Questions CNC Conversion.

[Ark1]

I have been reading in the forms here trying to obtain some answers about converting my TOS FN20 with 40 Taper tool holder to CNC.

I purchased from this site the CNC Cook Book and it has helped but my lack of experience has left me a bit short of total comphrension of what I am trying to accomplish.

My existing Milling machine is a solid unit and weighs about 2000LBS.

Quill 3 1/8"
X 12" Lash .012" (Screw) 1 turn of the hand wheel moves the table .200"
Y 7" Lash .004" (Rack and pinion), 1 turn of the hand wheel moves the spindle .100"
Z 13 3/4" Lash .000" (Screw.) 1 turn of the hand wheel moves the table .050"

It currently has Power feed on all axis and a 3 phase coolant pump. The gear head spindle moves on this machine and the table can be removed to present a T slot vertical table to bolt up an engine block to. I have not yet done a torque measurement on the hand wheels to find out what driving force will be required. The unit has it's gear boxes submerged in about 2 gallons of oil. Nice, but it weeps then collects dirt and dust on the machine.

My hope is to make this a kind of Hybred/manual/CNC machine. In all of the reading I have been doing my thoughts are to drive the hand wheels with belts and reduction to either steppers or servos. 4:1 reduction ratio.

I think I will use Mach3 software. Does this program or any program have an allowance for the lash my machine has. Or for instance if I was to use servos could I purchase from ebay glass slides to feed back to the computer? Is an encoder and encoder whether or not it is rotary or linier? Or, I could remove the encoder from the servo and purchase small ball screws and nuts, fasten the nut to the bed and as the bed moves it will drive the ball screw which is attached to the rotary encoder, with a possible step up belt drive to obtain better resolution?

What I want to use the machine for is to make exhaust flanges from steel or stainless steel. Accuracy isn't really a huge issue here .012" out of round will not affect the fit of the weld between the parts to be welded. Speed isn't a real issure here either. But currently I cut the parts on a band saw, edge mill to size, then hole saw the port rough dia. and then use a boring head to bring to finish diameter. A lot of set ups and time and chances for error.

In all of the reading I have been doing, some say for simple jobs CNC isn't the way to go. I agree, my thoughts Hybred. I can still use the machine manually as the hand wheels are still there and the machine power axis is there still as well. A bonus would be if the DRO would work on the computer screen. At 53 my eyes aren't what they use to be.

Big wish list I know, but when working with car parts a machine with Mass is a big benifit.

Also, Mach3 would I be able to profile a combustion chamber on a cylnder head? Or is this consider full 3D.

Opinions? Would love to read them.

Thanks.

TonyK.

[TOTALLYRC]

Originally Posted by Ark1 I have been reading in the forms here trying to obtain some answers about converting my TOS FN20 with 40 Taper tool holder to CNC. I purchased from this site the CNC Cook Book and it has helped but my lack of experience has left me a bit short of total comphrension of what I am trying to accomplish. My existing Milling machine is a solid unit and weighs about 2000LBS. Quill 3 1/8" X 12" Lash .012" (Screw) 1 turn of the hand wheel moves the table .200" Y 7" Lash .004" (Rack and pinion), 1 turn of the hand wheel moves the spindle .100" Z 13 3/4" Lash .000" (Screw.) 1 turn of the hand wheel moves the table .050" It currently has Power feed on all axis and a 3 phase coolant pump. The gear head spindle moves on this machine and the table can be removed to present a T slot vertical table to bolt up an engine block to. I have not yet done a torque measurement on the hand wheels to find out what driving force will be required. The unit has it's gear boxes submerged in about 2 gallons of oil. Nice, but it weeps then collects dirt and dust on the machine. My hope is to make this a kind of Hybred/manual/CNC machine. In all of the reading I have been doing my thoughts are to drive the hand wheels with belts and reduction to either steppers or servos. 4:1 reduction ratio. I think I will use Mach3 software. Does this program or any program have an allowance for the lash my machine has. Or for instance if I was to use servos could I purchase from ebay glass slides to feed back to the computer? Is an encoder and encoder whether or not it is rotary or linier? Or, I could remove the encoder from the servo and purchase small ball screws and nuts, fasten the nut to the bed and as the bed moves it will drive the ball screw which is attached to the rotary encoder, with a possible step up belt drive to obtain better resolution? What I want to use the machine for is to make exhaust flanges from steel or stainless steel. Accuracy isn't really a huge issue here .012" out of round will not affect the fit of the weld between the parts to be welded. Speed isn't a real issure here either. But currently I cut the parts on a band saw, edge mill to size, then hole saw the port rough dia. and then use a boring head to bring to finish diameter. A lot of set ups and time and chances for error. In all of the reading I have been doing, some say for simple jobs CNC isn't the way to go. I agree, my thoughts Hybred. I can still use the machine manually as the hand wheels are still there and the machine power axis is there still as well. A bonus would be if the DRO would work on the computer screen. At 53 my eyes aren't what they use to be. Big wish list I know, but when working with car parts a machine with Mass is a big benifit. Also, Mach3 would I be able to profile a combustion chamber on a cylnder head? Or is this consider full 3D. Opinions? Would love to read them. Thanks. TonyK.

