Hardinge CHNC retrofit- Another one on the way!

I was trying to get the vertical slide to work properly. It has 2 limit switches one at top and one at bottom. Inside classic ladder I had a rung that was supposed to be a latching relay that would break open when the down limit switch was hit. I had a M code latching the relay, however i couldnt get it to unlatch for whatever reason, so I just run the vertical slide on a timer now.

As for the 3d printer I am still collecting parts and hope to start building it this summer. I have not used the IRC yet, but that is good to know as Im sure I will have problems when I start this project officially.

The last time I looked at my cut-off slide I recall there are solenoids that control air to a cylinder to move it down and up. I think there are screws that adjust the cut depth. I used M10x g-codes to to move the slide down and up. I have never used it for real parts. I just use a parting tool in the turret. If I had the time I might consider adding a ball screw to the slide, which might make it useful for other operations.

You don't have to use Classic Ladder. A comp written in C or Python or even shell script could work. You can likely use whatever programing skill you happen to have.

It has been a while since I had my Hardinge HNC, but as I t recall, it the part off slide was an air over hydraulic, with a needle for feed adjustment, and it simply was M code to turn it on, then sat at spindle RPM until it hit the bottom of the stroke and returned a completion signal with the other limit switch. They were very handy, particularly if you had the parts chute as well. Other than the GE550 control, it was a very nice machine. should be relatively simple to get set up.

The vertical slide is hydraulic, the hydraulic pump is driven by an air motor. There are actually 3 ssr's that control it, one turns on the air motor, the other two control the up and down functions. The only part I was having trouble with is understanding ladder logic programming. I could get the circuit to seal, but I couldn't get it to unseal when the bottom limit was hit. Now I am just running it on a timer which is ok, but has one problem. As the hydraulic fluid heats up the viscosity drops and the slide moves faster, when it reaches the bottom of travel it bounces which I believe is bad for the pump and seals. You can see this in the video I posted above. I use the vertical slide quite a bit, especially for bar feed work as I always use the part chute when parting.

I think converting the slide to a servo and ball screw would be reasonable and allow for much better motion control. CSS (constant surface speed) could be used. feed rates and cut depths would not depend on stop adjustments.

The ballscrew would actually be a pretty easy way to go. I used to use mine for doing delrin and stainless parts. With the delrin, I liked it as I had a vacuum hose mounted to pull away the chips and when the slide came down, it pushed it away and a little rubber flap flicked the part down the part chute. a big advantage on a machine like that is if you are only doing straight part offs, and not needing to profile, you save a tool position on the turret. Wish I hadn't sold the machine, as it was deathly accurate with .00001 offsets and repeatability with the resolvers. Only bad side I had heard on the resolvers was when a tech I had come in decided the backlash was set too tight and and adjusted it. A Hardinge tech told me that that they always run them on a test bed and check the output and adjust it for noise with an oscilloscope, not gear backlash. I think Alloy Craft is mistaken, as on the HNC, there was no air motor except for the turret index, and the part off chute was simply air going to the top side of a tank with oil in it and the air pressing on the oil caused it to pressurize the line. There was a needle flow valve to control speed, and then it was simply a matter of pressurizing the other tank to return it. The HNC also had a safety feature connected to the spindle power. It had a small pressure switch, that was activated by the cover being closed and the little blocks covering the air bleed holes on the tubes supporting the plexiglass covers. Every machine I ever saw, had a C-clamp or vice-grip pinching the line so they could run with the doors open to see better when trying out new programs.

5axisormore wrote:

... a tech I had come in decided the backlash was set too tight and and adjusted it. A Hardinge tech told me that that they always run them on a test bed and check the output and adjust it for noise with an oscilloscope, not gear backlash.

This factory oriented procedure reminds me of another, the unique high density terminal strips that need a special ($$$) tool to make or break the connections. I replaced these with my own screw terminals.

5axisormore wrote:

I think Alloy Craft is mistaken, as on the HNC, there was no air motor except for the turret index, and the part off chute was simply air going to the top side of a tank with oil in it and the air pressing on the oil caused it to pressurize the line. There was a needle flow valve to control speed, and then it was simply a matter of pressurizing the other tank to return it.

That is how mine is too.

5axisormore wrote:

The HNC also had a safety feature connected to the spindle power. It had a small pressure switch, that was activated by the cover being closed and the little blocks covering the air bleed holes on the tubes supporting the plexiglass covers. Every machine I ever saw, had a C-clamp or vice-grip pinching the line so they could run with the doors open to see better when trying out new programs.

My machine had the hose removed. A lot of the machines I have seen have scratched and crazed windows, but the windows are easy to replace with standard plastic sheet, which I did on mine.

The constant air bleeding is a bit annoying. The bleeding is due to the collet closer when open having pressure on the spindle shaft sleeve seal, which by design can not have a perfect seal. The closer doesn't leak while closed, and the pressure can be turned off while open, if needed. Another source of bleeding are a couple of bleed jets at the ends of the air circuits in the carriage. These are needed to make sure that lubricated air reaches the full length of the lines. This normal bleeding starts my compressor fairly often which is a bother noise wise. I have been considering mounting a small quiet compressor in the machine which would run more often, but hopefully be quiet and eliminate the need to run an air hose to the machine. Or... I could just put the compressor outside in a shed.

The chnc is definitely a Air motor driving a hydraulic pump. I had to rebuild it to get the vertical slide working. The air motor is a gast vane style, attached to a small hydraulic tank with a reversing solenoid valve, see the pic below, this is a photo from ebay but the same as mine.

Yep, That's an air motor all right. Mine was an HNC, older technology, but still pretty hot even by today's standards for accuracy. sounds like Kirk's machine is similar to mine. I think the CHNC with the Allen Bradley control used the air over oil system too. That was the only machine the Hardinge guys told me to avoid. They said go with the GE550 with the Microstore over the AB any day. Did they use the hydraulics for anything else besides the part off? Seems like a lot of effort to replace something simple that worked. As I recall, there was an M-code that would also send air pressure to the bar feed so it only have feed pressure when you opened the collet., which cut the power to the spindle until the collet was closed too. Kirk's comment on the wires is true too. The biggest problem with the old machines was the oil would cause the insulation to harden and then break the wires if you moved the cables too much, or if you moved the machine. If you found one that ran with oil instead of coolant, they usually never wore out the ways, although the oil usually ended up staining the paint and making the shields look trashed.

Fred

My machine originally had the Allen bradley 7300 control, I was glad to get rid of it. After spending a week trying to get it to work, I cringe at the sight of the AB 7300 now.

I think using the air motor allows for higher hydraulic pressure meaning quicker rapids and more cutting power, I believe the last version of the CHNC made uses this set up as well. The cut off slide is the only thing that the hydraulic system runs.

On the wires mine were in pretty good condition. The guy I bought this from said this machine was indoors at an aerospace contractor its whole life so it was in pretty good mechanical condition. I believe mine has always run on oil and that's how it is now. Water based coolant would be nice since oils make such a mess. but I worry about rust issues since the coolant tank is not easily accessible. I will most likely change the windows out at some point, mine are pretty hazy.

On the ladder logic, I finally got it working last night. I had my notation wrong on one of the ladder rungs, I just had to name my latching contact the same as my coil. Works like a champ now.