Cutting box section

[dan.taylor.1]

They don't get anywhere near as hot when you let a GOOD disc do the cutting and don't lay into it.

The cutting I was doing was a notch in a piece of plate I'd made a hole in. But also have had to lop off the end of a piece of digger bucket edge to make it into a log splitter blade, that stuffs about 20mm, 9" made it no problem. I've cut 45mm round bar with my 9" to make new pivot pins for a few machines, ideally that's a bandsaw job, which is no use in the middle of a field running off a genny.

Dan

 

[Kent]

Yes Bill its like the guy with the spoon really isn't it now. You really need some gas bottles to cut that and pre-heating shouldn't go a miss either if you planning to weld that 1" plate into a bucket

 

[Kent]

They don't get anywhere near as hot when you let a GOOD disc do the cutting and don't lay into it.

The cutting I was doing was a notch in a piece of plate I'd made a hole in. But also have had to lop off the end of a piece of digger bucket edge to make it into a log splitter blade, that stuffs about 20mm, 9" made it no problem. I've cut 45mm round bar with my 9" to make new pivot pins for a few machines, ideally that's a bandsaw job, which is no use in the middle of a field running off a genny.

Dan

Get a chop saw, ideal for the pin job on site and don't cost a fortune, also good for box. Sure its an abrasive wheel one I use and in a toss up between an angle grinder and the chop saw its no contest. 240 v 13 amp matabo,very recommended were a bandsaw aint practical.. remember the motor is not through a right angle gearing and the discs are far bigger / faster running with no kick back to worry over !

 

[dan.taylor.1]

I have a tct chopsaw now, didn't back then though.

 

[Wallace]

An essential item for cutting straight or 45 degrees cuts
http://www.spiritburner.com/fusion/fbbuploads/1299584980-Grinderstand.jpg

I had one of those for occasional use with a 9" grinder, needed squaring up everytime the grinder was removed and refitted so I ended up with a cheap grinder permanently fitted. Worked well enough but you end up with stacks of discs that still have a little bit of life left in them you can't bring yourself to throw away and a lot of mess to sweep up!

 

[fixerupper]

The abour on my 9inch grinder is the same size as my mini grinderette , so discs used on one get to live again .....result ...jeff...

 

[rich r]

Surely if you're using a slitting disc correctly in a grinder, then there's barely any load on the bearings and motor as you're letting the disc do the work, not forcing it through the metal? There should only be light pressure enough to keep the disc in contact with the surface.

 

[MattF]

I just plain disagree on cutting thick plate
you guys should feel how hot the mechanism gets on a 9" after a reasonable cut. You just cant cut much with a 4 1/2" before the disc is all used up anyhow.

I am wondering actually why anyone should need to cut 20mm plate with a grinder? sure you might need to put a chamfer on it or take a corner off here and there with a grinding wheel but actually put a cut in, nah that's got to be bad measuring Order it the right size to begin with next time

Anything gets warm during use. If you're getting something too hot, it's generally your technique or a poor choice of machine, and not the machine itself which needs sorting. Any form of cutting tool should be worked at or below its optimal rate. You try ploughing through more quickly and you'll obviously do neither the cutting tool or the machine any favours. As much as I dislike grinders for anything, even to me it sounds like you're arguing the toss on this point just for the sake of arguing, seeing as multiple people are obviously using them successfully in this scenario.

 

[mr migwire]

4 1/2 inch grinder with a 1mm inox cutting disc is my weapon of choice, the trick is to let it do the work and dont force it. thin cutting discs in a 9" are ok but flex a bit, i cut the 3/8 plate for my work bench with the 4 1/2. slow and steady ......
for pipe, box, square and round stock most of it goes in the cut-off unless fancy angles are involved, hoses for courses i suppose.....