Hi Tony,
For what it is worth here are my observations.

1. 0.012" backlash is an awful lot for a CNC machine. The computer can only do so much.

2. The Y and Z should be OK but if you can do anything to eliminate the backlash, that would be better.

3.Mach 3 is an excellent program but it has some limitations. You can't put the encoders on the table. They must go on the ends of the motors.
Mach 3 has backlash comp but again the 0.012 on the X is extreme.

4. Mach 3 will in fact do full 3d machining and do it well.

5. A Rogers machine board will allow the encoders to be read back onto the computer screen for use as a DRO while doing manual machining.

6. My machine was originally CNC so it doesn't have hand wheels. While I rarely miss them, I find it only takes a few minutes extra to do the simple jobs via CNC and then I save months of time on the difficult stuff via CNC so I don't lose any sleep over this.

7.As long as you can program it, Mach 3 will profile the combustion chamber for you.

8. Since you are not going to be doing full CNC production, 3 Gecko G320x servo drives with appropriate motors running at ~75v should be fine. You may have to adjust the pulley ratios since you have different lead screw pitches. Himmykabbible has a nice setup using 4:1 reduction. Search for his setup on the zone.

9. If you want to spend more money, the DSPMC/ip, which I use, is real nice but may be overkill for what you want to do, considering what the final cost will be. It reads the encoders back onto the computer screen and it can control analog servo amps, analog spindle motor, and it has lots of I/O. All the I/O is great for switches and knobs and such but it depends on what you really want/need the machine to do.

10.The power feed for each axis becomes redundant with the addition of servos. The jog buttons or a pendant really makes it easy to do the one off quick cut.


Mike

[Ark1]

I am not sure how I posted this in this section however you have answered points that I have not been able to find.

Mainly the servo drive/motor rotational out put must all be equal to table for each turn of the hand wheel that it drives.

As for the lash in the X there are anti-lash nuts on the machine that have adjustment. But since I purchased the machine used the Pin Wrench to make the adjustment didn't come with the Mill. I will have to make one and see where it gets me. It is my understanding that any reduction in by belt or gear driving should increase the resolution at the expense of speed, so a 4:1 reduction should resolve down to .003" on the X as it now stands.

I will follow up on the Rodgers Board and the post from Himmykabbible. Plus the other drives you suggested. I would like to see where my money takes me with the conversion project.

All of this currently is in the planning phase however, as time passes it becomes apparent that updating of equipment is nessessary.

As for programing, well the last time I worked with Auto Cad was release 10, about 15 years ago. Time to catch up.

Thanks for the comments.

TonyK.

