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Posted by BRAD on August 15, 2008, 9:38 am
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Hi,
Hoping someone with some sense can help.
I've being having problems for a long while now with 4 1/2" and 9" angle
grinders that I cannot seem to fix.
The trouble lays with the grinder 'snatching' while using metal cutting
discs. Recently, I had a new 9" disc burst when the grinder suddenly
snatched. Good job I was wearing goggles. Am I using the grinder 'upside
down' ? and thereby the disc revolving the wrong way?
The snatching seems to only be when I've been cutting a while ..... is it
because I have relaxed my grip? and holding it too loose?
I've just cut some concrete blocks and the same thing happened with the
'snatching'.
Any helpful comments welcome, especially where safety is concerned.
Cheers
Brad.
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Posted by Mark Rand on August 15, 2008, 12:22 pm
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>Any helpful comments welcome, especially where safety is concerned.
Holding loosely will make things worse.
Allowing the blade to tilt to the side will lead to breakages.
Allowing the blade to "dig itself into a hole" so that a larger length of the
blade is in contact and, particularly, some of the blade forward of the centre
line. will cause it to jump. The cutting part of the blade will ideally be the
part at the centre line to just on your side of it. keep the blade moving so
that the cut surface stays flat, rather than hole shaped.
Might not be correct, but it works fairly well for me.
Mark Rand
RTM
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Posted by BRAD on August 16, 2008, 6:22 am
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> wrote:
>
>
>>Any helpful comments welcome, especially where safety is concerned.
>
> Holding loosely will make things worse.
>
> Allowing the blade to tilt to the side will lead to breakages.
>
> Allowing the blade to "dig itself into a hole" so that a larger length of
> the
> blade is in contact and, particularly, some of the blade forward of the
> centre
> line. will cause it to jump. The cutting part of the blade will ideally be
> the
> part at the centre line to just on your side of it. keep the blade moving
> so
> that the cut surface stays flat, rather than hole shaped.
>
>
> Might not be correct, but it works fairly well for me.
>
>
> Mark Rand
> RTM
Hi, thanks for that. I'm thinking that I'm actually using the grinder
upside down. Should the arrow on the gearbox point upwards?
I'm using the grinders by holding the trigger in my right hand, and the
handle in the left hand. The gearbox is to the left with the blade to it's
right. The arrow on the gearbox is pointing upwards. I've tried the
grinder the other way around and it make the snatching much worse.
Confused again.
Brad
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Posted by moray on August 16, 2008, 7:58 am
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>
>> wrote:
>>
>>
>>>Any helpful comments welcome, especially where safety is concerned.
>>
>> Holding loosely will make things worse.
>>
>> Allowing the blade to tilt to the side will lead to breakages.
>>
>> Allowing the blade to "dig itself into a hole" so that a larger length of
>> the
>> blade is in contact and, particularly, some of the blade forward of the
>> centre
>> line. will cause it to jump. The cutting part of the blade will ideally
>> be the
>> part at the centre line to just on your side of it. keep the blade moving
>> so
>> that the cut surface stays flat, rather than hole shaped.
>>
>>
>> Might not be correct, but it works fairly well for me.
>>
>>
>> Mark Rand
>> RTM
>
> Hi, thanks for that. I'm thinking that I'm actually using the grinder
> upside down. Should the arrow on the gearbox point upwards?
> I'm using the grinders by holding the trigger in my right hand, and the
> handle in the left hand. The gearbox is to the left with the blade to
> it's right. The arrow on the gearbox is pointing upwards. I've tried the
> grinder the other way around and it make the snatching much worse.
> Confused again.
> Brad
It doesn't matter what way up you hold the grinder. The arrow is only to
tell you which way the blade turns.
Snatching is a feature of angle grinders.
Main tips to limit are-
* slowly touch into sharp corners (ie the corner of square bars)
* try and keep as little of the blade sticking through the material as
possible (ie. grind along the surface of a plate, rather then grinding in
from the end)
* when you're cutting deep stuff where a high proportion of the blade is
in/through the material, keep the grinder as inline with the cut as
possible. It only takes a very slight bit twist and the blade will
snatch/jam in the grove.
* Don't force the grinder into the material.
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Posted by Graham on August 16, 2008, 8:44 am
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wrote:
>
>> wrote:
>>
>>
>>>Any helpful comments welcome, especially where safety is concerned.
>>
>> Holding loosely will make things worse.
>>
>> Allowing the blade to tilt to the side will lead to breakages.
>>
>> Allowing the blade to "dig itself into a hole" so that a larger length of
>> the
>> blade is in contact and, particularly, some of the blade forward of the
>> centre
>> line. will cause it to jump. The cutting part of the blade will ideally be
>> the
>> part at the centre line to just on your side of it. keep the blade moving
>> so
>> that the cut surface stays flat, rather than hole shaped.
>>
>>
>> Might not be correct, but it works fairly well for me.
>>
>>
>> Mark Rand
>> RTM
>
>Hi, thanks for that. I'm thinking that I'm actually using the grinder
>upside down. Should the arrow on the gearbox point upwards?
>I'm using the grinders by holding the trigger in my right hand, and the
>handle in the left hand. The gearbox is to the left with the blade to it's
>right. The arrow on the gearbox is pointing upwards. I've tried the
>grinder the other way around and it make the snatching much worse.
>Confused again.
>Brad
>
I wonder are you "pushing" the grinder? When I use one I pull it, so
the arrow points down with the dust / sparks going between my legs and
off behind me, I then shuffle backwards on a long cut. Holding the
grinder same as you but blade on the left and the side handle pointing
up.
I don't put hardly any pressure downwards, and allow the weight of the
grinder to do the work. I also strongly echo Mark's comments about not
allowing the front of the blade to cut or twisting / tilting it.
I'm a bit OTT when it comes to safty but in 15 years I have only ever
have 1 disc explode on me, and that was my fault, however I don't use
the abasive disks for stone and only diamond. For metal I will only
use a disk less than 6 months old and only then if I can guarantee
myself that it has been stored correctly and not been knocked or
bumped. I also never slow the disk after cutting by pressing it
against something, and I'm always careful when I put the grinder down
not to bang or rest it on the disk. Also disks usually have to run in
a particular direction, marked by arrows on the disk.
Again, might not be right, but works OK for me!
Graham
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