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Shop Tip: Quick and Easy Aluminum “Soft Jaws” for the Lathe

One of the first things you’ll discover as a beginner is the tendency for chuck jaws to dig into the workpiece. Jaws are hardened steel and will leave a mark on just about anything you put in them – especially if the part spins. So how do you keep the jaws from marring your work? Some nicer chucks come with jaws that allow you to attach aluminum soft jaws to them.

Soft jaws have several advantages, especially when you need to hold a custom workpiece. For example, you can also make or buy a set of soft jaws and bore them out to the perfect size to hold the workpiece, and since you’ve bored them on lathe, the jaws will hold the part perfectly concentric to the spindle axis.

As you can see from above this can be especially helpful when you want to hold smaller parts made of soft metal.

But what about when you just want to hold a part without marring it? Are expensive/custom soft jaws necessary? NO!

Do you have a soda can lying around? If so you’re in business.

First, cut the can open (carefully) with scissors, and cut the aluminum into strips who’s width roughly match the size of you’re jaws. Make them long enough so that they can wrap around 3 sides of the jaw, and fold them around a piece of metal approximately the same width as your chuck jaws – my 6″ scale is perfect for this.

Next, slip them over the jaws. Folding them gives them a shape that allows them to grip the jaws – that way they stay in place – which is a lot easier than trying to slip pieces in around the part.

Finally, insert your part. You’ll be able to tighten the jaws a bit more than you would be able to normally, but the can is only about .004 thick, so you still need to be careful. Also, if the part spins replace the jaws – they wear through instantly.

I hope that helps! Obviously real shim stock (brass, aluminum, etc) would work as well, but aluminum cans are cheap – and you’ll be recycling at the same time!

Do you have a different method that you like? If so, please share it with our readers on the forum via the link below.

 

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About Tyler

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

5 comments

  1. Great info Tyler. The ability to add real soft jaws is an advantage of having a chuck with bolt on jaws.  Unfortunately, a lot (most) of the smaller chucks do not. It's nice to be able to customize a set of these jaws for a specific job by step boring, or even for a sacrificial application for close up facing or boring.  The beer can method is good in a pinch (get to drink it firstWink), but a good set of formed brass shims should be in every tool chest.  To prevent them moving and to help in loading the material, use a small piece of double side carpet tape as I described in another post (Tape it to Make it). Place the piece on tape on the side of the shim, not the load bearing surface. It will make life much easier when chucking your part.

  2. Yea, one of the disadvantages to using a soda/beer can is the aluminum is very thin (about .004 if memory serves). If the part spins even a small amount it tears through the aluminum and scars the part. Brass would be better. I just got some brass shim stock and I plan to make a more permanent set of soft jaws out of it. But for the last couple of years aluminum cans have served me well. 

  3. Gallon cans that originally held turpentine, linseedoil, etc. are better than pop cans, as they are steel and thicker than pop cans.

  4. Good idea! Thanks John. Although one of the things I like about the aluminum is the fact that it's softer than the part I'm holding, so there's less risk of damaging the part. 

    Or if you happen to live in South Africa your soda cans ARE made out of steel instead of aluminum. My wife and I spent our honeymoon in SA and the first time I drank a soda I kept thinking I had one last sip left in the can (because the can was noticeably heavier). It took me a minute to figure it out. Finally I asked a local why the can felt so thick and heavy and he explained that it is cheaper to make the cans out of steel than aluminum over there (I guess they have mines producing ore for steel, but they have to import most of their aluminum). 

  5. Also remember to use shims from the same can, I used beer can shims to rough in my mini-mill column and they could vary between cans as much as .0007″.  When your squaring a colomn that can be a lot.

     

    Louis