abrasive wheel steel cutting chopsaw problems.

[greybeard]

I have an older porter/cable 14" chop saw for cutting steel. Nothing wrong with the unit itself, but I've been having trouble with the wheels just stop cutting on certain things. Cuts fine on the vertical walls of 5"x 2" x 1/4" channel, but when it gets down to the flat surface, it soon just stops cutting. Same way with 3" X 4" x 1/4" square tubing. It will cut the top section ok, and on down thru the sidewalls, but soon after reaching the bottom, the cutting ceases. Plenty of travel left on the pivot.
The abrasive wheel is fine--I can put a different piece in and it will start cutting the vertical walls right away so I'm not doing anything to the blade itself. Blade is still spinning, but no cuttings being spit out (no sparks) and no matter how much pressure I put on the handle it won't cut any further.

It's almost as if I am putting too much or too little pressure and have changed the metal to a hardness beyond which the wheel can cut. (makes no difference which brand abrasive disc I use--Dewalt, Sait, Morton--all do the same thing.)
It has to be something I am doing---What's happening and what am I doing wrong?

 

[john s]

Sounds like too much pressure. "Hardening the Steel" I use them a lot in my career and haven't had this problem. Have you tried flipping the piece over to see if that changes anything?? If you can't get it resolved PM me and I can talk to some of my fellow co-workers see what's up. Good Luck

 

[greybeard]

I kinda think it is too little pressure or the fact that I frequently pick up on the handle, glance at the cut, then get back into it. I cut one today, with just the same pressure all the way thru, never letting up and it cut it all right. I've used them lots in my life and never encountered the problem before, but usually didn't cut stuff this big with a chopsaw. We always had a slow rpm toothed blade with coolant to cut big stuff with--or a horizontal bandsaw. I "think" allowing it to cool for a second or 2 when I pick up off of it is causing the steel to carburize or case harden.

I was a machinist at one time for about 10 years and I ran into this problem machining some A2 cutlery stainless steel for Johnson & Johnsons suture needle formers. The end mill HAS to always be "pulling a full chip" or the steel hardens beyond the rockwell hardness of the carbide end mill.
Flipping them isn't easy, since I'm cutting off of full 20' lengths. Lots of trouble to get it all leveled and squared back up and I really need the pieces cut flat and square in both directions.

 

[Ouachita]

I've had the same problem as long as I can remember. Depending on the size stock your cutting, make a "spacer" to move the piece away from the fence, and/or another to space it up off the table. This places all sides of the stock at more of an angle to the cutting wheel

 

[Angus Cowman]

I have seen the same problem especially with my help that thinks you have to stand on the handle(push with all there might) to cut anything

it seems the Blade itself is glazing over and what I have found that works is to tap the blade on what you are cutting a few times while it is running it seems to knock the glaze off and will cut better after that

 

[B&M Farms]

Alot of the blades you buy now are junk. If you can find them, stick with Norton brand abrasive grinding and cutting disc. We use them at work and they seem to last longer and work better. They also make metal cutoff blades for chop saws with carbide teeth that cut really fast but they are more expensive.

The hotter carbon steel gets, usually the softer it will get. Heating carbon steel will not make it harder unless it is super heated and quenched. That said, certain soft alloys like stainless steel are usually harder to cut or drill.

 

[greybeard]

The blade is definitly not glazing over. When it does stop cutting, I can put a piece of scrap of the same material in, and the same blade will cut it right down thru the top and thru the vertical walls--using the same blade. I've tried the tap thing too--no change.
I've been in town since my last post so haven't had a chance to do anything else today, but I still think that uneven pressure on the final bottom wall is case hardening the steel.
(I said Morton in my other post--meant Norton)

 

[jedstivers]

I have to turn metal a 1/4 turn a lot of times to get one to cut.

 

[B&M Farms]

The blade is definitly not glazing over. When it does stop cutting, I can put a piece of scrap of the same material in, and the same blade will cut it right down thru the top and thru the vertical walls--using the same blade. I've tried the tap thing too--no change.
I've been in town since my last post so haven't had a chance to do anything else today, but I still think that uneven pressure on the final bottom wall is case hardening the steel.
(I said Morton in my other post--meant Norton)

I guess it could be case hardening the metal if its getting hot enough and the abrasive disc contains carbon. If its cutting down the verticales sides and then giving you trouble on the flat surfaces it may just be because its trying to cut more metal at once. You might try rotating the tubing or channel to cut the last part.

 

[Ouachita]

I've used the Norton wheels. They are better. But still makes a world of difference to make a fixture of sorts to hold the square or rectangle material where you aren't cutting any surface "flat". If your cutting a lot of steel it's worth the time. Also helps to use the smallest diameter wheel necessary for the job. The angle and amount of surface the wheel contacts at any given time makes a difference. Less surface contact is better in my limited experience.

 

[johndeerefarmer]

I just cut 18 pieces of 2 x 2 x 1/4" square tubing. Going through the flat sides takes lots of down force, once you hit just the two walls it's easy. Then when you hit the bottom flat side again you really have to press down.

I always try to cut metal so that I am going thru the least amount of steel at once. For example I also just cut some 3 x 3 x 1/4" angle. I put it in the chop saw like a triangle with the point up. If I had of laid it down flat I would be trying to cut through a 3" flat surface.

Basically you just need to bear down on the chop saw until the sparks fly. My B&D industrial chop saw was bought probably 15-20 years ago and is still going strong and it's on it's original brushes. Lots of the time I will actually use my forearm and press down with my upper body weight.

 

[breed549]

safety glasses, gloves, stand on it!