Buying a CNC? Do Your Homework!!

[Gary Campbell]

I have been fortunate to have visited over a hundred CNC equipped shops doing both service work and as a presenter at user gatherings or "camps" as they are often called. I would guess that I have met a little over 500 users, both newbie's and advanced operators. I saw many of these CNC users multiple times, often once before they actually purchased a machine, and then after their purchase at a gathering, or later to service their machine.

I qualify myself as "experienced" and "fortunate". Experienced as being nowhere near "expert". Fortunate as I have been employed by 2 CNC companies and have operated all of their respective models and have watched numerous other brands operate along side. Some costing hundreds of thousands of dollars more. In an effort to help a new CNC purchaser with the difficulties of that purchase, I will share some of the words of wisdom that have been passed along to me, mostly by persons that I have watched "grow up" in the CNC world.

The majority of my personal CNC experience was in a cabinet and high end woodworking shop and sharing that experience allowed me to receive numerous questions and anecdotes from cabinetmakers and woodworkers regarding their own CNC experiences. The experiences of small cabinet shops are not atypical from anyone looking to implement CNC into their business, and in some ways may apply to a hobbyist, but the ones I choose to share at this writing are geared to those small (1 to 5 man) shops.

I will present these with a bit of tongue in cheek attitude, first making a blunt statement and then giving the backup info. It is my sincere wish that you will remember the somewhat blunt lines well into your purchasing process.

Do Not Set a Budget!

You don't have a clue on how to set a budget yet, but it seems it's the first thing CNC shoppers want to do. You will look all over the internet and wish that the machine that has all the cool features cost only as much as the lowest priced one that you can find. I recommend that you set your budget last, and I will give some direction on how to do that.... LAST!

I understand that you must factor affordability into the equation, but those that do not factor ROI (Return on Investment) into the equation make a serious mistake. ROI often makes the price difference between two machine models as simple as a $5K "printing press" that prints $20 bills to a $10K "printing press" that prints $100 bills. In both cases the software learning curve is the same. The ability to have the machine pay for itself is drastically different. It is the difference between years in the former compared to months in the latter. Of course, your business must have work, and you must desire to grow it.

[Gary Campbell]

Learn Some Terminology First

Find out what the most common CNC terms are, learn what they mean, and learn what they are going to do for you. Servo, stepper, closed loop stepper drives all provide the motion . Motors come in many sizes designated as a NEMA XX size. NEMA 23 and 34 are the sizes most sub $50K CNC machines use. The motor torque is rated in ounce inches, like foot pounds on car engines, only smaller units for smaller motors. The higher the "oz in" the more power the motor has.

Rack and pinion, ballscrew, gearbox, belt drive all convert rotary motion into linear. Spindle, router, drills actually spin the bit you will need to cut your material. I won't even get started on how many different kinds of bits there are.

Welded steel, bolted steel, solid aluminum and aluminum extrusion provide the framework for the machine. Complicated? We've just begun. V rollers, round linear rails, and profiled linear rails all provide the smooth motion surface that high quality CNC cutting requires.

Motion control is provided by control software in the control computer. There are "branded" proprietary versions that are made to operate only that make of machine. Others can operate many, even most brands. Some require hardware purchase, some do not. Some run industry standard Gcode, while others do not. Some are easy to learn, others are not. You will find some advantage to finding a good one and sticking to it. A good one is stable and does not create problems for it users, both new and experienced. How data is transmitted to the machine can be a limiting factor is you have a heavy work load.

Parallel (old printers connected this way) ports are getting hard to find in computers anymore and have known data limits. USB is much simpler to find cables and ports for, but also has low data limits. USB is often problematic as the Windows operation system seems to not care that there is a CNC connection, especially when it is time to "check on" the ink in a printer or other USB device. The most expensive (read as best) systems include hardware that allows dedicating computer resources to CNC control. Not surprisingly, the most popular systems are the cheapest and of course, the most problematic. The difference between the least and most expensive is not as costly as 1 days machine time. DO YOUR HOMEWORK!

