I would have loaned you the clapper assembly for you to copy for the cost of shipping... but as long as you are having fun V/r HT1
That note is a little weird. There is no way the clapper will be anywhere close to 3% of the bell. I would guess more like 20%. The bell will only weigh 9 lbs and the clapper will be at least 2. As far as the quality of the bell goes, if it isn't right it isn't done. Pete
I finally got after this project today. I've actually been making patterns for other parts over the last couple of weeks- clapper, wall mount, and bracket mount. I still have to make the bracket pattern as well as the eye bolt and acorn nut. These parts are a helluva lot bigger than they look in the drawings! That eyebolt for the clapper is 5" long". I'm just going to cast a 7" cylinder and machine that one. Anyway the sweeps went well. Other aspects of the procedure were a bit of a bastard but the sweeps themselves turned out great. I made the outer profile as shown on the drillpress. I started with a fully rammed drag. I have a George Forman rice steamer that's about 9x9x8" deep that was just perfect for the job. I rammed it full, struck it off and flipped it onto the drag. Mounted it onto the drillpress table and went at it. The beveled cutting edges worked fine with some galling but easily re-smoothed. (In case you were wondering the drill press was unplugged). The trouble came as a result of a design error. As you can see from the drillpress photo the upper portion of the bell had very little draft. In fact, as designed, it had none. Instead of reworking the profile and risking ruining it I canted it a bit when I mounted it to the shaft. That bought me some forgiveness but not much. When I lifted the cope the sand pattern stuck and lifted with it briefly and then fell out. Of course it fractured and was unusable for the second sweep, but the cavity in the cope was good. I just re-rammed the rice cooker, changed out the profile, and swept the interior form. Sounds simple. Took most of the day. I think I'm going to cast this in aluminum and use it for a pattern. Pete
Your confirming what I have always heard anticdotally. Sweeps are alot of work, every time I have heard it come up in conversation everyone with experience rolled their eyes and started cussing and the patternmakers started glueing up wood to get on the lathe V/r HT1
As an an experienced molder I'm not surprised to hear you say that. What I wrote above is the short version. I had two dropouts while lifting the cope. I ended up revisiting ESC's post above as well as Ammen's book. For the third attempt I stapled an additional set of lathe strips around the perimeter of the cope at the parting line as well as threaded rods for internal supports rammed in. You can see one of the rods poking through in the picture above. In fairness to the process lack of draft was the primary culprit, again a basic patternmakers error, but ramming against that sand pattern without cracking it was a real nail biter. Fortunately none of my failed attempts broke the sand pattern. That happened at the end but yielded a good cope. Ammen indicates ramming that core as you build up and sweep. It would require superior sand and a much more skilled hand at ramming control than I would ever hope to have to make that work. Sodium silicate would probably be a more sure way of doing it. Setting up for a one-off has certainly been a lot of work but I wouldn't write the process off -it obviously works- but it wouldn't be my first choice if given an alternative. Pete
I'm awfully glad I chose to cast this in aluminum first. I had been concerned about damaging the outer form in the process of ramming the cope and although it didn't break apart it got bruised pretty good. Another rookie mistake in the gating. I gated in 2 places along the bottom edge with a deep runner and gates in the drag only. I wanted to keep the gates off of the exterior edge to make cleanup easier. What I neglected to consider was that the bell was designed with a sharp edge at the bottom. One of the gates froze off immediately and the whole bell filled though the single remaining gate. I haven't cut it off yet but I'll be interested to measure the actual cross section. I made a second bell casting in the same pour with a smaller cast iron pattern. Very thin cross section. I had attempted this one before gated from the bottom and it failed to fill completely up near the top. Close but not enough. Today's attempt was from the top and wasn't even close. The pattern is just too thin.
