Hardinge CHNC conversion

Vince, saw your post on the Mach group and wanted to check out your machine. Very nice!

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It was broken in two places, one entire edge and one corner. I had spent several hours on another day cleaning and stripping it of paint. Even so, it was still a pain to weld. I just could not get it clean enough. I had to use a method a friend of mine calls "pylon” as in "pile it on".

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From the picture the casting looks like aluminum which is porous (and can be very porous). Some cheaper cast automotive wheels will actually leak air through the casting. No doubt it had soaked up lots of oil/water. You might have luck baking parts like this in the oven to try and evaporate any oil/water in them. Just don't let the wife catch you :)

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Originally Posted by Jeff-Birt

You might have luck baking parts like this in the oven to try and evaporate any oil/water in them. Just don't let the wife catch you :)

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I am familiar with the over method. I was just being lazy. Since I do all the cooking, my wife does not get much say with what I do with my oven. It is a Kitchen Aid convection oven that has a nice feature called dehydrate. You can set the temperature between 100 and 140 degrees and it will run in convection mode with the door open. I use that a lot to do a post cure on carbon fiber parts I make. I also use that for curing smaller painted parts. When I remodeled my kitchen I put in a BIG exhaust fan (for when my wife tries to cook), and it works well when I am baking parts.

Vince

I was busy this weekend with other projects, but I did get a chance to spend some time cleaning more parts, doing a little painting, and making a new end plate for the cross slide bearings. The original was pretty chewed up. I can't sand it because it was silk screened so I would loose the logo. It took me three attempts to get it right, but I think it will look good. I plan on filling in the lettering with the blue paint and the rest will be black.

Vince

I have been getting lots of little things done, painting and cleaning wise. I also found an air collet closure in a town 50 miles away. Then on eBay, I found a 4" air chuck. I was a little worried that those items would be hard to come by. I still need to find the worm gear or the entire air motor for the turret.

The black oxide finish came out well as can be seen in the picture below. I was a little worried about what would happen on the areas that still had the original black oxide, but my fears were unfounded.

Today I should be able to put the lathe up on the stand.

Vince

I worked on the lathe for an hour this morning before work. I got in at 5:00AM. I worked another 3 hours after work. I got the lathe mounted on the stand! I also spent some time painting and sanding. I have to finish painting the bed end mount before I can start installing the carriage ball screw.

In the mean time I am working on installing the motor. I ordered the belts from Hardinge. Once the belts arrived it was easy enough to get a three slot pulley to match for my motor ($50 with the adapter included). The CHNC pulley is about 4". I bought a 2.6 inch pulley. That way I will get a bit of a speed reduction. My motor is 1750 rpm, 4 pole. I am hoping to get plenty of low speed torque. For the higher speed I can run the motor as much as 400HZ. This would give me about 6000 rpm at the spindle, though I am going to limit the speed to about 120 Hz and 3000 rpm.

Getting the old pulley off the motor was going to be tricky without a gear puller. Since I have more smarts than money, I put together a gear puller made out of strut and strut angles. As an electrician I have a lot of it around. It took about 10 minutes to make, less time than it would have taken to drive to a store. The gear came right off (as can be seen in the picture). It did help to put some WD40 on it a week ago to soak in.

Now I have to make a motor mount. I am thinking of using the same strut for the mount. With any luck I will have the motor mounted and turning by next week. One of the pictures shows the future location for the motor with the belts hanging down. To the left of the belts I found 4-4ohn, 50 watt resistors mounted on a heat sink. I removed them and will remount them in the cabinet and use them for breaking resistors. The motor would have made them difficult to access in their previous location.

Vince

The good news is I have the spindle turning, the bad news is work was so slow I had to take an unpaid day off, the good news is it gave me time to get the spindle turning.

I built my motor mount out of strut. After getting everything installed, I found that the factory supplied belts were a little on the short size, (5" longer would have been better), which caused the zerk fitting on my motor to hit the bottom of the coolant tank. For now I removed the zerk and plugged the hole. When I see how much money I have left at the end of this project I may order longer belts.

I installed my GE AF-300 mini VFD ($134 including shipping from eBay) in the power cabinet under the main input terminals. As can bee seen in the picture, I am feeding it with single phase, even though we have 3 phase available at this shop. At home (were the lathe will go when I am done) I only have single phase and I wanted to make sure everything works on single phase.

Above and to the right I installed a 120V to 43V transformer which I will use for the DC power supply. Once rectified it will give me 60VDC. I got a little carried away when I was removing the old contactors from the cabinet and cut the wires from the oiler. I will figure that out later.