[Gary Campbell]

Beware of the "Hype"

In the last decade small CNC sales have become very competitive. Each CNC company wants an edge to increase sales. There are many companies that "spin" or "hype" normal specs into something that sounds above normal. Of course, most of the companies have different features, either in construction or simply because they purchase different parts than some other companies do.

To gain sales these different features are hyped into "unique" and then farther into something akin to "magic", at least as it compares to the competition. There is no magic. The transformation from "what we sell" into "magic you will buy" is marketing. The fact is, that in today's competitive global marketplace, if you pay less for one machine than another, you simply received less. Less in quantity, or less in quality, but be sure there is less of something.

If you are self employed making a product, then you are an American manufacturer. Spend some time thinking about supporting other US manufacturers. Although it is virtually impossible to get completely away from lower cost Asian made components, many US CNC companies make an effort to do this by including as many US made components as they can and still stay competitive.

Pay attention to the "catch phrases". As you look at online brochures or talk to a company's sales person, do your homework and find out if that company has something legitimate to promote or they simply have something different. Some use outright sleight of hand by directing you in one direction so that you won't look in another. Also beware of the industry "buzz words". Anytime a successful marketing campaign from one manufacturer uses a "buzz word", their competitors will try to find a way to include that word or phrase in their respective advertising.

Pay attention to what "they" don't say. Watch out for specs that are published for one model and not another. Find out what is NOT included with a product and what it will cost to add it. Add in the cost of the items that are not included.

COMPARE APPLES TO APPLES!!!

[Gary Campbell]

The Forums are the Best (and Worst) Source for Information

"Lurk" for a while before you post
Review a few weeks worth of posts and find who the "local gurus" are.
Try to find one that has a similar business to yours. Read his advice to others.
Look back in older threads for your questions, you can be assured they have been asked before.
Believe those that post pictures of work you wish you could do.
Don't go to the Chevy forum and expect impartial comparisons between a Ford and a Chevy.
Many that use their machines the least, post the most.
Remember that those that have purchased the least, will often praise the abilities of their lesser features the most.

Be thankful that we have these sources for information

[Gary Campbell]

Make a "Good", "Better", "Best" Chart

Find someone that you trust, sit down and apply "good, better, best" to each of the items in the terminology section above. Many of the manufacturers post them, there is also a brand comparison on this forum that was compiled by a university. Compare the features on one brand to another and find a few brands that have the most "better and best".

There is little magic here, the best costs more than the better, which in turn costs more than the good. There is, as you might expect, some difference between "brands" of today's products, but not as much difference as there is between "types". Here are some of my good, better, best items that I feel make a difference to how well, or how long your CNC works. In some cases the choices are self explanatory, in others I will add a few words of explanation.

NEMA 23 Steppers (G-), NEMA 34 Steppers (G), Closed Loop Steppers (Btr) (only a real advantage if greater than 800 oz in torque), Servos (Best)
Gearbox Steppers with rack and pinion (G-) (have minor backlash when new, increases with use), Straight Steppers with belt reduction on rack and pinion (G+), (no backlash, but requires adjustment), zero backlash ballscrew & nut (Btr) (limits speed, expensive, seldom used on axes over 4' on sub $50K machines) No best in this category as all are fairly equal. Note: All require cleaning, lubrication and adjustment to perform at their best.

Handheld Router (G-) (made for occasional handheld use only, horsepower is drastically overrated, higher run out degrades cut quality), 3 phase electro spindle (Best) (greater torque @ lower RPM, software adjusted RPM, made for continuous use, low to no run out) Please note that I didn't mention noise. The cutting noise from a bit, dust collector and vacuum hold down are loud enough to drown out the sound of any router or spindle. Now if you plan on reading while you cut 4 hour 3D files with low stepover, then you can use noise as one of your criteria.

The frame differences are pretty self explanatory. Heavier welded units will produce the best parts for the longest times, but they often require garage doors on the work area and a concrete floor for proper installation. Extrusion versions are OK for light duty, but will deform with time, faster when motion and weight is applied. Most are hobbyist grade. Beware of lower quality Asian imports that are painted or "assembled" in the USA. Lack of support and repair parts have negated a low price for many users.

