GD85 Posted June 20, 2009 Share Posted June 20, 2009 Good morning, One quick question for the experts here... what's the best process to polishing forged repousse/chasing punches? I made a set recently. Am mostly happy with the way they have turned out, but am missing something because no matter what I have tried I cannot get them perfectly rounded. They work alright, I think (just started messing with copper) but I still am leaving a few unwanted marks on the work. I made them by first forging the rough shapes. Second step is wire brushed to see clearly what needs to be filed or sanded. Third step is using the belt sander or file to round off edges. Then aggressive wirebrushing to smooth whats left over. I am thinking its just experience and patience that I am lacking? Does anyone have any process improvement advice? Is there a magic chasing tool polishing widget that I don't know about? Ok... off to the scrapyard. Thank you, -Grant Quote Link to comment Share on other sites More sharing options...
arftist Posted June 20, 2009 Share Posted June 20, 2009 (edited) Polishing anything involves the same steps. 1. Course grit 2. Finer grit 3. Even finer grit. 4. Etc. until desired level of smoothness. Some tips; Remove ALL scratches left by previous grit size. Change direction of stroking to better see scratches, left to right, top to bottom, left upper corner to right lower corner, right upper corner to left lower corner. Jump grit sizes by as much as possible to save time. A typical polishing job may go as follows; 100 220 320 400 600 For mirror polish, one would follow with one or several wax combined abrasives and buffing wheels. Edited June 20, 2009 by arftist spelling Quote Link to comment Share on other sites More sharing options...
DocJohnson Posted June 20, 2009 Share Posted June 20, 2009 Grant, With a bit of a grin, I note that unwanted marks on my work are due to errant blows or a misplaced tool. I suspect I will always need more practice. I am in no way, an expert. As far as finishing the tools, I use progressively finer grit wet or dry paper, hand sanding, to take out scratches. I use 320, 400, 600, looking for scratches in good light before proceeding to the next finer grit. I then use a cotton polishing wheel with a fresh charge of polishing compound. The six inch wheel is mounted on one side of a bench grinder. I have a "rake" to clean any grit out of this wheel, before I put on the polishing compound. In a few moments I have a mirror polish that does not transfer scratch marks and that will move over the work with less friction. The configuration of the working ends of any tool is very important and I rarely see it discussed. A chisel with an uneven cross section will tend to move sideways. To check for symmetry, I use a well lighted, white background, and keeping the tool out of the light, so I see just its dark outline. I look at the sides and edges for flat spots or other errors. If I am intentionally making an asymmetric tool, I check it in the same way. My first attempt at repousse was a result of a workshop taught by Gene Olson from Elk River, Minnesota. We made tools and decorated the lids of Altoids tins. I have given many of them as gifts, resulting in people giving me all the tins they have been saving. I use hard plasticine for a matrix or backing material for most work, saving the pitch for finer lines. My thanks to Gene. Grant, I hope this helps, DocJohnson Quote Link to comment Share on other sites More sharing options...
markb Posted June 20, 2009 Share Posted June 20, 2009 Post some pics we'd like to see your work. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted June 20, 2009 Share Posted June 20, 2009 100, 220, 320, 400, 600 I see no reason to include 320 in that list, as its so close to 400. many grits are made, but not all are needed for us. We all need to experiment a bit to find out what jumps in grit we can make in our jobs. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted June 20, 2009 Share Posted June 20, 2009 I note that even 1500 grit paper leaves marks on my planishing hammer. For a really fine finish you need to buff with polishing abrasives as suggested above. Charlotte Quote Link to comment Share on other sites More sharing options...
arftist Posted June 20, 2009 Share Posted June 20, 2009 I see no reason to include 320 in that list, as its so close to 400. many grits are made, but not all are needed for us. We all need to experiment a bit to find out what jumps in grit we can make in our jobs. Hi Steve. I found I have a hard time getting 220 scratches out with 400. It seems to go faster for me if I use 320. It certainly can be done, but it is more work, in my opinion. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 20, 2009 Share Posted June 20, 2009 If it's the rounded profile you're having trouble with try slack belt grinding, off the platten. Without the platten to back it the belt will wrap around the part a little so grinding smoothly rounded cross sections is much easier. Frosty Quote Link to comment Share on other sites More sharing options...
blksmth Posted June 21, 2009 Share Posted June 21, 2009 3M make a great pad for polishing most anything. They are called Scotch-Brite surface conditioning disks. They come in course, medium, fine, and very fine. They are made in several sizes to fit angle grinders. I find the 7" size most useful. With them it is very easy to take out grinding marks, high spots, and put that final shiny polish on hammer heads, anvils, and other tools. These pads attach with a velcro like backing so they are easy to change. They are so much easier to use than different grits of sand paper on a belt grinder or by hand. Last I knew you could buy a pad and 3 grits of disks in a 7" kit for appro. $40. You buy them from machinery supply houses such as Enco or possibly your local tool supplier. Quote Link to comment Share on other sites More sharing options...
Quenchcrack Posted June 21, 2009 Share Posted June 21, 2009 (edited) I agree with blksmth; Scotchbrite wheels move the metal without removing it like normal abrasives. They come in 6" wheels to mount on your grinder and in different grits for non-ferrous and ferrous metals. You would prolly have to google for a local distributor but a welding supply shop might have them. Edited June 21, 2009 by Quenchcrack Quote Link to comment Share on other sites More sharing options...
