Laser on mild steel ?

[Perry Holbrook]

I'm working on a design for a potential corporate gift commission. One of the ideas is to have the forged copper sculpture I'll make,set on a wood block with a thin gauge mild steel plate on top of the wood. They were talking about putting a brass plate with some verbage somewhere on the piece.

Instead of that, I am considering the verbage directly on the steel. The entire piece will be an abstract so the verbage needs to blend with the rest of the work and not look too commercial.

The steel plate will be about 5"x7" with maybe 25 words and possibly a corporate logo. Is there a problem with any of this? What should I expect to pay for about 75 of these? Is this something an SMC member would be interested in doing?

Thanks, Perry

[Bruce Volden]

Perry,



Most of us on this site have CO2 lasers which will not engrave into the steel.
We use a product which when applied and lasered over leaves a permanent dark (black) mark on the metal. It will only come off by removing a thin layer of the metal. If the steel you're looking at is polished up nice (~satin finish) the results are often stunning. Pricing would vary I spose by locale, if I were to bid this job I would think a reasonable charge might be 6-8 bucks each. But I'm out here in no mans land;) I'm sure others will chime in also.


Bruce

[Dave Fifield]

Cermark can work well on SS (not sure about mild steel though - won't that rust?), however if you want the engraved look (as opposed to the silk-screened look) then I suggest you talk to someone with a Nd:YAG laser that will mark the steel (engrave it).

:Dave F.

[Perry Holbrook]

Thanks for the replys so far. So I need to polish the surface first and then I can either have a silk screen look with 1 laser type or an engraved look with a different laser type, right?

The sculpture will be copper and the base wood, so I would probably spray the whole thing with lacquer so the steel will not rust. I may want to patina the steel as well, so that would need to be done before the laser, right?

Perry

[Mike Hood]

Another cool with steel would be gun blue or gun black. You can then etch it directly onto the steel. You'd want to clear coat it immediately, but suspect it'd work nicely. Lots of firearms are laser etched in that manner.

[Michael McDuffie]

Another cool with steel would be gun blue or gun black. You can then etch it directly onto the steel. You'd want to clear coat it immediately, but suspect it'd work nicely. Lots of firearms are laser etched in that manner.

I've done the slides on a couple of Glocks and while you can read it, there isn't much contrast. If you don't need it to stand out, you could go this route.

Michael

[Dave Jones]

You might also want to consider a rotary engraver (older style "traditional "engraving). It would cut the letters deep into the metal.

[Kevin Z. Johnson]

why steel?
there are some plastics that that look at metal, thats what we have directed our customers to.
one other product you can look at is AlumaMark.

machining steel will become very expensive, I would if you have to go that way talk to a tool and Die shop the smaller the better. More than likely you will have to provide a CAD drawing or pay for that also.

[Joe Pelonio]

Depending on the design, it might look really cool to have that steel cut with a water jet. There are waterjet people in most big cities.

[Rodne Gold]

By far the best way to do this in a 75 piece qty is to have the part spun cast. A master is made and is then encased in a vulcanising rubber and the mould is then split , the rubber is capable of withstanding the temp of low melting point metals like zinc alloys etc. The rubber mould is put in a machine that spins it and molten metal is poured in. The mould can be reused many times. The nature of spin casting means that the spun item has a fairly "rustic" look and if plated with antique copper or bronze and then tumbled , the finish will look pretty much antique with any recesses being darker than the raised section. Lots of corporate gifts and other items are made this way.
A good site to look at for examples of this is:
http://www.rootsofcreation.co.za
So how does the laser come into this equation?
Well you use the laser to make the master , and perspex is an ideal medium (it does get destroyed and warped in the mould , but the mould is perfect - we make 100s of masters)
You can achieve all sorts of effects , for example you can laser the letters to stand proud and put a texture in the background or simulate a distressed plate and even laser cut a recess to locate your sculpture , the plate can be cut in ANY shape.
You will generally find the minimum thickness is about 2mm , but 3mm is better. Spincasting is a cheap way to produce something in metal.
Here are some items produced with perspex masters and reproduced in metal
http://www.tokerbros.co.za/final%20wae%20pics/promo/spun%20cast%20items%205896.JPG
http://www.tokerbros.co.za/MEDNEW_70_1.jpg
You can plate antique nickle for a steel like effect and if you use a scotch pad or sandpaper on the master you can get a brushed effect. You can alos layer the master for some 2 1/2 effects or use something like pratly putty to add features to the master. The moulds go to about 150 degrees C for about an hour , so whatever you use has to withstand this. (like wax would not work , but resins , formicas , phenolics , chemical wood , wood , clay etc will)
Spincasting mould costs are round $30 here and items go by weight , but to give an example , a 53mm diameter 3mm disc costs me less then US$0.50c and that is supplied from a spincaster (I dont do it)
On smaller qtys , expect to pay a higher price , but you can more or less extrapolate what it should cost you from my area (4" sq)
You also have no corrosion problems , most plated items in spincasting are laquer dipped after.

