cliff1959 Posted January 4, 2009 Share Posted January 4, 2009 Hi newbie in England here, this forum looks like a good place to ask this question. Does anyone know how I can successfully make a 4in (10cm) diameter copper hemisphere?, I need 56 of them for a Dalek I'm making out of old copper hot water cylinders Thanks for any ideas. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 5, 2009 Share Posted January 5, 2009 Welcome aboard, glad to have you. You're at least the second person from Devon on the forum. Cool. I'd spin them. It'd give you the perfect excuse to pick up some more equipment and learn a new skill too. Win win! Metal spinning You can find lots of examples with a web search for "metal spinning." The pics are Dad spinning a large radar reflector (probably) and the other is Dad spinning hot, I used to do a lot of torch holding in his shop. Frosty Quote Link to comment Share on other sites More sharing options...
ironrosefarms Posted January 5, 2009 Share Posted January 5, 2009 cliff1959, welcome to IFI! I wish I had an answer to your copper question but it isn't my specialty by any means. Great to have ya and look forward to seeing you around IFI Frosty, those are great pix of your dad... Sherrie your sister? Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 5, 2009 Share Posted January 5, 2009 Sherrie was Dad's business partner's wife. I wish I had more pics of him spinning but there weren't many taken. I don't think there's even one of me spinning as a kid. The radar dish (probably) was taken before 1955 in the basement of one of the houses we lived in. It was a daylight basement with a garage door, I remember it clearly though Mother didn't believe me till I described the basement stairs and my attempt at flying down them. That didn't end . . . well. Frosty Quote Link to comment Share on other sites More sharing options...
divermike Posted January 5, 2009 Share Posted January 5, 2009 Frosty, I envy you the time you spent with your dad, what a learning experience, I hope to have my son look back with fondness on the time we spend welding and farting around together. Quote Link to comment Share on other sites More sharing options...
John B Posted January 5, 2009 Share Posted January 5, 2009 Hi Cliff, If you haven't got the facility to spin them, you can anneal some copper discs and raise them on a leather sandbag, or into a hemispherical form on a tree stump or swage block, Do they have to be copper? And how are you going to fix them? I ask because it will affect the cutting for the blanks you will need to make these. You could go to Cockington Court and have a word with Rex the blacksmith there, he may be able to help, otherwise see Blacksmiths Guild Home and pop up to Westpoint and see me there on one of the courses dates shown, and I can explain and show you a couple of ways to do them. Quote Link to comment Share on other sites More sharing options...
cliff1959 Posted January 5, 2009 Author Share Posted January 5, 2009 Thanks for the replies so far. Frosty ... the spinning looks interesting but that would leave me with a hole in the centre of the hemisphere. But it's a technique which looks a lot of fun to have a go at. John ... I'm only a mile away from Cockington so talking to Rex and picking his brains may prove informative. Yes, they do have do be in copper and I intend fixing them using solder, the rest of the Dalek is in copper. or into a hemispherical form on a tree stump. Do you mean beating the copper into a hemispherical 'hole'. I have tried this but I found the metal gets very, very thin in the centre although the form was made of concrete ... how would a tree stump be utilised? Would you have to carefully chisel a hemi into it? I had a look at the Westpoint course dates page. Would you require me to book on the course date or just pop in for a few minutes of instruction? Another option I'm looking at is trying to obtain copper hemi's from a ball float manufacturer but this could prove expensive. Quote Link to comment Share on other sites More sharing options...
John B Posted January 5, 2009 Share Posted January 5, 2009 Just pop in for a chat and a look, Spinning would not leave a hole in the centre. Did you anneal your copper first before beating it? And I think your technique may have been wrong, you probably tried to push it too far too quick, against something too solid, (you are stretching the material as opposed to forging it) the backing needs to have some give in it until you achieve the finished dimension, then you can planish against something solid to remove any marks. it also stiffens up the article by work hardening it. What was the blank size you used? Far easier to chat and show, bring a blank along on Saturday and lets have a go, some time about 11? Quote Link to comment Share on other sites More sharing options...
Bentiron1946 Posted January 6, 2009 Share Posted January 6, 2009 You might try MetalMeet - for Metalshaping Enthusiasts & Professional Metalshapers for some other was to work sheet metal. They seem to do a lot more of the thin gauge stuff over there then we do over here at IFI. I have picked up some good tips on forging and and shaping thin stuff there.:rolleyes: Quote Link to comment Share on other sites More sharing options...
blafen Posted January 6, 2009 Share Posted January 6, 2009 I think for heavily dished objects like that you would need a copper disc that was thicker near the center to counteract the thinning of the hammering process so the side view of the disc wouldlook like this () sort of. Quote Link to comment Share on other sites More sharing options...
