I have a decent, but fairly standard, DeWalt drill. I was going to buy this attachment so that I can drill a hole in a metal shed (to install a fan): https://www.amazon.co.uk/Bi-Metal-Circular-cutting-Aluminium-Plywood/dp/B0C5S2SLNB/ref=sr_1_1?crid=33ZWDR8LTKVEX&dib=eyJ2IjoiMSJ9.ARPeSrNGQMPRNfjzQ9nT8LphOneBxp2bq77vCw3dNc09_eghTYXsvasiAUgoqvNZIFu6aPsLXKQQ1YeOPkiAFgNe3dYxf3f0-Nlf3FL7pXrjp3ElUq7r0i18Y6Cv-O6IBGyYsyqILTHtRZ8C2H4wTDvop6UaSS9o6pk0XcKDbiuXyBLFFjsDmbMt7IHB7xKmbgz5r1WS1uh902DLQGyFKtHAOwoGlU2tBaBHlxfIWQfZI6BicmWDDXsLcSKDS8WY9_fD3tHAQMYy3JjmNH2nNzAD8RbRTiaoj1tFVE29kaE.bDwPej6-V36XehdviYliDWy8assgN-rpKps7FC_sPjU&dib_tag=se&keywords=hole%2Bsaw%2B105mm&qid=1709312139&sprefix=hole%2Bsaw%2B105mm%2Caps%2C90&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

 

Will this go straight into my drill, or do I also need an arbor, which appears to be the case with competing products, such as this one from Screwfix: https://www.screwfix.com/p/erbauer-multi-material-holesaw-102mm/42986#product_additional_details_container

 

I'm totally clueless, this will be the biggest hole I have ever drilled. What does an arbor do?

Edited March 1, 20242 yr by Adsibob

It looks like the ebay one comes ready to go.  Be warned that these can sometimes catch in the material and twist your wrist.  When it starts cutting, just adjust the speed and pressure so it makes decent progress and clears away as it goes.  You will see when you have the right balance of pressure and speed.  Wear goggles too as an eyeful of swarf is a bit uncomfortable.

You need the arbor which the one from Amazon includes. You need to buy it separately for the one from Screwfix. Don’t be tempted to cut quickly, go nice and steady. 

The teeth on that one look a bit coarse to me for cutting metal.

Your first link is a complete hole saw that will fit the drill and get you going.

your second is what trades generally use, so you can swap out hole saws and arbours when individual parts wear

Remember to get some cutting liquid, squirt of WD40 

 

easier if someone else sprays the the saw while you hold on with 2 hands!!

if the drill has a clutch use it

Both your options will probably do the job. Personally I'd opt for something from the likes of Starrett, like this one made for sheet steel: https://www.amazon.co.uk/Starrett-FCH0400-102-Hole-Saw/dp/B01AWFCKDM?th=1 together with the appropriate arbor: https://www.amazon.co.uk/Starrett-Quick-Hitch-Arbor-Extra-Length/dp/B001LF8F0A?ref_=ast_sto_dp

 

50 minutes ago, Adsibob said:

What does an arbor do?

 

The arbor holds the hole saw in place, allows you to attach it to the drill and it drills a pilot hole in the centre of the hole and acts as a guide.

 

For the size of hole you're looking to make, use a slow speed on the drill and be patient.

 

A little cutting fluid like CT-90 can also help to prevent heat build up and eases the whole operation a little bit.

If you mean metal cladding about 1mm thick then I have used very ordinary 110mm hole saws from toolstation. One use and throw away. That was on high quality steel cladding. Most is softer.

Yes, as above, beware of wrist wrenching, especially if it isn't  a flat part of the sheet. If you could find a saw with smaller teeth and made just for metal then  it would be easier, but they cost a lot more.

Yes, you need an arbor. It has pins that lock into holes in the base of the saw. Your link shows the cutter with an arbor but it will be extra.

Thanks guys. Can’t figure out from the source how thick the metal is. It just says: “made from strong, thick, galvanised steel, which means it is rust-resistant”. 
 

The overall weight is 99kg and there is 9.23m^2 of material in total.

 

 Average density of galvanised steel is 7850kg per cubic metre. That means I have 99/7850 of a cubic meter of steel

 

 so thickness is about 1.4mm thick. Does that sound about right?

 

 Obviously calipers would be useful here, but I’m saving up for some hole cutting tools…

Is this your bike shed?

 

Just get the cheapest hole saw and it will be fine.

No need to go overboard with this.  It is a simple job as you will find out, in about 30 seconds of starting.

I have used those Amazon ones on wood and @saveasteading is right, mind your wrist, if(when) they jam they kick like a mule.

9 hours ago, Adsibob said:

Thanks guys. Can’t figure out from the source how thick the metal is. It just says: “made from strong, thick, galvanised steel, which means it is rust-resistant”. 
 

The overall weight is 99kg and there is 9.23m^2 of material in total.

 

 Average density of galvanised steel is 7850kg per cubic metre. That means I have 99/7850 of a cubic meter of steel

 

 so thickness is about 1.4mm thick. Does that sound about right?

 

 Obviously calipers would be useful here, but I’m saving up for some hole cutting tools…

0.5, 0.7, 1.0 & 1.2mm are the most common thicknesses. 0.7mm being mostly used. I would hazard the crenulations increase the surface area so probably 1mm thick.

Thicker sheets are often softer metal so it should be ok.

 

45 minutes ago, George said:

crenelations increase the surface area

Quite a lot. And the overlap. So 1mm or so seems likely.

 

Professional cladders would cut this with snips but it is a great skill. Another option is to use a nibbler. Again takes practice. So try the hole cutter. Start slowly.

Use the hole-saw (Erbauer one will be a stronger option) to first drill a template hole in some waste material such as 12/15mm plywood / OSB. Then, lay that on the item to be drilled, with a knee on the wood or clamps. Use that to prevent the hole-saw from 'departing' and use high revs / little downward pressure. Bobs your Uncle, no need for Fanny.

The critical thing is to keep the saw at 90o to the workpiece, and do NOT stop drilling until you are 100% sure you are through the metal. A good option is to put timber under this so you have something other than air underneath the cut (keeps the saw trained right the way through the cut)