That motor diagram shows only two wires to the armature 'A' terminals which would imply it's a permanent magnet motor so no field windings to connect. Is the motor body slightly magnetic at all to a screwdriver tip?.
I don't think so. I think it just has 3 wires (one is a ground) but I'll check in the morning to be sure. If there are no field wires then I think I just plug in the armature ones and the AC ones into the controller and done if I understand correctly.
If there's only earth and two wires then they'll be from the armature/brushes and ignore the field terminals on the controller unit. Since the advent of cheap permanent magnets, field windings have become rarer: just compare the size of a compact modern car starter motor with a starter from a 1970's car with field windings. The modern one is about half the size and higher torque as the field is from permanent magnets and doesn't sag with the battery after a few tries.
Old DC motors had field windings for a variety of reasons (like no practical power electronics for variable speeds) so it was done with different modes of operation and it wasn't until the 1970's that the first ceramic magnets were discovered by accident and that made it much cheaper to bung in some permanent magnets for the field. Permanent magnet motors stay strong even as your car battery gets old and tired and gives reliable starting when a field winding starter with it's higher load would start to slow down as one example of the advantages. AC induction motors are a bit different, in my living memory an Australian/UK motor manufacturer Brooks Crompton Parkinson pretty much had the local small AC motor market sewn up. They found it economical to produce the one motor and give it different current rated overload breakers depending on the horsepower rating, so a 1, 1.5, 2, 2.5 and 3Hp motors of a given type were identical but had a different breaker and sold for different prices. If you changed the capacitors and the breaker you could upgrade the lower rated motor into a more powerful one. This meant the physical size was that of a 3Hp even if it was a 1Hp motor, i.e. a larger motor. These days a cheap AC motor is running on the ragged limit, with minimal copper, the magnetic steel running close to it's saturation limit (a bad thing for losses) and need a cooling fan even when not under load. There is no margins built into modern cheap motors to save a few cents in manufacturing costs.
Hmm well I hooked up the power as described. Only 4 wires no field wires. And I'm not getting anything. No sign that its working. Not sure whats wrong?
Is the run/stop/jog switch set to run and the speed dial off zero?. In the photo of the front panel it was set to "stop".
Yes I tested it a bit more. I think the controller is working. Looks like its putting out 93 volts but the motor isn't spinning up. I do remember many years ago I accidentally plugged the motor into 120v ac instead of 90v dc. I don't recall anything popping or even starting up. Is there something inside I should look at to see if there is a short/damage other than just checking the windings? I checked the armature and there isn't a graphite slide block but there is this odd looking spring? Any ideas if it is missing the graphite block or is this a model that doesn't have one?
It's got a commutator. Brighten up the commutator with 2000 grit, make sure the grooves aren't spanned with old graphite from the brushes.
Is this the right brush? 16-109 part number. I bought 2 of them. Hopefully arrives next week sometime. http://www.carbonbrush.com/bostonbrush.htm Also where does the graphite block insert into? I don't see where it would fit, I'm guessing under the brush spring somehow. I suppose I'll figure it out when they arrive. It's weird that both blocks are missing from the motor. There is a fine layer of graphite coating the commutator and other parts inside though so it must have had them at some point.
I just found this thread, good luck on this project. Single screw extruders are finicky-picky beasts at best - they're happiest in a continuous process.
Hmm interesting. Hopefully it works then. I originally made it to make wax sprues for casting because they are a major pain to make by pouring into molds and too expensive to buy premade. So hopefully it works for that purpose, or if not, at least work for mixing/extruding clay! Either way a fun project. The graphite brushes are shipped, so hopefully I'll get them this week sometime and hopefully they fit, and hopefully that's why the motor wasn't working.
When you get it running I think you'll find that you'll want to keep it running. Starting single screw extruders and getting them dialed in is a PITA. You've got a fairly simple process so it might not be so bad. Cereal extruders use the heat and the pressure to cook the dough, AND extrude a shape. You're just trying to use the heat and pressure to extrude a shape I once watched as the operators were having problems with the cutter that sliced the rope coming out of the extruder into cereal sized bits. They ran that thing for 45 minutes putting over 1500 lbs. of extruded cereal rope on the floor while they waited for the cutter to be fixed - because it was simpler and faster than stopping, cleaning, and restarting the extruder. If the screw extruder is doing its' job correctly you'll probably find that you need less heat at the discharge end, might even need some cooling. If you haven't already done so, you might also want to add threads to the drive end of the screw. When the screw gets stuck in the barrel you're going to want an "EASY" way to pull it out.