V rollers on non machined, non hardened rails (G--), V rollers on hardened machined rails (G-) (do not contain force in all directions), Round linear rails (Btr) (bearings wear grooves into rails in time), Profiled linear rails (Best) (the industry standard for higher end products)

[Gary Campbell]

Set Aside Time to Learn

In order to become proficient as a CNC designer and operator you will have to learn a number of completely new skill sets. Machine operating software, vector based design (or CAD), a graphics program if signs are your thing and the toolpath variations that go along with them. (CAM) Each of these has their own separate learning curve timeline, which may be tempered by your own prexisting skillset. Being strong in one of the design areas, like cad or the graphic arts usually is a big plus.

Your success as a CNC user will be directly related to the amount of time spent getting familiar with your new found "tools of the trade". Most of the better software packages offer tutorials in the form of included or online videos. Some software vendors and CNC manufacturers offer training classes or even training on your site. Spend the time and get the best that you can afford, it will shorten your journey to proficiency.

The following is a timeline of average usage hours to attain noticeable skill levels:
Machine operation: 40 hrs - adequate, 100 hrs - good, 200 hrs - very good
CAD/CAM: 100 hrs - adequate, 200 hrs - good, 3-400 hrs - very good
High end specialty softwares (cabinet, graphic, 3D modeling & design) 3-400 hrs - good, 1000 hrs -very good

Please note that these are average times, I have seen some that are up and running in half the above times and also those that were still struggling at double the average. Virtually all CNC's can use the same design software and none of the control softwares are much easier (or harder) than the others. Do beware of those that would give a little quiz that you self grade and leave you with the impression that even with no computer knowledge you will be proficient in 5 hrs.

Be assured that your results will be directly proportional to the quality and length of time you spend honing the craft. Think of the CNC learning curve as similar to that of learning to play a musical instrument. You have to learn the music and then you must practice many hours to become good. Many more invested hours and you can become great.

To quote a friend: "Only the best musicians can get the best results from a Stradivarius. Same thing with other tools. The best operators get the best results". PERIOD

[Gary Campbell]

Words of Wisdom (from Those Ahead of You)

"The things I learned in my first year were not related to what I thought I knew prior to purchase."

I thought I did my homework, but I really didn't have a clue"

"I wish I really knew what the machine would do for me before I bought it"

"I should have bought the next size up"

"I could use a little more power"

"I didn't realize there was so much to learn"

"I can't believe what this CNC did for my business. Why didn't I do this 10 years ago?"

[Gary Campbell]

I am Buying a Helicopter????

Most cabinetmakers I've spoken to have found that the majority of items that they researched prior to purchase turned out to be not the things that became important after they gained experience. Before any major purchase a small business owner will base his research on his/her experience. Prior equipment purchases will give you experience in checking and comparing specs needed for the job at hand. Prior vehicle purchases give some experience in dealing with the stress associated with major (5 figure) expenditures. Neither will actually be of much value for a CNC purchase.

I use the helicopter analogy not only because I am fairly sure that few of us have ever purchased one before, and the following reasons:

It's evident (to you) that you need one to be competitive going forward with your business, as a "helicopter" will decrease the time to complete a given work set, raise the quality of your product and allow you to complete more work with less employees and become more profitable......BUT.....

You don't have a clue how to "fly it"
You don't know how to maintain it
You don't even know what the parts are called, what they do, or where they are located on the machine
One look into the cockpit (screen) and you will see nothing familiar
You will have to make a major commitment to "training hours"
You will need a lot of other equipment (software) to make/keep it operating, but don't know what they are or how much they cost
You have a big job on the horizon and you think you can learn to fly the helicopter in time to use it for that job.
When warned not to buy the "helicopter" for an upcoming job, your response is: "I have to, that job is paying for the machine"

In most cases a larger, more powerful "helicopter" will pay for itself much faster than a smaller less featured unit, be overworked less, therefore break down less AND allow you to enjoy expanding your business in the future by not choking work flow. In other words, your equipment will be ready to grow your business when you are. Not the case with undersized equipment.

