Instructables

30-Second Demonstration of the CIR Sand Casting System

FeaturedContest Winner
video 30-Second Demonstration of the CIR Sand Casting System
In only 50 seconds, the CIR Sand Casting System allows for the replication of a residual limb. This model can then be modified and used to create a final transtibial (below-the-knee) prosthetic socket. The technique eliminates the need for plaster bandages and Plaster-of-Paris, and requires only:

1. A large container
2. Silica sand
3. An air compressor capable of maintaining a vacuum
4. A metal pipe for connecting to vacuum pump
5. Thin plastic bags
6. Rubber bands

The contents of this presentation/publication were developed under a grant from the Department of Education, National Institute on Disability and Rehabilitation Research grant number H133E980031. However, those contents do not necessarily represent the policy of the Department of Education, and you should not assume endorsement by the Federal Government.
seeing it used with an amputee, start to finish would be nice. I would be concerned when it came to the vaccum with the limb in the sand
arniethelip2 years ago
I hope this site is still being moderated. It would be great if you could answer my question: If I understand correctly, the final positive cast is made of sand that is being held in shape by vacuum, and that presumably once the vacuum is cut off, the sand would just fall from the mandrel. How then is this cast used to fabricate a lamination? How is the vacuum maintained throughout the process of lay-up, etc.?
CIRnetwork (author)  arniethelip2 years ago
Thanks so much for your questions!

The positive cast is in fact made of sand and is contained within a second plastic bag. It is sealed in this bag using rubber bands and/or tape, making it possible to maintain the shape for a short period without vacuum applied - this also allows for modifications to the positive model if needed. After creating the positive model, the cast of the socket can be made using a draping method as would traditionally be done for a plaster positive model.
The Forbes logo has to be displayed for at least 2 seconds, right?
nicoluxe4 years ago
I just voted from the link on Facebook. I think this is very clever. Awesome. It seems very simple, almost too simple. Has this actually been used on a person yet?
CIRnetwork (author)  nicoluxe4 years ago
Thank you so much for voting!

The CIR Sand Casting System was developed and tested in Chicago, and underwent independent evaluation in Hanoi, Vietnam in 2004. In 2005, the BMVSS-Jaipur Limb Program in Jaipur and New Delhi, India adopted the technology, which (as of 2007) was replaced by an improved version of CIR Casting System. Currently, this newer casting method is widely used in India and Thailand. A modified version of the CIR Casting System was used in Thailand to fabricate prostheses for two elephants who were injured by landmines.

