2500IC Wax Pattern Repair

p/n 33-D207 Rev A

The 2500 IC is capable of printing a wide variety of patterns. This includes small delicate features and large robust features. Wax has been used for centuries as the go-to material for investment casting applications. It’s no secret that wax patterns are fragile and should be handled with care; damage and breakage can occur and render your pattern useless. Some techniques can be used to attempt to repair defects or breaks caused from the handling process.  There is quite a bit of information available on the worldwide web if you search for "repair wax figure" or visit sites such as http://www.freemanwax.com/how-to.html or the jewelry forums. Also, there are many videos on YouTube if you search for topics such as wax welding or wax repair. Hand carved wax models have been used for lost wax casting of art and jewelry for centuries and there are abundant tools and products and classes available. Our studies have shown that all of the usual repair methods for molded wax patterns work with the 2500IC printed RealWax™ patterns.

 

NOTE: Remember to follow all local safety codes and procedures when working with hot or sharp tools.

 

Section 1:  Missing Material such as Holes and Voids

Through normal handling of wax you may encounter gouges, dents, or scratches in your patterns. These can be

repaired easily by one of two methods:

              Method 1: Melting VisiJet M2 ICast and depositing into void

              Method 2: Application of paste and patch wax into void

Method 1:

For Small Holes and Depressions

Dents, dings, and scratches can be filled in using excess VisiJet M2 ICast material. If you have a non-repairable pattern consider melting this for use in repair. If you need material please contact applications support for a small complimentary disk of M2 ICast Repair Wax.  Generally, a minute amount, such as 2-3 drops, is all that is required for most small holes, unless you have a long scratch or furrow.  Excessive application of the repair material should be avoided, as it only creates more work later to remove it. Use a torch, heated soldering iron, or hot wire and melt tiny amounts of solid ICast Wax on the tip, moving to new locations after the melted wax drips down.  Then use wax carving tools, scalpels, knives, etc to slowly and carefully shave off excess repair wax. Stop when there is still a very slight raised amount.  Use a gentle abrasive scrubber or #0000 steel wool to slowly remove the remaining excess repair wax.  Smooth and blend the repair into the surrounding surface.  Inspect for complete fill of all voids.  If necessary, repeat the drip-shave-smooth process to take care of any places that were missed.  See Section 2 for more info.pic 1.jpg

Cylindrical wax bar with text and grooves engraved to a depth of 0.040 inch (1 mm).pic 2.jpgRepair wax dripped on negative features.

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Shaving thin layers of excess repair wax from a filled in groove.

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Surface after first pass of filling and then smoothing with scrubbing pad.

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The surface after second iteration of fill and polishing is smooth and flat with text completely filled in. NOTE that although the text and groove locations remain visible, the surface is smooth and glossy, as witnessed by the light reflecting off the surface.

For Very Large Voids and Valleys

Prepare wax surfaces to be filled by gently roughing the surface with an abrasive pad and clearing the surfaces of any additional wax pieces. Melt VisiJet M2 ICast in a wax pot, an electric frying pan, or in a small dish using a hotplate, or other controlled heat source. Ensure that the wax is completely liquid. Place tape on portions of the pattern that need to be protected from leakage, and accidental drips. Tape can also be used to form a mold to contain the molten wax. Try to isolate the void or gulley under repair. Pour molten wax into the void to be filled. A spoon or small ladle is a useful tool to apply the liquid wax. Act quickly so the molten wax does not freeze onto your dispensing device. It is OK in this step to add excess wax to the void. Allow wax to cool and remove any tape. Use wax-carving tools to remove any excess wax from the pattern.Clean up and smooth repaired surfaces with abrasive pads or ultra fine steel wool, as in previous section on repair of small holes and depressions.

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Before repair

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After repair

                                                                                                                                                

Pic 8.jpgTop view after repair.

Method 2:

Shallow dents and scratches can be filled using paste / patch wax. There are many commercial types of paste and patch wax available for minor repairs in patterns, gates, and runners—some are more malleable than others. The type of defect you need to fix will govern which type of wax is used. The technique is identical to that used for filling voids with putty or caulking.

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Typical void that can be repaired.

Apply a generous amount of soft malleable wax onto a gloved finger. Push wax into any small void or negative feature. Smooth out the surface or shape the paste wax with your finger. Wipe any excess away using a soft, lint-free cloth.

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Application of patch wax to the void.

