Hey everyone! I have a question. I'm working on a tower clock restoration project that will ultimately lead to a scaled replica build. In parallel with this work we/I have some replacement parts that will get reverse engineered and re-cast, followed by final machining. Is there a certain type of brass I need to be talking about when requesting quotes and getting this job done? There will also be some cast iron pieces. Is there a certain cast iron I need to be considering? This would be for frame parts, mostly. Of course I will post all about the construction process as it's happening. Really looking forward to this! Thanks for any help! Scott
Sounds like a great project - sorry I can't help withyour technical enquiry, but looking forward to following along on the construction progress All the best Conwae
I will definitely post a construction thread. It will end up being a very slow-going thread, but I'll definitely share.
Hi Scott, I'm not familiar with casting or the composition of cast iron, but I'm also interested, so look forward to any advice shared by forum members. I have seen some home workshop casting videos on YouTube (mostly casting scrap brass and bronze), so I'm sure there is also information on casting iron. I'm curious to see your progress, as I eventually want to cast an iron plate to support a regulator pendulum suspension. Good luck with your research, and keep us posted! Best wishes in the meantime, Paul.
There is some wonderful YouTube videos on making foundry patterns. I've learned a ton there. I've also been doing some reading on the process, but the videos really do a great job. The size of the "pattern" will be dictated by the material that is being poured, due to shrinkage rate. Depending on the cast iron (not sure what we should be using for clock frames, and such) it may have a shrinkage rate of about 1% where Brass is about 1.5%. I think the types of cast iron or brass to consider for clock parts is really what I'm looking for. Materials today are obviously a little different than 100 years ago. So any info anyone can share on what types of materials are suitable today for large clock parts (tower or street clock size), would be great. Thanks guys!
I had a lot of wheel blanks, plates, and other parts cast up in yellow phosphor bronze. It is much harder than brass, very wear resistant, and does not have to be hammered to increase its strength. All that said it ia a pain to machine, it requires sharp tools to cut it well. If you need strenght out of the mold it may be a good way to go with tower clock parts... Phosphor bronze is an alloy of copper with 0.5-11% of tin and 0.01-0.35% phosphorus. The tin increases the corrosion resistance and strength of the alloy. The phosphorus increases the wear resistance and stiffness of the alloy. These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain. The phosphorus reduces the viscosity of the molten alloy, which makes it easier and cleaner to cast and reduces grain boundaries between crystallites.
Great! Thanks Jim! That's good info. Is it hard on tools or is it just that you need to have nice tools and have your "speeds and feeds" under control? The price of horological type cutters being as high priced as they are, that could get expensive quick, if it destroys tools easily. Is cast brass NOT a good option at all, this day in age?
There are better options than old style cast brass. Most cast brass requires hardening by pressing or rolling or hammering it after casting. Some of the more modern alloys, such as yellow phosphor bronze are hard, tough, and substantially stronger than plain cast brass. As mentioned previously, sharp tools are needed. And yes, feeds and speeds come into greater importance. And I use coolant/lubrication when cutting teeth on wheel blanks.
Okay. This is GREAT information! I was not aware of the post process required. It seems starting with a forged brass billet might be a good option, as well, for some of the smaller parts that can be machined. There are ways to achieve a cast finish to help with authenticity of the part. This gives me A LOT to think about and consider.
Also, if you don't mind me asking, can you give me an idea of a cost comparison for Yellow Phos Bronze casting? One things for sure... reproducing parts for old machines is always cost prohibitive.
The cost of casting clock sized parts is far more in the making of the patterns and molds than in the materials used. It has been a long time since I have had any of the parts cast so anything regarding the price I paid would be irrelevant. I generally supplied the patterns but that is an art all into itself. Today, it is hard to find brass foundries, and related material foundries, at all. EPA, OSHA, cost/profit issues, and the like have put many out of business and the few that remain in business tend to be either pricy, or not interested in small jobs, or some combination of both. But, some do exist and will work with us on the sort of work we need done.
I agree, on all accounts. Seems that's happened/happening to many industries. Also understandable on pricing irrelevance. Thanks for the input, none the less. It's appreciated!
Hi Scott, In the late 1970s I had the opportunity to discuss duplicating some antique cast iron chandelier parts with a local (Milwaukee, WI) foundry. Learned of the differences in Grey Iron and Stove Cast. Most modern foundries cast grey iron as it is highly refined and best for most work. The Stove Cast is most like the antique iron used where thinner sections in relation to the length are desired. Stove Cast had phosphorus in it which is considered an impurity but it allow the iron to be more fluid. I was advised that there were foundries in the southern U.S that still used the older recipes to cast wood burning stoves. I went into this explanation because if you are scaling down your parts enough, you might run into the problem that Grey Iron will not flow well into the thinner areas. I have heard of an Amish foundry in PA that does quality iron casting, and in short runs or one offs. A quick look at my bookmarks turned up this page from the Vintage Machinery.org site: Foundry Sources - VintageMachinery.org Knowledge Base (Wiki) The first paragraph on this page offers IMHO the best advice regarding contacting these sources. Many of the people restoring older machinery run into the same problems we do so this should be of a help.
I'd be happy to assist anyone who has a foundry available but with no means to produce a mold or investment positive in plastic using 3D-printing. You'd have to supply the source file as I'm just getting into the printing part of this world and haven't learned how to use any 3D modeling software, yet. www.Thingiverse.com has thousands of 'things' that are already defined, downloadable & ready to print and I've just been printing those models, so far (Like upgrade components for the printer, itself.)
That is some great information! Thank you sir! Very good points and a great link to-boot. I've visited that website in the past for identifying some equipment I own. Great resource!
That's a great gesture. I've considered doing some of this as well, since most of my parts will have CAD files. The RP machines we use at work, tend to have some shrinkage and often need some work to get a good finish, but nothing you couldn't just shoot with a high-build primer and proper coating to get back. What are you using for a RP machine/3D Printer?
Sir? ..................... Thanks for the honor but I feel old enough already I hope we are all on a first name basis here.
Interesting! Amazing that a person can purchase a 3D printer for that cheap, now. I might have to look a little closer at some of these smaller DIY machines. Seems like it could be handy for many things I work on, so I don't have to springboard off of machines at work. Without getting too far off on a tangent here, there is some great information out there about creating casting/foundry patterns using an RP part. I found many helpful videos in the past on the entire process starting with an RP part and all the way through the casting and finishing process.
I was talking with a gentleman out of the UK that mentioned they cut all their tower clock wheels from what they call "Gunmetal LG4 Bronze". Does anyone know what the equivalent US material would be called? Here's what I found on the material: Leaded Gunmetal LG4 | NovaCast I suspect the Phosphor Bronze that Jim has mentioned is probably a more viable solution.
