Tuesday, January 4, 2011

SATYR (Armature for nymph Day 2)

 I got some great feed back yesterday so lets start the day with an attempt to explain a bit more about the "how and why" of the armature support. You will want to consider the following three concepts: placement of support, balance, and size of support at the same time.
PLACEMENT OF SUPPORT
I have taken the original sketch and laid in the two basic armatures as red lines. The 14 gauge wire will support each of these figures on its own so I know that I will not need any special support just for them.

The green line is the support for the entire piece. We want this support to be along as direct a line as can be from the base to the bulk of the second figure. It will bend and curve to fit along the male armature but is relatively strait. The picture shows the green support stopping at the hand of the female but we really want the support to run all the way to the shoulder so we are close to the bulk (torso) of the supported female.

SIZE OF SUPPORT
This is going to be an experience issue. I have worked in bronze and other metals for about 20 years so I have a "feel" for how metal stresses and fails. A nice test at home for those who did not manage a foundry is to take some different rods of assorted diameters, bend them in an arc, and hang some weight on the end.
A 12" figure will use about a pound of clay. A 3/16" tube will support this but tubes are weak once they are bent because they want to flatten. A rod of the same diameter will support this amount of clay without folding. there will be deflection once we have the weight of a figure on the rod so we will take this into account when we sculpt the arm of the male. You can do the same test for larger or smaller figures by using the amount of clay used in that figure and smaller tubes and rods.

BALANCE
Once the armatures are assembled, you can work out the balance issue. Each figure will weigh about the same so I want to make the hands the center of a seesaw with the same weight on each side. The hands will align over the foot which inserts into the base so if the piece pivots, the weight stays balanced. All I need to do is gently adjust the bends at the ankle and shoulder until the figures stand in the base without falling one way or the other. Test this by pushing then side to side. they should right themselves without falling over.
I hope this explains the process a bit more for you.

 FEMALE ARMATURE
As mention before, the female armature starts out as a simple wire armature just like we used for Tristan. I have then straightened one arm and shoulder and cut down the wrapping of the spine to open half the armature so we can build on it.
Keep in mind-SIMPLE. The standard armature will support the clay. The spine has four wires in it so it is very rigid. If we transfer the stress of supporting the figure into the spine, she will hold herself up without anything else added.
She will simply be hung from the support by her arm so no extra support is needed in the legs.






I cut a 5/32" tube as long as her spine and shoulder added together and slipped it over the 14g. wire. We are going to build a rod in place on the armature by slipping tubes over tubes for support.
 Now we slip a 3/16" tube over the smaller tube. It is the same length. The extra wire is cut off so it will not stop the rod as it slides into the arm.
 Now we slip a 7/32" tube over the last tube. This tube is the length of the spine plus the length of the shoulder plus the length of the arm. If in doubt, raise the other arm and so she is in a diving pose and cut the tube even with the other arm.
This tube is larger than my support rod so it will slide down the rod to the male hand. I now have what will become a hollow arm on the woman which slides over the solid support rod from the male.
 This assembly is gently bent in a series of small bends being sure not to bend beyond the shoulder where I have three layers of tubing to support each other. The arm must be kept strait to allow the rod to side in easily.
Just a precaution here, I have added a small tube to the other arm following the arm around the shoulder and into the spine. This will join the two sides of the body together so a crack will not form down the back from too much stress on one side.
The spine is now foil taped back together.For larger figures, you will want to solder this connection.
She is bulked out with foil and covered with tape.

Tomorrow we will start on the male torso.
Have a great day!

12 comments:

  1. Hi Mark!!
    Where do you purchase your brass rods? I have found them on ebay but they are pricey there. Wondering if you have a better place to buy them from. Many many thanks. From a very grateful self taught artist to another! Carla

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  2. I get the brass rods at Lowes. Tubing can be found at a local hobby shop which carries RC cars and trains. Happy hunting.

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  3. Great!!!! Thank you so much!
    Can you please also tell me what tool you use to cut them? And are there tools that will help me bend them? other then a very strong man? lol

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  4. Sure Mark, You make it sound so simple. Kind of like Noah saying he just needs some gopher wood and a few animals! You Rock!

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  5. So, no wonder you know so much about building your armatures to handle stress! I work in a gray iron foundry myself but I sure don't manage one and wouldn't want to. LOL Mark, I do have a question though. Can the tubing be heated and then bent to the shapes? Someone recommended to me a while back to heat my tubing and then bend it to keep it from buckling. Could this cause any problems with handling the stress? Or would this be sufficient for all us women who will have trouble bending the tubing? Thx bunches!

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  6. Tubing can be cut by either using a micro tubing cutter which is just like the plumber's pipe cutter but closes smaller for the small diameter tubing. Or using a utility knife by laying the tubing on a hard surface, placing the blade of the knife on the tubing perpendicular to the length of the tubing where you want to cut the tube, and rolling the knife forward and back enough to score the metal. Grab it with both hands and snap the tubing at the score. You can also purchase a cutting wheel for the Dremel Tool and just cut the tubing to length. There are more solution to this issue. Let me know if theses do not work.
    You can heat a rod to bend it. You will need a small torch and will want to quench the metal after bending to keep a bit of temper to the metal. Tubing is hard to bend when heated. the walls of the tube will want to collapse under the the bend if not heated uniformly. Try a test piece and see how it works. Keep in mind that too high a temperature will weaken brass tubing. Brass is made of copper and zinc which melt at different temperatures. You can actually burn the zinc out of a thin walled brass tube and have only copper remain which is softer than brass. In the foundry we would melt the copper then just before pouring submerge either zinc or tin in the molten metal then pour the brass or bronze (depending on which metal you use).

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  7. I cut my rods and tubes with something called a razor saw...you can get them at michaels or hobby lobby where they sell stuff for pine wood derby...it works great. just thought Id throw that in there, hope you dont mind mark :)

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  8. Excellent!!! I ordered my tubes and rods and will be going to my beloved store - Michaels - for the razor saw! Thank you so much Mark and Karen. Can't wait for the materials to get here to get started. I am so excited!!!!
    I can't thank you enough Mark for this opportunity to work "beside" you.
    Blessings, carla

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  9. Mark, this is pretty much the physics lesson I was looking for. Thanks!
    Bev

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  10. Thank you Mark and Karen for helping us with all of the information,I now know all I will need. I have the tubing, the wire and the clay yea!! My hubby donated a pencil torch to me he also said it comes with lessons lol.I am sure I will not be using the torch.To tell you the truth I could not refuse such a wonderful gift :) So I will have to go shopping for some foil tape and a dremel cutting wheel.Mark I hope you do not mind if I work on the size I normally make 5 to 7 inches tall I am so afraid of doing a big sculpture I just don't have enough experience or confidence to make bigger. Although I want to participate and absorb everything I can form your wonderful Blog :) Thank you

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  11. Mark, how long is the solid brass rod running from the base to her arm? I don't think my rod is long enough! Does Lowe's have these rods?
    Thank you, Dianne

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  12. Interesting armature design Mark! Thank you for sharing your technique.

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