Advice for Testing a new CNC Lathe - C and Y Axis

Hello PM Community,

We just purchased a used Samsung SL2500BY lathe with full C and Y axis capabilities.

We are looking for any pointers, feedback, or advice on how to check this thing to ensure that it cuts what we tell it to cut.

Our first priorities are to check the alignment of the head stock, and then the tail stock.

To achieve this we will take long cuts on a piece of material and measure the straightness of those cuts.

For the head stock, we will take a 15.0" long cut on a piece of 3.0" diameter 6061 aluminum. The 3.0" diameter will be turned, and so will jaws.

The material will be choked up a great deal, sticking at least 6.0" into the draw tube.

We will also face it and center drill it for the following tail stock check.

For the tail stock check, we will use that same piece of material, but pull it out from the chuck, and take a 20.0" long cut holding on to it with jaws on one end, and a live center on the other end.

Once again we will check the straightness of the material after making that cut.

Any feedback or criticism you can offer about our plan is most welcome.

Thank you

That sounds like a good plan. Just make sure that you are taking light cuts with a free cutting tool so that deflection isn't factoring in to the equation.

I would then check the turret to make sure that an ID tool holder is on center and that a test bar put in to the holder is parallel to the spindle.

Hopefully, your machine hasn't been knocked around too much and is still in good condition.

This might sound nuts by why not make your parts and check them ?

"This might sound nuts by why not make your parts and check them ?"

If it was just a 2 axis lathe, yeah it could just be a small "Oh Crap...."

Throw in a 2 more axis thinking your going for it without knowing what the machine will really do?

I'd say it would depend on op's experience with a C & Y axis machine

For starters I would put an endmill in an axial live holder, then cut a square using polar interpolation, then cut a smaller square on top of that one using X and Y. Make sure they're the right sizes and true to themselves and true to eachother. Then if you're feeling frisky you can bring in a radial endmill to dust one of the squares, bottom cutting and see if that makes chips.

Pretty sure if I bought a new machine, the seller of that said machine, would be chained to the machine until I knew it was making a good part, ESPECIALLY if it was a new machine I had not clue how to run...

The OPs machine is used.

mjk said:

"This might sound nuts by why not make your parts and check them ?"

If it was just a 2 axis lathe, yeah it could just be a small "Oh Crap...."

Throw in a 2 more axis thinking your going for it without knowing what the machine will really do?

I'd say it would depend on op's experience with a C & Y axis machine

Click to expand...

Well, I will freely admit, I know next to nothing and C and Y axis lathes, a small bit of experience with an Integrex.....

But if OP only needs +/-.005" why not just cut it and see? It's been quite a while since I have run or programmed, any cnc lathes, but don't they have single block, distance to go, G5x position, etc to prove out?

I was going off that it is "new" to them, ie the title says "testing a new CNC Lathe"

I own one NEW machine, all the rest of my machines were "new" to me. All, save 2 (bought from HGR for scrap), had a test part, or pieces, run by the owner, to show me that it made good parts. And THEN they showed me how to run it.

My very first CNC Mill, I went up and spent an evening with the guy, he showed me everything from starting it up, to programming, to loading programs, the control because I had never run a huge Fanuc'ing pile of S before, along with everything else I needed to know, AND we ran a couple test parts so that I could measure geometry to assess the condition of the mill.

Soo... I stand by my original statement

wmpy said:

That sounds like a good plan. Just make sure that you are taking light cuts with a free cutting tool so that deflection isn't factoring in to the equation.

I would then check the turret to make sure that an ID tool holder is on center and that a test bar put in to the holder is parallel to the spindle.

Hopefully, your machine hasn't been knocked around too much and is still in good condition.

Click to expand...

Thanks for the advice.

Yes we will take light cuts as you suggested. We ordered a 3 jaw chuck and it still hasn't arrived!

In the meantime we checked two ID holders at 180 opposites of each other and both were really well centered.

That's a great idea about the test bar - we will try that too.

D.D.Machine said:

This might sound nuts by why not make your parts and check them ?

Click to expand...

Hah yes we are going to do that too. We are leaving no stone un-turned!

Camputer said:

For starters I would put an endmill in an axial live holder, then cut a square using polar interpolation, then cut a smaller square on top of that one using X and Y. Make sure they're the right sizes and true to themselves and true to eachother. Then if you're feeling frisky you can bring in a radial endmill to dust one of the squares, bottom cutting and see if that makes chips.

Click to expand...

Yes - excellent advice. We will do that for the face and for the OD as well - both circular and square shapes.