Rose ET in our new forum (subforum)

#1
OK, now that we have a forum (subforum) that has been expanded due to its general title, here's a little rose engine "ET" on sterling I did for a custom pen. Chris has seen this already so I can see him goin' "ho-hum."

This simple pattern came from a little project I did with a 1916 Lienhard rose engine that has some rather high amplitude rosettes mounted on it. I could have changed some of them out but that effort is a real PITA. The rosette is a 12 lobe deal and since they're like 7 inches in diameter it took this experiment to see how it would turn out on a small workpiece. The rosette essentially looks like a slightly rounded regular dodecagon and the amplitude of the pattern is about .070"

Squishing all that down to less than a half inch diameter resulted in that nice star pattern. The interesting thing about cutting this pattern, as all of the experts know, is that the cutter spends most of its time going sideways and dragging the cutter inways that it wasn't designed to cut. The cutter had the typical "Daniels" angles and relief except that I do not have any positive rake on top. I use 0º top rake. So, even with the cutter going sideways, it turned out OK and I love the illusion of stacked stars. The other thing about the combination of the size of the cutter (.060" wide with "Daniels" angles) and the diameter of the pattern onthe workpiece is the the smaller the diameter, the shallower the cut practically speaking. On a larger diameter cut the guide comes in to play limiting depth but at these very small diameters (with my cutter dimensions) the cutter cannot penetrate as deep as the guide would allow without significantly smearing the cut. So I opted to let it do what it was going to do. Next time, given the motivation I will grind a smaller cutter on the lines of .040" wide with about 45º*front relief and around 30º, if I can make that happen, for side relief. This is all going to be in carbide. I might even reduce the included cutting angle to, maybe, 130º - 135º. Guide DOC is set to about .003" (80µm) and that's plenty deep but, again, with the current cutter geometry all I get is a nice scratch when diameter gets down to .25" or less but this pattern didn't quite get down that far. The diameter of the pen cap is .590". Rubber (on a bearing) diameter was 5/8" which really didn't account for much in ultimate pattern shape.

Cheers,
Rich
 

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#2
This is so four weeks ago ;)

I'm interested in seeing how other cutter geometry makes this easier. I also wonder how a diamond drag graver would work in this kind of situation. It is obviously designed for this kind of radical direction change, but I wonder if the cut would be acceptable.
 
#3
Rich
Nice pattern. I like the 3D effect and it demonstrates the advantage of not running the pattern into the centre.

I've been experimenting with using a 0.050 HSS wide chisel shaped cutter with a 30 degree front relief and about a 5 degree positive front rake to excavate 1" D fine silver discs prior to engine turning. The excavations are circular, 4 thou deep and are designed to set set everything up for champleve enamelling. Once the excavations are completed, a conventional Daniels ground cutter, again about 50 thou wide, is used with a 40 though wide acetal geed set for 3 thou deep to do engine turning in the excavations. So far, this has been working out OK although there is a HUGE amount of eye strain, even with an Optivisor. The reason for the thin geed is to enable the cutter to incise the ET pattern as close as possible to the right hand side of each excavation. I still have a couple of layers of enamel to apply to this one and then some serious polishing before it's ready for a bezel but I will see if I can attach a pic here to give you a sense of how it's shaping up. (I have no idea if the pic will show up here; what I get in typing this is the file location for the pic.)

/Users/ramsayholmes/Pictures/iPhoto Library_2/Masters/2012/08/26/20120826-161740/P1030564.JPG

I'm a bit unclear why so many guys use carbide rather than HSS when cutting in SS or fine silver. HSS is so much easier to grind and I find it holds the edge quite well. I realize that carbide is tough stuff but we are cutting pretty soft metals, they don't get hot in ET and generally the cutting is pretty small scale. I've used a good microscope to compare HSS cuts in fine silver with the same cuts done with carbide and I'll be darned if I can see a difference. So unless you anticipate using the same cutter many times between sharpening, why carbide when HSS does the job so well?

While I'm on it, have you tried using Sterlium Plus instead of conventional sterling? Stuller seems to be a bit vague about the composition but I'm pretty sure they have replaced some of the copper with iridium, germanium and something else. In any event, while I doubt that it will accept enamelling, I have used a torch on it (not as much firescale as SS) and it accepts a 2-56 tap quite well. I've used it for a couple of lid handles (anchoring the lids with stainless 2-56 hex head bolts) and there is no tarnish on the Sterlium - so far - despite frequent application of sweaty fingers pawing away at the handles.
Ramsay
 
#5
Rich
...
I've been experimenting with using a 0.050 HSS wide chisel shaped cutter with a 30 degree front relief and about a 5 degree positive front rake to excavate 1" D fine silver discs prior to engine turning. The excavations are circular, 4 thou deep and are designed to set set everything up for champleve enamelling. Once the excavations are completed, a conventional Daniels ground cutter, again about 50 thou wide, is used with a 40 though wide acetal geed set for 3 thou deep to do engine turning in the excavations. So far, this has been working out OK although there is a HUGE amount of eye strain, even with an Optivisor. The reason for the thin geed is to enable the cutter to incise the ET pattern as close as possible to the right hand side of each excavation. I still have a couple of layers of enamel to apply to this one and then some serious polishing before it's ready for a bezel but I will see if I can attach a pic here to give you a sense of how it's shaping up.