that bell should weigh 10 Lbs after machining old school bells where sized(pounds) this way as the design only had small variations to try and achieve harmonic tuning . the cheap knock off bells will often include the weight of the mounting bracket in the weight of the bell to convince you you are purchasing a quality bell. remember the DOD instruction being used to make this bell, can be traced back to the 1900's I considdereed making these bells for sale . this is the bell that Navy ships and small boats use for their quarterdeck bell. Submarined use one of these for their ships bell, I contacted Loeffler bell a few years back and got a price quote so I could see where I could realistically price them, My quote was $1543 for bell and all hardware, with a 4 week turn around I could never find a customer base wiling to pay anywhere near that for a bell so I abandoned the project, after 2 I sold one for $500. and still have one that need polished . I'm lucky enough to have borrowed an actual bell to use as a pattern. as I mentioned above I have never met a foundryman that was excited about using sweeps. seems a very specialised technique ... Loving this thread V/r HT1
I'm making forward progress on this project. I need more bronze before I cast the bell itself, but it's coming. I machined the pattern for the hanger bolt out of aluminum and am working on the pattern for the bracket/arm in V-Carve and will cut a split pattern for that out of Baltic birch on the CNC, so I'll be casting those items soon. I cast the wall mount and matching bracket block already and sent those to my machinist. The dovetails that those require are out of my wheelhouse (plus I don't want to buy the required tooling), and that guy is starving these days so I wanted to throw him a bone. Here's my finished clapper. It still needs to get finish-finished, but the filing is done! Pete
im curious why the dovetales are out of your wheel house, I included them in the pattern and cast them in, will try to include a picture later V/r HT1 P.S. you might have to remind me
Truth be told I really dont want to buy the 1/2" dovetail cutter. I would very much like to see the picture. Pete
this is the pattern for the wall mount , the second two pictures are it on a rough casting(it's actually still on the gating , next time I will just ram up the entire thing. I have A leoffler bell and rang one regularly during my 20 year career, the wall mount and the bell support are cast, and not particularly tight , but it works perfectly, as you can see V/r HT1 https://www.facebook.com/video.php?v=2060894493930179
ince we are doing pictures, here is an actual USN 10Lb Leoffler bell here is the Clapper, no part of it is machined it's sanded wher it contacts the Bell then Buffed, the hook to hang the clapper is cast open, then squeezed ever so slightly so it is not easily removable side view to show that the lanyard loop is thinner then you would expect this picture shows the detail on the letters, that round font allowes the Pattern to be cleanly pulled from the sand, IF you keep track of the location of the letters and pop the cope with a little love this gives detail of the bell and arm there is very little machining on this bell, looks like just the very top, and a small circle in the center of the bell so the loop bolt has a flat spot to seat. if there had been much machining the U.S. would be gone I suspect they use a slack Pipe belt sand , and a 12 inch buffing wheel, probably with a preliminary sand blasting with walnut of glass media V/r HT1
I took a stab at the bell today. As I showed above, I made an aluminum pattern from the sweep mold. Because I had rammed the outer form several times before I got a good cope the mold yielded a less-than- perfect-shaped casting shown above. After a lot of time on the lathe a loads of sanding I got the pattern in what looked like pretty good shape. What I've discovered though is that the bell as a whole is out of whack dimensionally (height) and there are variations in cross section where there shouldn't be. I poured a nearly full A10 and still came up short. While reshaping the pattern I had taken too much material off the top of the bell and as I found out today I had left myself only about 2mm thickness on top instead of 9. It probably wouldn't have filled even if there was enough metal. Also the upper vertical portion of the bell is also way too thick: over 13mm in some areas where it's supposed to be 9. Although I didn't weigh the bell by itself, what you're seeing in the picture with spru and runner is 20lbs! There's something wrong with that. This all started with inadequate draft on the sweep patterns and I've paid the price for my oversight. I'm going back to the drawing board on this one. It's a lot of work down the tubes but so be it. I knew I was pouring hot today but I didn't think it was that hot. I suspect that's the cause of the surface defects both inside and out. Pete
Looks like mold swell? Good try though. Next one should do it! I'm taking notes. I will be making a 13" bell soon.
Starting over from scratch eh? Too bad, but it does sound like you have a couple little problems with your pattern. Good try Pete, bet you'll nail it next time. Jeff
I think you should have gotten that bell, your gating system is way too big I would have ran a 1/2 X 3/4 inch runner ( start with 3/4 X 1 and sand draft onto it or cut it in the tablesaw) the sprue looks too big no larger the 5/8 at the bottom that Bob Paluka pouring cup wasted tons of metal. just put on a cup if your ingates do not have the same or a larger cross sectional area as the runner metal will spray into the mold causing all sorts of turbulance the finning on the interior of the bell is very hard to avoid it takes skill and practice to get a good solid hard ram on the interior of a bell. the xterior of the bell looks (good) but unusual I dont think I have ever seen the fins run up and down , it is pretty common to have some ugly fins running around the lower section of the bell, but I have never seen them up and down. remember you are pushing the limits of petrobond here so ram hard, but evenly. fix up the pattern and try it again, I think you will get it Very good first try V/r HT1 BTW I have seen bells come out looking like an anthill project because of a soft ram
