In another thread, a member asked about saving a guide bar after hitting his chaps - the nose sprocket seized up:
http://www.arboristsite.com/community/threads/help-can-i-save-the-bar.256137/#post-4785989
At a recent GTG we did a chaps test/demonstration that also seized up a couple of nose sprockets. I followed my own advice from that other thread to save these bars, and took pictures along the way. Only difference is that these are both Oregon-style bars, without the additional side shims that the STIHL bars have.
1. I drove the rivets out on both bars using my chain breaker. The Husky 5 rivet tip (3/8" pitch) had dimples on one side indicating the direction they were installed. On the Oregon single rivet bar (3/8" low profile) I had to guess which side looked factory flat, and which side looked peened over.
2. Slide out the sprocket assembly on an old towel in case any of the tiny bearings try to escape (26 in this Husky 5 rivet bar; 15 in the Oregon single rivet bar)! Sliding them out on thin cardstock (e.g. 3X5 card) helps to keep things together. You can see how the protective fibers from the chaps are wound right in with the bearings, and are not just between the sprocket and the inside of the guide bar.
3. This is all it takes!
4. Single rivet bar for reference. Notice the difference in the size and construction between the sprockets for the standard 3/8" and 3/8" low profile pitch chains (I should have overlaid them when they were out!).
5A. Zip-lock bags are your friends! Took the parts like this to the parts store.
5B. While the nose sprockets were out, I dressed the rails and de-burred the edges. Much easier to do like this. I was also able to de-burr the actual nose (with a ScotchBrite wheel) with the sprocket removed.
6. Reassembly is the reverse. Slide the card all the way in to keep the little bearings from dropping through the rivet holes. It may help to pry apart the bar tip with a small screwdriver.
7. I would have preferred to use new rivets, but my dealer would have to order them, and these had pressed out pretty cleanly (no metal break away, like what frequently happens with chain rivets). So some gentle persuasion with a ball-peen hammer and a small anvil.
8. Same thing for the 5 rivet sprocket. Once the sprocket is close, a little manipulation with a scratch awl helps align the other holes. Small nails can be used to hold things in place while setting the first rivets.
9. Done. Lubed the bearings up with some light oil (3-in-One) to keep them happy until used.
Philbert
http://www.arboristsite.com/community/threads/help-can-i-save-the-bar.256137/#post-4785989
At a recent GTG we did a chaps test/demonstration that also seized up a couple of nose sprockets. I followed my own advice from that other thread to save these bars, and took pictures along the way. Only difference is that these are both Oregon-style bars, without the additional side shims that the STIHL bars have.
1. I drove the rivets out on both bars using my chain breaker. The Husky 5 rivet tip (3/8" pitch) had dimples on one side indicating the direction they were installed. On the Oregon single rivet bar (3/8" low profile) I had to guess which side looked factory flat, and which side looked peened over.
2. Slide out the sprocket assembly on an old towel in case any of the tiny bearings try to escape (26 in this Husky 5 rivet bar; 15 in the Oregon single rivet bar)! Sliding them out on thin cardstock (e.g. 3X5 card) helps to keep things together. You can see how the protective fibers from the chaps are wound right in with the bearings, and are not just between the sprocket and the inside of the guide bar.
3. This is all it takes!
4. Single rivet bar for reference. Notice the difference in the size and construction between the sprockets for the standard 3/8" and 3/8" low profile pitch chains (I should have overlaid them when they were out!).
5A. Zip-lock bags are your friends! Took the parts like this to the parts store.
5B. While the nose sprockets were out, I dressed the rails and de-burred the edges. Much easier to do like this. I was also able to de-burr the actual nose (with a ScotchBrite wheel) with the sprocket removed.
6. Reassembly is the reverse. Slide the card all the way in to keep the little bearings from dropping through the rivet holes. It may help to pry apart the bar tip with a small screwdriver.
7. I would have preferred to use new rivets, but my dealer would have to order them, and these had pressed out pretty cleanly (no metal break away, like what frequently happens with chain rivets). So some gentle persuasion with a ball-peen hammer and a small anvil.
8. Same thing for the 5 rivet sprocket. Once the sprocket is close, a little manipulation with a scratch awl helps align the other holes. Small nails can be used to hold things in place while setting the first rivets.
9. Done. Lubed the bearings up with some light oil (3-in-One) to keep them happy until used.
Philbert
