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General CNC Chat => Show"N"Tell ( Your Machines) => Topic started by: rpseguin on July 07, 2007, 10:33:38 AM

Title: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 07, 2007, 10:33:38 AM
Ok.
I have a Hardinge CHNC (serial # CNC 532) and it is very clean and nice and was apparently holding super tight tolerances before the control failed (a blessing I'm sure :-).

Anyhow, I have cleaned it up, and am in the process of getting it ready to work.
My plan:
-use Mach 3 turn to drive it
-I have an Axxus DB1 parallel port breakout board
-I have a 12V MPG (I know 5V is preferable)
-use the still mounted DC servos (ElectroCraft 660) with some GeckoDrive G320 or G340 drives
-pull the resolver/tachs off and put encoders on X and Z. Since I want 0.0001" positioning, and the ballscrews are 0.2" pitch, 500 CPR encoders in quadrature should give me that.
-figure out some inexpensive method for controlling the turret. I'm all ears.
-Get a drive for the DC spindle motor. Not sure how many KW, but it looks like 3+ KW or so. It is a permanent magnet DC servo, 3500 max RPM. Anybody have specs on this and drive recommendations where I can control speed/direction from Mach 3?


I'm open to suggestions on how to best get this thing up and running (turret, spindle, ...).

I've attached a couple of pictures of what it looked like when I got it (NOTE: brown stuff is not rust, but some kind of oil buildup/enamel), after a little bit of elbow grease/WD40/rags/..., and the DC spindle motor.

More pictures are available and I will have followup posts as I make progress.

Thanks!
-Ralph

Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 07, 2007, 05:38:37 PM
Did a few more things in the past couple of days:

-started adding in the chip shields (hopefully not prematurely).  I still have to figure out how to mount the rollers onto the top bars.  The holes drilled into the chip shield are too small for the threaded rod on the rollers.  Anybody have pictures of their roller wheels/bearings on their chip shields?

-I pulled off the X and Z axis tach and resolvers.  Off to ebay?

Next steps:
-measure up and figure out mounting for axis encoders on the ballscrews.
500 CPR in quadrature should yield 0.0001" positioning with a 5 TPI ballscrew

US Digital  E2?  E5?
http://www.usdigital.com/products/e2/

Looking for info and suggestions on the DC spindle servo motor.

Thanks!
Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 10, 2007, 10:19:14 AM
I ordered some G320 drives yesterday.
Looking forward to getting those.
Going to order some US Digital E2 500 CPR encoders soon.

For the Mach 3 spindle pulse encoder, can you just uses a regular encoder and use the Z (index) pulse?

Title: Re: Help! Hardinge CHNC Retrofit
Post by: Brian Barker on July 10, 2007, 05:41:20 PM
The index pulse is to small :( You need to have a much longer pulse to have it work with Mach 3


Check out cnc4pc.com they have a pick up that will work very well

Thanks
Brian
Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 11, 2007, 04:22:15 PM
Cool.
Got it.

Just finished talking with someone from Hardinge who says my DC spindle motor is rated at 5HP (size seems right),  so I guess using a geckodrive to drive it as a C axis servo (says servo motor on the plate, but not voltage/wattage/...) isn't in the cards.

Was looking at the ballscrews and pulleys, ...
Both X and Z are geared at 4:1, so the 5 TPI ballscrews are effectively 20 TPI from the motor's perspective.

I am definitely planning on mounting the encoder onto the ballscrew.  So at 5 TPI, to get 0.00005" positioning (0.0001" diameter), I need a 4000 PPR (1000 CPR) encoder.


If I were to use a motor mounted encoder, to get 0.0001" in diameter, or 0.00005" in radius, I need 1000 PPR (0.00005" positioning/radius), or 250 CPR encoders.
Is 250 CPR too low to be good on a DC servo motor with a Geckodrive G320?
Would 500CPR be preferable?

Comments?

