In Search of the Perfect CNC Part 2

Last month in Part 1 (see Sign Business September 04, page 50), we discussed the importance of knowing the capabilities of the different types of drive mechanisms, motors, material hold-down mechanisms and table controls for CNC routers. In our search for the perfect unit for our shop’s needs, we also found it important to research table construction, various options, hidden costs and peripherals needed to have a functioning piece of equipment in the shop.

TABLE CONSTRUCTION

Weldment considerations: Probably our most important feature was edge quality. At Reid Signs, we cut a lot of plex and aluminum for very demanding architectural applications. We needed to be able to have a near polished edge right off of the bit.

Edge quality is determined by a number of things. Vibration is the big killer of great looking edges. Vibration is also where a lot of sound comes from too, so you kill two birds with this little bit of advice: get the biggest, heaviest machine you can afford. For us, the German built, Flexicam Stealth 5' x 8' machine was perfect. Sheer mass can overcome vibration, gives you great edges, increases tool life, lets you operate at much higher speeds, and results in reasonable noise levels.

If you think about it, a tiny router bit is being asked to do a lot when cutting through stainless steel, hardwood or aluminum. The powerful forces created by cutting these harder materials are going to reveal themselves at the weakest point. The sides of our 1,600-pound gantry are made of 1'' stress relieved steel so deflection is impossible there.

To further eliminate deflection, we chose a solid, stress relieved base unit (or weldment) as opposed to a bolt-together aluminum frame. The bearing cars are spaced far apart and operate with absolute precision, eliminating another point of unwanted movement and inaccuracy. Every part of the machine, from the frame to the moving parts needs to be well designed to counteract the ever-present deflection demon that is waiting to kill your edge quality.

Of course, the machine you choose should reflect the type of work you intend to do and not every application calls for a machine capable of surviving a car bomb.

TECHNICAL SUPPORT
Tech support is an area which, by itself, may determine which machine you buy. First of all, every manufacturer is going to tell you they give great support. During my research, I was actually surprised to hear a representative from a particular company volunteer slanderous statements about all of his competition!

Carefully consider the information you are being handed. Ask for and follow up on ALL of the references given to you. A good company should be able to give you a long list of satisfied installations.

Here in Seattle, we’re fortunate to have a few CNC companies whose headquarters are close by. I decided however, that proximity of tech support wasn’t a big enough factor to entirely influence my decision. The Internet has allowed me to shop for the best deals all over the world; it has made our company your next door neighbor no matter where you live. I can make and FedEx a product to your door in about the same time it takes to do it locally.

I decided to leverage this same concept to technical support. These days, a successful CNC company is selling units all over the globe and has very advanced systems in place to support what they sell. If they didn’t, they wouldn’t last very long!

We recently had a support issue with our Enroute CNC software program. I called them and they linked directly up to my computer, saw what I was working on, saw the problem, and fixed it while I watched. I just sat there and watched the screen move and change while listening to the tech guy explain the process to everyone in our office over our speakerphone.

In the case of our 4,800-pound CNC machine, we certainly aren’t going to ship it back, and the frame isn’t the part that would break anyway. Anticipated support problems are more likely to be spindles (worst case) to small electronic components that are easy to ship and plug right in with easy instructions.

Early on, we decided that we actually wanted to play an active role in servicing our own machine. I want to understand it inside and out, so that if something does break, I can quickly repair it. Some companies require you to buy a plane ticket for their technician. Make sure to specifically ask how a company handles their short and long term support. Most machines are serviceable by their owners and aside from adjusting the delicate tolerances of some parts, are really pretty easy to understand. So after figuring out where we wanted to be on the support issue, I decided that buying a machine from someone down the street or across the globe didn’t matter as long as they had an exemplary service record and an awesome machine.

THE HIDDEN COSTS!
The cost of the machine is not your final number. It actually is just the beginning. Discovering these late-breaking costs, admittedly, was a little deflating. Initially, I forecasted the right amount of money for a unit based on careful research but as the purchase turned into a reality I learned about some of the other things I needed, or would want to have.

For us, the whole idea of a CNC machine was based on the idea that we could bring a measurable amount of automation into our shop. Our success with Summa digital printers taught us that when you can truly walk away from a machine during production, that is the moment when you realize the benefit from your investment.

Whether we’re talking about printers, cutters, or CNCs, the main point for us is if we can’t walk away from it, we haven’t gained much automation from the investment. At Reid we run a very stripped down shop at least as far as employees go. We hire the best people we can find, and we buy the best equipment we can afford. This combination has given us production capacity that rivals much larger shops. It’s been a very successful formula for us and we have continued to build and expand upon that simple concept every day.

Tool Changer: This philosophy brought us to another major question in our purchasing decision. Do we spring for the $25k tool changer? To stay true to our principle, Yes! I got hit hard with that decision though. I was not prepared for it and hadn’t factored the cost into the equation. I hadn’t heard much about it and didn’t really know too many people who had one, so I figured it would be an item we could grow into.

But I looked at the reasons why we were buying the machine, and again, the big reason was automation. If we were chained to the machine by having to change bits, then we haven’t automated! If we can’t walk away, then we can’t let it run all night. Our night jobs are our “second shift” and are as important as our day jobs. We realized the benefit of “the night shift” in 2002 when we loaded our Summa DC1 with a fresh complement of ribbons and sent it a hundred feet of banners to print while we went home to sleep. In the morning, the “night shift” left us with printed, saleable items.