I have a hook slot cast into the screw that I can use to pull it out! Luckily I thought of that too at the design phase. Do you know what the tolerances have to be on the industrial stuff between the screw and the barrel wall? I think mine are about 1 mm clearance between the barrel wall and the screw. I had it much tighter but after I welded the barrel and it warped I had to remove some off the screw to make it fit. I've been worried it won't push material out if the gap is too big. I also wonder about cooling and heating. For wax I'm betting that I'll need to heat it from a cold start to break the sticky hard wax tension then maybe once its going need to cool it. I bought several programmable temperature controllers and pipe heating rings to experiment with.
0.040" is a LOT of gap, the wax is going to want to squirt back down the barrel to the low pressure end. The screw/barrel tolerances should be tight, the higher the extruder pressure, the tighter the tolerance. Our new extruders run in the 3000psi range, I don't remember what the old single screws ran at, but it was the same product so it was probably a similar pressure. At our pressures that crap will squirt out of ANY place it can find. Where you welded in the square tube would be the low pressure end and is not AS critical. You are doing a "low" pressure extruder, so it might not make any difference. I'd say try it and see if it poops out wax straws. You don't really care how efficient the extruder is, just that it poops out wax - from the right spot. If it doesn't there's still some things you can do to fix it: 1) Can you get the barrel in your lathe and use a steady rest so that you can grind that out the offending area? Maybe using a long nosed die grinder? You wouldn't really HAVE to do it in the lathe, it'd just keep the barrel more concentric if you did. This would probably be the fastest solution. 2) A hone with really LONG stones, stones that can span the opening, might work too. Unless the stones span the opening there's a good chance that they'll get hung up as they cross the opening. 3) You might be able to make an adjustable lap too and use lapping compound, much like the model engine guys do to hand lap their cylinders. Run the lap in your lathe at really slow speed and hold the barrel. Be ready to let go of the barrel and shut down the lathe if it grabs. Just be aware that lapping is REALLY slow, makes a mess, and takes forever - but it does work. 4) Ever hear of a D-bit? Custom build a ginormous D-bit and bore the cylinder back out to the proper ID. You might even be able to redneck engineer a way to do that in a floor mount drill press. This is the low pressure area after all so the fit isn't as critical. Once you've got that area opened back up to the barrel ID, I'd try building up at least the high pressure end of the screw and getting a tight slip fit in the barrel. Regarding the heating/cooling, you're right. We start out heating the barrel and running a lower feed-rate. Then you ramp up the feed-rate to the desired rate and get a stable process. By that point you're taking the heat off and starting to cool the barrel so you don't burn the product. With different products YMMV. You get this thing running and you're going to be making production quantities of straws. Then you can start getting fancy and make different shaped dies, round straws, square straws, straws with holes - the mind boggles. Don
Hmm I'm a bit stumped. The graphite brush blocks arrived. I put them in and connected them all up but powering the motor up doesn't do anything. No movement or twitches when powered. I did notice that manually rotating the motor shaft one way seems to be easier than the other direction. This seems to reverse when I switch the wires around to the dc controller. But otherwise I can't see any effect of it being connected. Is there anything I can do to further check where the issue is? I'm not sure where to go from here other than clean the commutator with sandpaper as suggested above.
There is a diode in the speed controller for "Back EMF" that conducts and shorts the motor in one direction of rotation and makes it harder to turn. That's proof that you have the brushes in correctly and the motor more or less works. The speed control on the other hand is not working possibly the enable/disable input needs some attention and is disabling the speed control?. Looking at your diagram there needs to be +24 Volts on terminal 9 for the run/jog switch to work properly, can you measure that terminal to ground with a meter and see 24v?, maybe test the toggle switch and see it's not broken by bridging terminals 8-9 temporarily. Ok so looking at the speed control actual photo and the diagram, the control in the diagram is a reversing speed control (4 x SCR's in bridge configuration, no back EMF diode)) where the actual unit doesn't appear to have that.....so you're going to have to check all the fuses on the board are good and see how the enable /disable terminals work (no terminal 9). Can you get a photo of the jog/run switch itself and where it's connected to the control board?.
Quick and dirty way to test the motor...Hook a 12v battery to the motor. If it turns it's the controller.
Hmm interesting. I'll give that a try. I actually have a 12 or 24 v car battery charger that would probably work too. I can test with that. I'll have a look at the controller but to be honest I'm not super confident I know how to test with my multimeter. I'll have a look and see if connections seem good though. And the fuse on the controller. Maybe thats blown somehow?
You could really do with the actual instructions for that exact board so you can see if the enable/disable terminals need a link for it to function. A multimeter would let you check any fuses for continuity too.