[Rodne Gold]

In addition to this , you can actually do this at home with minimal investmemt , it's a slightly different type of casting called "cold casting".

You make your master in the laser , however you do NOT have to use high heat resistant materials.

The reason is cos you will be using a RTV silicon to make the mould, Essentially this is a flexible rubber like mould that can also withstand stuff like molten peweter or resins but it vulcanises at room temperature - IE needs not heat , hence the name
RTV = Room Temperature Vulcanising
Big advantage here is you can build up masters with ANY materials , wax , whatever....
All you do is put the master on a flat surface face up , build a dam around the master with playdough type plasticine or whatever is handy, spray the master with mould release agent or dust with talcum and then mix and pour the 2 part silicon mould rubber. When cured , peel off the rubber , turn it over and you have a cavity mould you can pour stuff into.
In this case you will be using a general casting resin + metal powder. (or just a resin if you dont want a metal item)
You will mix up around 70% metal powder to 30% resin by weight and pour this into the mould and will end up with a casting that looks , feels and acts like the metal. You can polish it , patina it , sand , grind etc and it ages like the metal. Powdered metals can be had in aluminium , bronze , brass and copper.
You could also use the same mould to cast lead or pewter or tin.
You can go a lot further with this , like make 2 part moulds like this for 3d items such as your sculpture.
The downside?
Well metal powder is very expensive.
Most larger items are done with this metal/resin being painted onto the surface of the cavity to form a skin and then pouring much cheaper stuff to fill the rest. Some folk use plaster of paris and lead shot if the part needs to feel real heavy.
Go speak to any co that supplys resins , they should have all the bits and pieces for you to mould and cast.

[Joe Pelonio]

Rodney,

That's a lot of good information that I'm sure most of us didn't know.

Perry doesn't have a laser though, so he'd have to farm out that part too.
I wish I had time to try that. I have metal powders that I put in clear and spray for finishing things, and have a resin supplier next door. Maybe this winter if things quiet down.

[Perry Holbrook]

This is all very good information. My main concern with all of this is the plate needs to blend with the rest of the art. A common element of my work is the contrast of mixed media in each piece. We have not finalized the final design of the sculpture, but I'm pretty sure it will be hand forged copper. The copper will be darkened with liver of sulphur and buffed. The base will either be figured wood or maybe heavy glass. I thought a patined steel plate would fit.

Would any of your answers change if I made the plate of soft copper?

PS
I don't normally post here so some of you may not be as familiar with my work as the folks over on the main page. If any of you are interested my web site is kopperwood.com I make several other things but right now I am only showing my small boxes. I make all of the box bodies and the tops.

Perry

[Keith Outten]

Soft copper, brass and aluminum can be machined on a CNC router. You might consider using Corian for your engraving plate, there are lots of interesting colors and this year Dupont has several new marble/granite colors available. Any engraver can engrave very fine detail in Corian and paint fill to match your project. I just finished resawing to 1/8" thick Corian for ADA Braile plaques a couple of days ago so very thin plaques are possible.

The moulding process that Rodne decribed is very interesting. I would investigate that further if I were you Perry. I did some aluminum sand casting in junior high school and it was lots of fun with interesting results. Rodne's techiques are more in line with today's technology and probably more affordable than most of us realize.

.

[Dave Jones]

Another process for copper is acid etch. Circuit boards have a thin copper layer that is acid etched and can have extremely fine detail (a few thousandths of an inch).

You can have the text turned into a high contrast image on film, then expose a photomask on the copper. Then etch it in ferric chloride. Then simply wash off the photo resist.

You could maybe also sand blast copper through a lasered mask.