Title: Re: Help! Hardinge CHNC Retrofit
Post by: polaraligned on July 11, 2007, 07:05:23 PM
I don't think you want to mount the encoders onto the ballscrews.
Your servos have a 4:1 reduction and the ballscrews are 5 TPI.
The system may break out into oscillation because of the backlash
between your reduction/ballscrews/motor. 
Your following error will be way more than the Gecko's can handle.
They are great drives but sadly they have one shortcoming, and it
is a big one.   The following error is permanently set at 128 encoder
counts.  Not good. 
There is not a single servo drive currently on the market that takes
step and direction and is capable of driving large servos reliably.  Rutex and
CNC Teknix are both having serious troubles with their drives and are
in the redesign process.
Gecko has the short coming I mention above. 
I am using small 12.5 in-lb Baldor servos with 1000 line encoders
driving a series 1 BP mill with 4:1 reduction between motor and
ballscrew.  I am using Gecko drives and they are probably the best
currently out their until CNC Teknix and Rutex get their drives
redesigned.  I have constant problems with my drives going into
error state due to the small following error.   The only solution is
to keep my drive rates low.  I use 80 IPM rapids when my motor is
perfectly capable of driving my table at almost 200 IPM.
Granite devices is the best drive available if you can deal with a
12.5A peak current for your motor.  http://www.granitedevices.fi/
Most of us need 20A or better for our larger machine tools.

Best luck,
Scott




Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 11, 2007, 07:20:17 PM
Have you tried with the encoders on the ballscrews?  Is that the way your machine is set up right now?
My CHNC has C0 ground ballscrews on X and Z, so I don't think there will be much backlash on the ballscrew, but I haven't checked them out yet.
I will measure it when I get a chance with a 0.00001" indicator when I get a chance.

128 counts of following error on a 4000 CPR encoder is  128/4000 -->  3.2% of a rotation, or 11.52 degrees.
That seems like quite a bit to me.  I cannot imagine having that much backlash in the system.

One other reason for mounting the encoders on the ballscrews is that it ls already set up for that (the tach and resolver were mounted to the ballscrew).  The Electro Craft E660 motors that are already there don't have any back shaft for mounting encoders on them.  I'd prefer to just leave them sit as they are if I can.  Ie, pulling off the motors, machining and mounting encoders, ... seems like a hassle.
Also the gearbox/pully/encoder compartment is sealed off from coolant, whereas the motor bodies are exposed to it (splash cooling? :-)

If I had the money, I would retrofit with a full up CNC control with full servo closed loop.  As it is, I don't have money :-)
Getting the wife to ok buying parts is a hassle already.

Title: Re: Help! Hardinge CHNC Retrofit
Post by: DennisCNC on July 11, 2007, 10:18:26 PM
Scott, have you looked at Viper servo drives?
Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 12, 2007, 12:25:10 AM
BTW- the Hardinge parts guy told me that my spindle motor replacement part cost was $13000.00!!!
Maybe I could sell it back to them for half of that and buy all the parts I need :-)

Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 12, 2007, 12:28:50 AM
Anybody using Agilent HEDS-9733 optical encoders?
Quality?
Reliability?
Durability?

Mouser has a good deal, but minimum quantity is  100 pieces (group buy??)
http://www.mouser.com/search/ProductDetail.aspx?R=HEDS-9733%23U53virtualkey63050000virtualkey630-HEDS-9733-U53

Title: Re: Help! Hardinge CHNC Retrofit
Post by: polaraligned on July 12, 2007, 06:46:09 AM
I don't have the encoders on my ballscrews right now.  I use 1000 CPR
encoders on my motors.  I am just warning that if you have some backlash
in your system,  having the encoders on the screws can cause serious
dithering problems.  The system has to be tight.  Some used machines can
get a bit sloppy.

Having your encoder on the ballscrew will help you with the 128 count problem
that the Gecko drives have.  The 4:1 reduction you have between the motors
and the encoders will actually cause the system to see the encoders as 250
line units which is more ideal for Gecko's. 

Just the inertia can cause these drives to trip if accelerated too high. 
Once the commanded position is 128 counts out of sync with the encoder
position, the drive will trip.  I can trip my drives by just spinning the motor
too fast. (over 2200 rpm or so).

Dennis,  I looked into the Viper drives and was not really impressed with their
construction.  I would like to hear some feedback from someone who owns one.


Good luck.



Title: Re: Help! Hardinge CHNC Retrofit
Post by: Nick on July 12, 2007, 09:33:36 AM
  That drive motor looks like the ones I have - 4HP and you need a Focus 5hp dc driver for it. There also is a 90v dc brake that you have to release before turning it on. Grab the spindle and try to turn it, make sure the lock pin isn't in and you'll see. The little rectifier in the original cabnet is used to operate this.

  The alernative is replace the dc motor with a 5hp AC motor with an inverter contol. About $1200 job but will be easier to control and they last a lot longer than the dc job in there now. Also, no brushes to deal with and you eliminate the brake release control and timing problem.

  Has anyone solved the turret indexing operation control and encoder feedback to artsoft control?

