DC motor help Barber Coleman Lathe

Hi All,

I have posted in the general section, but likely should have started here for direct advice.

I have a Barber Coleman 1610Tx42 lathe, 1961. It has an old drive with thyratrons in it. It is quite a piece. I was told the drive was bad, the motor is good. I have no proof of either, this is from the former owner who is trustworthy. Not sure what to do here but I would like to see what my options are. I have a couple of other smaller machines that will be using 220 3 PH so I am considering buying a RPC and a drive for the Coleman, just not sure which one or the best route. I am just completing my shop, the power will be on within 10 days: 220v single phase, 200A.

The motor specs are:
240 Volt, FL amps 28, field volts 240,
Feld amps: 1.32 / 0.26.
C Rise: 70
Frame: B286A
MFR: The Louis Allis Co. Milwaukee, Wisconsin

I have seen comments regarding the VFD but I am not sure they would be right for this machine. Galco, BICL and American Rotary are referenced quite a bit here.

This looks like a great old machine so I am hoping to get it going. Any advice would be appreciated.

Thanks,
Jim

Your shop is going to be powered by 240 single phase and the lathe needs 3 phase input to run. According to the tag the control circuit voltage is 120 volts. It doesn't say any thing about DC so if the motor is DC then the machine is going to rectify your 3 phase input and deliver the correct amperage and voltage to the motor. The previous owner had a problem with the machine, so there is probably a problem, if it were me I'd wire the machine 3 phase, check the input voltage to the control circuit, make sure it is 120 to ground and trouble shoot from there, see what works and what doesn't. Be careful checking live circuits, don't touch anything, use your volt meter probes to do the touching and make sure hands are not on the steel probe part. Keep us posted about your progress and how you do your test, photos are a great help. You mentioned that you were considering a frequency drive, I hear they work great, I don't have any experience there. I build a home made rotary phase converter from a 3 phase motor. Good luck again let us know. Tim

Hi Tim,

I will be following up ASAP when I get power. The plate here was for the input to the whole system, I will post the motor plate as well in a minute.


Thanks,
Jim

Looked at your photo of the tag again, it says 220 volts three phase, that voltage can usually be anywhere from 208 to 240, so I used the 240 in description, same with the 110 it can be 110 to 125 and I used the 120 as the description for that. If there is a tag on the motor that could tell us a lot about what the motor is. If infact if it is DC it will have brushes. So If you have correct input voltage to the motor and it doesn't run it could be as simple as needing brushes. DC voltage at 220 volts will melt skin or set your body on fire if your body makes a connection, USE CAUTION!!!! when checking those circuits live.

Tim

DC Motor

Hi Tim,

Everything I have says DC, which complicates things as you have said. Here is the motor plate attached, hard to get a decent image.

Jim

Motor Plate

Here are a couple more.

I just read your other thread and as you've said the tag is hard to read and yes it is DC. I thought the tubes in the power box might be they way they converted AC to DC, I sure don't know how they work, but they should have AC voltage in and DC voltage out. I also though I read that you have the schematics for the electrical sys.......if you do and can scan them in an down load them I am sure some one here, like matt_isserstedt's who is just brilliant with this electric stuff or maybe even myself, (can muddle through) can set you in the right direction. Very nice shop by the way, lost mine in my divorce but trying to get back to it.

Tim

Last two photos of tag are sure nice. I see that they are swapping the armature leads to change direction. There are going to be some pretty heavy contactors to power those connections. They will handle the current flow at 240 volts and 28 amps, if they are damaged corroded or pitted you might not be getting enough current across them motor could be sluggish if only getting some of the current it needs.

Tim

Hi Tim,

Thanks for your patience and insights here while I figure out what to post and refer to. I will definitely scan the drawings in and/or send them pm and on the site. I am happy to try to repair the system or if there is any risk due to age, to find a safe solution with newer technologies.

I am not looking to dump $$ but the machine was free.

Sorry to hear about your shop loss, hope you come into another one soon.

Jim

The Thyratrons should indeed be making DC, in much the same way as more modern SCR type drives. An SCR and a thyratron do very similar things in very similar ways.

