View Full Version : Sherline CNC sold under Spectralight name

03-17-2005, 01:23 PM
I have recently acquired a 1995 Spectralight CNC mill. After doing some research, I found that it is a Sherline machine that was converted to CNC and sold under the Spectralight brand name. The unit consists of a 3-axis mill with a control box and ISA control card for the computer. The control card broke and was disposed of years ago by the previous owner, and the mill has been sitting in storage since.

The connector on the back of the control box is 25 pin, and I tried going straight to the parallel port of the computer and using TurboCNC. I tried changing pin configurations, but I never could get a response from the mill. Does anyone have any idea's on how I can interface the control box with my computer?

I contacted the OEM, but they want $2000 for a new PCI control card and proprietary software to run it. According to the previous owner, that's as much as the whole unit cost when it was bought new in '95.

Thanks for any help you guys can give.

03-17-2005, 02:19 PM
You're probably going to have to switch it over to an aftermarket board like a xylotex or similar controls. Not sure what components you have but it sounds like the controller is what you're missing.


03-18-2005, 10:58 AM
I was hoping to avoid doing that. The machine has a controller box that has spindle control, x-y axis, z-axis, and robot labled connectors in the back, with a 25 pin input connector. I haven't looked at the model of driver IC's yet, but I hope to do that tonight. This box looks like it should be able to control the unit, but I don't know what the ISA card was for. The only thing I can figure is that the card did the processing and generated the step, direction pulses needed, and the box "amplifies" this to a level that will drive the steppers. I think this should be able to be done via the parallel port if I can decipher the pinout on the connector.

Fred in NC
03-18-2005, 11:43 AM
A few years ago I worked the interface to a chemical analysis machine, which was already obsolete at that time. I used an ISA card that is very similar to a printer port, with a DB25. The BIG difference is that it has 24 IO lines in it. The printer port in a computer has 3 channels of 8 bits each some of which are used for control purposes, but with the right hardware you can use all of them. The card, if I remember correctly, was only about $40. I think it was from B & B Electronics.

However, without docs, I think it will be very difficult to decipher the interface.

03-19-2005, 12:40 AM
Well, after some checking around and talking at length with the original owner, I think we have a ISA controller board on the way. I was hoping it would be here today, but no such luck. As soon as it comes in, I'll do some testing to see if I can figure out a way to use the mill without the board. I guess I need to make some sort of breakout board to aid the testing process. I'll post my results here in case anyone else ever comes across one of these things.


03-29-2005, 10:46 AM
Well, looks like Fred hit the nail on the head with his last post. The controller board for this thing finally arrived. It is an ISA board with both 25 pin and 9 pin connectors. It appears that that this board is using all of the pins for I/O, unlike the standard parallel port. The software that came with the controller is pretty nice. It looks a lot like a windows version of TurboCNC. Now I have to generate some g-code and see what this thing can do.


Fred in NC
03-29-2005, 01:26 PM
James, would you mind posting the source for your parallel card? B&B Electronics used to carry them, but they are not listed in the web site. Also the cost. Thanks!

03-29-2005, 10:49 PM

The controller card came from a company called Learning Labs. The fellow who got the card for me teaches a "Career Technology" class at the local school, and they do a lot of business through this company. They are a reseller/distributor for the spectraLIGHT CNC mills (converted sherline) and most of the other things that they use in his class. Since everything is going to PCI, he was able to get them to send an ISA card that they were just going to throw away after doing an upgrade at another site. Also, since his machines are already upgraded to PCI, and using the latest software, he gave me the old software disks that they no longer use. Luckily, I got them before he went through the file cabinet and threw out all of the outdated stuff. So I really lucked out getting this stuff for free, compared to the $2000 they wanted for the PCI card and software.

I am going to post some pics as soon as I can borrow a digital camera. But, of course, I had to go ahead and install the thing so that I could start playing around with CNC.

By the way, Do you know where I could get some T-slot clamps for holding down the workpiece? I looked at the Sherline website, but I hate to pay $25 for two little clamps. I already have the T-slot nuts and some short cap screws (about 1/2" long), so all I relly need are the actual metal clamps.



Fred in NC
03-30-2005, 11:58 AM
James, glad you got such a good deal on the card and software!

As for clamps, I am not sure what size you are talking about. Enco and Grizzly carry most usual sizes. For small nuts, clamps, etc. try www.littlemachineshop.com - they have good service and prices, and some specials that are worth looking at.

