Abrasive Saw Issue

[like2wheel]

Having an issue using an abrasive saw .a couple years ago I was widening some wheel dollies so I was cutting some heavy stock. The abrasive saw seem to cut ok for about a quarter of the way through the 1/2” thick barstock, then seemed to slow considerably. I purchased a new abrasive wheel (14” Firepower), but the results are still the same. Also tried a Harbor freight wheel with the same results.

Fast forward to today I’m installing hydronic heat and cutting some 3/8 all-thread for the plumbing standoffs. Now using a little 7 inch cut off saw that I have, and I have run into the same issue. it’ll cut about quarter of the way through the all thread, and then seemed to slow considerably. New Dewalt cut off blade. It seemed to take minutes to cut through some measly 3/8 inch all thread. So I reverted to using my reciprocating saw.

What am I doing wrong? Is there some sort of secret in terms of speed and pressure?
Is my wheel glazing? Some sort of work hardening happening to my stock?
Baffled.

 

[Wamsutta]

For cut-off wheels I use the Benchmark brand. I get the thinnest wheels I can get in a given diameter.

I've never had the issues you're describing with that brand.

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[Steve_P]

I've had this issue on my 14" abrasive cutoff saw as well, but only when cutting >1" diameter solid bar. I guess the wheel gets overheated and somehow goes "bad". I've not had any issues on tubing, or solid stock under half an inch, and mow right thru it.

 

[Rusted Nut]

Any saw will do this when cutting round stock. At first you’re only cutting a small slice, but as the blade cuts halfway, the blade is cutting through a bunch more material. The cut will speed up once it get small again. Just the opposite when cutting hollow square tube.

 

[The Cobbler]

unlike a carbide saw blade, there is no kerf on abrasive wheels, I suspect it's a case of increasing friction on the edge of the blade as it gets deeper in to the cut

 

[PCustoms]

unlike a carbide saw blade, there is no kerf on abrasive wheels, I suspect it's a case of increasing friction on the edge of the blade as it gets deeper in to the cut

Kerf, or set?

 

[Beerhippie]

Kerf, or set?

Kerf is the effect. Set is the cause.

 

[Steve_P]

unlike a carbide saw blade, there is no kerf on abrasive wheels, I suspect it's a case of increasing friction on the edge of the blade as it gets deeper in to the cut

Yes, there is no kerf. But you've obviously not experienced this; the wheel is essentially ruined after this and it's not from the edge contact; it's not from excessively bogging them down- I don't just lay on it until I hear it decreasing in RPM to deliberately destroy them; there's some sort of heat over time issue on the OD, the cutting surface, that then totally ruins them from future use unless maybe I want to cut a 1/4" round bar. An hour later that **** wheel is still **** on the 1" bar and a new wheel is fine.

 

[jar944]

Yes, there is no kerf. But you've obviously not experienced this; the wheel is essentially ruined after this and it's not from the edge contact; it's not from excessively bogging them down- I don't just lay on it until I hear it decreasing in RPM to deliberately destroy them; there's some sort of heat over time issue on the OD, the cutting surface, that then totally ruins them from future use unless maybe I want to cut a 1/4" round bar. An hour later that **** wheel is still **** on the 1" bar and a new wheel is fine.

Abrasive wheels can glaze over.

 

[tarbellb]

Between the wheel glazing, sparks, heat, poor cuts, and noise I quickly decided that abrasives saws are the worst and went band saw

If you havent ditched this heap yet, your best approach for cuts is a heavy chop and release action (pecking) on repeat
Even then you might still get glazing

 

[Rusted Nut]

Yes, there is no kerf.

Yes, an abrasive blade leaves a kerf.

 

[Beerhippie]

Yes, an abrasive blade leaves a kerf.

Be awful hard put to call it a cut if it didn't.

Set just makes the kerf wider than the saw blade.

 

[RoninB4]

Examine the wheel when it's stopped. It's either glazed, loaded up with material, or both, Your technique of constant contact with light pressure allows this to happen. Get a dressing stone for the wheel and use it. Even wheels on a surface grinder or snag grinder get loaded up and require dressing to ensure fresh sharp edges are exposed. The abrasive is supposed to disintegrate at a controlled rate that depends upon the material, pressure, and duration in time to disintegrate, it's called a friability index and is important for abrasives.