The motor is DC, and by varying the triggering of the thyratrons the result is an effect somewhat similar to a light dimmer. With appropriate feedback and circuit design, it can work very well indeed. Monarch 10EE have been made with the same technology (as well as earlier motor generator and later BFD type drives).

Keeping the DC drive would mean some work... but replacing ithe drive with a newer DC drive might mean nearly as much, and using a VFD would mean replacing the motor entirely. Could be worth it.

JST and Bill,

I have confirmed through both the drawings that came with the machine and the physical labeling of the drive itself that this machine requires 220 3 ph to start with. I also found that coolant pump motor is 3 ph as well, powered thru the system. So it looks like some requirements are becoming clear. I think that a) finding someone to look at the drive, then b) finding a new DC drive if need be, might be the order. Last resort would be pulling everything and starting completely over ac. I will need 3 ph for other machines so are RPC unless I use Vfds on everything. Static phase converters appear to be out of the question and vfds will require some thinking on the 3 speed hembrug and the Colman. Does this make sense?

Thanks,
Jim

3 phase would be expected, there are 3 visible thyratrons..... The single phase WIAD monarch has 2 (plus 2 for the field).

The first thing to do is see if the motor is good. Check the brushes and commutator. If the commutator is clean and the brushes are not worn down, you can test the motor with a couple of car batteries in series. Disconnect the field and armature, parallel them, and hook it to the batteries with jumper cables. It may not develop enough torque to pull the lathe spindle, if not, take the drive belt off. It should run fine unloaded and come up to a resonable speed.

I can probably test and repair the thyratron drive. I am one of the few people left who worked on them when they were the only game in town. One of the few advantages of being 78. There are damned few others. Do you have a schematic? The picture only shows three thyratrons. Are there more? To get 240 volts from a 240 three phase line, there must be some diodes somewhere because you need to bridge rectify the power. I worked on one drive in a letter sorting machine in the Monsanto headquarters that had three thyratrons controlled and three just acting as rectifiers. Expensive rectifiers, but it worked well. If you want me to work on it, I can use my Monarch 10EE for a load. That won't pull full current, but it will be enough.

Bill

It would seem if you had 220 3 phase with it converted from single coming in , the workings of the electric in the box would convert it to dc . I may be wrong but what system would bring dc in at that voltage from the power line ? What's the advantage of a dc motor ? Seems ac is a bit better for machinery .

Thyratrons and the Whole Shop with a Phase Perfect System

Hi Bill,

Thanks for making me laugh. You and my father are cut from a similar mold. He was here this week helping me move everything in. I just spoke with him on the phone and he chuckled at your comments on knowledge and age. Sad in some ways but true.

I agree with all the troublshooting points below. It will take me some time to do this as the motor is large with little access, so it would have to be pulled. I was just out there staring at the system, there is a whole control system below the thyratron bank as well. Alot of hardware.

However, I will still need to generate 220 3 phase for the current drive so I am somewhat limited as to options for this lathe, as it needs a variable motor speed. There is no other speed control with it. Just Belt: Neutral : Gear. Everything was controlled with the pot.

So from all the comments it sounds like the cleanest way would be to supply power to the motor directly with a Phase Perfect system, which I think would run the whole shop. I am reading on them now and they seem to be able to provide three phase and DC power from a single phase input. I am looking at the systems on American rotary, Phase Converters | Power Transformers | Power Accessories | American Rotary

Thanks,
Jim

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The first thing to do is see if the motor is good. Check the brushes and commutator. If the commutator is clean and the brushes are not worn down, you can test the motor with a couple of car batteries in series. Disconnect the field and armature, parallel them, and hook it to the batteries with jumper cables. It may not develop enough torque to pull the lathe spindle, if not, take the drive belt off. It should run fine unloaded and come up to a resonable speed.

I can probably test and repair the thyratron drive. I am one of the few people left who worked on them when they were the only game in town. One of the few advantages of being 78. There are damned few others. Do you have a schematic? The picture only shows three thyratrons. Are there more? To get 240 volts from a 240 three phase line, there must be some diodes somewhere because you need to bridge rectify the power. I worked on one drive in a letter sorting machine in the Monsanto headquarters that had three thyratrons controlled and three just acting as rectifiers. Expensive rectifiers, but it worked well. If you want me to work on it, I can use my Monarch 10EE for a load. That won't pull full current, but it will be enough.

