I have been carving model stonework for quite a few years now and I always seem to find new ways of doing it. I’ve tried various tools over the years and found what works best for me. The first thing you need to realize is that working with plaster is not as hard or scary as it seems. It’s not without it’s weaknesses, but with careful handling no harm should come to your castings, unless you drop it. Even then, if you are above a table or a carpeted floor there’s a good chance the piece will survive.
Hydrocal plaster is not as hard as everyone makes it out to be and it is very easy to cut and carve with sharp tools. The major drawback is the copious amounts of dust that has a tendency to go everywhere. That means you need to wear a mask if you plan on cutting through it with a bandsaw, or any grinding and sanding devise. Using a file or doing a little bit of cleanup with a knife is not bad and is what most people will need to do with our castings for fitting and blending purposes. A small shop or portable vacuum is a blessing for cleanup.
Basic Hand Tools
You may think that I use a dental probe (dental pick to those of you not in the dental profession), but I rarely use in my stonework. What? Everyone else uses them! Why not me? Because they really don’t do a good job. They have a tendency wander as you drag them and no amount of re-dragging them through the same groove will correct that part you don’t like. The groove just keeps getting deeper. They are not that sharp either.
The Hobby Knife
The hobby knife is my do-all tool. I used to use a scalpel, but they are fragile and the blades can break when using them for the “Chatter Technique”. Most modelers have at least one hobby knife so that’s what we’ll use for teaching. You want to find a hobby knife holder that you like with a butt load of #11 blades to go with it. I have bought or come into possession of knife handles that could not keep the blade in the collet and most of those came from cheap set. Those were the cheap-O’s from somewhere far east and ended up far into the garbage can. I finally found what I think is the best design for a hobby knife.
It’s nothing fancy, but it is quite functional. Instead of rotating the knurled collet clamp on your typical hobby knife, there is a draw-bar that runs through the handle’s tube and when twisted pulls or releases the collet into or from it’s tapered receiver, thus tightening or loosening the blade. It has a kind of soft, but hard plastic sleeve that grips quite well, but is also the bearing surface for the draw-bar collar to seat and turn that seems like it will eventually get smashed or mushroomed out. A washer would help, but I’m not sure it’s totally necessary, yet. I’ve seen it under various brand names and I have some that say “The Toolman” , the guy I bought them from, so I assume you can get your name silk screened on them if you want to advertise your business. Below are some links to the knife and extra blades.
The Dental Lab Handpiece
A Dental Handpiece is similar to a Dremel like moto-tool although I think it is better for the work we will be doing. My biggest like about the handpiece is the quick change collet. No need to hunt down the wrench you know you just left on the workbench. Simply twist the handle and the collet releases the bit. Load up another bit, twist the handle and go to work. Easy.
The other nice thing about handpieces is that they have a foot control. If you have ever used a moto-tool with a foot pedal then you know what I mean. Mind you, not all foot-pedals are alike. Some are capable of variable speed, while others are simply On-Off. That’s really not a big issue because you can “bump & grind”, which basically means you give it some gas momentarily, then back off while grinding, using the the cutting action to slow the bit down. Repeating as often as necessary.
And, that’s about it for hand tools. Believe me, I have tons of hand tools filling up tool holders in my shop, but for carving realistic stone-work, the knife and handpiece cover 99% of what I need.
Below are links to a few hand pieces from different manufacturers.
Handpiece carbide burs
You are going to need some diamond burs to grind down the carbide burs. Honestly, this is not required if you don’t think you need super fine grout lines, but if you do you’ll have to do a bit of modifying because there are no engraving bits small enough that are commercially available, without taking a home equity loan out to buy them. NOTE: Dental Lab Hand-pieces use a 2.35MM (.093 or 3/32″) shank bit. They will not accept a 1/8″ shank. Which is good because all of the 3/32 stuff seems to be quality, where as a lot of the 1/8″ shank burs seem tot be of lesser quality. i.e. don’t buy Dremel or Harbor Freight burs and expect them to fit much less cut worth a darn.
If you need properly ground burs for grout work you can purchase them here, but they are not cheap because I have to grind them by hand. If you want cheap, grind them yourself.
Files are one of those tools that don’t get much fanfare as some other tools, but having a set and knowing how to use and take care of them is a must, if you want to be a good modeler. Files are simply multi-toothed cutting tools that shave off tiny amounts of material on each stroke. Since the teeth are small they have a tendency to fill and pack up with shavings which causes the file to ride up over the work-piece preventing the other teeth from cutting. Since the material packed in the file teeth is the same material and hardness as the work-piece it is very easy to gouge the piece and mess up the surface finish rather quickly. So, you need to get a file card to clean out the teeth. You are probably envisioning a 3 x 5″ index card, but I’m talking about a small board with a bunch of short wires sticking out of it that is used to clean out the teeth of files. It actually gets it’s name from carding wool, which is basically the combing of wool. They sell them anywhere they sell files. Even Amazon sells them.
The Vixen File
There are all kinds of files out there, but there is one that is perfect for filing on plaster and it is the Vixen file. Originally made for doing body work on cars specifically for filing down lead solder and Bondo like fillers. A Vixen file will create an absolute flat and smooth surface as long as the operator doesn’t rush the work. The beauty of the Vixen is the large teeth or gullet between the teeth. These gullets allow large quantities of shaved material to flow out of the file thus reducing the chance of shavings getting packed. If they do, pull out your trusty card file and clean them out.
