How to Change the Oil in Headstock of Geared Head Metal Lathe, Tips & Tricks



How often should I change the oil in my geared head metal lathe, and what oil should you use for the gears in the headstock? What’s the best way or how should I change the oil in the headstock of my metal lathe? We have a lot of customers that buy our metal lathe owner’s manuals looking for the answers to these questions. Some of the metal lathe manuals cover lubrication and oiling really well, some don’t hardly cover it at all, and some have outdated information. I’m going to share some of the tips, tricks and techniques we use in our shop with our geared head metal lathes that can be applied to most geared metal lathes in any shop, but, as always, I highly recommend a instruction manual.

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Starting with some information about oiling your metal lathe is usually better than having none, and before you take my word on anything, you should always cross reference it with what your manual recommends. Plus, your lathe manual will hopefully include a chart  with all the different points you should lubricate, and each model has it’s own points that don’t like to get dry.

bradford lathe lubrication chart


How Often Do You Change the Oil in Your Metal Lathe Headstock?


I was doing research before I wrote this article on oiling your lathe, and I read through our huge selection of operator manuals from different manufacturers that cover intervals for how often you should change the oil in a geared head metal lathe. As you can imagine the time varies from one metal lathe company to another. A lot of them state that the oil should be changed out every 6 months, and a lot simply say keep the oil up to the fill line or top it off repeatedly.

“We never change the oil in the heads of our metal lathes in our shop”

Unless you are operating your geared head metal lathe 8 hours a day 7 days a week, you probably don’t need to drain your oil every 6 months in your metal lathe no matter what the model is. Honestly, we never change the oil in the heads of our metal lathes in our shop. My father and I are the only ones operating them, and we aware of the conditions of how they are being used. If your lathe is in an industrial environment, where you can’t keep track of the use by the different operators, it might not be a bad idea to change the oil once a year while you perform general maintenance on the lathe.


There are times when you do need to change the oil:

  1. When we purchase a brand new or used lathe. Obviously you don’t know the history of a used lathe, but even a brand new lathe should be drained and cleaned out. You really can’t buy a new lathe made in the USA anymore. More than likely it is coming from Asia. We work 12 miles from Grizzly Industrial’s Springfield, MO showroom and warehouse. I’ve gone through hundreds of their new machines, and they all have metal filings and cast iron dust inside of them. Nothing against Asian machines, but just always make sure you clean them out before you use them.
  2. When something goes “Clink-Clank”. If things aren’t sounding right inside your geared head metal lathe headstock, and you regrettably have to find some wrenches to take the cover off to see what is creating your new noise, you may need to change the oil in your headstock. It’s a lot easier to work on the inside of the headstock of your metal lathe without a pool of oil that you keep pulling your wrenches or flashlight out of.




How to Drain & Flush the Lubricant & Oil Out of a Geared Head Metal Lathe?


Most geared head metal lathes have a threaded plug at the bottom of the headstock. Generally they seem to be on the side opposite spindle, and hidden by the gear cover. These are usually just threaded holes in the casting without any sort of drain, funnel, or trough to keep the oil in your headstock from getting all over your metal lathe bench or chip pan when you open it. I’ve seen all sorts of methods to easily and cleanly collect the oil from the headstock. My personal favorite is the taped bag method.

Below is a Grizzly G4003 12″ x 36″ Gear-Head, Cam Lock Spindle, Gap Bed Metal Lathe that I was fixing up. A shaft that holds a gear was broken off at the warehouse, and I needed to replace it to get the metal lathe going again. So I needed to drain the oil in the headstock to replace this part.


The plug for the oil was on the bottom of the casting of the headstock on the opposite side of the main spindle. What I did was tape a one gallon Ziploc right below the plug of the oil drain. Once I take a wrench and unscrew the plug the oil runs right down the side of the headstock of the metal lathe into the bag. You need to make sure you use a large enough bag to capture all the oil in the headstock. If for some reason you misjudge it, you can always put the plug in and replace the bag, then repeat.




I find this to be the simple, and easiest process to capture the draining oil from a geared head metal lathe. Sometimes there may be a lot of particles or sludge in your headstock, and you may wish to flush it out. Before you start flushing out your heastock there are a few things that you should keep in mind. If’ it’s not very dirty, I would recommend not flushing the headstock out. Usually you have a bunch of open bearings inside, and it is better that the particles or sludge stay at the bottom or crevasses where they belong then risk getting a particle inside a bearing. It can only take one particle to mess up a good bearing at the stress and tension they are under.


If you do feel like your headstock should be flushed out, then this is the procedure I recommend. I would try to vacuum out everything and get in there with a brush to keep the particles out of the bearings. Then I would try a mixture of kerosene and oil. To flush out the headstock. If it is really bad, then you may need to use a water hose with pressure.


If you use water, you are going to want to let everything dry for a day or so. Then after the kerosene and oil flush, and letting it dry, you will want to turn every shaft individually by hand. We are trying to see if there is any dirt or particles in the bearings. So are going to want to do this slowly and with your most sensitivity. You are trying to feel for any hesitation in the bearings. The Standard Modern metal lathe manuals actually recommend you fill the headstock with an oil and kerosene mixture, and run the lathe without a load for a few minutes. When you are finished draining the oil, flushing and servicing your metal lathe, then you just need to fill it back up with the correct oil.