  For some pics of my project http://www.janick.com/cnc/
Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 13, 2007, 04:09:46 PM
Thanks.
I looked at their site, but it says up to 2HP in all places except one.
In any case, I'm sure there's a lot of DC speed control drives out there, just a matter of finding one that I can drive with PWM and that is within my very limited budget.

The Gecko G320 drives arrived yesterday.  I have to get some encoders and then I'm off to making things move.
I'm still waffling on what resolution encoders to go with.
I'm thinking 1000 CPR.


Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 20, 2007, 05:24:29 PM
I found some stepper motors that have the encoders mounted on them, so I pulled them off.
One is a US Digital E2 500 CPR (upper picture), which is perfect.  The bore is even .250", which is the machined shaft size on the Hardinge ballscrews.

The other encoders (bottom picture) I have are anonymous.  I counted, and they look to be about 500 line.
They have 8 wires on them, so I suspect they may be differential, but I don't know for sure.
Anybody recognize  these encoders (bottom/lower picture)?  They came off some small Vexta, NEMA 17, 2 phase stepper motors.

Unfortunately, the bore size on the other/anonymous encoder is only .190", and I don't really want to bore it out, so I think I'll just get a shaft extender of the right size and mount it on the ballscrew shaft and mount the encoder on a riser block.

Might take a couple days to get the time to do this.
Weekends with 18 month old twins and a 3 year old are kinda chaotic :-)

More to come...
Title: Re: Help! Hardinge CHNC Retrofit
Post by: rpseguin on July 20, 2007, 05:34:07 PM
I don't have the encoders on my ballscrews right now.  I use 1000 CPR
encoders on my motors.  I am just warning that if you have some backlash
in your system,  having the encoders on the screws can cause serious
dithering problems.  The system has to be tight.  Some used machines can
get a bit sloppy.

Right.  I'm worried about it as well.  We'll see once I get things wired up what happens.

Having your encoder on the ballscrew will help you with the 128 count problem
that the Gecko drives have.  The 4:1 reduction you have between the motors
and the encoders will actually cause the system to see the encoders as 250
line units which is more ideal for Gecko's. 

Hmmm.... I think that your numbers are reversed there.
With a 4:1 reduction, 1 turn of the motor is .25 turns on the ballscrew, or 4 motor turns=1 ballscrew turn.
So, with a 4000 PPR encoder mounted on the ballscrew, every motor turn is 1000 pulses.
Or is that what you mean, that it gives more leeway/slop on the motor?

Title: Re: Help! Hardinge CHNC Retrofit
Post by: cjmerlin on July 21, 2007, 09:13:38 AM
Hi, This pdf file of the HEDS encoders may help.



Regards
Title: Re: Help! Hardinge CHNC Retrofit
Post by: lyfordln100 on February 08, 2008, 07:59:09 AM
I have a Hardinge CHNC that I would like to replace the GE Mark 550 with the Mach3. Has anyone actually done this and if so, did you keep your documentation?
Any help would be appreciated.
Title: Re: Help! Hardinge CHNC Retrofit
Post by: brians machineshop on March 28, 2008, 06:19:14 PM
hi i just got a hardinge chnc 1980 model Allen Bradley 7360 cnc control, serial #ncn-367-n/c chucker.
Its in really good condition.
i was offered 1200 for the control, so I'm thinking of switching to a mach 3 w/x15-255 monitor.
does any one know how to use the tack and resolver?
I'm also thinking of going with a D0-06DR for my plc ya or no?
got to go for now any help will be GREATLY APPRECIATED
Brians machine shop
Title: Re: Help! Hardinge CHNC Retrofit
Post by: DennisCNC on March 29, 2008, 12:34:56 AM
I say take the money for the control!  You can't use tachs or resolvers you will need encoders if you plan on using servos.  As for the PLC ise one of these: http://cubloc.com/product/01_01.php,   very easy to program and cheap.
Title: Re: Help! Hardinge CHNC Retrofit
Post by: brians machineshop on March 29, 2008, 09:22:54 AM
thanks Dennis,
Ya i think i will take the cash.
On the cubloc what one do you recommend?
and what else will i need to get the cubloc going?
The motors are still good on this machine and i have extras so i would like to use them.
machmotion tells me there is a gizmo i can hook to the tac/resolvers that will translate the signal. butt I'm not sure what it is called.
my biggest problem with this retrofit is that i have an order do next week and that job was suppost to pay for this machine so right now I'm looking for the fastest and cheepest way to get that job out.
It's like retrofit 911 lol.
thanks again
Brian's machineshop