By David P. Monyhan (retired)
In several previous posts we’ve discussed various maintenance requirements for your big machines – surface grinders, crank grinders, cleaning machines, etc. Now we’re going to take a look at five other devices that play an important part in building the best possible engines for your customers – the air compressor, hydraulic press, brake lathe, bench grinder and seat grinding set.
Air compressor
We generally take this unit for granted, but let’s face it; it does supply compressed air to all of our machines. If this machine goes down the whole shop goes down until we get air back into the system. Trust me, blowing into the end of your air impact wrench just ain’t gonna get ‘er done.
Be honest, when was the last time you changed the oil in your air compressor? This should be done at least every year. Use non-detergent 30-weight oil, but as always, double check your owner’s manual and follow the manufacturer’s recommendations for the proper weight oil. You may also want to consider using a “compressor cool” additive to keep the compressor oil cooler and minimize condensation in the pump.
Next inspect the drive belts for wear. Always replace these in matched sets to maintain a balanced tension from drive to driven pulley. Also, make sure your belt guard is doing its job. If it’s just hanging on, take the time to affix it properly to the machine. Remember, “safety first!”
If you look under your air storage tank you will see a water drain valve. Compressed air creates condensation and condensation in water. During the humid summer months you may need to drain this reservoir daily and during cooler months, at least once a week. I recommend an in-line water separator and automatic oilier attached no less than 10 to 12 feet from the air compressor. This distance allows the air to semi-cool before going through the filter allowing it to better do its job. Keep in mind some of your high dollar machines need air to run and you don’t want any water to create rust or contamination in the air system.
Now follow all of the air lines that run through the shop. Are there any leaks? If there are, you’re wasting money in electricity to replenish the air supply. Take the time to repair any air leaks you may find.
I recommend placing automatic oilers at the air stations that feed your air tools. Most of your machines come with filters and oilers. Unnecessary water and dirt in your lines will shorten the life of your air tools. There are these little caps that I like to see used to cover the nipple of your air tools when not in use, they are an inexpensive and easy-to-use way to keep debris from getting inside your air tools.
Hydraulic press or H-frame press
Many shops have a hydraulic press for a variety of pressing jobs. Be sure to change the hydraulic oil at least every two years. Replace it with a high quality, non-foaming type or whatever the manufacturer recommends.
Does your press have a tonnage gauge? Does it work? If not, replace it. It’s important to know how much pressure you’re putting on a part. Some presses use air over hydraulic to create the necessary pressure. Again, make sure there is an oiler and water separator on the press and periodically clean and add fresh oil.
Inspect your pressing tools for nicks, burrs, mushrooming etc. If your tools are mushroomed, you are just waiting for an accident to happen. Replace those worn tools. Always wear eye and face protection during any pressing job.
Brake lathe
If you turn drums and rotors in your shop, the brake lathe needs attention as well. Put a dial indicator on the spindle and measure run-out. If you see more than .002” run-out you need to either straighten that arbor or order a new one. Check the drive belts for wear, inspect the pulleys and clean or replace as necessary. Inspect your cones and adaptors for nicks and burrs and de-nick or de-burr as required. Organize your tools by size to speed the mounting of the various drums and rotors.
Inspect the dovetail ways on your machine. Clean and adjust the gib to allow free movement without binding. Caution … DO NOT lubricate the dovetail slides on your brake lathe. Lubrication will attract dust and chips and will cause premature wear on the slides. Look over all the controls, knobs, switches, boots, seals, and safety guards and replace as necessary.
Dump the chip tray every day. You can add these cast iron chips to your wife’s rose garden; it actually adds iron nutrients to the soil. Wipe the machine down and repaint when necessary.
Bench grinder
Inspect the grinding wheels and dress to insure they are straight and true. Look at the wire brush for any missing sections of wire and replace the whole wire brush as needed. Inspect the bearing for noise and replace as required. Make sure your safety shields are in place and always wear eye and face protection.
Seat Grinding Set
I know that many of you have those really cool “cylinder head machining centers,” but don’t forget the importance of keeping your seat grinding kit up to par. This is a must-have tool for those single combustion chamber jobs, as well as those small displacement valve jobs that don’t easily mount to your cylinder head machining center. Plus, I know that many of you use your seat grinding kit each and every day for all of your valve jobs. Inspect your dresser diamond. Make sure it has a point. Make sure the threads the diamond screws into are clean and re-tap as required. Check the stone holder pilot in the dresser; over time it will wear and needs to be replaced. Measure the ID of the stone holders for wear. You can simply put a brand new pilot into the stone holder and pull it out, listening for a popping sound. This popping sound tells you that the clearance is tight. But we’re machinists and I recommend that you measure the ID to eliminate any guess work. Spin the stone holder and listen for any bearing noise or grit contamination noise. Replace the stone holder when you hear any bearing or grit noise.
Next, organize your pilots according to size. Measure the pilots at the top and the bottom and note the difference. If you have more than .001” in wear, the pilot is junk and needs to be replaced. If the tops of your pilots are worn your valve seat concentricity will be severely compromised.
If you use an air grinder, clean and lubricate it daily. If you use an electric grinder, pay attention to the trigger assembly. See any sparks when you press the trigger? Replace it before somebody gets shocked. On either unit the nose bearing assembly will wear and replacements are available. The drive end is also subject to wear. It must fit snugly into the stone holder. Here’s a tip for you, cut a piece of leather about the diameter of a dime and put it into the stone holder. This will act as a cushion and help control any jumping or chatter of the stone holder. One other thing, use bounce springs when grinding your valve seats. These springs allow the stone to automatically lift off the seat and actually leaves a nicer finish, while controlling chatter.
I know this may seem like a lot of extra effort for these “smaller” machines but remember, if you take care of them, they’ll take care of you.
See you in the shop!
Don’t forget, if you have more questions, contact the Goodson Tech Department at 1-800-533-8010.