What Oil or Lubricant Should I Put in my Gear Headed Metal Lathe Headstock?


I always recommend that you check the manual of your lathe and go by what the manufacturer states. We have manuals here if you need one. But sometimes, if you have an old lathe, you get an old manual that has outdated information. Generally for most people that have a personal or small shop, I recommend non-detergent Mobil DTE Heavy/Medium 20 Sae Grade Circulating Machine Oil. This will suite most lathes just fine. Some metal lathe manuals I read do recommend 30 weight, but unless you are running your lathe 8 hours a day, it probably doesn’t matter a whole lot if you aren’t sure. You can pick up a gallon of this oil at Enco. I recommend getting on their mailing list, and waiting for a free shipping and percentage off sales. Either weight of oil should be fine, but you need to make sure your oil is non-detergent.


mobil heavy medium 20 sae lathe oil


Detergent Vs Non-Detergent Oil for a Metal Lathe or Machine


You need to use non-detergent oil in almost every machine. What’s the difference? Detergent oils were introduced in the 1950’s. They have additives in them that are designed to suspend and trap particles. Detergent oils are what you put into a modern car with a oil filter. The idea is the suspension carries the particles to the filter, which is replaceable.

Non-detergent oils are just straight oil, and they let all the particles sink to the bottom. These are commonly used in small engines without filters like two stroke engines, lawnmowers, tractors, etc.. Since the headstock of our geared head metal lathe doesn’t have a filter, we want all the particles to sink to the bottom, and stay out of the gears and bearings.


Please let me know if you have any other recommendations, questions, or ideas about changing the oil your geared head metal lathe in the comments below.


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How to: Measure and Size a Drill Press

Drill Press Articles (Part 1 of 5)

Drill presses have been around for quite a while. We use lots of different ones in our shops for different operations, and we have manuals for many of them. They are designed mainly to help keep precision while drilling holes. Of course, drill presses can be used for many other things like sanding, wood shaping, and more, but we’ll get into that later in this series of articles. There are lots of different sizes and types of drill presses, and this series of articles is to help you identify what type of drill press you have or what type of drill press you may want to purchase.

How Do You Measure a Drill Press?

The first thing people ask us is how to size a drill press. What is the difference between a 15″ or 17″ drill press? The measurement is simply the distance from the center of the spindle to edge of the column, then doubled. So if you measure 7.5 inches, you have a 15 inch drill press. This is referred to as the swing of the drill press which is the largest diameter piece this drill can handle. This is similar to the way a lathe is measured.

Next Article

The next article will be on the differences between bench top and floor model drill presses, and the advantages and disadvantages of both.
Please feel free to post comments and questions on this post or any ideas or topics you would like to discuss on future post. And remember if you need a manual for your drill press, we have all of them listed here: Drill Press Manuals. 

How To: Measure the Size and Swing of a Wood or Metal Lathe

People often ask us how to measure the size and swing of their wood or metal lathe. Lathes are generally described by the maximum size of material that can be cut or machined on the lathe. Before machining a workpiece, the following measurements must be considered: the diameter of the work that will swing over the bed and the length between lathe centers. Often you will see numbers like 14×40 or 9×42 describing the size of a lathe. So what do these numbers mean?

Wood and Metal Lathe Sizes

How to Measure the Lathe Swing and Size

What does the term “swing” on a lathe mean? The first number is referred to as the swing of the lathe which is the maximum diameter of a piece or work that can fit in the lathe. If you have a lathe and want to measure for the swing, you simply measure from the bed of the lathe to the center of the spindle, and then double that measurement. If you measure 6″, then you have a 12″ swing lathe.

Measure Swing of Metal Wood Lathe


  • Special Note: Sometimes there can be some discrepancies between the actual measured swing and the swing the manufactures label the machine as being. I’ve only seen this on larger geared head metal lathes and European metal lathes. Some foreign lathes were made on metric standards, and they rounded to the nearest US standard size. Some companies labeled them based on the measurement from the top of the cross-slide for the tool holder on the metal lathe to the spindle.  For example this Bradford Metalmaster geared head metal lathe series had actual measured swings of 14.5″, 16.5″, and 18.5″, but Bradford labeled the lathes as 12″, 14, and 16″.


Keep in Mind

On metal lathes, it is important to know the swing over the carriage where your tool holder sits. A lot of companies will give you this specification, and some companies in the past have used this measurement as the size of the “actual” swing of the lathe. It is obvious, if you have to cut something over the carriage of the lathe, it will make your working swing smaller in diameter.

Measure Swing of Metal Lathe



How to Measure Distance Between Centers on a Lathe

The second number in the sequence 14x40 is referred to as the distance between centers. This is the distance between a center in the headstock to a center in the tailstock. This gives you an idea as to how long the working area of the lathe is. However, a lot of companies in the 40’s or before used the size of the bed as the second number.

Measure Distance Between Centers Metal or Wood Lathe

Depending on what tooling and what kind of cuts, drills, bores, etc… you are trying to use can vary the maximum length of material you can work on in your lathe.


A 10×24 lathe can handle work that has a diameter up to 10″ and a length between centers of 24.”

If you need any help identifying your lathe please feel free to send us pictures and information to We’ve identified hundreds successfully.
Please feel free to post comments and questions on this post or any ideas or topics you would like to discuss on future post. And if you need a manual for your lathe, we have all of them listed here at the links below:

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Wood Metal Lathe Manuals