Grinding metal - "gouging" better than "plunging"...

[skotl]

Interesting vid from Jason @ fireball

I must admit that I knew how this was going to go, but didn't think the results would be so extreme. "Plunge" cutting (going straight through the material) is three times faster than "gouge" cutting (where you take a little off the surface each pass).
However the cutting disc lasted ten times longer for gouging than plunging - six cuts vs. 60 - quite the saving.

 

[Screwdriver]

Yeah I was surprised by just how much difference it made - about ten times longer lasting!

 

[JEZGUZ]

He even had a guard on the grinder too

 

[Sean64]

This guy has an amazing workshop

 

[Pete.]

This is no secret to concrete cutters the reason is similar but not exactly the same. When you're using a diamond saw blade to cut concrete quite regularly you'll find yourself cutting along a rebar - you don't (usually) know where they are within the concrete after all and even if you did they are often running slightly off-parallel to the cut so avoiding them is difficult. You can run up and down the bar a few mm at a time but it's MUCH quicker to take a deeper, slower-moving cut and do it in one pass, if you have the power. The reason is that the point loading on the blade is very high when the power of the saw is concentrated in one small area whereas it's spread around more of th circumference when taking small cuts. Higher point loading = greater erosion and faster cutting. Also less heat input into the metal.

 

[James1979]

He even had a guard on the grinder too

That’s what surprised me the most!

 

[mtt.tr]

I'm surprised that this is surprising,

 

[8ob]

I'm surprised that this is surprising,

Thin discs never cease to amaze me, if they made grinding discs from the same material they would last a lifetime

Bob

 

[nickk]

I think you need to factor in glazing of the disc,where the disc can’t cut because new sharp grains of the medium are no longer exposed,often leading to the operator pushing,it then becomes necessary to cut where there’s a thru cut situation,eg,part of the disc at the bottom is in fresh air,with less heat build up,the disc can wear away,exposing new grain material with the consequences of quicker wear rates.

 

[Dcal]

Thin discs never cease to amaze me, if they made grinding discs from the same material they would last a lifetime

Bob

I have one of those grinding discs.
It's a Kingspore and completely useless for the reasons given by @nickk above.
I also think it's the reason my 30 year old Hitachi 9" grinder let out the magic smoke.

For thin cutting disks the Pferd EHT range are utterly amazing.

 

[Barking Mat]

Thanks @8ob , clearly missed this thread.

 

[Migmac]

My old boss used to give us real earache if we plunge cut. I didn’t realise how much more cutting we got from gouging.

 

[Memmeddu]

TBH
I "gouge" the cut till I'm confident that the disc will go straight plunge cutting.
I've never found any difference ,I believe it would depend upon material thickness and wheel quality.
I don't cheap on cutting/grinding wheels or drill bits

 

[Lewis_RX8]

TBH
I "gouge" the cut till I'm confident that the disc will go straight plunge cutting.
I've never found any difference ,I believe it would depend upon material thickness and wheel quality.
I don't cheap on cutting/grinding wheels or drill bits

In test he used Pferd discs so high quality and they were better for gouge cutting