Welding Acrylic: Difference between revisions

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Acrylic is one of the best materials to use on a [[Laser Cutting|laser cutter]] because of its versatility, transparency, and ease of cutting/etching.  However, acrylic is notoriously difficult to bond with glues and other adhesives in a clean fashion and scratches easily when trying to remove unsightly residue.  Welding acrylic is easy to do with the right materials and can create incredibly strong bonds with little to no residue left over.
The [[Laser Cutting|laser cutter]] can be used to create 3d models by cutting individual thin layers and then stacking them together to create a full size object.  This is useful for creating prototypes that may be too large to be [[3D Printing|3d printed]].


This project requires beginning with a 3d mesh model (either a .stl or .obj file), such as would be created for a 3d print model.  These models can either be created from scratch using 3d design software such as [[Solidworks]] or [[AutoDesk Fusion 360|Fusion 360]], or it can be downloaded from sites such as [https://www.thingiverse.com/ Thingiverse] or [http://www.mcmaster.com/ McMaster-Carr] and modified using a program like [[AutoDesk MeshMixer|MeshMixer]].
Acrylic objects can be held together with adhesives such as [http://eclecticproducts.com/products/amazing-goop.html Goop] or sealed with various caulk products. However, for a solid bond that is as strong as the material itself, a chemical weld is the easiest method for bonding. Welding two acrylic parts essentially joins them together as a single piece and forms an incredibly strong bond.  Acrylic cement works by dissolving the plastic of the objects to be bonded, then as the solvent evaporates the two objects essentially form together as a single object.


Effectively this project can completed using any type of [[slicing software]], but the simplest and most effective program to use is [[AutoDesk 123D Make]].
You'll need some acrylic cement (I recommend [http://www.tapplastics.com/product/repair_products/plastic_adhesives/tap_acrylic_cement/130 TAP Plastics] and a syringe to apply it to the objects.
[[Image: 123DMake.JPG|left]]
:1. Download and install [[AutoDesk 123D Make]].
:2. Open 123D Make and click "Import", then select your model file.
:3. Set the dimensions for the output files that you would like under "Manufacturing Settings".  Enter the length and width of the materials you will be cutting the model out of on the laser cutter, if you know them.  If you don't know the length and width of your materials you can edit them later in [[Inkscape]], however it is '''very''' important that the thickness of the material is correct.  Ignore any error messages that pop up at this point.
:4. Adjust the size of your object under "Object Size".  Note that if you keep the "Uniform Scale" button selected, the software will maintain proportionality of your object so that when you change one dimension, the others will adjust accordingly.
:5. Select your chosen "Construction Technique".  The standard is "Stacked Slices", but feel free to play around with other options to learn how they behave.
:6. Adjust your "Slice Direction" if your object is not oriented the way that you want.  When selecting this option, three rings will appear around the object with a small cone on each.  Select a ring with the mouse and drag the small cone to the correct slice direction on your model.
:7. Assembling your model will be much easier if you have a wooden dowel (or two) to hold the pieces together.  If you'd like to add dowel holes, select "Dowels" and set the diameter and shape of your dowel.  Often the program will insert multiple dowels in your model, you can delete unnecessary dowels by clicking the orange circles that identify their position and deleting them.  You can also move the placement of dowels by clicking the orange circles and dragging them with the mouse.
:8. The "Modify Form" option has options to make your model hollow or make sure that your model doesn't have holes ("Shrinkwrap").
:9. When you are finished with the options, you should see a number of pages laid out on the right side of the screen.  These are the pages that will make up the output to the laser cutter.  If there are no pages, there may be an error between your "Model Size" and the "Manufacturing Settings".  Try adjusting the size of your model until output pages are generated.
:10. When you are satisfied with the output, select "Get Plans".  A screen will appear showing the output files that will be generated.  You can change the "Layout Arrangement" from "simple" to "nested" to fit more parts on a single sheet. Select .pdf as your file type and click "Export" to save your output files to your computer.  These files are ready to use on the laser cutter!


If you want to make adjustments to the files, you can use Inkscape to edit them.
'''WARNING: Acrylic cement is a flammable solvent.  Wear safety glasses, prevent any skin exposure (wear rubber gloves), and avoid any heat/flame sources.'''
:A. Open Inkscape.
 