Section 2:  Excess Material such as Bumps and Ridges

You may occasionally find raised areas and slight protrusions from the surface of your patterns. There are a variety of methods that may remove these areas of concern:

Method 1:Wax pen, temperature controlled soldering iron or heated tools

Method 2:Wax cutting/carving tools

Method 3:Gentle Abrasives (#0000 steel wool, non-scratch Scotchbrite® scrubs, etc), or buffing with soft lint-free cloth

Often the best approach is to use a combination of these methods, starting with the more aggressive wax removal tools, and ending with abrading and polishing. It is important to patiently remove small amounts of excess wax. Avoid all urges to rush, it is very easy to slip with sharp tools and create new damage, worse than the original problems. Slow and steady is the watchword for all wax repairs.

NOTE:  Do NOT bring torches nor open flame near your patterns, as it is likely that this will melt or distort or damage them beyond repair.

PIC 11.jpg

Wax pattern with intentionally placed  0.040 inch (1 mm) tall hemispherical positive bumps.

Method 1:  Warm tools, such as a heated spatula will readily melt and smooth out defects extending from the pattern surface. It is difficult to prevent melting of adjacent regions and creating a larger defect area, so we do not recommend this approach unless it is commonly used for sprue/gate repair at your facility and you are an expert and well-practiced in the art.

Method 2:  A sharp chisel, scalpel, hobby knife or similar tool can be used to shave down bumps of wax extending from the pattern surface. Use light pressure and short strokes to gently shave away the excess. Be wary: wax will cause tools to grab and stick unpredictably, leaving chatter marks and unintended high and low spots.

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Bumps have been shaved down by 5-15 passes with scalpel.

Method 3: 

Gentle abrasive pads such as Scotchbrite™ and ultra fine steel wool are perhaps the best way to attack minor protrusions. Be sure to use the least abrasive pads available, as coarse pads will readily damage your pattern surface. Apply gentle pressure and stroke back-and-forth over the defect in several directions. Only a very small amount of material is removed with each pass, so take your time and do not give up quickly. As in sanding a wood or metal surface, several levels of abrasive pads should be used.  Start with the coarsest and finish with the finest. Eventually, you will begin to polish the surface which is a sign that repair is nearly complete. Inspect from several angles to ensure that all the defects have been removed in all locations and that the pattern surface is smooth and uniform.  Do not worry if the white surface is removed or looks slightly scratched, this is merely a cosmetic condition and will not be visible after casting.

13a.jpgBumpy region after buffing with mild abrasive pad.

            

Very minor bumps and filaments can often be quickly buffed away with a soft cloth or a gloved finger in just a few passes as shown below.

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Wax pattern with 0.020 inch (0.5 mm) tall hemispherical bumps that can be removed by a gloved finger.

Section 3:  Complete Pattern Breakage

Sometimes patterns break in such a way where you are left with two or more pieces. Typically these types of breaks occur during handling or accidental dropping. Some breaks lend themselves to repair more than others.

Breaks with a nice clean cross section can easily be bonded together—smaller cross sections or small features may be more difficult to bond back together consistently. Alignment of broken patterns must be done strictly by eye. This may leave you with slight imperfections at the joint of the broken pieces.

The overall idea here is to unite the pieces and turn a major defect (broken) into a minor defect (irregularities along the mend line), and then repair the minor problems with the techniques previously covered. Although there are many ways to bond multiple segments of wax patterns back together, here are two techniques we suggest you try:

Method 1:Wax welding using a wax pen, wax welder, or temperature controlled soldering iron

Method 2:Gluing and positive reduction via mechanical abrasion

Method 1:

Prepare surfaces of wax to free them of debris and trial fit for alignment of the two pieces.

Use a wax pen or soldering iron with a small tip or attached wire at moderate heat—not too hot. ~ 175F (80 C).

It is often a good practice to use a fixture to securely hold your broken pattern together while under repair.  Mate the pieces together and melt the iron's tip about halfway into the joint between the broken pieces and remove.

This will weld both sides of the break together. Allow the wax to freeze and repeat additional times in other locations along the break.  When possible, be sure to weld on all outside surfaces of the break.

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Pattern with undercut break

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Pattern with welds (hot wire visible in upper right).

Once the welds have cooled and united the pieces of the pattern, the next step is to repair the minor damage done by the welding.  Drip repair wax to fill in the valleys and depressions made by the hot iron and create a positive weld bead.

A fine tipped hot iron can be used to carefully spread and smooth out the excess wax.

 

NOTE: This can be the last step of the repair if it is easy to grind away the bead and clean up the metal surface after casting.

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Weld bead (side 1).

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Weld bead (side 2).

                                                                                                                           

Alternatively, use a patch wax to fill in any depressions; smooth; and then skip the next two steps.

