The Engravers' Bible
Most engraving systems fall into two basic designs: a fully self-contained system where the mechanical and electrical components are in the same chassis, or a system where the engraving table and electronics controller are separated. Given the variety and possible configurations of systems on the market, only generalizations can be made here, and it's recommended that you obtain the proper maintenance instructions from the equipment manufacturer.
The first rule of thumb most equipment manufacturers will preach is "never do anything more than preventive maintenance on your own". There are good reasons for this. It's not that they want to make lots of money servicing your system, or make service a difficult part of running your business. It's simply easier to do it at the factory. Training an engraving equipment operator with limited electrical or mechanical skills to pull serious maintenance is difficult if not impossible. Even if you have the skills, the documentation that the hardware manufacturer can provide is generally limited to the basics, and no hardware manufacturer wants to give away their design secrets by giving you all of their schematics. The things you can do and should do are the basic preventive maintenance as prescribed by the manufacturer.
Here's a sample of the typical work that you can perform:
Most electronics maintenance is limited to cleaning the air filter and blowing the dust out of the unit. As long as you can gain access easily without disturbing any of the electronic components, you can blowout the control unit with a little compressed air (no high pressure). Always disconnect the equipment from the power source first. Never assume that the voltages inside the controller are not harmful. It's a mistake you may only make once.
Occasionally you should inspect the cabling for frayed wiring and insure that all connections are tight. This is especially true if you tend to move the equipment in your shop regularly. We often forget to tighten up cable screws and can have intermittent connections that appear as other types of engraving problems.
Any other maintenance to the controller will most likely need to be performed by the manufacturer. This may include tuning in drivers, checking output voltages in the power supply, etc. This is not the kind of work you will want to do and should be left to the experts during an annual checkup.
A little advice - keep some spare fuses handy for the control unit. If you have a boot-up problem, the fuse may be the first thing to check. It's also a good idea to use the recommended fuse. Failure to do so will definitely cost you some extra money.
Here's where some extra effort on your part will save you costly repairs and equipment down time. First, you need to realize that certain components of your table are working all of the time and need cleaning. We can first start with the spindle since it's doing most of the work when rotary engraving. If you are not using a vacuum system to remove chips from the engraving area when cutting plastic stock, you will need to periodically remove the spindle nosecone, retainer ring and micrometer and clean them. If you're careful, you can brush off the inside and outside threads of the micrometer before replacing. Use something soft such as a toothbrush. You do not want to damage the fine pitch threads of the micrometer. Also, be careful not to cross thread the micrometer when putting it back onto the spindle. Remember, never oil the spindle. The only place you can oil or lubricate is the threads of the micrometer. A very tiny amount of white grease or a drop or two of oil is plenty. Any more than this is asking for trouble.
On some older models of spindles, there is a felt washer located near the end of the spindle shaft. Remove the nosecone and retainer and inspect the washer. You may need to brush the washer clean of chips and occasionally re-oil it. Its purpose is to act as a barrier to chips and debris and prevent them from working up into the spindle bearings.
You will also want to inspect the spindle to insure that it spins freely. Remove the spindle belt and spin the pulley. There may be a little resistance but it should spin evenly and without any feel of grinding or audible noise. If it has a high pitch or grinding sound when running, or feels hot to the touch after a few minutes of operation, you probably need new bearings. Given the cost of a new spindle, a bearing replacement is a bargain.
Something else you can check for is spindle run-out. The first effect of a run-out problem is poor letter quality. This is not easily detected since it tends to occur over time. If you do notice a difference in engraving quality, it will be variations in the line width. Run-out is the play that can be measured at the cutter tip. Bad bearings, a worn out spindle shaft, or an undersized cutter can cause it. If you think you have play in the spindle and you're sure it's not in the carriage assembly, send the spindle in for maintenance. Ignoring it may cause further spindle, cutter or equipment damage. Allow for down time of several days unless you have a spare spindle available. It's recommended that you invest in a spare spindle as a backup. It's not unlike having a spare tire for your automobile. You would not want to be stranded with customer deadlines and no way to complete the job.
Another tip - Buy for your system a spare motor belt, spare controller fuses and a set of motor brushes for your spindle motor (if required). It's cheap insurance and saves you down time and the expense of overnight freight on a $5 or $10 item.