[james mcgrew]

I sent this to a "Shopper" who is potentially Moving on Based on Price alone as competitor is dumping his price just to make the sale ... Thanks Gary for putting in words something that can take weeks maybe months to explain under some conditions.

This is MY Email to Him

"And I promise I will leave you alone !! it is rare I see someone take your methods as hard on a cnc machine, to me a product a product sells itself , My father sold Real estate as a career from the early 60s to the late 80s, he once was quoted when asked "Mr Mcgrew How is it you sell so many Houses" ? he responded I don't sell houses, Houses sell them selves, My job is to find and show the client the one he ask for and wants, While protecting him from what he cannot see" !! ( You can tell I loved my Dad)

The reason for this email is a post Gary wrote this AM for any one in the Hunt for CNC. this is our job on the forum to find Info and get it out there. I hope you find it Interesting reading !!"

http://www.camheads.org/showthread.php?t=3904

[Gary Malone]

Great advice Gary, thanks for posting that info!!

[Gary Campbell]

What Makes CAMaster Unique?

This exact question was emailed to me this week by a prospective purchaser. The truth is that even though we have some very nice features, very few if any of them are "unique" in the sense that no one else would offer them.

Here are a few of the things that we, the guys that build them, feel allow our product to have a leg up on the field:

One piece welded frames. We use a tubular steel frame that is welded and then powder coated, supplied to us by local vendors. All of our 8' and longer have an attached weldment that is milled and drilled to ensure that the linear rails are coplanar and parallel. Our Cobra models have an additional milled weldment to ensure a very precise alignment for the servo transmission to rack gear.

In house parts. The majority of our components are built in house using billet 6061 aluminum. Prior to cutting, the majority are surfaced on all sides, on our HAAS machining center, to ensure parallel and perpendicularity.

Motion support on linear rails. We use HIWIN brand 15 and 20 series profiled linear rails and bearing blocks. These rails and bearings are installed into milled datum's, and fastened into CNC bored and tapped holes.

Self adjusting transmissions. All models now include self adjusting transmissions (on R & P axes). This virtually eliminates spur gear to rack backlash. This feature, coupled with timing belt reduction, allows us to provide all the lower cost advantages of rack and pinion propulsion with the least backlash.

Independent Dual drive. Our dual drive Y axis machines have independent control. This enables the machine to "square" itself each time it initializes.

Functional 4th (Rotary) Axis. Our fully installed, "Recoil Ornamental Lathe's" are functional "right out of the box". Standard motors on 8' and longer machines are 1200 ozin, and belt reduced to provide over 3000 ozin of torque. Enough to turn a blank that is 12" diameter by close to 8' long.

Robust Z axis mechanics. Every model is equipped with ballscrew provided motion on the Z axis, and an air counterbalance is provided for all but the lightest of cutting heads.

Fully assembled. Fact is, our machines are assembled, calibrated, tested and ship ready to run. All the machine specific adjustments are installed into the control computer, which is included. Your machine, tested with your computer, ready to run "right out of the box".

WinCNC Control. We use WinCNC exclusively as a controller. Long known as the "gold standard" in the industry, it is nowhere near the least expensive option, but by far the most dependable. WinCNC hardware has proven to be near bulletproof.

Digital Drive Systems. For 2014 all of our Stinger models have digital stepper drives. Digital drives provide much greater holding torque, smoother operation and less heat than analog versions. They are also much less sensitive to EMI and RF than their analog counterparts.

If you have done your homework, you will see that we do have some very nice features, some of them slightly unique. What is very unique is that we offer all of these features in one package, and we can ship it to you assembled and ready to run.

Another great CAMaster feature is our user base. This is a hard working group that, like many other forum based groups, gives freely of their knowledge to help new users progress. What makes them unique is that they are a group that has made a conscious decision to buy a product that is not simply the least expensive option out there. This is evident in the higher quality of posts on this forum, especially when compared to some others.

