Any downside to buying a 125mm angle grinder rather than a 115mm one

[marcusthehat]

Arrived earlier today, a 125mm 18V LTX Metabo, with 25 No 115 discs when I had, understandably, ordered 125's, DOH !!
P.S.
My simplistic/intuitive understanding of "bursting" forces on a spinning disc, are that they are greatest at the periphery, what happens near the centre is not a factor.
So a 9" cutting disc designed not to burst at 6600 rpm, is actually being less stressed when run at 11000 after being worn down to 4.5".
Unless the disposable cutting disc is so highly engineered so that the outer cutting edge is stronger than the centre material,
but a visual inspection would seem to indicate homogeneous material and construction throughout.
I am only talking about cutting discs, the dished centre in a grinding disc, may well be a weak area, or at least, not intended to be used for grinding, but if the centre dish is the same on a 9" as a 4.5" I rest my case.

I tink this horse is now well flogged dead btw.

mth

 

[76masseyman]

I have to buy the little discs because when I wear down a 9 inch I put it somewhere safe, but can never find it again when needed. So I go to the 9 inch, and it's not worn enough to remove yet.

Plus, I'm not that tight !!

 

[TripleSix]

I tink this horse is now well flogged dead btw.

At least you have a grinder to cut it up with to get it out of the shed...

 

[marcusthehat]

And see link
https://thefarmingforum.co.uk/index.php?threads/how-to-move-a-dead-horse.16734/

EDIT
I laughed so hard when I first found and read this thread, the stuff any good forum is made of.
Might even read it again.

 

[Pheasant Surprise]

whats the price difference on the disc's

Like about 2p

Just bought some 10-packs of Dronco “Attack Inox” 125mm slit discs works out @ 55p a disc from Parker Tools

https://www.parkertools.co.uk/EngProduct/1216759/Dronco-Attack-Inox-Tin

 

[Skimmer]

Either I'm not reading you correctly or you're getting mixed up??

9 inch grinder 6600 rpm, 4.5 inch 11000rpm almost twice the speed!! When that 9 inch disc is worn
down its still doing 6600rpm regardless of what size it is, you then put that disc in a 4.5 inch grinder and nearly double its rotation!! Thats why its bad practice to put them in a smaller grinder when they are worn, unless that grinder is rated at the same rpm as the bigger one.

I don't know what the manufacturers say or what they will take, but I do know from first hand experience of seeing it happen that they can and will shatter. Whether they were bad discs to begin with or it was the speed difference I don't know, but seeing it go and the state of the lads arm from the shrapnel its not a risk that I will take for the sake of a few quid.

A neighbour did this and had a disc shatter badly lacerated his arm for the cost of a 115 disc.

 

[mikep]

Re the dead horse and used 9" discs. Bear in mind the 9" disc was designed to run at 6600or so. What suddenly upgrades it to run at 11000?
Just because linear speeds are the same it doesnt change the facr that they are made to run safely at different rotations.

 

[marcusthehat]

Ah Tink that is a Red Herring as opposed to a Dead Horse Sur!
mth

 

[marcusthehat]

My farmers son intuition/uncommon sense was absolutely correct, & see HSE linked document;

Peripheral and rotational speed
28 The maximum operating speed is marked on every wheel in two ways:
(a) the peripheral surface speed which is given in m/s;
(b) the rotational speed which is given in rpm.
As the wheel wears down in use, the effective peripheral surface speed will reduce if the rotational speed remains constant and may result in a reduced grinding efficiency.
To counteract this, the spindle speed can be increased, providing the maximum peripheral surface speed of the wheel is not exceeded.
Always ensure that the spindle speed is reduced to its original value before fitting new wheels.

This paragraph from the bottom of page 12, of 53 pages, & see linked doc.

http://www.hse.gov.uk/pUbns/priced/hsg17.pdf

regards

marcus

 

[tinman]

115mm is a half worn 125mm

in a nutshell, well said.

Grinders imo are the work of the devil but a nessicary evil all the same.
id never consider buying a 115 grinder, indeed i have a 115 slitting disc here by mistake and id say the only day it ill ever get used is the day i have nothing else.

How good do people find the metabo, I’m torn between that and Milwaukee

i like the Metabo grinders, have 4 of them here, 1x 9" , 2 125mm's and a low boy version for the tight places.
However,
inside the last 10 odd mths Hitachi bought Metabo (or at least their power tool side of things), a few months ago the pair were sold to an outfit called KKR.
now nobody can say for sure but kkr dont have the best rep when it comes to investing money, indeed the complete opposite is more the norm so its hard to know now if metabo will still be around in years to come, id sincerely hope they will but its a bit up in the air.
problem with all that is if its run into the ground will spare parts still be able.
https://thefarmingforum.co.uk/index.php?threads/bit-of-a-change-for-hitachi.252848/#post-5581130

 

[marcusthehat]

Well with a Mexco 6mm thick by 125mm dia diamond raking disc, I cut a 4.0m long track(for lead flashing) with a fully charged 4.0 AmpHr battery, about 25mm deep, quite impressive performance for such a handy cordless tool I thought.
Admittedly only through marble dash and scratch coat and just tickling into the dense masonry blockwork below.
mth