GD85 Posted June 21, 2009 Author Share Posted June 21, 2009 Thank you all for the advice. I probably should have been more clear in the original posting, and I apologize if I wasted anybodys time. The real issue I have been having is not to much polishing (so that they shine) but removing the high spots/final shaping. Probably due to my inexperience I am having a hard time with both machine and hand tools (beltsander, files, angle grinder etc w/ flap disc) and tend to take too much off and/or leave high spots. I can get these tools close, and then hit with a wire wheel but there still is usually a line left. As soon as I try to even it out with the belt sander or file I lose it until I have sanded/filed too much and the tool is smaller than intended. The biggest problem I have had is trying to create a half sphere that is smooth and does not have ridges. After typing all this, it really sounds like I need to work on file control. Filing is pretty new to me, but it it slow enough of a process so that there shouldn't be an excuse for taking too much off. I will look into the 3m wheels, and depending on the price may or may not give them a try. The wire wheels (on angle grinder) seems to work pretty well for smoothing without removing too much metal and are reasonably cheap at the flea market here. Thank you again, -Grant Quote Link to comment Share on other sites More sharing options...
jeremy k Posted June 21, 2009 Share Posted June 21, 2009 Grant - one of the most important things to remember while triing to make a tool smooth that has a round end whether its a contant curve or compound, is to never stop moving the tool during grinding(hesitating will cause your flat spots). Keep the preasure against the grinder/belt/file light untill you get the hang of moving the tool in a arc during the removal process. You'll get it - it just takes a little practice with you hand/finger movments to get a nice even smooth fluid movement to grind the tools the way you want. - Good Luck - JK Quote Link to comment Share on other sites More sharing options...
blksmth Posted June 21, 2009 Share Posted June 21, 2009 I think those 3M Scotch-brite pads are just what you are looking for. After the initial investment of buying the pad, and considering how well they work, the price isn't so bad. Quote Link to comment Share on other sites More sharing options...
David E. Posted June 22, 2009 Share Posted June 22, 2009 As JK says you have to keep it moving, just like sharpening a drill if you are using a belt sander. If you are using hand tools then keep them moving, if you file flat you get a flat spot, it is all about practise. After roughing out get strips of emery cloth/ paper, put the punch in a vise at the end of the jaws so you have room to put the length of sandpaper over the top of the punch and work each hand in an up and down motion close to the sides of the punch, this will eliminate flat spots and give an even radius to the head of the punch. Quote Link to comment Share on other sites More sharing options...
Charlotte Posted June 22, 2009 Share Posted June 22, 2009 A suggestion for you : keep a piece of scarp copper or lead handy and check your work as you go along. Quote Link to comment Share on other sites More sharing options...
KNeilson Posted June 23, 2009 Share Posted June 23, 2009 Grant, I have done lots of this. One of my biggest improvements came with using a Loupe (10x) to check the shape of my tools before the final polish. Depending on how big of a radius your wanting, try drilling a accurate row of holes increasing in size along a scribed line in 16 ga alum. Then saw almost in half (along the line) and file to finish. This should make you an accurate radius tool. If you can find a cheap drill guage this same idea will work also. Shape should come first, then finish (polish). Check between grits with the loupe to ensure quality. Final finish with a cloth and metal polish. If you cant see flaws with a loupe, I can guarantee you wont notice with a naked eye.Frosty wroteIf it's the rounded profile you're having trouble with try slack belt grinding this is good advice, if your doing it by hand, hold the tool vertical, the file or emery paralell to it, and file in a downwards motion rocking the heel of your hand to level ( or more) as you work. This will give you a better radius than holding the tool horiz. and filing towards the tip. Hope this helps...... Kerry Quote Link to comment Share on other sites More sharing options...
Duckpond Posted June 24, 2009 Share Posted June 24, 2009 I made a jig out of 30mm round bar, i cut a section about 50mm off, added a handle, and drilled a 10mm hole in it . I use it to make 10mm rivets and 10mm punches. I slide the punch down tll it grabs, and mark that spot, then tidy the high spot with a fine file. Quote Link to comment Share on other sites More sharing options...
CBrann Posted June 24, 2009 Share Posted June 24, 2009 I like the 3M wheels, but I have to find a way to slow down my grinder... 10K RPMs they just melt from friction! For "domey" shapes I do most grinding and filing, thenI start with sand paper on a hand rubber block, and work thought the grits. Spheroid objects are very difficult, as their surfaces are smooth, but change in 3 dimensions. (As opposd to tapers that only change in 2 dimensions, therefore fit nicely on flat grinding and filing tools) Does anybody use rubber abrasibive wheels as a between sandpapr and polishing wheel? I got the idea from jewelry making, to remove scratches prior to polishing? Quote Link to comment Share on other sites More sharing options...
DocJohnson Posted July 14, 2009 Share Posted July 14, 2009 markb had asked to see a picture of some Altoids tins. It has taken me since 6-20 to get the picture and figure out how to post it. Quote Link to comment Share on other sites More sharing options...
DocJohnson Posted July 14, 2009 Share Posted July 14, 2009 Seems it did not paste the thumbnail, I'll try again. Quote Link to comment Share on other sites More sharing options...
bamboolongbow Posted July 16, 2009 Share Posted July 16, 2009 What about white rouge on a buffing wheel for a final polish? Quote Link to comment Share on other sites More sharing options...
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