Grinding Disc Failures - The Causes?

[Muggins the Mug]

i think hes using them to grind the weld right down to the bare metal so he can re use it for welding, not finishing the weld- i think

Exactly, it's called recycling. Well, until I can find a local steel supplier who'll do me some small offcuts to practise on.

Regards,

Ian.

 

[chriskelland]

Hi All,

Same old story, buy decent kit. I'm not saying that all cheap stuff is rubbish, but I feel a lot happier using Norton or Bosh. I did try some Titan disc's from Screwfix and was surprised what a nice disc they were to use. Also buy the correct disc for the job. Try not to get too long a feather on the edge of the wheel, it can be unsupported if the mat gets worn away, thats the bits you heard coming off. 45 degrees is about right. Don't force the wheel let it cut at it's own speed. I don't know about never using hard disc's but I do get very good results using Zirconium instead of AlOx with a backing pad.. It leaves a very smooth finish without scratches and seems to cut forever.


Chris.

 

[irondarren]

Zirconium is far better than alumin Oxide, much harder lasts longer but costs more. Hang on zircon is alumin oxide well sort of lol

 

[chrisg3103]

it also helps not to overheat the disc, did an abrasive wheels course years ago as part of my apprenticeship. just basicly a guy going on about how horribly your going to die if you dont install a grinding wheel properly (bench grinders)

discs are designed to be self dressing, thats what the fabric webbing bits for. but looks a bit like the outer edge of your disk is cloged with muck. means this bit wont be cutting and the rest of the disc is so probaly overheating and flying off. are you grinding slag as well as weld?

also i tryed a 40 grit flap disc at the weekend for the first time. was so impressed i ordered a box of 10! mucking fagic

btw mr mugs i have a little square (100 x 100 ish) of 8mm plate you can have if i remember to bring it home, or you can search for a steel supplyer in irvine, and tell me i have to go to ayr!

 

[NeilH]

it also helps not to overheat the disc, did an abrasive wheels course years ago as part of my apprenticeship. just basicly a guy going on about how horribly your going to die if you dont install a grinding wheel properly (bench grinders)

discs are designed to be self dressing, thats what the fabric webbing bits for. but looks a bit like the outer edge of your disk is cloged with muck. means this bit wont be cutting and the rest of the disc is so probaly overheating and flying off. are you grinding slag as well as weld?

also i tryed a 40 grit flap disc at the weekend for the first time. was so impressed i ordered a box of 10! mucking fagic

btw mr mugs i have a little square (100 x 100 ish) of 8mm plate you can have if i remember to bring it home, or you can search for a steel supplyer in irvine, and tell me i have to go to ayr!

what did your teacher tell you about installing a grinding wheel on a bench grinder properly?

im always swapping and changing mine depending on what im doing. coarse/medium/fine grit....wire wheel etc etc

 

[Hitch]

I was expecting to see the remenants of a disc on a grinder.

That has done that beceause its work a bit sharper than what is ideal.
Or course, providing you are wearing your safety gear, you wont come to any harm.

If i get a disc that starts to do that, just hold the edge at a right angle to some scrap/edge of bench and just wear it back a bit.

The softer discs dont tend to do it quite as bad

 

[Normsthename]

Zirconium is better than alumin Oxide, much harder lasts longer but costs more. Hang on zircon is alumin oxide well sort of lol

Zirconium is a different material to Aluminium Oxide
Typically Zirconium Discs are Blue in Colour, and are much harder wearing than Aluminium Oxide.
I used to use Zirconium to sand Stainless Steel, but I have now switched over to Cubitron Discs
They are even better than Zirconium, and they are also ' Self Sharpening' as you sand the pad stays sharp.
Not cheap, but well the worth the extra expense

Andy

 

[Muggins the Mug]

are you grinding slag as well as weld?

btw mr mugs i have a little square (100 x 100 ish) of 8mm plate you can have if i remember to bring it home, or you can search for a steel supplyer in irvine, and tell me i have to go to ayr!

Hi Chris,

No, there's very little slag left on the weld as most of it's been chipped off/wire brushed off.

I'll swap you that piece of 4 inch square plate for some Lidl rods I bought last week, if you want them. Perhaps they'll be better than those Halford ones I gave you.

Regards,

Ian.

 

[gavuk]

what did your teacher tell you about installing a grinding wheel on a bench grinder properly?

im always swapping and changing mine depending on what im doing. coarse/medium/fine grit....wire wheel etc etc

bench grinder
1.check speed of disk is suitable for machine
2.must have paper washers on
3.check date on wheel
4.do a ring test suspend from string and tap ,should produce nice ring,if not bin it
5.don't overtighten as wheel and locking nut will self tighten
6.min gap between toolpost and wheel .

angle grinder
1.check speed of disc against machine
2.only use correct size disc for spindle
3.grinding disks use lock nut with locating spigot towards wheel
4.cutting disk (usually)reverse lock nut so recess is towards wheel
5.don't overtighten,hand tight is adequate,will self tighten in use,only use a spanner for undoing
6.always use a gaurd,not always possible with wire cup brushes.
7.locknut should always fit into recess on wheel if there is one,normally writing on disk towards gaurd
as this is safety , if i've forgotten anything please feel free to add to the list ..Gav

 

[chrisg3103]

what he ^ says saves me some typing

mandatory now in marine engineering cadetships, one cadet was told to change a grinding stone on a ship many years ago. fitted a dud stone, turned on the grinder and it went off like a hand grenade, was killed outright.
when these things go they just fragment apparently

on a lighter note mr mugs, might want to keep hold of some rods welding rods are actualy very handy for other stuff once you chip the flux off

 

[NeilH]

bench grinder
1.check speed of disk is suitable for machine
2.must have paper washers on
3.check date on wheel
4.do a ring test suspend from string and tap ,should produce nice ring,if not bin it
5.don't overtighten as wheel and locking nut will self tighten
6.min gap between toolpost and wheel .

angle grinder
1.check speed of disc against machine
2.only use correct size disc for spindle
3.grinding disks use lock nut with locating spigot towards wheel
4.cutting disk (usually)reverse lock nut so recess is towards wheel
5.don't overtighten,hand tight is adequate,will self tighten in use,only use a spanner for undoing
6.always use a gaurd,not always possible with wire cup brushes.
7.locknut should always fit into recess on wheel if there is one,normally writing on disk towards gaurd
as this is safety , if i've forgotten anything please feel free to add to the list ..Gav

cheers for the info mate.

one thing i do is i never stand in front of the grinder until its fully up to speed. i switch it on when standing by the side of it.