03-30-2005, 01:59 PM
Thanks Fred for the info. I think I will have a camera this evening, so hopefully I can get some pic's up tonight.


Fred in NC
03-30-2005, 02:08 PM
Clamps: I could not find small ones for my x-y table. I made a few from 1/2" x1/8" steel from the hardware store. I just rounded any sharp edges. For example, I made a set from 2" long bar, 1/4" hole in the middle, one end with 1/2" bent at 45 deg angle. I think the bolts for this one are 5 mm. List of sizes with drawing for tnuts:

03-30-2005, 02:20 PM
Thanks again Fred. I was just looking at the LittleMachineShop website. They have a lot of good stuff for the small lathes and mills. Pretty good prices too.

I thought about making my own clamps, and will probably do that this evening. I have 4 T-slot nuts and 4 capscrew bolts, so if I can mill out 4 pices of steel, I should be good to go.


04-08-2005, 04:21 PM
Hi, I got a Spectralight Mill off ebay a little over a year ago. It came without the controller box or the ISA card, but I got a mill that was barely used and only to cut wax in a school shop. When I pulled the vise off the table it was black as new as if the vise was mounted in the center and never moved again. You will definetly need the ISA card if you hope to run from PC to controller to mill. I am not sure what year yours was made some go back as far as being Apple based then they moved to PC.

First thing I did was pull the unipoler steppers off (now in recycle bin awaiting possible lathe conversion ;) , then ordered the 3 axis Xylotex board and 3 surplus bi-polar stepper motors. With this setup I am able to run 1/8th microstepping. I still use the variable speed controller mounted to the front of the encloser for setting cutter RPM speed, soon I hope to wire it into the Xylotex board so I can code speeds and start/stops in my cnc output.

Only other things I had to do was wire up the power supply and mount it into a box with cooling fans and now I run straight out the PC to the board no ISA/Internal cards needed.

Total cost Mill w/encloser, Sherline Vise, Collet set, Hold Down set, Xylotex board, power supply and other odds and ends $586.00 including shipping for all ordred items. :wee:

System runs fine, I ran a pocket routine ( in hardwood ) with differing arc radiuses running in and out of each other into the shape roughly of a dog bone O=O , cut it out perfectly. I then took the same drawing and programmed a contour cut of the shape allowing a slip fit tolerance of .003", this cut perfectly as well and was right on for tolerance. When fitting the contoured cut piece into the matching pocket the fit was right on the money so much so that if you were to press fit them together all the way you would need to insert screws to grab with pliers to remove it.

I realize you want to spend as little as you can but you may find upgrading to a micro stepping board and newer stepper motors in your future, depending on what you want to do with the mill of course.

Please let me know how yours turns out and perhaps we can continue to share info over time on how our Spectralights are doing pluses/minues etc.

As for me I am now looking into the best way to go about sealing off the bottom of the enclosure to setup a flood cooling system, I think the tricky part will be getting the fluid to return to the tank from the bottom of the enclosure, but when there is a will there is a way!

Good luck with yours.



04-14-2005, 10:23 AM

Thanks for sharing. I'm glad to see that I'm not the only one here that has one of these neat little machines. I have the machine running, but not like it should. I'm having a problem with the z-axis. The stepper is really "grunting" to move it, and it's missing pulses, so the accuracy is way off. I've tried cleaning and lubricating the slides with light machine oil and I've adjusted the gib so that there was minimal drag, but still no luck. I guess the next step will be to swap the stepper with one from the x or y axis and see if I need a new motor.

In the future, I would like to upgrade to a controller such as Xylotex and replace the unipolar with some bipolar steppers, but that will probably a couple years down the road.

Sounds like you got a really sweet deal on your setup. I've not been able to do anything useful on mine because of the z-axis thing, but hopefully that can be fixed soon. I have a lot of little projects that I'm just dying to try.

Thanks again, Bowman, for sharing your info. I hope we can help each other get the most out of these mills.


04-14-2005, 03:45 PM
James, I know what you mean about the grunting sounds coming from the Z-Axis there are several reasons for this and I have suffered from it myself.

1) With the Spindle, motor, pullies and mounts for the whole headstock all on one side of the slide it creates an excessive amount of force to the front which is not counter balanced on the other side. I have seen several peoples DIY improvements to this problem with springs and counter weights. To me this is the biggest design flaw in the machine for its size. All that is needed to prevent the stalling which is the grunt telling you has happened is a small amount of force pushing up from under the headstock assembly to take a slight amount of weight off the headstock helping the stepper motor. I just put two finger tips on the end of the spindle housing on a positive Z axis move and with minimal pressure applied the grunting/stalling goes away.

