Polishing Bronze
1 Oct 11While visiting with Lin and Larry Pardey last week one of the many pointers he gave me was to cut the bottom tips off the bow rollers. I asked if he had found that they got in the way and he told me that he always intended to cut them off . . . but he built one pattern for both port and starboard bow rollers. That way you can have both port and starboard rollers cast from one pattern . . . but you have to cut the tips off the bottom of the roller when you flip it over to use on the other side. That's thinking ahead. Anyway, when I returned home I applied tape over the surface of the roller, drew a line with a pen on the tape and used my Bosch jig saw to cut the tip off and grind a nice radius that looks like it was cast that way. I smoothed out the rough edge of the cut 4 1/2" grinder. Then I polished it up with the sisal polishing wheels and wax abrasives. I think they came out great.
17 Sept 11I spent the last couple of days working on plans for the rig and the rest of the time I spent polishing some new bronze hardware. Previously, all the bronze I have had cast came from Port Townsend Foundry. Their work has always been superb. But these are parts were cast from the Pardey's patterns and they were located at a different foundry. I needed two bow rollers, a sculling oar lock, and some small brackets to secure the oil lamps to the stanchions that will be mounted in the center of the saloon and support the table. The parts arrived from the foundry un-polished, as in they still had the casting marks on them. They had come out of the sand and only had a quick grinding to knock off any flashings,etc.
Below:
1. Caswell Inc had everything I needed.
2. The Makita grinder modified for polishing.
3. This is how the bronze anchor roller arrived from the foundry.
4. The bronze after sanding through 400 grit.
5. After polishing.
I have, of course, polished bronze and brass like most folks but had never had to polish bronze from scratch. I did some research and bought some polishing supplies from Caswell Inc. They were easy to work with and told me what I needed. I bought two sisal buffing pads and a more aggressive spiral sewn pad. I bought a few small felt pads and a block of medium grit brown and a block of aggressive black polishing compound. I bought a wheel rake and an adapter that would allow me to attach the buffing pads to my 4 1/2" Makita grinder so I would not need to buy a stand along polishing machine. The plan was to clamp the grinder to the table and use it like a buffing machine. All these supplies cost about $75.00. I have since seen all the same stuff, though less heavy duty, at Lowe's.
I started by sanding the bronze with 80 grit sandpaper on my double action right angle sander. Then I worked my up through 120, 180, 220, and 320. I performed the final sanding by hand with 400 grit wet/dry paper. There were some defects and scratches that were too deep to eliminate as I would have had to remove too much bronze. All these parts, save the oil lamp brackets, will eventually load up with green verdigris anyway so a mirror finsh is not required. Next, I took the parts to the buffing wheels. The way it works is once the buffing wheel is spinning you touch the stick of abrasive to the spinning buffing pad and then start polishing. After lots of polishing with the black abrasive I switched to the brown. You keep polishing till you have the finish you want. In between I had to use my Dremel with very small polishing wheels to work some of the tight corners. I was never able to really polish out the inside flat parts of the bow roller because I could not get my DA sander in there. The procedures were the same for the other bronze parts as well.
The most exciting part of the whole event was in the last couple of minutes of the final polishing my 10 year old makita grinder gave up the ghost and caught fire! There were flames and smoke. I quickly unplugged it and dragged it out of the shop by the cord. I took it as a signal that I was done polishing. Though I learned a lot about polishing I have a real appreciation for the quality of work and the product produced by PTF. Their products do not require any work . . . they are ready to install. Nonetheless, I am satified with these parts and as I have all along I Iearned something new as I rebuild the Far Reach.
I hope to get back to installing overhead insulation this coming week.
I started by sanding the bronze with 80 grit sandpaper on my double action right angle sander. Then I worked my up through 120, 180, 220, and 320. I performed the final sanding by hand with 400 grit wet/dry paper. There were some defects and scratches that were too deep to eliminate as I would have had to remove too much bronze. All these parts, save the oil lamp brackets, will eventually load up with green verdigris anyway so a mirror finsh is not required. Next, I took the parts to the buffing wheels. The way it works is once the buffing wheel is spinning you touch the stick of abrasive to the spinning buffing pad and then start polishing. After lots of polishing with the black abrasive I switched to the brown. You keep polishing till you have the finish you want. In between I had to use my Dremel with very small polishing wheels to work some of the tight corners. I was never able to really polish out the inside flat parts of the bow roller because I could not get my DA sander in there. The procedures were the same for the other bronze parts as well.
The most exciting part of the whole event was in the last couple of minutes of the final polishing my 10 year old makita grinder gave up the ghost and caught fire! There were flames and smoke. I quickly unplugged it and dragged it out of the shop by the cord. I took it as a signal that I was done polishing. Though I learned a lot about polishing I have a real appreciation for the quality of work and the product produced by PTF. Their products do not require any work . . . they are ready to install. Nonetheless, I am satified with these parts and as I have all along I Iearned something new as I rebuild the Far Reach.
I hope to get back to installing overhead insulation this coming week.