diamond cutting wheel question

[Bob H]

I have a Pro Tec 115mm diamond cutting wheel; bought it a couple of days ago for £2.75 from a local hardware shop. It says on the packet to put the wheel on in the direction of the arrows. Yes ok. Now the arrows indicating direction of spin are on one side with some writing. ie size of wheel etc. So that means writing side up as it is placed on the spigot of the grinder.

Would there be any harm done if the wheel was placed the other way round? I noticed it seemed to cut better this way, or was it my imagination? Also I noticed that the blades were going a reddy blue in colour....burning I guess. Is that a sign of poor quality or too much pressure or? BTW, I am using it to cut concrete 50mm paving flags.

Thanks

[Lurch]

On Thu, 25 Nov 2004 16:49:37 +0000, Bob H strung together this:

1. If it's a cheap diamond blade don't expect miracles.
2. It's probably a bit undersized for more than one or two cuts in concrete slabs.
3. If it says it spins one way, then that is the way it spins. Safety related generally.
4. The funny colour indicates that you have got a cheap, undersized diamond blade, used improperly for the job in hand, and probably in a bit of an over zealous fashion.

[Bob H]

Ok thanks. Now then, on point 1. Yes I agree On Point 2. Yes it probably is, but I knew that before I bought it and it does what I want, sizewise that is. On point 3. Yes I agree there as well On point 4. Well, like I said in my original post, it looks like it was burning/getting toooo hot. I have used 4" grinders/cutters on steel extensively over the years when I was in engineering, and therefore I know what burning/too hot metal looks like. It seems like it does not like the pressure that the ordainary run of the mill £1.30 somethins do.

Oh well, lesson learnt. I'll buy a dearer one next time.

Thanks for confirmation on what I thought.

[Lurch]

On Thu, 25 Nov 2004 18:07:48 +0000, Bob H strung together this:

I've had a Makita 115mm diamond blade for £14ish. They went through miles of

[Andy Dingley]

Then use a 9", not a 4 1/2". That sort of cut is hard on a tiny disk, no matter who made it.

[Bob H]

[Bob H]

Yes I take your point, but it was/is a question of cost for what I was doing. I had to cut only 5/6 flags out of 18, and I made a cut about

10mm deep on both sides then broke it through. Now I am not very likely to use a 9" grinder/cutter for anything else, given that I bought the 4 1/2" one for only £24. It probably would have cost me that much to hire a 9" one.

Thanks anyway

[Andy Dingley]

Given the high cost of stone, diamond blades and the really cheap 9" machine from Screwfix (Kenzo ?), I'd be inclined to try and keep the dust out of my bearings.

[Bob H]

Is that a feature of that 9" machine...keeping the dust out?

Yes I found a wide variation of 115mm diamond cutting blade prices, from £2.75 to about £21 something. A point I noticed on the ones from B&Q which I looked at this morning, it said that a cut of only 12.5mm deep should be made, so hence me doing both sides. But that was not just on the 115mm ones, it also included 'upto 230mm'

[Andy Dingley]

A disposable 9" keeps the 4 1/2" running. With enough dust I can probably kill the bearings in the 9" at just about the same time as the design life of its gearbox.

[Bob H]

Not sure what you mean here 'A disposable 9" keeps the 4 1/2" running.' A disposable 9" what? Grinder, wheel?? how does it keep the 4 1/2" running?

[Stefek Zaba]

Translation: Andy has a good quality 4 1/2" grinder, which he loves fettling with. He chooses not to use it for cutting slabs, since (a) it's the "wrong" tool for the job (cutting depth is limited), (b) he doesn't want the masonry dust najjering the bearings in his decent grinder.

So he expresses a preference for buying a cheapie 9" grinder (these daya available at about the same price as a day's hire of a decent-brand but possibly rather worn one) and keeping it for slab cutting and similar rough jobs.

I'm kinda with him on this one, but would add welding gauntlets, thick trousers, decent workboots, and (most of all) standing to one side of the work as sensible setup for using the 9".

Stefek

[Bob H]

Ok right, gotcha now! Have you read one of my earlier posts in this thread in which I said what I read on the packet of a 115mm disc. Only 12.5mm deep cut for

115mm wheels and upto 230mm which is 9". So according to that it makes no difference in theory, but in practice with ordinary cutting wheels you can cut as deep as the wheel will allow.