The next thing you can easily do is to lubricate the table lead-screws. If you want to raise the hair on the back of the manufacturer's neck about the proper lubricant, ask him what should be used. Every equipment supplier recommends something different. The reasons are many, including their own experience with different lubricants. Some lead-screws are stainless steel and others are Teflon coated. Using the wrong lubricant on Teflon screws can break down the coating and destroy the screw. Get the recommended lubricant from the manufacturer and use it. Most environments require cleaning the screw and lubricating once a month. If using a fairly dry lubricant such as silicon, lubrication may be every few days. A lot of the requirement depends on the lead-screws nut as well. Compression type nuts versus self-adjusting may act differently when lubricated improperly.
Another place where a little maintenance will help is the linear rails and bearings that support the X and Y- axis motion. Under most conditions, very little must be done to maintain these items. Again, wipe them down periodically and use the manufacturer's recommended lube. If you have nothing else in the shop, you can wipe onto the rails a little 3-in-1 oil. Any excess must be removed or it will collect engraving chips that may cause other service problems. A little oil in the right situation will prevent pitting or rusting of some rails. The bearings that ride on these rails are sealed and usually need no lubrication for the life of the system unless they are removed for repair, etc. This is something that should also be left to the experts.
You can see that there's no need to get wild with the oil can. Most of the items such as stepper motors or drive motors require no lubrication and it would be detrimental to do so. There may be some parts that have metal to metal contact where the manufacturer will recommend a drop or two. When in doubt, leave it alone.
A little cleaning and lubrication can easily be done and will go a long way to keeping your engraver healthy. It will also save down time and an expensive service call.
Try to have your equipment serviced at least once per year. You may be able to work out a time when not having the engraving equipment will not disrupt your business. Perhaps you take a summer vacation or take an extended shut down during a holiday. These are good times to schedule the service work with the manufacturer.
Get to know the local equipment dealer as well as the business hours of the manufacturer’s service department. Keep this information along with phone numbers, the equipment serial numbers, your customer number, and software revision information close at hand. You can move through the service department and process much faster if you keep this information readily available.
Preventive Maintenance of Collets and Collet Nuts
Proper maintenance and replacement of these parts is critical as they directly affect job quality and tool life. Because these parts are exposed to extreme heat and dirt, it is important to inspect them every time you do a tool change. The maintenance listed is applicable to both engraving spindles as well as router heads.
Collets - Frequently inspect all collets for signs of damage or residue build-up from using coolants. Residue build-up can cause cutters to adhere to the inside of collets. This residue can easily be removed using a brass brush. Clean the outside of the collet using a mild solvent and rag. Take care not to damage the fine threads where the draw bar screws in.
Collet nuts - Inspect the inside surface of the collet nut for burrs that can often ruin a collet. Frequently clean and lubricate the threads. Also, keep the collet housing, located in the spindle shaft, clean and free of dirt and debris. Also, wax the threads of the collet nut with paraffin wax. This will allow you to get a much tighter grip on the tool.
I could easily argue that a spare spindle is a must have. Not having a spare spindle is like driving a car without a spare tire - if you get a flat, you're in big trouble. Treat the need for a spare spindle the same way. If your spindle goes down or needs a new set of bearings, you'll be out of business until the manufacturer can get you a replacement or repair the one you have. If you just can't afford a spare spindle when you purchase your new engraver, make it a goal to get one in the first year of operation. Cost - $350 - $750.
I already mentioned the benefits of the collet spindle above. You might consider using this as your back-up spindle. You would then have the added benefit of having it readily available when those special needs arise that require the advantages of a collet spindle.
It is good insurance to keep a small inventory of spare parts on hand to prevent unexpected downtime. Must-have’s include the following: motor belts, fuses, motor brushes for the spindle motor (if required), vacuum hoses (these tend to break on occasion), extra cutters, a spare spindle, and sharp upper shear blades. There is nothing worse than working under a pressing deadline and having to spend a small fortune on next-day freight to have a part sent so you can finish the job on time. And what will you do if the problem occurs after your supplier is closed for the day? Now it will be the day after tomorrow before your order arrives, and you'll have to break the news to your client that you may not meet the deadline!