I am still working on this issue myself but have found other possible reasons for it happening that I have yet to have time to explore.

2) 100 oz Steppers are not really that strong, they may be sufficient for X and Y axis but I am thinking of going to a 200-250 oz stepper for the Z axis. And depending on X and Y issues down the line I may up them as well.

3) Fine tuning of the Z axis is crutial to smooth movement. I believe Sherline has some new anti-backlash parts for all axis` you can install yourself as well. They also have CNC leadscrews for sale at Sherline not sure what the difference is so I can't tell if mine has them or not. I am thinking not since its an older machine. I had another user send me his details about how he solved similair problems if I can find it when at home I will post or email it to you.

4) Rapid speeds in +Z axis with weak motors can cause stalling and missed steps as well. Try different speeds retracting Z all the way to the top till you find the one that does not stall and then use it for you code for your Z moves, -Z moves can be faster since gravity is on your side going that way :)

5) Perhaps your contoller card is not working if your missing pulses. A pulse that ends up a missed step is still a pulse, but no pulse means no step no matter what and sounds board related to me or perhaps there is an .ini file or driver tuning option in the software that needs adjustment with regards to pulse train and your computers CPU speed, or acceleration/deceleration speeds. etc etc

Note: I have also run into problems with my X axis making a grunt stalling noise when making rapid moves but usually only along the same spot in the table travel. After looking at the situation I felt that it was either my coupling to the leadscrew from the motor was too tight or if you look at the free end of the leadscrew it has a tendency to whip which must mean the threads are not engaging smoothly through the carriage and causing binding. Another spot I think would be a big improvement and one easy to DIY would be to have a mount under the table and hole with a bearing inserted mounted on the leadscrews free end to hold it in a straight line along its entire length back to the stepper coupling.

I see you said upgrading your setup might be a few years away. I know money is relative in this hobby but to upgrade to the xylotex board and a few surplus bi-polar steppers and maybe a stout one for up top plus a power supply shouldn't set you back more than 225-250 clams for alot of increase in performance and precision. But alas when i was in college I got to use big Fadal machines and now I am out of school and still struggling to pay for this hobby even with sherline sized equipment :violin:

Anyway glad to hear back from you, hope you hang through the curve of DIY CNC long enough to be able to sit back and be in awe of what it can do.


04-18-2005, 02:31 PM
In my previous post, I mentioned that I was missing pulses. I guess that was not the correct term. The pulses are being sent to the motor, but it's missing steps.

Well, I had a little time this weekend to do some troubleshooting on the z-axis problem. I'm kind of confused with what I found. When making z-axis moves, I've found that if I make any sort of movement on the x-axis, then all subsequent z-axis moves are fine, even at higher speeds. However, if I start out with no x-axis movement, the z-axis will grunt and stall. I tested this at multiple feedrates, through using code, by manual jogging of the steppers, and the results were always the same.

Other things that I've tried:

1) Swapped steppers between the x and z axis'
2) Adjusted the z-axis gib for minimum resistance.
3) carefully inspected couplings, ballscrews, nuts, and slides to make sure there was
nothing binding.

None of the things I've done has affected this problem.

Any suggestions.


04-21-2005, 06:36 PM
congrats on a nice piece of kit, thinks are better when their cheap.
z axis can you adjust the pulse width in the axis setup if so increase it ( in turbocnc
one of my machines is running 30,000 hz it's slow but reliable)
alternativley try a counterweight - basically this will help pull the head up look on some
of the mini-mill sites/posts to see how this is done ,but i'm shure you know what i mean.
finally clamps- make your own out of ali ( sorry aluminum)a good learning program and you have tee nuts already and on a mill of this size and power steel is overkill


04-21-2005, 09:14 PM
Thanks Mike. I am using a proprietary piece of software that came with the ISA controller card, but I'll look to see if there are any adjustments that can be made. I can't complain too much. Like you said, cheap is good.

I finally was able to get a few pics of the machine.


09-21-2005, 05:17 PM
Hey James..!
Any chance you could tell me how i could get around the card issue? :)
Or where to get an ISA card?
Spectra light mill on its way...not sure if the card is included... Help...

09-21-2005, 05:47 PM
I have the same mill fully functional, I have not done much of anything with it yet, its seems to work good and has the wslm 3 software, the controller initilization software and configurator. I will be trying to run BobCAD/CAM on it, as soon as i figure out what I am doing.