I vowed that if I could find a CNC that produced the same unattended production, I would spend whatever it took to acquire it. Well, that day has arrived for us, but for the type of work we do, it turns out we have to have the tool changer.

All these machines are miracles for sign people, as far as I’m concerned. For what they are capable of, they should cost a lot more than they do; but don’t tell them that!

Air dryer: For us, along with the tool changer, we realized we needed a refrigerated or desiccant style air dryer to clean and dry the compressed air that is plumbed into the expensive parts of the machine.

Clean dry air is common for industrial machinery, but since we don’t really own any, we didn’t know that. There is an entire industry devoted to just that and there are no problems finding just what you need at competitive prices. We chose a Great Lakes refrigerated dryer for about $800. Also necessary was a $200 coalescing filter to grab the oil and sub-micron particles. If you operate a spray room, you may have the right kind of air already.

Air System: Air is one of those things that you don’t think about until you don’t have enough. We have a cold air gun that keeps the router bit and the part cool during machining. This is essential because if the part gets hot, then the size changes. The main advantage of a cold air gun is that it doesn’t get coolant all over everything. We all know what happens to MDF when it gets wet. MDF is what our spoil board is made of and if it swells, then our precise tolerances between the bit and the surface quickly become a distant memory.

But using this handy cooling device is the equivalent of drilling a 1'' hole into the side of your air tank. At about $650, it’s also like drilling a 1” hole in your checkbook. To handle the immense air requirements, we researched heavily and ended up buying a super-quiet 7.5-hp Sullair rotary screw compressor kicking out a very adequate 30cfm for about $3,800. Think routers require deep research? Wait until you start looking at air systems! Our clean air setup is connected in this order:

1. Compressor with integrated aftercooler to remove 60 percent of the water right at the source.

2. Coalescing filter- this cleans the sub-micron oil present in the compressor air.

3. Refrigerated dryer- this cools the air to 35 degrees which removes the remaining bit of water left in the air that the aftercooler didn’t catch.

4. Air storage tank- this is actually just my old shop compressor which I turned into my new storage tank by disconnecting the worn out pump from the top of the tank. Having this storage acts as a buffer against pressure drops. This is useful if the CNC is running and someone starts running an air tool at the same time.

5. Desiccant filter- total overkill, but I had one left over from a bad purchase I made just prior to learning about all of this stuff I am telling you. It also doubles as my $179 shrine to remind myself to learn before I buy. I have an entire shop full of other shrines too.

6. CNC router- Finally! At this point the air is so clean, it’s practically dirty again. All of this effort is just to make sure that no water or dirt gets into the 12hp HSD spindle. It’s kind of a shame we’re going to be cutting aluminum and stuff. We could be drilling teeth with this setup. Need a crown?

Dust collection: Of all the items we had to buy, only one was measured by how much it sucked.

We’re talking about a dust collector. The spindle on the CNC unit generates a constant flow of dust and debris and that stuff needs to get out of the way or your edges are going to suck too.

Suction requirements for our unit were a minimum of 1,100 cfm. We found many good units available capable of much higher and so we went with a Grizzly dual bag system with 2310 cfm for $600. We ran our own 6'' spiral ducts from the unit to the collector and after we were done testing it, small children and pets from around the neighborhood turned up in the filter. A screen quickly solved this problem.

Power: We finally got everything sorted out in our list, double checked everything, and we’re set to go! A cursory glance at the site preparation checklist told us that we needed three-phase power. We’re in an industrial area here at Fishermen’s Terminal and figured that would be a no-brainer.

Turned out that three phase has to be brought to our building via a new power run. A new power run requires either an underground line or a pole. It had to come from the substation to our facility and terminate into a three-phase panel. Again, this is specific to our location, but was another shocker at how much it costs just to bring a little extra juice to our building.

FINAL SURPRISES
Phew! So we’re up, running, all excited and we go to cut something but nothing works.

Forget something?

Software!

Let me tell you something you probably already know. Software is not cheap. There are some excellent programs available however, and there are huge differences between them. These differences are where you will really want to do your homework. Software helps your machine become operational in a way that is easy for you to control. It should bring automation (the main thing!) to the types of work you do, plan to do, or want to do. All of the programs I looked at had price tags that reflected varying degrees of control and user interaction. Some had annual maintenance fees that equaled 10 percent of their purchase price (a hidden cost within the hidden cost)!

These costs are necessary to fund improvements and I fully understand why they’re there, but I opted to go with Enroute3 which doesn’t have maintenance fees. I wanted our CNC software to be able to receive files from CorelDRAW and simplify some of the machining tasks that are unique to sign making.

Software was an area that I felt important to stay within the sign industry. I went a little outside our industry for the machine, but I wanted our software to be from our industry so that it could easily perform sign-type tasks. At around $7,000 the fee is not cheap, but research proved this to be an excellent value when compared to other options.

Price is relative though. Our software and CNC machine are allowing us to enter a very lucrative arena that frequently awards the early adopters with a one-job payback for most sign making equipment. We’ve experienced that a few times and I bet some of you have too (okay, maybe two jobs).

So if you’ve made it this far, you might be ready to consider one of these awesome units. The lifespan on these machines can be up to 15 years, so take the time to look at a lot of them and really put your mind into this process. We spent six solid months learning about all kinds of new equipment and figuring out what would be the best to meet our objectives. I highly suggest learning as much as you can about all the different components necessary to do this type of work. The things I learned along the way made the research well worth the time it took.

There was no way I could write a single article that touched on everything in the kind of depth this topic required, so do your own research, and remember, I’m no expert. I’m just a sign guy.

One who can make signs in his sleep...