The pulley on the lathe is 4.1" and the motor pulley is 2.6". This gives me about a 1 to 1.6 reduction in speed from the motor. I did this to get the most torque I could at low speed. With the VFD at 4HZ, the spindle speed was about 75 rpm. With leather gloves on, I could not get the spindle to stall, not matter how much I tried, which is good. I ran the VFD up to 155HZ which gave me a spindle speed of 3000RPM. I think everything sounds OK, but I don’t know how a CHNC should sound.

I took some amperage readings at different speeds and found something interesting. At 60HZ the motor drew 5.6 amps, at 120HZ it drew only 3.8 amps. At 155HZ it climbed back to 5 amps. My guess it that the back emf increases at the higher speeds and causes a reduction in current. If there are any electric motor gurus out there I would like to know what is going on.

The first picture shows the motor mounted. The second shows the power cabinet. I purchased a second VFD (small 1/4HP, $40 on eBay)) to run the 3 phase coolant pump. This was much cheaper than getting a single phase pump. This VFD will go next to the spindle VFD.

I still have three more days of painting before I can start re-installing the ballscrews.

Vince

Vince,
I am enjoying your tenacity and just a bit envious of it as well :)

Nice work.

Kenny

I found a guy that had some HNC servo motors, pulleys, encoders etc. I purchased the lot. They should arrive in about 10 days. This will make things a little easier since I won’t have to make custom mounts for the motors I have.

More painting today. I painted and filled the logo plate that is the ballscrew bearing cover plate on the end of the cross slide. See the pictures below.

I also made a video of the spindle running. The video does not do much, it was the audio I was interested in. I am not sure how a CHNC spindle should sound. I want to make sure it's OK before I progress too much further. The VFD and the motor make most of the noise, especially at low speed. If you have ever run a CHNC, take a listen to the video and let me know that you think. The lathe color looks a little funny because we have high pressure soduim lights in the room I am working.

[ame="http://video.google.com/videoplay?docid=-6032375020744455586"]Spindle motor test on a Harding CHNC[/ame]

Vince

As usual, I have been cleaning and painting. I spent almost 2 hours cleaning the micro switch on the spindle lock. The mounting plate and arm were covered with so much rust the arm was stuck tight.

I put the rear cover on the spindle and temporary covers over the motor and the lathe is much quieter, but there is still some spindle noise. I am guessing that the bearings have some rust pitting which is causing the noise. I talked with Jason at J&L and he said the bearing could be replaced, though the old ones usually have to be destroyed to get them out. He suggested checking the spindle runout. I used a tenths reading dial indicator and the needle moved about 1/3 to 1/2 half of a graduation. I am guessing the runout is better than .00004" (.001mm). Some of that may be bumps on the spindle. Since I will be running this lathe about 30 hours a year, I figure I have about 30 years before the bearings really become a problem.

I talked with a rep at GE about their VFD and various settings. He explained that the reason I was not seeing more amperage on the output of the drive was there is a DC component to the AC and a clamp on meter will not pick up this extra current. Most of the factory default settings were what I wanted for my setup. It has an output that I can read and use to display %power. I think I will set up a button in Mach to display % power.

I installed the carriage ballscrew and the cross slide. I think things will slow down a bit as I wait for parts I ordered. I found some HNC servo motors that will fit and save me a lot of time. They will not get here until late next week. I don't want to order my servo drives until I get the motors and can confirm their actual voltage.

I will also be spending more time trying to figure out the wiring and lubrication line routing. I need to replace all of the lines. Since this CHCN was not mounted on a stand, all the lines were just chopped off. It these little things that are going to eat up time.

I uploaded two pictures of my current progress.

Vince

Today I installed the cross slide carriage ball screw and the rear cross slide casting. I did not paint the casting because I thought I would need to do some machining on it to mount my servo motors. With the motors that are on their way, I should be able to use the casting as it is. I decided to paint the casting in place. This way I can continue to put the lathe back together.

The turret will be a little tricky. I have very little knowledge about how it operates. I will just go through the maintenance manual and put it back together as it says and hope that it will operate properly. I don't have the sensor that determines when the turret is in the proper position so I will have to come up with something for that. I am hoping I can get a servo motor to drive the turret and will then be able to control the position through the servo.

I will also have to come up with a way to add encoders to the motors. The original system used resolvers and tachometers.

Vince

Looking good Vince.

The spindle makes a heckuva whine, but I've no idea what one is supposed to sound like. My only thought is to simply see how warm the bearings are getting.

Cheers,

BW

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Originally Posted by BobWarfield

Looking good Vince.

The spindle makes a heckuva whine, but I've no idea what one is supposed to sound like. My only thought is to simply see how warm the bearings are getting.

Cheers,

BW

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Actually, the whine is the high frequency sound of the VFD. The sound from the bearings is a much lower tone, closer to 800 hz.

That's a good suggestion. I will let it run for a half hour and see if the bearing get warm and I'll report back. It the bearings don't get warm and the run out is OK, then it's probably OK.

Vince