticed with hole saws,it seems better if you stop and start the drill while drilling and always use oil.I mainly drill stainless,so mild steel is easier.Regards S.
 

Strima

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If it's squealing you're ****ing it... Slow and steady with plenty of lube, there's an insinuation in there somewhere...
 

freddo

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Stainless is a pain, slow speed and cutting oil. Once the drill bit starts to blunt it's game over.
I can't recommend cutting oil enough, I use a little Eagle 66 oiler to apply it. Makes drill bits last so much longer.
 

davesparks

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Is it me or when you have used a drill bit (especially metal) they are blunt same with hole cutters.
There's quite a science to drilling a hole in metal and getting maximum drill life and efficient drilling.
Some materials require lubricant to drill them, cutting oil for steel, wd40 for aluminium whereas other materials such as cast iron are self lubricating due to the high carbon content.
Running the drill too fast will wreck it, generally the bigger the diameter the slower the drill should be.
Drills work their best at specific cutting rates, cutting too little material at once can blunt them so a lack of pressure on the drill can kill the drill bits, but too much pressure can kill them too.
 

Megawatt

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There's quite a science to drilling a hole in metal and getting maximum drill life and efficient drilling.
Some materials require lubricant to drill them, cutting oil for steel, wd40 for aluminium whereas other materials such as cast iron are self lubricating due to the high carbon content.
Running the drill too fast will wreck it, generally the bigger the diameter the slower the drill should be.
Drills work their best at specific cutting rates, cutting too little material at once can blunt them so a lack of pressure on the drill can kill the drill bits, but too much pressure can kill them too.
I’ve heard that from the older guys I used to work with when I got into electrical maintenance during the late 70’s and it works great but like you said if you go wide open to drill you will ruin that bit quick
 
B

Bobster

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If you look at recommended speeds for most hole saws from manufacturers, a battery drill simply can't run slow enough.

I see it all to often people going like hell thinking it'll drill faster, actually counter intuitive for most metals. Slow an steady will go faster and preserve the tooling.

This is especially true with stainless, once it heats up, it work hardens and then most, even cobalt drill bits wont touch it. The amount of hole saws I've seen with their teeth melted is laughable.
 

davesparks

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If you look at recommended speeds for most hole saws from manufacturers, a battery drill simply can't run slow enough.

I see it all to often people going like hell thinking it'll drill faster, actually counter intuitive for most metals. Slow an steady will go faster and preserve the tooling.

This is especially true with stainless, once it heats up, it work hardens and then most, even cobalt drill bits wont touch it. The amount of hole saws I've seen with their teeth melted is laughable.
As well as the usual fast, high torque battery drill I've got a cheap (£30 bare unit) makita battery drill to go with it, it runs a lot slower and has less torque so runs hole saws better with a lot less grabbing and trying to rip my arms off.
 
T

Toneyz

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There's quite a science to drilling a hole in metal and getting maximum drill life and efficient drilling.
Some materials require lubricant to drill them, cutting oil for steel, wd40 for aluminium whereas other materials such as cast iron are self lubricating due to the high carbon content.
Running the drill too fast will wreck it, generally the bigger the diameter the slower the drill should be.
Drills work their best at specific cutting rates, cutting too little material at once can blunt them so a lack of pressure on the drill can kill the drill bits, but too much pressure can kill them too.
Some good advice there Dave thanks.
 

Timbo

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20190823_221915.jpgJust bought 2 sets of Metabo 1 - 13mm, 25 piece, for £5.99 + VAT each. Disposable at that price.
toolstoreuk.co.uk
 
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I use steel conduit cutting compound on the hole saw when drilling steel.
Massively increases hole saw life.
 

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