Messages

11

General Mach Discussion / Retrofit Recommendations for Sharp CNC Knee Mill Using Existing Components

« on: May 23, 2018, 03:24:27 AM »

https://photos.app.goo.gl/uy1vg5d0iz33WUFn1

I just picked up a Sharp CNC knee mill (Sharp HCV) with a Mitutoyo Millstar CNC control with Mitutoyo linear scales on X, Y and on the quill. I don’t know what generation of Millstar this is. 1, 2 or 3? Anybody? Anybody have manuals and documentation for the control?

The Millstar controller is an old Pentium S PC with a Galil DMC-1020 motion card, a whopping 4 megabytes of RAM in a case with monitor, does power on, but there’s a problem with the IDE drive failing to boot. Bad IDE hard drive would be my guess.
The PC has PCI (but I think no PCIe) slots.

It has Glentek brushed DC servo drives for X and Y axes and I'd like to keep/use them if I can.
I'd also like to keep/use the Mitutoyo linear scales.
Recommendations on hardware to get to adapt/use the existing Glentek drives and Mitutoyo scales with Mach 3?

Also, they replaced the head with a 3HP Gromax variable speed head. I don’t know anything about Gromax. Anybody have manuals they can share?

My kids have been helping me clean off some of the grit and dirt and rust with Scotchbrite and WD-40. The Y axis definitely shows some wear and a bit of scoring on the ways, but the overall machine is pretty solid.


Anyone have manuals for the Sharp mill?
Docs for Mitutoyo Millstar?
Docs for Gromax 3HP variable speed head?
Recommendations for way oil? Spindle oil? ...
Anybody have a Millstar hard drive that I could clone?

Is it worth it to try to resurrect the Millstar controller?

Or, would it be better/faster/easier/cheaper to try to convert it to Mach 3 CNC?
How to use the existing Glentek brushed DC servo drives with Mach 3? I'm guessing they take 0-10V input, but not sure.
How to use the existing Mitutoyo linear scales with Mach 3 CNC?

12

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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?

13

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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...

14

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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.

15

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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

16

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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 :-)

17

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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.

18

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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?

19

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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?

20

Show"N"Tell ( Your Machines) / Re: Help! Hardinge CHNC Retrofit

« 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!