Your Crankshaft Grinder

By David P. Monyhan (retired)

Your crankshaft grinder probably represents one of the single biggest investments you’ve made for your shop. Most of you purchased your grinder to insure quality, delivery and to enhance your shop’s ability to be self-sufficient. Hopefully you and your employees are taking good care of this sophisticated and expensive machine. To help you out, here are the basic maintenance requirements for keeping your crankshaft grinder in tip-top shape.

Level the grinder

When was the last time you checked the level on your crank grinder? This is an essential and fairly easy operation that will guarantee quality output from the grinder. Use your machinist quality level for this operation. This isn’t a level for construction, like you’d find at a home center, but one specifically for machinists such as those from Starrett®.

Follow these easy steps:

  1. Traverse the table left or right to expose the flat ways on the table. You may have to remove the splashguards to get to this area.
  2. Place the level on the flat headstock or tailstock way. This will allow you to level front to back. Some operators like a little back tilt to facilitate the coolant flow back to reservoir.
  3. To level left to right, traverse the wheel head back as far as it will go. Again, you may have to remove the splashguard to get to the ways. Make sure your leveling bolts have steel pads for support. If you don’t have level pads, take some flat stock 2″ x 2″ and counter sink a 3/4″ dimple in the center. These pads distribute the load and help keep your machine level.
  4. Double check everything and lock it down and re-install any splashguards that were removed.
  5. If your machine has wooden rollers and reservoirs for table and wheel head lubrication this is a good time to clean them out and give them fresh way oil. Check these oil cups monthly to insure they are always full.


That lubricator pump located in the front of your machine lubricates the wheel head slides ways. This pump is manually operated and a simple pull two to three times daily is all that’s needed to keep proper lubrication to this important area. Keep in mind on some machines this pump will also provide lubrication to the gears in the front gearbox. Make sure you always use a high quality way lube! NO MOTOR OILS!

The wheel head spindle is a totally different type of system than the ways. The wheel head spindle runs in a constant oil bath. Some machines have two or three sight glasses to view oil quantity. The oil level should be high enough to cover the oil level window located on the front lower portion of the spindle at rest. The upper sight glasses should be covered when the spindle is operating at speed. If you can’t see through these sight windows, replace them ASAP. Also be sure to keep the sight glass clean; it’s your only indication that you have adequate oil to the spindle. Most manufacturers recommend that the wheel head spindle oil be changed 250 to 300 hours after set up and every 900 to 1000 hours after that. Be sure you only use the spindle oil recommended by the manufacturer.

The headstock and tailstock spindle bearings are pre-lubed on later model machines, but the tailstock quill should have oil cups that periodically need to be filled with way oil.

Hydraulic Machines

If you have a hydraulic machine, the hydraulic oil should be change after the first 250 to 300 hours of operation and 2500 to 3000 hours after that. When you do decide to completely drain the reservoir and replace the hydraulic oil, take extra time to remove any film or scum that’s built up on the walls of this tank. Wipe it clean before you add the new hydraulic oil. Use only the highest quality hydraulic oil capable of 500 PSI/MIN. Some machines have a sight glass on the hydraulic tank to see the level of fluid.

If your machine has a pneumatic float system for the headstock and tailstock, there is a pneumatic lubricator the needs to be checked. Keep an eye on it and fill as necessary with light machine oil or air tool oil.

Coolant Reservoir

The coolant reservoir in later machines is mobile and easy to take to the teardown department for a proper cleaning. If you have an older model you’ll have to hold your smallest employee by the ankles to insure you can get to the entire coolant reservoir for cleaning and removing the sludge that builds up from the grinding operation.

An easy solution is to use a filter sock on the return/drain hose. This filter sock will trap the chucks of swarf and keep them from entering the reservoir. Believe me it’s easier to change a sock every week than it is to scrape out that swarf build up. You can wash the filter socks and reuse them, just don’t let them get in the house laundry; take them to a coin operated laundry down the street for cleaning.

Here’s another tip for you. Put some magnets in your coolant reservoir as well as add magnetic strips in your coolant return troughs. These magnets will collect the metal particles from the coolant. By removing the metal particles you will extend the coolant life. You can get magnets and filter socks from your favorite shop supply company.

