Router control

[davidw731]

Thi is my first post Machinist for 30 years Cnc for 15. I found a Newing hall NH600 engraver that is in great shape but has no control. I would like to convert it to a router by adding a Z axis. The mechanics are no problem. I don't know anything about steppers and PC controls. My question is are these steppers and control any good http://cgi.ebay.com/4-AXIS-CNC-Route...item414e12805e This way I won't have any compatibility issues. Thanks for any feed back

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[tgarson]

Hello David,

Please pardon my rambling style. I'm typing and thinking "on the fly".

I recently acquired a Newing-Hall TLC-400 and am in the process of discarding the old "brain" and adding a true Z-axis, so I can probably offer you a bit of assistance.

You don't say what generation your NH600 is. If it's an original TLC, it will benefit from the lead screw nut upgrade offered by NH. Later machines also have cleaned up wiring and plumbing, a lot of which will go away with a Z-axis conversion, but the "chain" type cable guide is nice to retain.

You might want to keep one of the pneumatic circuits so you can use the original spindle block assemblyy for straight up "nose contact" engraving, where part of the the spindle actually rides on the work piece, thus maintaining a constant cut depth when working with irregular surface material.

I have not yet made any chips on my machine as it's a work in progress, but the stock X and Y steppers seem to be reasonably decent. Unless yours is a much newer machine than mine, replacing the steppers also necessitates installing new lead screws and nuts, as the older machines have integral lead screw-steppers. I certainly would not replace that stuff until I had determined that they needed to go.....

The biggest hurdle you face is the spindle itself. It is not practical to convert the original pneumatic actuated spindle block to full Z motion, so you will need to either make your own or spend the (ouch) $2400.00 that NH wants for their version. I am in the process of building a Z axis based on a THK ball screw slide with a Proxxon rotary tool. I will need to fabricate a mount for the NEMA 17 size Z-motor I'll use and one to mount the slide on the NH gantry.

I've settled on a Gecko G540 stepper driver which will be used in conjunction with a relatively low cost controller. The controller, a CNC USB Controller ( www.planet-cnc.com) has moderate performance, but only cost me $170.00 with software (I have great hopes....) on eBay. All of this has yet to be put together and tested, so don't run out and buy based on what I say here.

My NH400 came with a controller, but it was only semi functional and was only 2 axis anyway, so I scrapped the computer and driver parts of its innards and kept the (quite stout) case with power supply to house the new electronics.

I'm still just past the dismantling point. I won't start seeing the new components arrive for at least a week. Once I have all of the disparate parts in one location, I'll start the building process. I'll try to take some photos as I go along and post them.

If all goes well, and I'm pleased with how well the overall performance of the machine is, I will probably adapt a more powerful motor/spindle to my Z-Axis. I also have designed a ground-up drop in replacement spindle block that would use the NH belt drive system and the NH spindles. It will cost me about $1000.00 to assemble a prototype, using an outside CNC shop to make the parts. I have a manual mill but the parts are too intricate for me to want to make it that way. Consequently, I'm going to hold off until I see how the "first step" goes. If I'm lucky, I can use the NH400 to make the pieces for the custom spindle block.....

Tom G.

[tgarson]

OK,

Here's where the Newing-Hall based FankenGraver project stands today (8/28/2010):
Basically, it's done.......! (Yah, nothing is ever REALLY done, but I can use it.)

For starters, I gutted the controller electronics portion of the TLC controller chassis. I rebuilt the power supply, including making it regulated, to provide 42 Volts DC at up to 5 Amps for operating the steppers.

I measured the resistance and inductance of the the stock steppers and decided that they should be able to handle the load I had in mind for them. My calculations indicated they would be best driven by 3.5 amps maximum per phase from roughly a 45 Volt supply.

I purchased a small THK (approximately 3.5" motion) zero backlash ball screw driven ball slide for my Z-axis. I removed the Tee-slot plate from the front of the gantry and replaced it with a custom machined (I have a small manual floor standing mill without which this project would have been immensely more difficult) "sandwich" plate that attaches the ball slide to the gantry. I initially chose a Proxxon IB/E rotary tool for a spindle. I purchased a very nicely made mount for the Proxxon from Widgetmaster and made an adapter plate to attach that mount to the ball slide. The THK slide was designed for a NEMA 17 size stepper, so I got about the most powerful one I could find, which has about a 2.5 amp draw per phase. After burning out the Proxxons motor carving up 10mm aluminum, I started over with the spindle motor. I purchased a Ridgid R2401 trim router (5.5 Amp motor) to use as a spindle and reconfigured my mounting scheme to accommodate it. I like the Proxxon, but it's just not enough tool. Once the new motor arrives from Proxxon (yes, Proxxons are repairable. Can you believe it?) and is installed, the Proxxon will become my preferred high speed rotary hand tool, which is what it was made to be, anyway.

