[OP]
Contributor
Below is a 12” brass locomotive bell up for auction. It appears to be a rough casting so was never used. I have a full size jet 1642 EV lathe and carbide insert scrapers. The thing weighs 20 lbs which I don’t see as a problem. I can turn a plug.
so can I clean this up?
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Contributor
Yes, HSS or carbide will readily turn it. Scraping will work best.Originally Posted by Roger Feeley
Turn slower than for wood.
Should polish up very nicely!
Last edited by Neil Strong; 06-17-2024 at 7:33 PM.
Neil
About the same distance from most of you heading East or West.
It's easy to see the Dunning-Kruger Effect in others, but a bit of a conundrum when it comes to yourself...
Contributor
Is it really brass, or is it bronze? Alloy will make a difference on how it turns.
Contributor
My first try would be with abrasives. Start course and go through the grits.
I would be nervous to try a tool without a tool holder. Abrasives yes. Perhaps even an angle grinder with a sanding disc, if a lot of material needs to go.
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Last edited by Maurice Mcmurry; 06-17-2024 at 9:02 PM. Reason: the lathe in question
[OP]
Contributor
No way to know. I can’t tell from the pictures. Is this a deal breaker?
Contributor
Yes.
As long as you can hold and drive it securely including TS support. Both to reduce chatter and to keep the casting pushed into the chuck or faceplate.
Brass was at one time routinely turned by hand (& even chase threaded by hand!)
Wear personal protection especially eye protection.
Use very low speeds. 300-ish FPM until you get comfortable, then maybe up to 500 FPM.
The tool and the work can get quite hot.
If it is leaded brass similar to 360 it will be relatively easy, but subject to tarnish.
Depending on your tool shape, it may yield incredibly sharp (I consider dangerous) needle-like chips especially if you scrape and it starts chattering.
Tool should have neutral rake and be essentially a wood scraper; sharpness angle being close to 85 - 90 deg, but you can manipulate the shear angles to do more cutting.
If it is actually bronze, it could be a little tougher; and might need lube.
Also might or might not need to start slower than 300 FPM.
Long ago quick experiment did not find it better than, say, Moly-D; but apparently old-timers sometimes used clabbered (spoiled) milk as the most successful option for high-copper content alloys.
Again, depending on alloy, any cutting oil, or lard, might be better than none. Ideally you would have flood coolant.
You will re-learn proper safe tool work: Rest as close as possible, controlled grip on the tool at all times, and a constant vigilance to exactly where on the tool it is cutting as you manipulate it.
I'd rather use form tools in a metal lathe and manipulate the compound, but i have and sometimes still do "free"hand turn some transitions and small work.
I don't suggest it for roughing out, but you can (I have) use an angle grinder while the lathe turns the work. There is a fine balance so the AG is not bouncing and following the contour. You need the protruding out of roundness to be reducing itself. When the part is round, then you can work more toward contour. Stay away from chuck jaws, & don't have anything (like a rest) that the grinder could be deflected in to and wedge, causing a big wreck.
smt
Last edited by stephen thomas; 06-17-2024 at 9:43 PM.
Contributor
The short answer is yes
have fun and be safe
[OP]
Contributor
Im satisfied that I can turn it but now I’m not so sure that I should.
http://www.bellsandbirmans.com/bells/bellfacts.php
this is an excellent resource and suggest that I might ruin the bell by turning. It seems that the quality of the castings can be very uneven. The foundry may have misaligned the core leading to a very thin spot or spots. There might be voids that turning would reveal. Looking at the bell, I assumed that it was a rough casting that was never turned. I learn that rough castings we’re often used without machining or polishing.
I’m still taken with the idea of mounting it on our 1860 farm house for a dinner bell. My family doesn’t share my vision. Maybe I can put it in the shop with a remote ringer…
Contributor
Its a neat bell! I would get the roll of 120 grit wet or dry plumbers abrasive out of my plumbing kit and start with that.
Contributor
I vote for trying abrasives before turning tools.
If the object isn't nicely round, it likely isn't, you risk a severe tool "dig-in" when a bump comes around. So feed any tool very slowly until it is trued up.
Contributor
Maybe get it soda blasted to preserve it but clean it at the same time.
Contributor
It's not that easy. Go to the local thrift shop and buy a small brass bell and do some turning on it. I do agree sandpaper is the best way to go.
Contributor
I make lots of tool handles with ferrules turned from brass gas compression fittings up to about 1-1/2" diameter, so I've never tried anything as big as your bell. The brass in the gas fittings turns very nicely with a small gouge. I keep the speed fairly low (a couple hundred rpm) and take a light narrow cut, especially while turning the flats off. Never tried a scraper for this job, though I did manage a pretty nice finish cut on one with a skew. Sandpaper followed by steel wool and then metal polish can give a perfect shiny finish.
You want both safety glasses and a full face shield when turning metal. Be sure not to rub your eyes with a hand that has metal filings on it!
[OP]
Contributor
Thanks to all,
the auction ends in an hour and the bid has gone higher than I am willing to spend given the lack of enthusiasm on the part of my family.
Contributor
Good reading on the bell article, thanks for sharing.
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