How to Properly Cut Lathe Soft Jaws — Part 1: Fundamentals and OD Gripping

In the first of a two-part installment, a Haas certified machinist explores our recommended lathe soft jaw cutting/boring techniques and the proper way to cut OD gripping jaws.

[ryanrosser]

These videos are exactly what I need to get new machinist up to speed and dispel bad practices. I've seen some crazy crap and it's always "that's how we did it at my last job". Thank you for these videos!

[balooc]

that last tip was really great. its brilliant to use the same jaws as much as you can to minimize time spending changing them back and forth!

[bebemariogaga]

My machining teacher showed me this video (and also part 2) when I had question about cutting soft jaws! I really enjoyed your two videos about soft jaws! I am on a manual lathe machine for the moment tho ;-;
I will get on the CNC after I finished learning manual lathe and manual milling. Can't wait to start CNC, machining is fun and I think I found what I want to do in life!

[haasautomation]

Hello Keith. Thank you for watching the video and fore the question.

There are two hydraulic pressure gauges mounted on every Haas Lathe that uses a hydraulic chuck and tailstock. One of the gauges reads the pressure that the chuck is presently set at and the other reads the pressure the tailstock is set at. In any of the wide angle shots in the video you can see the location of the two gauges on the lower left-hand side front panel. (continued)

[haasautomation]

Great question JJsCustomDesigns. The approach we take here at Haas is to match surface finish requirements to the type of work being processed. Generally speaking, if we are gripping a piece of raw stock we will turn the jaws to a rough finish (such as a 500 micro-inch). This gives good bite for heavy roughing on un-machined blanks where we are not concerned with damaging the surface of the part.

(continued)

[mariedillon]

With new machines and new chucks, everything is new and tight. The possibilities are limitless

[haasautomation]

(Continued)

In the case of very high roundness/concentricity requirements (less than 0.0005 TIR) it may be helpful to turn the plug as well. But consider also that at this level of accuracy there are many influencing factors.

Thanks for watching and the question.

[haasautomation]

Thank you very much BBMbattery Canada, we appreciate the comment and are happy you enjoyed the video.

[SirRootes]

That was a very informative and well made video. I am just a factory worker working on CNC lathes and now starting to program them from self-teaching (long story). This video has helped me a lot! Thanks for taking the time to make it.

[haasautomation]

Great comment, David. Abrasive particulate inside the work envelope is definitely a concern. However, in this case the volume of grit is very low. Also, on this ST-30SSY all the linear guides are shielded by protective covers and the guide trucks have protective seals as well. Hand filing the jaws is another option if abrasive sanding becomes an issue. Thanks for the comment.

[Cnexir]

Haven't thought of the two step jaws for that kind of application. It's duly noted. Thanks

[rodbuilder]

Boys and girls, if your going to be clamping DOWN on your work piece, you have to put your spider (or solid bar stock) inside the jaws. if you're going to be cutting on the INSIDE of tubing, or boring something, you need to use a ring on the OUTSIDE of the jaws, then go ahead and cut the OUTSIDE of the jaws to fit the inside of your part. You HAVE to support the side of the jaws that you'll be clamping against later. If you don't your part is going to wobble all over the place!

[DennisChaves]

Just wanted to thank you fine Haas folks for uploading this. I've worked in a machine shop for 5 years learning on-the-job as I go. I've never had any formal training/education. So I have giant gaps in my knowledge. This subject being one of them. Now I know how to bore soft jaws! Thanks! BTW we have 2 Haas lathes in my shop and they are my favorite machines to setup/operate. You folks make a fine product!

[urbanwillis]

Never able to use one, but I bought dozens of the Haas machines for AF and the Airmen customers in the field loved them. I wish I had bought the training software for myself after retiring from DOD. Then I might have been able to go back to work in the only job I ever knew in a machine shop. But, it is too late now. Boy have things improved over the years. There is allot to soft jaw turning in the CNC machines, but all the changes have improved on the accuracy in chucking needed on the CNC machines. All I ever had to do is clamp on a piece of steel with the parent jaws of the chuck and then bolt pieces of aluminum or steel to their face and turn a pocket the actual size of the parts to be chucked. It was all manual machines in my day. Boy howdy this is much better tooling than I ever used.

[haasautomation]

(continued)

These and the other important considerations covered in the video are the same whether the chuck is manual or hydraulic.

A few aspects of using a hydraulic chuck, such as how they are actuated, are not the same for a manual chuck. However these differences are small enough that, at this point, we have not planned on making a separate soft jaws video for the TL machines. Thanks for the question Paul.

[haasautomation]

Hello and thank you for the question CADtekk Designs. Your comment brings up a good question: Does the roundness of the plug affect the roundness and concentricity of the finished bore?

Although the plug itself does not have very accurate roundness, the bore cut into the jaws is still as round and concentric as the accuracy of the machine itself, since the jaws are spinning about the center of rotation of the spindle.

(continued)

[haasautomation]

Hello and thank you for the questions ELYOR01.

1. Yes, the Haas ST-30SSY, is for sale.
2. Please visit the Haas website, HaasCNC.com, to view ST-30SSY pricing for your country.
3. Yes, the ST-30SSY can produce camshafts, with the exception of finishing.

[vinaykumar-ewhh]

nice video very helpful, i was looking for a video were tool selection, and length of tooling holding is shown to avoid chattering especially for boring operation and spindle speed, feed rate selection

[haasautomation]

Thank you very much for watching and for the great comment Dennis.

[haasautomation]

Great to read defaultbomb12, thanks for watching and for the comment.