Wednesday , December 13 2017
Home > Lathe Projects > Free Metalworking Project Plans: Spring Center (Metal Lathe, Mill)

Free Metalworking Project Plans: Spring Center (Metal Lathe, Mill)


Material: Steel
Units: (in)

If you’re just starting out in metalworking, it’s not a bad idea to learn how to run a lathe. The first project I ever completed on the lathe was the Spring Center pictured below. At first glance it may look a little complex, but it’s pretty simple once you break it down into steps. If you’ve never used a spring center it might be a little unclear why this object would be useful, but it is!

So what’s a spring center good for? Basically it helps the user tap a hole.

img_0935To use the spring center, insert it into the chuck on the mill, drill press, or lathe tail stock. Advance the spring center toward the tap until the spring is fully compressed. Begin tapping as you would normally, but let the spring center apply pressure to the tap while you concentrate on turning the tap itself. As a side note, the photo showing the spring center in use also illustrates a handy way to protect a part from damage. Thin pieces of metal (in this case a sacrificed diet Pepsi can) can be used to prevent the vise jaws from marring the part.

Using the spring center will help you start a tap with ease because it helps maintain tap alignment along the axis of the hole being tapped.  All you have to do is concentrate on not breaking the tap!

100_0052The spring center is a great “First Project” for the lathe.  Once complete, you’ll turn to it over and over again the whenever you need to tap a hole.

In addition to the machined parts, you will need a suitable spring (which can be purchased or made from piano wire, welding wire, or any other suitable spring steel), and a cap screw.

– – – –

Update: Pictures of TroyO’s Spring Center

TroyO recently completed his own version of the Spring Center and he took pictures of the process. Below are pictures of the steps he used to complete his Spring Center, along with a description of each step by TroyO himself. Thanks for sharing TroyO!

“Here’s a shot of the completed project.


Here is a closeup of the slot… that’s right off the wanna-be mill, no cleanup other than sandpaper to deburr the edge. (I was surprised taking a close look at it… I expected some chatter marks but it’s really smooth.)


Here’s a picture to show how I used the socket head screw.


The image blow shows how I clamped the Spring Center in the QTCP tool holder to cut the slot. Pretty much just like a bit… I did some cleanup of the shaft after I milled it to clean up the marks from the set screws. I should have thrown a shim between the screws and shaft… ohh well. Note the same concept would work just fine in a turret toolpost, you’d just have to shim it until you got it on center. Secondary note… if you think ahead and machine the shaft to 3/8″ you could also hold it in a 3/8th boring bar holder.


To make sure that the part was aligned perpendicular to the chuck, I brought it flush to the face of the chuck, then locked down the toolpost.


Then I set the height using a centering guage… I could have used a dial indicator in the chuck as well and set it to the highest point. (A centering guage might make a nice project addition… but they are dirt cheap, LOL. I think I got it for $6.) Once I had the height dialed in I locked in the toolholder… now it’s square and on center and ready to cut.


Here’s what it would look like while making a cut (well, if the bit was spinning and the slot wasn’t already there, LOL).


Here’s a shot showing how I made the recess for the socket head screw. I used the same process for drilling the hole, although I stopped a little short and finished the through hole by hand after removing it. (I didn’t want to drill in to the QCTP holder.) I also started the tap a few turns after drilling but before removing the part from the toolholder. It’s a bit sloppy procedure-wise finish drilling a partly tapped hole, or to finish tapping without a guide and just counting on the feel to keep things straight, but it worked.


That’s it. I hope the pictures of my setup will be of use to someone!”
– TroyO

Thanks TroyO! I’m glad you took the time to share. Especially since you came up with a way for others to complete this project without using a mill. Now this project can truly be considered a lathe-only project!

Update #2 – Spindle’s Version Using Hex Stock

One of the things I’ve noticed with my spring center is it has a tendency to roll around on flat surfaces. So I’ve had it roll of my workbench on more than one occasion. Forum member “Spindle” has an excellent solution – he used brass hex stock to make his! Read Spindle’s original forum post here.

Spring Center Using Hex Stock

For those of you who would like to make your own Spring Center, here are the plans:

  Spring_Center.pdf (57.0 KiB, 9,689 downloads)
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About Tyler

Tyler is a hobby machinist and 3D printing aficionado. He teaches computer programming and web development at Highline College near Seattle. Tyler founded Projects In Metal in 2008 because he was frustrated by the lack of free plans available for hobby machinists.

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