Synthetic coolants need to be mixed according to the label on the container. Too much coolant in the water and your dial indicators will be sticky and you’ll have a heavy film of goo to clean off the machined surfaces. Too little coolant in the water and you run the risk of premature rust throughout your coolant system. Microbes or bugs are lurking everywhere just waiting for that hot summer afternoon to grow and cause a stench that would make a vulture leave a gut wagon.

Check coolant levels daily during the summer. You’ll have natural evaporation and will be adding coolant as well as water to keep the mix just right through the dog days of summer. If you get behind in this part of your maintenance you can add some Microbiostat to control the bugs or bacteria and fungi that join together to make up this horrible stench.

Take Control

Are there knobs and dials missing from your control panel? Are you using a pair of vise grips instead of the OE dial? Stop right now and get on the phone and replace those damaged switches and control knobs.

A well-adjusted machine

The wheel head drive belts will stretch over time so they will need adjustment. Squeeze the belts together – total deflection of about ½”. If you can’t adjust out the stretch and your belts are squealing; they need to be replaced. Always replace the belts in matched sets.

You have some high-accuracy bearings in the headstock and tailstock. These bearings are adjustable on most machines. Never allow just anybody to perform this adjustment. Consult your owner’s manual and call the tech department to get advice on doing this adjustment the right way.

Most machines also have a clutch that engages the headstock rotation. This clutch also will need to be adjusted periodically. Again, read your instruction manual for this adjustment.

High Precision Chucks

Your machine has 8″ or 10″ 3-jaw high precision chucks. These chucks are constantly being splashed with coolant and swarf. They need cleaning and the dovetail slides have adjustable gibs. Remove the chucks from the machine, note the phasing of how they are mounted to reference when you are ready to re-install. Take them to the solvent parts washer, and using clean solvent, start removing all the old grease. This is the time to remove the jaws. Make sure to use the chuck wrench to rotate the scrolls and remove the backing plates to insure all of the old grease is removed. Spray all the components down with some brake clean to remove any residue left from the solvent and take them over to a clean workbench for reassembly. Be sure to wipe off all surfaces and using a bit of chuck grease, re-assemble the chucks.

Before you re-install the chucks take the time to clean the cross slides. You can use solvent and brake clean here as well. Be careful not to get any brake clean on a painted surface. Use the same grease for the cross slides as you would use for the chucks. Now you can re-install the chucks. NOTE: These chucks and cross slides need to greased with high quality lithium based grease with moly. You can use lithium based extreme pressure grease. As always check with the manufacturer if you are unsure of the type of grease to use.

Take the time to deburr the table. You can buy a de-burring stone or use a broken piece of an old crank wheel soaked in solvent to remove any nicks or raised dents on the table. Check all of your dial indicators for free dial movement. Replace any worn or broken indicator contacts. Keep your in-process sizing gauge or Arnold gauge clean and free moving. Check the steady rest shoes for wear and replace as necessary. Steady rest shoes are available from the manufacturer or any full service shop supply company.

One more thing, if you are using your high dollar crankshaft machine as a polishing lathe, you are setting yourself up for pre-mature wear on all of the moving components. The un-controlled flying debris (abrasive and metal particles) created during the polishing process is getting into places you don’t want them to go. Spend the money and buy a polishing lathe. For an investment of just over $2000.00 you will prolong the life of your crankshaft grinder and will give you a separate work station to do your crank polishing.

Not all grinding wheels are designed to grind all materials. High performance and diesel crankshafts are harder than the standard Chevys and Fords. You need to have a specific grinding wheel for these types of crankshafts. Don’t buy your crank wheels simply on price. Buy your crank wheels from a reputable supplier who has the expertise in abrasives to advise you on which wheels are for what applications.

There is a slotting process for grinding wheels, which will increase the ability of the coolant to get to the radius or thrust flange area when grinding. By getting more coolant to this area you will prevent burning and speed up your grind time. I highly recommend slotting for all high-performance and diesel crankshafts. Ask your supplier about slotting your crankwheels next time you order.

Keep your dressing diamonds sharp and rotate them periodically to insure your diamond maintains it cutting point. Keep in mind, a cheap diamond will not last as long, and can cause delays or surface compromises to the finish you are trying to achieve.

Remember your crankshaft grinder represents a serious investment. It is also there to allow your shop to produce the highest quality component for the engines you build and sell. Keep this machine is tip-top shape, and it will last a very long time. If you don’t you will surly compromise your investment as well as your reputation for quality components.

See you in the shop!

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