I have a small Cannedy Otto rivet forge that I've been using. I love the thing, but yesterday afternoon, it started making a metal to metal noise when cranking. Today,it has gotten much worse, and it has become harder to crank. It still coasts nicely, but not as nice as a few days ago. I suspect one of the fan blades is hitting the case. I took video of it, and I will try to add it to this post within the next few minutes.

Here are some pictures of the forge.

What could I do to prevent this? I will have to wait for the forge to cool down before I can remove the blower.

If you crank really slow, the sound will stop. But cranking at any other speed, it will make the noise.

ETA: Just uploaded the video.
http://www.youtube.com/watch?v=hMRcpnFbCCs

Make sure that the fan spider has not shifted on the shaft.

Take off the shroud and examine the paddles: if One shows wear signs see if it is out of line and tweak it GENTLY back; or try filing the paddle a bit.

Many old blowers have a preferential turn direction---even if they are not supposed to, they work better one way than the other.

Check that the bearings don't need adjusting to shift things a bit in the other direction---if you blower has bearings like that.

BE GENTLE! may old blowers have quite fragile cast parts (and many show examples of prior fixes to those parts!)

One of the blades was rubbing the housing on the back. A little filing and it was all fixed.

Until now. See my next thread coming up.

looks and sounds like your fan blades are loose from shaft and probably hitting something a little ... i noticed as you cranked it up that the fan speed didnt match the crank speed ... check where its hittin something (might be a bit of cola or debris in the housing).also might oil up the gears a bit hard to tell if there good from here tho...good luck