Hardware advice

This looks like something I could absolutely do (substituting LinuxCNC for Mach 3). I could pick up one of Byte 2 Bot's parallel port hats, and run a BoB to drive the original Bridgeport electronics. However, it also seems like a lot of work to go through - just to rely on ancient, obsolete drives, steppers, and power supplies. In the end, I have an "oddball" system that is difficult to support. These original drives were also known to run pretty hot.

New stuff is not always the best either.

Some things were more consistently well-made back then (drill presses, vices, etc.).

Noadays, there's so much cheap junk that it can be had to find the good stuff, though it is there somewhere.

Though old electronics and software are generally garbage compared to modern stuff (though old Apple stuff is still pretty good).

Old engineering is also pretty bad.

The main reason some old tools are so sturdy is that nobody actually bothered to calculate how strong they actually needed to be, they just roughly overestimated.

If tools, cars, etc. were still overbuilt out of metal, we probably would have run out of steel by now!
 

I bought a DM860 from here: www.aliexpress.com/store/1102633485

It's pretty well made.

Not phenomenal, but good.

It works well and is much smoother in operation than the really bargain-basement drivers.

See what you think:
www.aliexpress.com/store/1102633485/page...p_sortType=price_asc

"www.omc-stepperonline.com/ys-series-3-ax...ower-supply-3-clys90
* Given the age of the steppers, many people are stating that they are likely weak - due to the age of their magnets and the type of magnets they used."

Also, while the stuff from stepper online looks nice and has nice aviation connectors, it has 3 switching power supplies.

Linear (Huge and heavy) are generally recommended because they are better suited to the spikey, noisy, intermitten current draw that stepper drivers exhibit, though either will do.

What magnets?

I'm 99.9% sure stepper motors have no permanent magnets.

Anyways, that can't be true; stepper motors are brushless.

Brushless motors should not, and generally do not, wear out.

I have absolutely no idea.

This machine has a huge cabinet for a power supply. That cabinet is full of transformers and such. I do not know if the power supply is "regulated" or "linear." When I look up those terms, they appear to refer to the same thing - a power supply that uses a transformer to regulate voltage, before rectifying and smoothing. What is the distinction I should look for? I'm positive that there are no modern switched power supplies in this machine.

I believe that this machine has several different voltages in the control cabinet. According to "Boss5" over at CNC Zone:
"You'd be spending your money in the wrong place. The original motors put out plenty if you feed them at the proper DC bus voltage and amperage. You should see 140 IPM with a 6 amp driver backed by a 160VDC bus. The matchbook sized hobby stuff is designed to run double stack size 34 motors, operates at relatively low voltage, and can generate about 200 watts under optimal conditions. Running torque starts at about 70% of holding torque values, and drops of rapidly with speed unless you have plenty of driver voltage to kick the motor in the rear and push out the constant torque zone (knee of the curve) to 1000 full steps per second and beyond, before it starts dropping. It takes serious voltage to overcome the winding inductance. If you are looking for 200 IPM, then spend money on new size 42 motors in conjunction with a proper driver.
You don't need a power supply, the stepper drivers of this style simply use 120 AC input. You can search ebay for used name brand American drives, like Pacific Scientific, Superior Slo Syn, Compumotor, or buy new China made product... goggle Leadshine. These are sold on ebay under various names, Keling appears to be a distributer that rebrands them. I'd go direct to the manufacturer's site, as it is very complete and they carry all the latest, not just old outdated models / stock. You can order online through their American distributor. Look for DM1182 or DM2282, these are digital drives sized for NEMA 42 steppers and you can buy the communications cable and download the programming software to tune for max performance, if needed. Runs around $200. A Gecko sets you back about ~$150, and then you need to build a power supply and provide a heatsink. If you want to save money, scout ebay and you should be able to find similar drives in the $75-150 range used from the previously mentioned American manufacturers, but they won't be digital programable, however robust for sure. Like I said, ditch the hobby stuff, get serious. Remember to wire the motor windings in series, they will accept 6 amps RMS (8.2 amps peak) without overheating, but make sure to use the current reduction when idle. FYI, the Bridgeport factory settings were 8.2 amps per winding unipolar, driven by 56 volts DC per winding. Wired in series, the heat load is identical to the factory setting if you use 6 amps RMS with a modern bipolar drive, and the windings will each see approximately 80 volts, thus the reliable top speed will increase to about 140 IPM, rather than 100 IPM. Make sure the machine ways are well lubed, it makes a difference."

