Ask the Expert: CNC Router Veteran Shares Practical Knowledge
Do you have questions about CNC machining? Get inside the head of router expert Jay Higgins in this one-on-one interview.
By Jennifer LeClaire
Getting the most bang for your router bucks takes a little bit of homework and a lot of practice. We canít put in the hours of practice for you, but we can provide you with advice straight from the mouth of leading industry experts.
Jay Higgins is one such expert. Higgins came to the sign world in 1993 from the CNC manufacturing industry. With more than 20 years of CNC machining to his credit, Higgins is uniquely positioned with a broad understanding of CNC tools, hardware and software. Higgins is currently the general manager of Capital Letters in Brooklen Center, Minn. and a respected CNC routing consultant.
SignIndustry.com asked Jay some questions that will help you reach new heights in CNC routing.
Q: In your mind, what are the biggest advantages for sign makers using routers?
The biggest advantages of CNCs in the sign industry are speed, accuracy and repeatability. CNC's also allow you to custom rout metal forms to help aid your fabricators in the creation of custom shaped aluminum constructed signs. This is a great advantage for modern sign companies. What was a tedious and manual chore of laying out patterns on aluminum and then jig saw cutting to get your custom shape, is now simply a matter of sending them to the CNC router to be cut.
Q: What are the most common mistakes sign makers are struggling with today?
The most common mistake is a lack of knowledge of basic machine principals. Also, the lack of knowledge of how to properly fixture your material to the table, as well as the availability of tools you can use to get the job done.
Q: Would you recommend that sign makers who have never used a router seek more formal training and education beyond what the manufacturer offers?
All people interested in utilizing CNC routing in sign manufacturing should take some sort of course at a nearby community college to better familiarize themselves with some basic machining skills. Unfortunately, very few schools offer this kind of training. I have worked with the Minnesota Sign Association in regard to this matter to bring it to the attention of local technical schools so that hopefully it can be a course that is offered to people in the graphics industry.
Q: How about sharing some practical tips for preparation? For example, which router bits works best with which materials?
Tools and materials are very important things to experiment with. A good rule of thumb: always use the largest diameter tool to rout the job that is allowable, and, always use the shortest flute length for maximum rigidity.
Q: What about router speeds? What speeds work best with various materials, like aluminum, high-density urethane, sign foam, etc.?
Speeds and feeds are directly related to the horsepower motor that you are using, as well as the type coolant system, and the coolant that is being used. A common mistake of most people is to slow down the feed rate and speed up the RPM. Big mistake. Generally, it will create too much heat and thus melt/weld the material.
Q: Which materials respond best to routing?
Some materials are more forgiving than others are when routing. Each material has its own set up procedure and feeds and speeds as well as the proper tool to be used.
Q: Are there certain types of materials that sign makers should avoid when using the router?
Materials to avoid include those that have a great deal of glue in them, certain irons, as well as stainless steel, as there are electrical discharge concerns there.
Q: What do you see in terms of upcoming trends in materials? Are there new materials being designed with CNC routing in mind?
I make it a point to continuously contact my suppliers and the manufactures of sign making materials to see what's being developed that can possibly be used to rout on the CNC router. I have also been selected to rout such test materials to give my evaluation of them. I don't know of too many new materials out there right now that are being developed specifically for the CNC router.
Q: How can sign makers more effectively utilize digital printing in conjunction with routed sign parts? Any practical tips there?
Using digital prints in conjunction with CNC routing is a relatively easy thing to do when they are in small formats. The problem with CNC routing a large format vector shape to match a digital print is that the digital printer will often distort the digital print disproportionately so that it does not match up easily with the vector cut shape. Allow plenty of bleed to the digital print, especially when the digital print is printed in more than one run.
Q: How can sign makers more effectively match files together?
File conversion and being able to recognize file extensions are very important "learned" skills. Some filters in design programs shrink, distort, and interpret objects, text, and shapes differently. Example: some .dxf files may look to have complete arcs but are really ploy lines or line segments that might not produce the outline shapes that you want.
Q: What is the best method for realigning a double-sided sign on a router in order to cut out the other side?
I personally like to rout double-sided signs in two pieces and them join them together back to back. This, of course, must mean that the shapes are symmetrical. If this is not an option, scoring an outline in your waste board, or building a contoured jig may be the answer. Dowel pins may be another way of realigning the shapes to the table as well from side to side.
Q: Moving on to finishing techniques, which seems to be challenging to many sign makers coming from a vinyl background, under what circumstances should sign makers pre-paint a blank?
Whenever it is possible to pre-paint a blank, do it. Apply your mask afterwards and rout the images as needed. This will allow you to fill in the areas you have just routed without worrying about slopping the paint all over the pre-painted areas.
Q: What primers work best with various materials?
I prefer to use a latex-based primer with sign foams. With aluminum, I prefer a self-etching primer. For PVCs, acrylics and foams generally do not require a primer, but roughing the surface does help the paint to take hold of the material.
Q: What about work flow strategy? Any practical tips there?
Always prepare for the next job coming down the pike. Group your jobs based upon material, tools, and set up procedures.
Q: Can you offer any other dos and doníts or practical tips in terms of driving the most creativity and profit out of the router?
Know what you can do with your router and inform your sales staff what you are capable of producing. Nothing is more embarrassing than selling a job for the router that cannot be produced and then changing the layout or materials after the job has been sold to enable you to produce the product. Always insist upon a layout before quoting a job over the phone.
Q: Can you offer some pricing tips?
Because of varying demographics, pricing should be based upon what you can produce and what your competitors can produce. Every job is different, especially for the CNC router. Know your materials and the speeds and feeds you can achieve and base your pricing upon that. When it comes to sign foam signs, $35 to $40 per square foot for finishing is a healthy number.
Q: Lots of sign makers spend their money on the machine, but then donít invest in the tools. What tools would you recommend as essentials?
Only buy solid carbide or carbide tipped tools. Due to the coolant system found on most CNC's, high speed steel tools generally will not last as long as carbide. The proper size collet for the shank of the tool is a greatly overlooked consideration. The collet size should match the shank size of the tool. Sleeving is OK, but rigidity is lost when this is done and, depending upon the material being routed, this could be a finish and quality concern.