[Joey Jarrard]

Very Very Nice !!!!! A must Read

[Gary Campbell]

Some do's and Don'ts. Actually, just the Don'ts

Here are some common don'ts that have been relayed to me by operators that have gained both proficiency and experience. They won't all apply to you, but hopefully some can be helpful.

Don't let the current layout of your shop determine the size or location of your CNC. The CNC will become an integral part of your work flow. Design your shop's work flow around moving material into and machined parts out of the CNC. It's a pay me now or pay me later scenario. Believe me when I tell you that moving air and electrical lines is not cheap. Especially when you do it 3 times.

Don't expect to be machining parts on your (imagined) time schedule without some form of formal training. All CNC mfgr's and software titles provide training at reasonable or no cost. USE IT!

Don't forget software. Purchasing software can be as difficult and as expensive as that of the CNC machine itself. Most mfgr's include a CAD-CAM program that is a very good, a very good, but none the less general solution. Signmakers can benefit from higher end graphics programs, cabinetmakers from specialty programs tailored to that one use and those that have unique machining requirements will find that there are higher cost software products that substantially increase both your ability, productivity and profitability.

I have seen cabinet shops with 10+ year old <$10K machines and $20K+ software packages that out produce, in both quality and quantity, shops with $50K+ machines and low cost software.

DO NOT PURCHASE A CNC TO COMPLETE A JOB YOU HAVE ON THE BOOKS. Commonly referred to amongst experienced users as a "Recipe for Disaster", and for the new user, will place possibly the highest amount of stress on them that they have experienced in many years.

Be honest with yourself. Unless you have CNC operational experience and are proficient in all the required software titles, you won't be able to make yourself happy with your CNC work for a couple months anyway. Do you wish to have your customers unhappy with it too? Chances are that even if you do get it out the door using the CNC, they will be unhappy because of the delay. As an option for the obstinate, you can hire someone with knowledge to come into your shop, and train you as you both put product out the door. Win win.

Don't expect your employee(s) to have the same enthusiasm about the CNC as you do. They may feel threatened about it replacing them, or simply be intimidated about learning new skills. These points have been brought up by employees at almost every new install I have completed, unless that employee was part of the driving force to implement the machine. I am not sure that I was able to put those fears to rest, but I did see some change of attitude when they were told: "This machine is only capable of replacing someone that does not know how to operate it".

Don't expect a CNC machine to put out "perfect" parts until the operator gains proficiency. Most brands of CNC are capable of +/- .002" accuracy. Very few if any, new operators are. It will take time to hone your craft. All materials, bits, feedrates, software titles and even the machines themselves have parameters that must be set and match up to gain the best results. Rest assured that your machine will be ready for very nice work when you as the operator gain the experience to balance all these variables into some of the nicest work you can produce.

[dustboy]

All great advice. Must read for anyone considering a CNC router for commercial use.

[bmilam]

Very informative information and I can attest to the truth in it. I've owned a CNC (another brand) for about a year. I bought it with no cnc knowledge and picked it primarily due to my budget. It didn't take long to realize the limitations that I have to deal with and my need to upgrade to a larger and all around better machine.

Your words of wisdom category is spot on! I have thought every one of those sentences.

Beware of the "Hype" is so true. The company I have now just came out with "magic" software initially described by them to compensate for flex in the table when camping down. Later changed the description that it was used to compensate for uneven material thickness and not the table. Guess they figured out too late that it sounded bad for advertising.

I've been lurking and doing research for probably 6 months and have gained a wealth of knowledge about the different machine options available. All the forums have the faithful that praise the machine and only use price as a reason that their machine is better than a competitors.

One thing that I didn't see (maybe I missed it) was forum support. I have found this to be the most active and supportive forum yet. It really shines positively when Camaster reps get on here and answer questions or when needed, I've seen members who have personally called Joey and others to get their attention of an issue and to deal with it immediately. I don't see that much or to the degree I see it here.

This is my favorite website to come to daily. Hopefully you'll be getting an order from me soon.