 

[Kent]

Anything gets warm during use. If you're getting something too hot, it's generally your technique or a poor choice of machine, and not the machine itself which needs sorting. Any form of cutting tool should be worked at or below its optimal rate. You try ploughing through more quickly and you'll obviously do neither the cutting tool or the machine any favours. As much as I dislike grinders for anything, even to me it sounds like you're arguing the toss on this point just for the sake of arguing, seeing as multiple people are obviously using them successfully in this scenario.

Perhaps, but you say it yourself "poor choice of machine" its not just the wear on the machine itself ( it don't really matter if its Bosch, Makita, De-walt or Parkside they all do the same thing when working) there are also accuracy of cut (which brings me back to cutting box section) who the heck wants to try and put a frame together if the cuts aint great to begin with, not me to be sure. Then the safety aspects of using the wrong tool for the job at hand, I have only got bitten once by a grinder and mine wasn't too bad (index finger about 22 yrs ago and I still have the white scar line) but I have seen two others get bad ones, both requiring a stay in hospital and yes both were pushing the limits of what you should undertake with a grinder. Don't get me wrong though, like I say I have just been cutting 2 ft x 4 ft holes in 5 mm plate sides of a boat using a nine inch Makita and cutting wheels this past week. A little plasma might have been ideal for this job but then there is the little compressor to go with it and the need for a 5mtr plus extension to domestic 13amp supply etc. and how much work will I get for such a thing?
Now when I needed some 40x40x4 RSA chopping up for braces what you think I did cut it with the grinder of my portable chop saw 355 mm blade and no kick back, almost entirely guarded blade in use at only 20% more than an equivalent 9" grinder in cost but infinitely more accurate and speedy at cutting box section (the thread) its a no brainer its the right choice of machine, you can even hire one if its just a one off at home

 

[fixerupper]

What is this kickback of which you speak ?.......Imho it's very hard to get kickback using a cutting disc in an angle grinder cos' the cutting disc is a disc .so the angle of cutting is always the same ie a tangent , and it ain't like a chainsaw that might be blunt ....You might get kickback if you move the cutting point past the centre of the spindle . ....I've used grinders of all kinds for near on 40 years never hurt me self ....jeff..

 

[Kent]

What is this kickback of which you speak ?.......Imho it's very hard to get kickback using a cutting disc in an angle grinder cos' the cutting disc is a disc .so the angle of cutting is always the same ie a tangent , and it ain't like a chainsaw that might be blunt ....You might get kickback if you move the cutting point past the centre of the spindle . ....I've used grinders of all kinds for near on 40 years never hurt me self ....jeff..

what can I say you can get kick back from pinch and all sorts of other stuff, even circular saws do it cutting sheet. Ok its not as fast and violent as a chainsaw tipping out and unlike the chainsaw you can usually control it with a little muscle but the process and principle is the same. I am struggling to believe what I am actually reading in parts of this thread now to be fair

 

[DanielW]

I had one of those for occasional use with a 9" grinder, needed squaring up everytime the grinder was removed and refitted so I ended up with a cheap grinder permanently fitted. Worked well enough but you end up with stacks of discs that still have a little bit of life left in them you can't bring yourself to throw away and a lot of mess to sweep up!

Hmmm! I suspect you have not come across the flaw in the design of the type I posted in that link?

I got my stand from Lidl at the time they was floggin em,took it back about a few days after using it(seems they dropped it from their sales due to others being returned.

Basically if using a standard grinder and normal sized cutting disc it fails to cut right through the metal simply because the tip of the body(metal casining) of the grinder hits the clamp section on the base restricting the grinder disc going any further,it only works if you put a bigger disc on the grinder but you can't get bigger than a 125mm disc for a standard grinder and there's no way a 230mm disc will fit on the grinder in the stand so bad designed stand.

 

[Wallace]

The stand I had didn't suffer with that problem so badly until the disc was well worn as it was for a 9" grinder. It did the job I bought it for and more so paid for itself but became redundant and sold when I bought a horizontal bandsaw which is much slower but quieter, cleaner and cheaper to run in consumables.