I added stop switches to both ends of all axis.

I had to perform a significant amount of rewiring to accommodate all of the additional (stop switches plus Z-axis motor) cables. I used DB37, DB25, DB15, and DB9 connectors distributed about in various locations as needed.

I built the Geckodrive G540 and the CNC USB Controller (http://www.planet-cnc.com) into the old TLC chassis and, for a first project, made a new front panel for the controller chassis. I added an E-Stop switch and wired it up to kill the output of the G-540 and also turn off the spindle (I reused the solid state relay that was already in the TCL controller chassis). Alas, there was no way to effectively use the triac dimmer style speed controller that the TLC came with because of the nature of the new spindle motor, so to the bone pile it went.

I left the two air valve solenoids, and their hoses, on the machine. I intend to use one to turn my coolant mist on and off. The other is for just in case I want to reinstall the NH spindle hardware and use it for "straight engraving", as unlikely as that may be.

I made two pieces of 4"x4"x.25" aluminum box tubing that fit under the side rails of the machine. For now they merely serve to hold it up far enough from the table to clear the underside of the vacuum table. Eventually those pieces will be part of a vertical frame extension that will allow me to add a tee slot table and take advantage of the 3.5" of Z-travel I now have without any interference from existing frame bracing components.

Because the CNC USB Controller has some internal buffer capacity, and is well behaved, I have had no issues operating the machine from my Thinkpad, but I am putting together a dedicated PC for it as I need my laptop back! Using the CNC USB software is pretty straight forward. It offers what features I needed and a fair amount more. It is also a work in progress, not meaning that it has bugs, but that it is in continuous development with new features and capabilities being added as time goes on. The hardware is also being improved. I2C is being incorporated to allow expander modules to be coupled to the standard controller for purposes of additional physical capabilities.

I've been very please with the support I have gotten from both plant-cnc and Geckodrive. Good people. I had the inevitable oops, slipping with a 'scope probe while chasing a wiring problem and managed to damage both the controller and the driver at the same time (yes, I'm THAT good!) Both companies came through with flying colors, getting me back up promptly and at nearly no monetary cost.

When all is said and done, I have to say that I probably did not save a lot of money over buying a small turnkey cnc router from one of the eBay vendors, but I think I have a better machine. Plus, I know this one inside and out and know that the quality of the materials used is first rate, giving me confidence that it won't fail due to fatigue of a cheap alloy or suffer from plastic flow in a few years. I have to stop short of claiming my much altered NH400 is now usable as a small mill, because it would not be very good with iron or steel (too much flex, not enough mass, for that) but I have already proven to myself that it can very effectively work aluminum and even brass and bronze, not to mention any and all plastics, wood, etc.

I don't have any pictures, but I'll see about taking a few still shots this weekend and posting them here (if I can figure out how to do it).

Tom G.

[tgarson]

I've attached a few photos of my machine to this post. It now sports the Ridgid 2401 motor, a five fold increase in power over the Proxxon I started out with.

[Kroko]

Very nice job. It is also good to hear that CNC USB Controller is well behaved.

Andrej

[signtrainer]

Tom ...
I just picked up an NH300 unit. While it SEEMS to be workable, at least the joystick moves all the motors around, I am considering either selling it to someone as a parts machine .... or .... converting it to a 3 axis unit, just as you did. What was the estimated cost in YOUR conversion?

Do you feel that YOURS was worth the whole conversion process vs. just buying one made up, on Ebay?


Richard / SignTrainer.com
"Sign Shop & Screen Printing Training Videos for Beginners"

A-1 Quik Signs & Custom Shirts
Woodruff SC
864-371-2005

[mugginsjm]

Hi Tom
I've just picked up your very fine write up on the NH. I too have acquired a NH400 and have the quandary of either replacing a couple of belts, finding and installing Windows98 etc or giving the machine a complete makeover like yours. I was wondering if you're still happy with your mods or feel that you would do it differently. Any guidance would be much appreciated.
John