[TOTALLYRC]

Originally Posted by Ark1 I am not sure how I posted this in this section however you have answered points that I have not been able to find. Mainly the servo drive/motor rotational out put must all be equal to table for each turn of the hand wheel that it drives. As for the lash in the X there are anti-lash nuts on the machine that have adjustment. But since I purchased the machine used the Pin Wrench to make the adjustment didn't come with the Mill. I will have to make one and see where it gets me. It is my understanding that any reduction in by belt or gear driving should increase the resolution at the expense of speed, so a 4:1 reduction should resolve down to .003" on the X as it now stands. I will follow up on the Rodgers Board and the post from Himmykabbible. Plus the other drives you suggested. I would like to see where my money takes me with the conversion project. All of this currently is in the planning phase however, as time passes it becomes apparent that updating of equipment is nessessary. As for programing, well the last time I worked with Auto Cad was release 10, about 15 years ago. Time to catch up. Thanks for the comments. TonyK.

In the order you answered.

1. not absolutely but if you use 4:1 across the board, you may limit an axis' speed.

2. Backlash in the screw is not effected by the gear reduction of the servo, it is still a large amount.

3. Try Via Cad. It has some nice features and it is what I use. They have a downloadable demo.

My Build log for the mill is here.

http://www.cnczone.com/forums/showthread.php?t=66994

Keep on dreaming and maybe the dream will come true.

Mike

[Ark1]

The first place I want to start is to have an understanding of what I need and more so what it does. Looking into the 320X drives it states that it is using encoders/resolvers with Quadrature. Quad means four, but four what?

Just a little encouragement here if you could spare the time.

Now looking on ebay there is a multiude of servos for sale, Fanuc, Sanyo Parker. Some with Amphenol connectors, other with Flat pin connectors and still others with a multi-lead cable. Is a servo a servo, I see some as brushless as well, but the 320x drive states it is for brush type motors. Can all servos of rated power be connected to the 320x drive or should the name plate match the output of the drive completly. Or are some a package deal and need there own drives?

Then there is the DSPMC/ip, I am going to guess that it is an elaborate break out board that uses some sort of processor to allow more Input/output connections from the standard db25 cable plug. And there is a software package that goes with it to interface to the computer running the machining software program. I think there is more to it than that but my lack of exposure to this equipement has now shined through.

Anybody with a few answers?

Thanks.

TonyK.

[TOTALLYRC]

Originally Posted by Ark1 The first place I want to start is to have an understanding of what I need and more so what it does. Looking into the 320X drives it states that it is using encoders/resolvers with Quadrature. Quad means four, but four what? Just a little encouragement here if you could spare the time. Now looking on ebay there is a multiude of servos for sale, Fanuc, Sanyo Parker. Some with Amphenol connectors, other with Flat pin connectors and still others with a multi-lead cable. Is a servo a servo, I see some as brushless as well, but the 320x drive states it is for brush type motors. Can all servos of rated power be connected to the 320x drive or should the name plate match the output of the drive completly. Or are some a package deal and need there own drives? Then there is the DSPMC/ip, I am going to guess that it is an elaborate break out board that uses some sort of processor to allow more Input/output connections from the standard db25 cable plug. And there is a software package that goes with it to interface to the computer running the machining software program. I think there is more to it than that but my lack of exposure to this equipement has now shined through. Anybody with a few answers? Thanks. TonyK.

Hi Tony.
An encoder in quad means the holes in the disk, say 500 are counted twice by each channel. This gives a 4x count as they count each hole on the rising edge and the falling edge of the signal. A 500 count encoder gives 2000 counts per rev in quad.
The g320x allows for greater flexibility in encoder choices because you can set the following error. Plus it has other nice features.

The DSPMC is not a Breakout board. It is an external motion control device that uses an on board "chip" that does all the step generation whereas the p-port uses the CPU of the computer to do the hard work. Since the chip on the DSPMC and other external pulse generators does the hard work, the processor is free to do the tough stuff, like surf the web and other important things. LOL

If you are using the DSPMC, you will need analog servo drives capable of taking the +-10v from the DSPMC. Eventually the DSPMC will do step and direction output but is waiting for rigid tapping and other stuff to be done first. There are few controls out there other than the DSPMC and the Galil that will run analog servo amps and talk to Mach3.
The DSPMC uses a plugin with Mach3 to make it all happen.
It will result in an excellent system, but it may be more money than you want to spend.
My used machine came with a power supply, analog amps, servo motors and a whole bunch of other stuff that made the dspmc a no brainer.
Since the encoder input is 2 MHz, I can uses much higher resolutions than 500 and still go fast. Mach3 through the p-port is limited by how dast you can generate steps, max 100 MHz and many people can only go 25 MHz on their particular system.