:B. Drag your .pdf into the Inkscape screen.  It will open a window to ask which page you want to import, select the one you want and select "OK".
:1. Pour some of the acrylic cement into the syringe.  Use a funnel if possible, or for small jobs use the syringe itself to draw out a small amount of the fluid.
:C. All of the objects will come into Inkscape as a single object, to edit individual objects select the main object and "Ungroup" them at least twice until they are all individual objects.
:2. Hold or clamp the pieces to be bonded as tightly as possible.  The cement will flow into the bond via capillary action, so the tighter they are held together the stronger the bond will be.
:D. Make any changes you want and then save them as a .pdf for printing to the laser cutter.
:3. Hold the syringe upright to prevent any fluid from leaking out.  If some of the cement leaks on to your objects, the best solution is to leave it alone and don't try to clean it up, if the spill is not disturbed before the solvent evaporates it should return back to normal without cleaning.
:E. Make sure that you set your line widths to 0.001" for lines that you want to cut.
:4. If using a squeeze-bottle syringe, before applying the cement, squeeze a bit of air out of the syringe while holding it upright then let it release right before turning it over.  As it draws air in it will prevent the cement from dripping from the syringe before it is in place.
[[User:Tschule|Timothy M. Schuler, Ph.D.]] ([[User talk:Tschule|talk]])
:5. Place the tip of the syringe right at the junction of the two objects to be bonded and either wait for the cement to begin to flow or give the syringe a light squeeze to start it flowing. You should be able to see the fluid flow between the two parts, the thinner the fluid level the stronger the bond will be.
:6. Drag the syringe along the two parts applying the cement along the entire bond surface. When finished, return any unused cement to the container and clean out the syringe with water immediately.
:7. The bond will be strong within about 10 minutes, but will not be fully cured for about a week or two. Allow the solvent to evaporate completely before testing its full strength.
 
[https://www.youtube.com/watch?v=hT6Ow_cBTps There's a very nice video describing this process from TAP Plastics].

Latest revision as of 07:05, 12 February 2016

Acrylic is one of the best materials to use on a laser cutter because of its versatility, transparency, and ease of cutting/etching. However, acrylic is notoriously difficult to bond with glues and other adhesives in a clean fashion and scratches easily when trying to remove unsightly residue. Welding acrylic is easy to do with the right materials and can create incredibly strong bonds with little to no residue left over.

Acrylic objects can be held together with adhesives such as Goop or sealed with various caulk products. However, for a solid bond that is as strong as the material itself, a chemical weld is the easiest method for bonding. Welding two acrylic parts essentially joins them together as a single piece and forms an incredibly strong bond. Acrylic cement works by dissolving the plastic of the objects to be bonded, then as the solvent evaporates the two objects essentially form together as a single object.

You'll need some acrylic cement (I recommend TAP Plastics and a syringe to apply it to the objects.

WARNING: Acrylic cement is a flammable solvent. Wear safety glasses, prevent any skin exposure (wear rubber gloves), and avoid any heat/flame sources.

1. Pour some of the acrylic cement into the syringe. Use a funnel if possible, or for small jobs use the syringe itself to draw out a small amount of the fluid.
2. Hold or clamp the pieces to be bonded as tightly as possible. The cement will flow into the bond via capillary action, so the tighter they are held together the stronger the bond will be.
3. Hold the syringe upright to prevent any fluid from leaking out. If some of the cement leaks on to your objects, the best solution is to leave it alone and don't try to clean it up, if the spill is not disturbed before the solvent evaporates it should return back to normal without cleaning.
4. If using a squeeze-bottle syringe, before applying the cement, squeeze a bit of air out of the syringe while holding it upright then let it release right before turning it over. As it draws air in it will prevent the cement from dripping from the syringe before it is in place.
5. Place the tip of the syringe right at the junction of the two objects to be bonded and either wait for the cement to begin to flow or give the syringe a light squeeze to start it flowing. You should be able to see the fluid flow between the two parts, the thinner the fluid level the stronger the bond will be.
6. Drag the syringe along the two parts applying the cement along the entire bond surface. When finished, return any unused cement to the container and clean out the syringe with water immediately.
7. The bond will be strong within about 10 minutes, but will not be fully cured for about a week or two. Allow the solvent to evaporate completely before testing its full strength.

There's a very nice video describing this process from TAP Plastics.

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