DeWalt Oscillating multi-tool - type of blades needed to cut through hardened screws?

[Rollerball]

The multi-tool is a DeWalt DCS355N-XJ

The screws are these:

https://www.amazon.co.uk/gp/product/B007MAEH5U/

I tried some EZARC Carbine blades in the multi-tool to cut some excess from the screws (the blades are specifically for hardened metals) - the screws were sticking through a fence which is why they needed their ends cutting off.

But ........ the blades were terrible and blunted after about three screws for each blade (I've been refunded, the blades weren't cheap).

What sort of blades should I use that won't blunt so quickly on such screws? Some from Dewalt's own I guess? But which ones?

 

[TimboTwo]

Angle grinder is your answer.

 

[ETAF]

try saxton tools blades
i use the heavy metal blades and i have cut coach bolts 10mm with those in the past
my be worth calling them to discuss for best blade

 

[big-all]

recyprical saw or hacksaw

 

[cdbe]

Angle grinder is your answer.

 

[big-all]

the biggest problem with oscillating blades is the short sweep meaning about 3 teeth doing all the work so after the first screw you have a comfortable valley with bluntish teeth
the best you can do is sweeping to and fro but because you keep dropping off the side the tendency is to be less adventurous and get hung up in the centre off the blade where as a recip or hacksaw will be many tens more teeth so although far more awkward will be far less blade intensive
and for hardened screws with the recip saw i just use knackered old wood blades and in general you get one or two per blade to the half-- 2/3cut and often a sharp tap on the head or a screwdriver in the side will finish the job

 

[opps]

I once paid £16 for a single Smart Trade 35mm Metal Buster Carbide Tipped Blade.

It managed to cut through the four screws that I purchased it for but on the first screw, I didn't move the oscillating saw enough and the blade lost four teeth within minutes.

As others have said, a reciprocal saw would be better.

As an aside, can't you remove the screws one by one and use bolt cutters to remove the excess before re-screwing. I have done something similar in the past.

 

[Deleted member 174758]

Waste of time trying to do this job with a multitool in most cases - in my experience the right tool is either a Dremel-type tool with an ultra thin metal cutting disc, or failing that a small angle grinder with a thin cutting disc (clumsier, though). In some trades they do use specific cut-off tools (such as the Milwaukee M12COT) which lies somewhere between a Dremel and a 115mm angle grinder. Be aware that the vibration induced by recip saws, multitools, jigsaws, etc can seriously damage more delicate structures (e.g. furniture, etc) and in any case if you are dealing with modern super hard drywall or steel woodworking screws the metal in the fastener is often nearly as hard as a
saw blade, especially cheaper blades

 

[bsr]

Surely it's better and quicker to remove the screw and put in one of the correct length?

Otherwise agree with an angle grinder, if it's fencing not cabinetry then no one will notice a small gouge.

 

[big-all]

Surely it's better and quicker to remove the screw and put in one of the correct length?

Otherwise agree with an angle grinder, if it's fencing not cabinetry then no one will notice a small gouge.

i must admit my brain completely missed it was a fence in my head it was a captive screw cutting between 2 surfaces like a pallet dismantle action but the give a weak point and hammer off still works but as a last choice after screw swap as others have said big grinders'minigrinder 'dremil type tool are far better as scuffed wood can looks carp for at least 2 years till weathered assuming not painted

 

[Deleted member 174758]

Surely it's better and quicker to remove the screw and put in one of the correct length?

Not always possible, though. From personal experience: when installing door handles it is sometimes the case that the screws supplied by the handle manufacturer are a millimetre or two too long. This results in the screw(s) pressing the side of the lock body when the rosette is screwed on place. This can sometimed either immobilise the lock, or at best result in the sprung latch not springing too well. It's all very well saying the handle manufacturer should supply the right size screws, or that we should use screws 2mm shorter, but if the handle/rosette set has come with specific size antiqued bronze or brass screws which aren't ex-stock it will simply never happen. So having the capability of shortening the screw by a couple of millimetres is a godsend. I sometimes come across similar issues when refixing ironmongery onto listed doors, in cases where the original screws are shot and need to be replaced. In that case it may be necessary to substitute modern screws which are a slightly different size, and trim to length to prevent splitting of the wood.

BTW in many cases I am backing the screw out, adjusting and replacing it rather than cuttimg in situ