OK, so what other kinds of equipment do you need if the knife and handpiece do all of the work? Well, these other tools are not totally necessary, but convenient. These are dedicated machines or tools just for stonework, but they can be used for other projects. I try to not use them for anything else and leave them dedicated to the cause. Deciding whether you need them, or which ones you want first is something you will have is up to you. I’m just recommending them. You have to remember that I use them in a manufacturing environment where I need speed and efficiency.
Compressors are way up on the top of my list of useful shop equipment. Not only are they good for blowing crap out of tight spaces they are useful for running all kinds of air tools. That’s subjective to the size of your compressor, but if you buy one big enough you can impress Joe down the block when you need to work on your car, too. But honestly, for carving plaster, most of the time it is used to blow dust away. You can use your mouth to blow, but you’ll never get the dust out like a compressor with an air nozzle and you’ll probably pass out. Even a small airbrush compressor will work to blow off dust, but I prefer much larger due to the fact that I have a bunch of airlines to fill and I also use pneumatic tools for other things, so I need the volume.
I love a bandsaw. I tried a scroll saw, but unless the part is held down against the table the part will have a tendency to ride the blade on the up stroke then get slammed back down onto the table with dire results. It doesn’t take much and it’s quicker than you saying “aw Sh..” . The little presser foot that you adjust to keep the work-piece from riding up will scratch and gouge a plaster part. They are static and only work for even thicknesses, whereas stone walls have irregular faces. So, say no to the scroll saw!
The bandsaw on the other hand is always cutting in one direction, down and against the table. If you do want to purchase a band-saw I would recommend one with no less than 12″ wheels. One with 14″ wheels are better and one with larger wheels is even better and reduces strain on the blade’s weld. Now, the band saw I purchased is a Craftsman with a welded frame. It’s OK, but not super great, but it does do the job fairly well and it keeps me from using my 17″ Grizzly band-saw, which cost me a lot more.
A note on Cast Iron tables
I don’t know why designers want to use aluminum for machine tables, but they do and they suck. Aluminum has a tendency to smear and gouge and grab when used as a bearing surface. There is no better material for a machine table than one that is made out of cast iron. I’ll argue that with anyone. The only problem is it’s hard to find small machines that don’t have aluminum tables. The Craftsman saw I have has a decent CI table and it does make a difference, I only wish my disk sander had one.
This is one of those pieces of equipment you wonder if it’s worth buying. All I can say is mine has gotten it’s fair share of use and I would feel naked without it sitting in my shop. Like I said in the previous paragraph about cast iron tables, it doesn’t have one. This is the only drawback of this particular machine. Other than that, it’s paid for itself in saving me time. I do use it occasionally to shape wood and clean up some metal parts, but it’s mostly for plaster. I plan on getting a stand alone sander one of these days just for wood and plastics and leave this dust maker for plaster only.
Not everyone is going to want to install a dust collection system, but if you do any amount of plaster carving you are going to want to have a shop vacuum ready. I opted for a more (semi)permanent solution, but it’s no more than a Shop-Vac, a few joints of 2″ PVC electrical conduit and a handful of 2″ PVC plumbing fittings. Most of the parts are not glued and are press fit. This allows me to make changes without having to break out the hacksaw. I did glue some of the trickier configurations, or places where the conduit had a tendency to come loose, but on a whole most is simply shoved together. Also, I never sat down and tried to balance the system, which technically I should, but it works and I have better things to do, so what’s the use. The Shop-Vac uses a 2-1/2″ connection, but the hose that comes with it is 2″ and I haven’t found any 2-1/2″ PVC pipe or fittings, so the main trunk lines are 2″. I can’t physically operate two machines at a time, so it’s not like I need it pulling dust for two machines at the same time, so the 2″ system works fairly well. Even at the far end of the system, way down in my basement about 70 feet away it sucks good.
I use electrical conduit because I can get long sweeping 90’s that makes less work on the shopvac. Remember, each corner or bend causes a slight amount of friction that reduces the efficiency of the system. The broader the bend or curve, the more easy it is for the dust to travel through.
I’ve read a few comments about using PVC for dust collection and the adverse build up of a static charge that could set off the dust and cause and explosion. I call BS. There is a slight static build-up as evident in the picture above of my vacuum room, but it’s not enough to get a shock nor start an explosion. In fact, it would be kind of hard to start an explosion within the pipe as the pressure is negative, so I’m not worried. I guess it would be a good idea to add a grounding wire just in case, but that’ll probably never happen seeing I’ve been running this way for the last ten years and nothing has blown up, yet, knock on wood.
Every once in awhile I need to mill the edge of some plaster piece and the router is nice to have. Granted, I had to rig up some fixtures to hold the parts because you can’t simply hold the piece up to the router bit, but for facing of an edge, you can’t beat it. I used it a lot in the beginning to mill off the backsides of my cut stone strip masters, but once I had my fill of those i seldom used it for plaster work. However, it sure has come in handy for edging boards that I use for building flasks and fixtures. I bought mine years ago at the Home Depot, but you can build them very easily. It’s really just a piece of Formica covered particle board with a hole in for the router bit to stick up through. I use a front fence vs the back fence that most table are set up to use. This allows me to make perfectly parallel edges on a slab of plaster.
The units below are about as basic as they come.