Pretty enameling - love that color! So your enamel is going into only a .004 deep pockets? Interesting it's so shallow - very cool. Thanks for posting that. On the guide, I have some Delrin AF that one day I'll use to make one. I think a plastic surface is a great way to go

...

I'm a bit unclear why so many guys use carbide rather than HSS when cutting in SS or fine silver. HSS is so much easier to grind and I find it holds the edge quite well. I realize that carbide is tough stuff but we are cutting pretty soft metals, they don't get hot in ET and generally the cutting is pretty small scale. I've used a good microscope to compare HSS cuts in fine silver with the same cuts done with carbide and I'll be darned if I can see a difference. So unless you anticipate using the same cutter many times between sharpening, why carbide when HSS does the job so well?

I just happen to have the sharpening equipment and the cheap and conveniently available carbide cutoff tools. I just did a recent calculation of how much use my current straight line cutter has and it has done close to 25,000 cuts and it still has a workable edge. I don't have a comparable experiment with HSS but I'm pretty sure it would be less. Even with that longevity of carbide it really isn't a huge deal to pull a cutter and re-sharpen it but I'd rather not if I don't have to. So I've opted for laziness (smiley face here)

While I'm on it, have you tried using Sterlium Plus instead of conventional sterling? Stuller seems to be a bit vague about the composition but I'm pretty sure they have replaced some of the copper with iridium, germanium and something else. In any event, while I doubt that it will accept enamelling, I have used a torch on it (not as much firescale as SS) and it accepts a 2-56 tap quite well. I've used it for a couple of lid handles (anchoring the lids with stainless 2-56 hex head bolts) and there is no tarnish on the Sterlium - so far - despite frequent application of sweaty fingers pawing away at the handles.

I use Argentium for the clips on my pens because not only does it have the germanium addition but it hardens up better than ordinary sterling. It submits to engine turning just about as well as ordinary sterling.

Ramsay
Comments above in blue italics

Cheers
Rich
 
#6
I use carbide for a few reasons. First I can get a higher polish on it than HSS. I'm polishing on a Glendo Accufinish down the 0.5 micron. I've found the results of that better on carbide (I use Micro100 carbide which I find is nicer than other types of carbide I've used). YMMV. I also need to sharpen less frequently. I touch the cutter up with the 0.5 micron wheel every 10 hrs of engine turning, and rarely have to regrind it (I still haven't reground the first cutter I made 3+ years ago). Even though the application isn't as stressful as turning at high speed on a simple lathe, the cutter is affected by use. Material will be left on the cutter surface, and it will dull. I don't mix cutters between different types of metal either. I have a brass cutter, and I have silver cutters. I suspect I sharpen more often than others do.

I use Argentium, but I've spoken with a number of jewellers who use Sterlium. Just like Argentium they've added some amount of germanium to it to make it tarnish resistant. That makes it pretty much useless for enamelling on (the enamel won't fuse to the germanium oxide layer, and occasionally the oxide will do odd things with the enamel colour). I'm thinking of trying to enamel Argentium 960 which has a higher silver content, but haven't gotten around to it yet. I also like the fact you can heat harden Argentium after working it with a torch.

Nice colour. Any reason why you're only going 0.004" deep?
 
#7
Rich and Chris
There were a couple of reasons why I excavated to a depth of only 4 thou.

First, the fine silver disc was only .025" thick and, being fine silver, doesn't have much structural strength. I was not planning to dome it - which would have added strength - because I have never tried excavating a domed piece using the rose engine and it's really important that the bottom of the excavations be dead flat across their width. Otherwise, the ET will look weird. The excavations are 4 thou deep but the ET pattern cuts are an additional 3 thou deep within the excavations. I figured that at least 2/3 of the disc should be structurally sound and with the valleys of the ET cuts 7 thou below the disc's surface; that is, 28% of its thickness, that seemed to me about as far as I wanted to go. I could have added a few thou in the excavations but not much more since I didn't want the finished enamelled disc to flex (and crack the enamel) when I bent over the bezel.