Bill

reedeprintice said:

It would seem if you had 220 3 phase with it converted from single coming in , the workings of the electric in the box would convert it to dc . I may be wrong but what system would bring dc in at that voltage from the power line ? What's the advantage of a dc motor ? Seems ac is a bit better for machinery .

Click to expand...

Reedeprintice,

You are correct. The orignal system converted from 220 3 phase to DC. I would have to convert 220 single to 220 three phase and then to DC with the current original thyratron drive. This becomes a problematic in my limited mind.

As I am realizing (a bit slowly btw), this machine needs a variable speed motor, as it really has no other way to change speeds as I commented to Bill just Belt and Gear. So i guess to keep this my options are the following:

1) Phase Perfect for the shop: If I understand this correctly - the unit will output DC and three phase from a single phase input. Seems to be asking alot. I figure I will be able to use a pot on the machine for the motor speed?


2) Switch to larger single speed 3 ph AC motors on the Colman and Hembrug and put VFDs on every machine I have and control each independently.


3) Get a Phase Perfect, switch to a larger AC motor and put a VFD on the Colman only, let the others run off of 220 3 ph as they were originally wired.


Likely my logic is off here somewhat with the Phase perfect, so please excuse and correct me.

Thanks,
Jim

reedeprintice said:

It would seem if you had 220 3 phase with it converted from single coming in , the workings of the electric in the box would convert it to dc . I may be wrong but what system would bring dc in at that voltage from the power line ? What's the advantage of a dc motor ? Seems ac is a bit better for machinery .

Click to expand...

Both have good and bad points. A DC motor will develop full torque at zero speed or very low RPM. The torque can also be very smooth if it is fed with a reasonably clean DC, while AC tends to be impulsive with the cycles. OTOH, such a DC motor is much more expensive for the same output and a really smooth one requires a complicated winding on the armature. Cheap DC motors cog badly because they have fewer slots and bars on their commutators. I recently worked on a Leblond Makino CNC mill with a DC spindle motor and was struck by the similarity of the commutator-brush layout to the 3 hp Monarch 10EE motor. The 3 hp Monarchs are big ugly mooses, but they have no discernible cogging. Smooth drive at 1 RPM.

For a variable speed application the variable frequency drive for an AC motor has even more components than a DC drive because they convert the incoming AC to DC, then use that to power a circuit that produces AC at different frequencies, so there is no advantage from that standpoint. Personally, I prefer DC, but that is partly because I don't like to work with switching transistors. I'm a mag amp guy, but that is a lone voice crying in the wilderness.

Bill

Thyratron drives on an RPC

Jim, I got a PM box full message. My PM box is always full, no matter how much I clean it out. Email me at [email protected].

Thyratrons are like snap action switches. Once turned on, they stay on until the voltage is removed, usually at the end of an AC cycle. Their output is controlled by waiting for some part of a cycle to turn them on, the earlier in the cycle, the more output. Then at the end of the cycle when the voltage crosses zero, they turn off and need to be triggered again. Whether one will work on an RPC with the manufactured phase varying with load depends on whether the timing for each thyratron is synchronized with the phase that particular one is running on or is from a single timebase for all three. The latter can produce some undesirable results.

The first thing to check on the thyratron drive is to turn on the power and see if they all light. The filament will only show a dull red glow which may be hard to see. If you can't, leave it on for a while, remember to turn it off, and see if they are all warm. The price of replacements may affect your decision.

Bill

No. Pp outputs ONLY 3ph. NOT dc. U still need a dc drive or new ac mtr and vfd

Ac motor May well NOT work as well as that dc! Learn more on that b4 changing to ac motor....

U missed another alternative; replace that old dc drive with a New modern one. We supply those all the for retrofits. I th ink we can even supply from 1ph as e if need be: fu ll wave rectify 1ph is prob ok compared to the tubes 1/2 wave....

Dam phone keybrd... meant all the time above. At least get price of a new dc drive so u have all the facts o compare options.