Use wax carving tools and/or hot shaping tools to remove excess repair wax down to pattern surface.  Take care not to gouge or drive the edges of sharp tools into the pattern surface on either side of the weld.

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Removing excess repair wax from raised weld bead.

Finally, use abrasive pads and/or very fine steel wool to polish out any remaining imperfections. Take care that the small bits of your pad or steel wool that break off during use do not remain stuck on the surfaces.

Below is the pattern with all repair operations complete.

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Repaired and finished pattern.

Wax Welding can also be used to join sections together to form a pattern larger than can be printed.  Below is an example of two sections of a 16-inch diameter guide vane being joined.

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Two sections fitted together and ready to be joined.

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Two sections joined with wax welds.

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Close up of wax weld bead between two sections.

Method 2:

Although there are no glues specifically made for adhering wax to wax, we have found that some very quick-setting commercial adhesives, based on cyanoacrylates or similar polymers, can produce a strong bond between two pieces of VisiJet M2 ICast wax.  If you choose to use a superglue, be sure use proper ventilation and personal protective equipment; always follow the manufacturer's instructions. Obey all your local safety codes and procedures for handling cyanoacrylates. You will also need to check that the residual adhesive is compatible with your casting process and burns out cleanly.

Prepare surfaces of wax pieces to be joined by gently roughing the surface with an abrasive pad and clearing the surfaces of any additional wax pieces. Trial fit the pieces together to check for alignment.

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Typical type of repairable break. Abrasive pad used for cleaning the mating surfaces.

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Surfaces cleaned of any debris and lightly roughened to promote bonding. Trial fit of two components to ensure alignment has not been altered due to the break.

Apply superglue to only one of the broken pieces. There is a critical amount of superglue to use; too little and you will not get a strong bond, too much and some glue will leak out of the seam and be difficult to remove later. Excess glue can crack and slightly damage your pattern surface when it is removed. The amount of material will depend on the cross sectional area of the break.

Optional:  Apply the manufacturer's recommended accelerant, or activator, to the glue-free broken surface. This will speed the curing of the superglue bond. Some brands of superglue do not require the use of an accelerant, but we suggest it as an easy way to ensure the bond is set properly and quickly. Accelerators can reduce the bonding time from many minutes to seconds.

PICS 22.jpg

Superglue applied to just one mating surface of broken pattern.

Gently push the two pattern pieces together. Be careful in alignment. With no alignment features, the fitting must be done by eye. You will not have a lot of time to ensure this is correct, and you typically have just one chance to get everything right before the superglue cures.

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Example of a bonded pattern that had superglue ooze out of the seam. Ensure that the alignment is correct at this stage prior to the hardening of the superglue.

If any superglue oozes out of the seam, you can wipe it away with a paper towel or lint-free rag before it hardens. If the superglue cures before you remove the excess, then you can use an abrasive pad or wax carving tools to gently remove the cured superglue.

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Use of an abrasive pad for removal of the hardened superglue. Be very careful at this stage to not alter any unintended surfaces.

25abc.jpgPattern after glue has set and been cleaned up.

 

Apply patching wax to the seam by finger to fill any voids or defects caused by joining the two pieces of patterns together. Many paste and patch waxes work for this application. If your preferred wax does not work please consult the table at the end of the document for known working solutions. Alternatively, melt and deposit VisiJet M2 ICast onto the seam as described previously.

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Generous application of paste wax for filling in of voids and seams. Apply by finger and gently press into any voids. Smooth out with finger and remove any excess.PICS 27.jpg

Void filled in with patching wax.

The quality of the final joint depends on the nature of the break; breaks which are relatively clean and over a large cross sectional area are ideal for repair. While the entire procedure for repairing breaks is not overly difficult, the process will become much easier after a little practice.

Products Compatible with Visijet M2 ICast

We have experimented with commercially available repair products and found that they are compatible with printed patterns from the 2500IC. The list is by no means comprehensive, and there may be other products that you can use. We expect that any product in use for repair of injection molded wax patterns can be used on 2500IC RealWax™ with standard techniques. All the materials listed here are in no preferential order and will need to be verified compatible with your local investment and casting processes.

Patch/Paste/Repair Waxes

Freeman Red and Green Patch-Eze

Kerr Disclosing Wax – Ivory

Paramelt Cerita 2-U3

Remet Premiere Patching Wax & Premiere Patching Wax II

Westech Patch Waxes PW2-PW5

Wolf Touch-Up Wax and Relief Wax

Glues

3M Scotch Weld CA40H

Loctite 401

Accelerants/Activators

3M AC09

Loctite 712