Secondly, from experience I have learned that Soyer's deep blue transparent colors - while spectacular - can overwhelm shallow engine turning and that it takes a bright light for the ET cuts to reflect well through more than a couple of layers of these colors. (This doesn't apply to the lighter Soyer transparents.) For this and other reasons (avoiding bubbles and pits) the trick is to apply very thin layers of enamel. This enamel is applied using a wet packing technique whereby fine grains of glass are mixed with distilled water and applied with a tiny sable brush. I do my wet packing under a binocular microscope so I was fairly confident that I could make each layer no thicker than 1 to 2 grains of glass. In short, I did not need anymore than 4 thou to give me the depth of colour I was after. The blue in the pic is after two layers of enamel have been fired. If it were thicker it would have been that much harder to see the ET. I've tried using clear flux to build up the enamel after the main colour has been fired in but it's like looking into a well and I don't care for it.

I take your points on carbide and would probably use it if I could figure out an acceptable way to get a 1/4" carbide square cutter down to a 50 thou tip without spending all day doing it. What I do is to use Taig HSS parting tools, held upside down, and with the Daniels or chisel tip ground on the face using the Accu-Finish. This saves me a huge amount of time because I don't need to do the grinding/cutting to get to a point where I can put a properly ground end on the cutter. The acetal geeds are easily cut to fit the Taig parting tool on a milling machine.

Chris, if you do try enameling Argentium 960 would you please let me know how it works out. I read something about it on Ganoksin but the results were sort of vague.

So many things to try; so little time!
Ramsay
 
#8
...
I take your points on carbide and would probably use it if I could figure out an acceptable way to get a 1/4" carbide square cutter down to a 50 thou tip without spending all day doing it. ... I use the cutoff tools in the picture from MSC. It doesn't take long at all to grind one of those.

So many things to try; so little time! Ja!
Ramsay
Check out the MSC catalog page snippet ...
 

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#9
Rich
Many thanks for that reference to MSC. They don't ship to Canada, which is why I usually ignore them. There are times, such as this one where our alternatives of KBC and Travers don't stock the 1/4" left hand carbide parting tools, where MSC's shipping policy is sort of baffling and annoying. These cutters look ideal. I'll make alternative arrangements to get some. Merci beaucoup!
Ramsay
 
#10
A dremel with a diamond cutoff disc will take care of rough shaping carbide tools.

I'll let you know when I try the Arg960. There aren't a lot of suppliers in North America for it yet.

I tend to use thicker silver for enamelling on, and counter enamel everything except tubes. I've found that 0.5mm silver is usually too thin to enamel in any useful size (small disks for cufflinks are about it).
 
#12
Thanks for that link. Nobody seems to carry those tools from Micro100 but having a part number helps. It'll certainly save me some grinding in the future…
 
#13
Chris,

MSC carries one that is the equivalent; however, it's 6"long and has to be cut off. The carbide may be as good, but the finish does not hold a candle to Micro 100. If you need someone here to obtain the Micro 100 stuff I can do that or send you to the local dealer who will get it for you.

David
 
#14
David,

I am using the Micro100 tools right now, and they are nice. The link I was referring to was Rich's in post #11 since it has a part number for the left hand cut off tool. It's an odd ball tool and people don't seem to include it in their catalogues. But with the part number I should be able to get it ordered through my regular suppliers. If I have an issue getting them I'll let you know. That 0.040" wide cutoff tool should save a lot of time shaping the tool.

Thanks
 
#15
Travers Canada lists them and there's a lot more suppliers of the Micro 100 line and those particular tools in the US that probably ship as well. I see Travers has an office in Quebec.

I use the MSC bits and I get, I think, good results. One of these days I'd like to see the difference between candles. The MSC ones are made through their Accupro line but I don't know exactly where they're made.

Cheers,
Rich
 
#16
Rich,

I believe the difference between the Accupro and the Micro 100 is only on the surface finish. Given that you likely hone every surface on the tool that cuts I seriously doubt if you would notice the difference. Some Accupro stuff is made in the US, and some of it come from elsewhere. Allegedly, their engineers have examined the grain and pronounced it as good.

David
 
#17
Yes, I polish the cutting edges but just for grins sometime I'll have to try the Micro 100 line. They are a bit more expensive.

On the tool bit thing, the Travers Canada part number for the Micro 100 LC-250040 is 21-100-907 for the 1/4" shank .040 bit width at $19.50 each. The Micro 100 They told me two week delivery. That's Travers Canada - not Travers USA.

Cheers,
Rich
 
#19
Rich,

I don't see myself going Ho Hum, and I doubt Chris will tire of seeing it either.

Ramsay,

Let me know if you need me to acquire anything on your behalf. I cannot remember who told me to use the part off blades, but I hit myself in the head and wondered why I'd been so obtuse. They work great.


I'm posting an old email I wrote in the other thread as I think it fits better.
 
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