Bentiron1946 Posted January 6, 2009 Share Posted January 6, 2009 If you use a big hydraulic stamping press you will not get much distortion but he doesn't have one. He is doing it the old fashioned way, by hand. Some thing of the center is expected but will only be marginal. It isn't going to wafer thin if he does it right. If he tucks the edge it will be OK. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 6, 2009 Share Posted January 6, 2009 You don't need a center hole to spin, it only makes it easier to center the blank. Frosty Quote Link to comment Share on other sites More sharing options...
azIRonSmith Posted January 6, 2009 Share Posted January 6, 2009 Hmmm, hand hammering a copper hemisphere takes a lot of practice and skill. Especially to make it look good. When you were hammering into the wooden form, were you just hammering mostly in the middle? Most coppersmiths will actually layout a spiral or concentric pattern to hammer the disc. This keeps the metal evenly stretched. This will keep you from thinning one area too much. Also don't forget to anneal (heat to red hot then immedately quench in water) often. Could you use something made of foam or wood and just paint it to look copper afterwards? If it has to be metal, could you would use metal bowls and then paint it copper? You could also copper plate them if you want a "real" copper look. Quote Link to comment Share on other sites More sharing options...
cliff1959 Posted January 6, 2009 Author Share Posted January 6, 2009 Just pop in for a chat and a look, Spinning would not leave a hole in the centre. Oh, I saw a picture online that showed a bar going through the centre of the workpiece when fitted to the lathe ... more than one way to skin a cat then.Did you anneal your copper first before beating it? Sort of, more by luck than judgement, I heated most pieces just to aid bending so it sort of got annealed.And I think your technique may have been wrong. Yes, you described exactly what I did. What was the blank size you used? Just a little bigger than what was required, perhaps 3cms bigger.Far easier to chat and show, bring a blank along on Saturday and lets have a go, some time about 11? Unfortunately I'll be in Bristol this coming Saturday but there are others listed so hopefully I can make one of those. If anyone's interested I'll post a picture of what I've built so far? Quote Link to comment Share on other sites More sharing options...
cliff1959 Posted January 6, 2009 Author Share Posted January 6, 2009 Here's a picture so far whether you want to see it or not Hours so far amount to about 650 and everything is made from scrap copper hot water cylinders except the temporary plunger.http://www.iforgeiron.com/forum/images/attach/jpg.gif Quote Link to comment Share on other sites More sharing options...
Finnr Posted January 6, 2009 Share Posted January 6, 2009 Nice, very Whovian. Finnr Quote Link to comment Share on other sites More sharing options...
homesteader Posted January 6, 2009 Share Posted January 6, 2009 Cliff1959 I have dished or what is usually called dapped fairly large pcs. of copper as well as sterling silver on a homemade dapping block which is a container of melted lead which is then dished in to the desired shape and size. I have used large ball bearings for this purpose or the punch which I will further describe. The copper must be annealed before forming. I have done the forming using a wooden dap which is a rounded pc. of wood such as hickory or similar hardwood. the length and diameter will depend on the pc. being worked. Something of this size would take a pc. around 3' inches in diameter by around 8" to 10" long. One end needs to be rounded to the same radius as the dapping block and smoothed to use as a punch to force the copper to conform. You can narrow the other end down to handle size. You then beat the punch with a wooden or fiber mallet to force the copper to shape. As you force the copper it will become work hardened and so will need to be annealed again as many times as necessary to complete the forming in this case twice will probably do it. If it needs to be a very smooth surface I would make a tool from a block of steel again about the same diameter as the dapping punch and rounded to the same radius but shorter and weld a foot to it the same square as the hardie hole on your anvil. It will have to stand far enough above the anvil to allow you to work the pc. inverted over your now steel dapping punch. This time reverse the pc. and and gently hammer out the bumps from the outside until it is as smooth as you need it to be. I know this sounds like a long process and it will be but a lot of the time will be in building your tools. Once the tools are finished it is an assembly line operation of repetition. Hope this helps. Quote Link to comment Share on other sites More sharing options...
lwhiway Posted January 11, 2009 Share Posted January 11, 2009 quote:how would a tree stump be utilised? Find a nice sized diameter tree stump with a flat cut good end. Hog out the stump/wood to the shape/dish that you need and start hammering/dapping in. Like all have said already, the secret to working your copper is in keeping it in the annealed state. Quote Link to comment Share on other sites More sharing options...
Ian Posted January 12, 2009 Share Posted January 12, 2009 Funny I stumbled across this post three days after getting hold of a 6ft tall copper water tank for free. Intend to use the copper for some repousse work, dishes being a probable project too. I've seen bowls spun in copper, and brass and even steel, none of them had holes in the middle, the machine clamped from either side of the plate. By the way, that Dalek looks the dogs mate, top bombing Quote Link to comment Share on other sites More sharing options...
rock-n-time Posted March 24, 2009 Share Posted March 24, 2009 A little late... What you are doing is raising. As one said coppersmiths lay out a spiral or circles spaced evenly from the center. you need a radios steak or a muchroom steak. a raising hammer. a planish hammer.TIME! and if thay are going to gether mak shur you put a hole in it! i can give more info. Quote Link to comment Share on other sites More sharing options...
beth Posted March 24, 2009 Share Posted March 24, 2009 cliff i LOVE your dalek! youve come this far you got to finish it in copper... Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 24, 2009 Share Posted March 24, 2009 Actually I'd go try to find some copper toilet valve floats, cut in half for 2... Quote Link to comment Share on other sites More sharing options...
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