Straighten a chainsaw bar

[Swami805]

Not reel related but thought I'd see if the brain trust might have an idea of how to straighten a bent chain saw bar. It's a 47" bar and it still kind of works but doesn't cut straight.  A new one is about $400 so if there's a chance of fixing this one it's worth some hassle. Any ideas?
Thanks!!

[Ron Jones]

I've never tried to do it to anything anywhere near that big, and I've never really been successful at it. My best results have required three vises and a ball peen hammer, but I've never really gotten them "straight."

Good luck

The Man

[PacRat]

How badly is it bent? Will it show in a photo? I normally wouldn't mess with a bent bar but $400 is a lot! I would make a jig with high spots on the end with something to push down near the hump of the bar (sort of like how they straighten a blade on Forged In Fire).

[Keta]

Is it bent or is there a burr on the track?   If bent you can straighten it with a press, if it is burred you can file it off.

[Swami805]

It's bent, hard to see when you look down it but enough to make it unusable.   One of the boys got it pinched in a tree and bent it getting it out
What kind of shop would have a press that would work?

[PacRat]

Have you tried a local chainsaw shop? They have likely seen this before.

[Keta]

Have you tried a local chainsaw shop? They have likely seen this before.

Yup. 

[Midway Tommy]

If it's a gradual bow you can block it on the concave side in two places six or eight inches away from the high spot on the arc. I would clamp the bar to the blocks. Then with a block on the convex side at the high point use a pipe or bar clamp and draw it gently towards straight or a very little past straight. Use something solid to draw against like the edge of the table or bench you are working on. It will most likely spring back a little the first time. Also, you may want to use a torch or heat gun to heat it up a little bit.   

[oldmanjoe]

  Hard to say with out picture , but it can be done .    Some times it is easy with a half cut in a log , saw off and bend the bar in the opposite direction .
         And some times done with 2    2 by 4s and a c clamp .     I will tighten the chain  more than normal to avoid kinking the chain valley to straighten
         a bar  , than readjust chain .
   Check the chain a bent tooth will make a curved cut as well as dull teeth .

[Wompus Cat]

If it's a gradual bow you can block it on the concave side in two places six or eight inches away from the high spot on the arc. I would clamp the bar to the blocks. Then with a block on the convex side at the high point use a pipe or bar clamp and draw it gently towards straight or a very little past straight. Use something solid to draw against like the edge of the table or bench you are working on. It will most likely spring back a little the first time. Also, you may want to use a torch or heat gun to heat it up a little bit.   

Tommy is Right on the Money here .
Depending on what the bar is  made of (ie) Grade of metal would make a repair recommendation different   however the basics of straightening any metal the basics are identical in that you need to reverse the impact that caused the bend in the first place with more energy beyond the bend . Meaning you need to push back beyond the plane to reverse the pressure on a linear application so when your repair is accomplished it will be flat again . It is most difficult to  explain  but I guarantee it Can be done if you consider the factors and have done it for 50 years ......lol

[Midway Tommy]

Thanks, Henry.  One thing I forgot to mention is that when setting up the blocks make sure they are tall enough to prevent the bar from twisting. In other words, so they are at least as tall as the height of bar when standing on edge. 

[Gfish]

A pinched bar(47"? man that's long) will often get a compressed area where the chain runners go through(what Joe's calling the "chain valley"?). If you get the bar straight, but it smokes as it heats-up(chain oil burning) or won't get up to normal high-speed, there could be that issue. I don't know if it could be fixed, but for $400 you godda try, I would.
Did the user have to run for it as the tree went backwards? No wedges, huh?

[Swami805]

The guy was in the tree being removed, we had to lower it down in pieces. He didn't get the back cut right and the bar got pinched. The bar got pinched when he was trying to get it out. It's a big powerhead (880) and weights alot, hard to get any leverage 20' off the ground.
We only have one saw shop it town and all the other ones within about an hours drive are owned by the same guy. They'd rather have you buy new stuff than fix what you have.
We have a small shop, I think I'll try the clamps and some heat.
Thanks for all your help, I'll let you know the results

[Keta]

Heat will alter the temper of the metal. 

[Ron Jones]

If it's a gradual bow you can block it on the concave side in two places six or eight inches away from the high spot on the arc. I would clamp the bar to the blocks. Then with a block on the convex side at the high point use a pipe or bar clamp and draw it gently towards straight or a very little past straight. Use something solid to draw against like the edge of the table or bench you are working on. It will most likely spring back a little the first time. Also, you may want to use a torch or heat gun to heat it up a little bit.   

This is what I meant by three vises. I always seem to go to far or not far enough. I also used the third vice as a "press" by opening it against the bar. I guess it is what we had.

Good luck
The Man