To date, the CIR Sand Casting System and the newer CIR Casting System have been applied to between 2,000 and 3,000 individuals with below-the-knee amputations.
Jaycub4 years ago
So this is a prosthetic leg made out of sand?
CIRnetwork (author)  Jaycub4 years ago
Thank you very much for your question. This technique allows for the creation of a positive sand model of a residual limb that can then be modified and used to fabricate a prosthetic socket. It is designed to be used to replicate the residual limbs of individuals with lower limb amputations. The difference between the traditional plaster-based approach for creating a positive model and the CIR Sand Casting approach is that when the socket is made, a model made of plaster will require portions of the plaster inside to be chipped off (left) while with the sealed-sand model, the plastic bag can be cut open to drain the sand (center). De-molding the formed socket (right) with the CIR Sand Casting approach is rapid and safe.
Image.jpg
Templarix474 years ago
i dont get it
CIRnetwork (author)  Templarix474 years ago
Thanks very much for your comment. The longer version of the video might be helpful in clarifying the details of the process.
=SMART=4 years ago
what were you casting ????
CIRnetwork (author)  =SMART=4 years ago
As described above, this is a process for casting a model of the residual limb of an individual who has a below-the-knee amputation. This model can then be modified and used to fabricate a final prosthesis.
Ahhhh ok, i couldnt see what limb it was, I was looking for an arm shape haha
mycroftxxx4 years ago
Ahh, brilliant as always. Looking at this in a wider context, is there any way to reasonably integrate this process with your other prosthetic-forming techniques like the heat-gun-and-PET-bottle work done using a plaster positive? It seems obvious that if the thin plastic sheeting were replaced with something more heat-tolerant, a single craftsperson could take an amputee and go from no prosthetic to having the beginnings of a sheath ready for integration into a leg in less than 5 minutes. Assuming that's the goal, what candidates have the required flexibility and thermal tolerance? Now, if you could be so kind as to dump some instructions on the gel-bag prosthetic measuring system and the X-Shape Pylon, I would be _really_ grateful.
CIRnetwork (author)  mycroftxxx4 years ago
Thank you very much for your comment. The plaster model was used for making the plastic soda bottle prosthesis because it can be reused many times to form multiple forearm prostheses. If the CIR Sand Casting procedure is used to create the model of the residual limb, the plastic bag used to contain the sand will not be able to tolerate the heat from heated plastic soda bottle. However, it is possible to cover the positive sand model with a balloon, which can tolerate the heat. In addition, the plastic soda bottle prosthesis was designed as a light-duty prosthesis for some simple self-care functional activities. Using the flexible soda bottle to fabricate a prosthetic leg is not structurally suitable. Please note well that an individual's residual limb should not be used as a model to form the plastic soda bottle prosthesis. The other prosthetic technologies developed by the CIR are too complicated to be posted online and are only appropriate for training workshops for those who have received formal professional training in prosthetics.
nlawrence4 years ago
Interesting. I don't know if you know, this technique was developed and patented in the UK somewhere in the late 1970s for prosthetic limbs, exactly as you are doing. They also scanned the good leg and used an NC machine to mill a (left to right inverted) lower limb from wax; then roll molded it in foamed plastic to give a light weight leg that matched the good leg. I am glad to see it still being used.
CIRnetwork (author)  nlawrence4 years ago
Thank you for this information. Do you happen to have any additional details about the UK patent? The first US patent related to this technology was issued to WJ Mead in the 1940s. At that time, many researchers worldwide were trying to develop a useful, simple procedure for fabricating prostheses, however a preliminary search of did not yeild any publications describing the technical details associated with a UK patent in the 1970s.
heathbar644 years ago
Ok, let me see if I understand this correctly. You seem to be using the vacuum, sealed on top by plastic bag, simply to compress the molding sand around the model. there must be a vacuum hose on the bottom of the bucket somewhere. then it looks like the tube you insert into the middle draws a vacuum to compress more sand into the cavity to form the copy. Is that it? That's really coool!!!
CIRnetwork (author)  heathbar644 years ago
Thank you so much for your comment. The molding tube is a specially constructed device using a large PVC pipe (8-inch in diameter) filled with clean (dust-less) sand. It has a connection in the bottom for either compressed air or vacuum suction. In order to allow for insertion of the residual limb, the sand inside must be fluidized by compressed air first.

Following the insertion of the mandrel (steel pipe) into the cavity of the negative mold, the plastic bag seals the sand in the negative mold around the mandrel. Once sealed, the vacuum suction is applied through the top of the mandrel to solidify the sand in the cavity of the negative mold. When the vacuum suction is disconnected from the negative mold, the negative mold becomes a loose mass so that the solid positive model, which is still held under vacuum suction, can be removed easily.

Please note that the process was developed for making prosthetic limbs for individuals with below-the-knee amputations. There are a number of other technical steps involved in the process of fabricating a properly fitted prosthesis. A further improved method of creating prosthetic devices, the CIR Casting System, has also been developed and used to train professionals in the developing world. The CIR Casting System was also modified and used to create a prosthesis for a young Thai elephant who was injured by a landmine blast.
red-king4 years ago
could this be used for casting other things?
CIRnetwork (author)  red-king4 years ago
This casting method could be used to cast other items, however it is especially useful for casting the residual limbs of individuals who have undergone below-the-knee amputation. It can be used for casting anything that does not have an undercut area, or does not have fine details.
I recall an old episode of "Mission Impossible" in which the team cast a front grille of a car using sand casting. The whole idea was to convince the people at the border that the guy that owned the car was trying to smuggle a couple kilos of Platinum out of the country disguised as a late sixties car front grille. I don't know if any copies of that episode exist, but it would be worth researching.
Looks like a pretty brilliant process! Although, it's still a bit vague... I'd love to see some more in depth details on how this was done!
CIRnetwork (author)  thecheatscalc4 years ago
Thank you so much for your comment. There is a longer version of the videothat may help better explain the process, as well as videos of other related techniques that may be of interest. Thanks again!