I have no idea if any part of this machine works. I have not attempted to apply power to it, nor do I have access to 460V 3-phase power in my shop. It looks like the mice living in the bottom of the control cabinet might have been nibbling on some wires. Most of these sat in the corner of a shop for decades. They spoke a proprietary language, and the way you provided them programming was by a reel-to-reel tape drive that read holes on a punched paper tape. These machines were basically obsolete when they were new.

Sure, "they don't make 'em like they used to."

However, the benefit of modern China stuff is that it's cheap, readily available, and more-or-less standardized. If I replace the steppers and drives, I'll have the same steppers and drives that countless others run. That will make potential issues easier to troubleshoot. Also, if something fails, it's cheap and easy to swap in a new component.

The DM860 is exactly what I'm considering. It seems to be well-regarded. However, from what I've read, it will not work properly with my existing steppers. I would need to go with a DM1182, instead.

Most stepper motors (except variable reluctance steppers) have permanent magnets. Modern steppers use rare earth magnets - making them smaller, more efficient, and more powerful. Brushless motors also have permanent magnets. Their magnets are located on the rotor, rather than in the stator (the reverse of brushed motors).

I understand that a transformer-type power supply will produce less noise (harmonics?) than a switching power supply. However, does it make that much of a difference in this application? Has anyone had trouble with a LinuxCNC system working correctly on a hobby-grade machine, due to the use of switching power supplies on the stepper drives? I can certainly investigate re-using one of the power supplies this machine came with - apparently, several others have done this. The appeal of the switching power supplies to me is that they are readily available and modular. However, I'm not "stuck" on using them!

gm001 wrote:

Sure, "they don't make 'em like they used to."

However, the benefit of modern China stuff is that it's cheap, readily available, and more-or-less standardized. If I replace the steppers and drives, I'll have the same steppers and drives that countless others run. That will make potential issues easier to troubleshoot. Also, if something fails, it's cheap and easy to swap in a new component.

The DM860 is exactly what I'm considering. It seems to be well-regarded. However, from what I've read, it will not work properly with my existing steppers. I would need to go with a DM1182, instead.

Most stepper motors (except variable reluctance steppers) have permanent magnets. Modern steppers use rare earth magnets - making them smaller, more efficient, and more powerful. Brushless motors also have permanent magnets. Their magnets are located on the rotor, rather than in the stator (the reverse of brushed motors).

I understand that a transformer-type power supply will produce less noise (harmonics?) than a switching power supply. However, does it make that much of a difference in this application? Has anyone had trouble with a LinuxCNC system working correctly on a hobby-grade machine, due to the use of switching power supplies on the stepper drives? I can certainly investigate re-using one of the power supplies this machine came with - apparently, several others have done this. The appeal of the switching power supplies to me is that they are readily available and modular. However, I'm not "stuck" on using them!

You forgot the most important reason: Linear power supplies are really, really heavy!!!!!!

That's why everyone sells switching power supplies, the shipping cost for a huge transformer would be astronomical.

I would definitely avoid Ebay.

It's overpriced for what you get.

AliExpress has some low-quality stuff, but at least it's pretty cheap.

I suppose making your own rectifier could be fun, but an integrated rectifier is nice, easy, and simple.

Yep. I'm thinking that there's enough copper in this machine, to cover the cost of a significant portion of this conversion.

Transformer copper is nor worth much tho.

I think toroidal (I'm assuming the transformers in question are toroidal) transformers are wound with wire made from some alloy that is more malleable than normal copper due to the fact that I think the wire must be wound onto the spool, unwound, wound onto the bobbin, unwound, and then finally wound onto the core of the transformer.

Source: www.peelscrapmetalrecycling.com/scrap-yard-in-mississauga/
"
NO 1 BRITE COPPER $5.95 lb
NO 1 COPPER $5.82 lb
NO 2 COPPER $5.45 lb
TRANSFORMER COPPER $4.62 lb
"

Since copper prices appear to be steadily increasing, likely due to increasing demand and decreasing supply (much of the world's useful copper has already been mined), you might be better off holding onto copper as an investment.

You are probably better off selling the transformers as-ison Kijiji or kraigslist or something.