As a generalization, any DC brush servo can be attached to the G320x. There are a few things to understand. The G320x has an 80V max limit, so if you hook up 160v servos, they will run about half speed. The drive has internal current limiting and will protect it self if the motor attempts to draw more than the drives allowable max current.

"Good" DC brushed servos will go ~2000 hrs between maintenance calls which can just be brush replacement to full blow throw them away, all depends on how hard you use them.
How long will it take you to put 2k hrs on your machine?

On the subject of cost, you could go with 3 g320x, a breakout board such as the ubob from Candcnc, and drive it from the P_Port on a windows computer.

http://www.candcnc.com/

A 75v power supply from antec or one of the other zone advertizers, some wire and away you go.
Of course it is easier to type this than to do it.


Mike

[Ark1]

The concept is starting to take shape in my mind and what you are doing with your build is far more than I require in mine. Not to say that once I get to 'A' that ' B' may look a whole lot better.

Looking at your build and I am on page 2 now it appears that the power supply that you have mounted is 3 phase and huge. All the I/O that you need to operate your machine really isn't an issue with mine. 3 Axis and for now just operate the spindle speed that I can set with the gear head selector. I/O is to turn the motor on or off, although is does have reversing as well. Coolant on and off would also be needed. So the DSPMC is more machine than I need or my machine could really handle. The parts I make are 1 or 2 off but the time needed to do it by hand and within tolerances is the limiting factor that CNC could resolve.

The X axis is still an issue that I have not had the time to resolve by adjusting the anti lash nut. I may have to change that screw to a ball screw.

In your last post you stated how many hours I have used the machine, I am a hobby machinist. Since I have owned the machine maybe 2000 hours over 15 years. So finding a set of servo's off ebay would be a big benifit and the Gecko Drives from my reading can use a pulse encoder. Since all my axis have different travel for 1 turn of the hand wheel belt drives with reduction to bring each axis into the same turns per motor per inch travel seems like a good thing to do. The X axis only needs 5 turns of the hand wheel to travel an inch, but it also requires the most amount of torque to do so.

So if I have this right, Servos at about 75 volts and I am hoping for about 500 in/oz of torque. Gecko drives, a break out board, and computer to run it.

I have find the Rodgers board to read back the encoders on mach3 in manual mode. Will that still work with my train of thought?

Currently I am trying to finsh my Deck as I have been at it since May, a lot of time and expense to build it and the weather in southern Ontario is turning colder and the fall rain has started delaying my completion. It is a hard wood deck that requires more thought and head scratching to install than a soft wood deck. Here is a shot of my shop, 12 foot ceiling with a 10'x 10' roll up door, room for a car hoist or project and heated for the winter.

Thanks again.



TonyK.

[TOTALLYRC]

Hi Tony,
Yeah, I did do lot to mine and it is not finished.
The huge transformer is what came with the machine so it is what I used.
My X and Y are ~5tpi with a 2:1 belt reduction. It gives great rapids with the NEMA 42 size motors. Hiimykabbible I believe uses something like 4:1 with servos from keling. He still has plenty of power and speed.

I was able to get brand new, in the box, SEM servos for about $35 each, shipped from eBay. I was able to get 6 so there are deals out there sometimes.

The Rogers board will work for what you want to do.

http://www.rogersmachine.net/encoderinterface.html

Nice job on the deck.

Mike

[malti2104]

hi all thanks for your preious help with other problems before, can any one advise how to set up mach3 to run a laser i have been trying all sorts of combinations so far i manged to get it to cut letters an shapews and comes on and off at start and finish of the cut, but i cant turn ot off between charcters it leaves a week burn line between letters.
also how can i set the hieght of z it seem to always go up 10 mms i need it to be 3 mm

thanks mike