Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: bennettdan on February 15, 2011, 03:48:35 AM
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Hello,
I have a purchased a Milltronics Partner 4 Milling machine and it has been stripped of the electronics all except the spindle motor. I already had some Allen Bradley AC servo amps and .73Kw motors for the axis that accept Step/dir and also +/- 10v for control.
I want to be able to have closed loop control and I was wondering what are my options I have seen the Ajax and the dspMC/IP control boards and I like them but I want to look at all my options before I descide.
Also like I said the machine had no servos so do you think the 1hp servos have enough power for this mill?
I will look into all suggestions and thanks in advance for the info.
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If you have DDM or DSD drives then using Step/Dir will give you closed loop between the motors and drives, so no need for Ajax or DSPMC.
One issue you may have is if using the parallel port then you will likely have to use electronic gearing in the drives as you will be unlikely to get the pulserate required from the parallel port. I use the SmoothStepper which allowed me to get my lathe from 3m/min with 2:1 electronic gearing to 15m/min with 1:1 electronic gearing.
Not sure the size of your mill but I tried H-3016 motors on my Beaver mill at 1:1 gearing between motors and screws and they were not enough, I ended up with 4030 and 4050 motors, but its a heavy mill so they might be fine for you at 1:1 connection if thats what you are doing.
I am however about to redo my Bridgeport as a test machine for different hardware and I am going to use the 3016 motors on it but I will be keeping the original 2.5:1 gearing that the Bridgeport had and it is fine in the initial tests I have done.
Hood
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Thanks hood for the info
I knew that I would have closed loop between the drive to the motor but I will not have feed back into Mach like the Ajax would have and I though that would be better to have to guarantee the steps sent where steps received or am I not understanding the Ajax system completely?
I have some 2098-DSD-005 drives and MPL-A310P-MK motors that have .73kw(1hp) of power at 5000 RPM max.
The Partner 4 mill is close to size of a Bridgeport Series 2 that I had a few years back.
I will look into the smooth stepper but I want closed loop back to Mach in case of missed steps.
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I dont think the Ajax will be true closed loop to Mach, it may have encoder feedback which if an error is more than a pre determined count then it will fault but not really closed loop.
I have the following error on my drives set to 20 counts and if it ever goes outwith that it will fault my drives and signal to Mach to halt. That means if my motors are ever out of position by (5mm/8000)*20 = 0.0125mm and I have never had that happen yet except when I was initially setting up the machines or I have crashed them.
The only advantage I would see from the Ajax system, if it is like I suspect, is you would not need to rehome after a fault as the DROs would get updated from the encoder.
On to your motors, I think you would need to gear 3:1 to have a chance of using them with a mill the size of a Bridgeport series 2, my other mill, Beaver NC5 is about that size and the 3016 motors I tried were supposed to be 1Hp with continuous Torque of 2.2Nm and they were not good enough at 1:1 gearing. Your motors are only 1.58Nm cont torque.
Hood
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Hood
The 3:1 would allow what kind of speed with the smooth stepper would you say I would get with the Motors I have on hand?
I don't mind it being a little slower sense this is going to be used in my home shop and I could always upgrade the motors and amps later.
What do you think would be the best torque/power motor for the Mill size I have with 1:1 gearing?
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I have just had a quick word with Brian as he was on his way out and he said Ajax and Galil are closed loop but not had a chance to querie him further as he was heading out.
Ok regards the motors, you will obviously get 5000rpm out of them so ballscrew would be going at 5000/3 = 1666 rpm so if you have the standard 0.2pitch screws that would be 333IPM you would get. Not sure what count your encoders are, think they are probably smart encoders but as the SS can pulse at up to 4MHz you should not have an issue there.
Hood
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Ok talked to Brian a bit more and from my understanding it seems how it works is Mach still plans the trajectory and passes that to the Galil (Ajax likely the same) and the Galil controlls the motors to keep them on track. The encoders are fed Back to Mach and the DROs are updated from that feedback but Mach does not actually update the trajectrory with that feedback.
So in other words it is the same as you would have with using the Step/Dir on the DSD's with the exception that there is no DRO update in Mach from the encoders. There will likely be encoder feedback at some point with the SmoothStepper but its not likely to be in this revision of it.
I can see a few benefits from the encoder feedback but in real terms it will not make your machine any more closed loop than it would be without them, well as far as the actual machining is concerned.
Where the feedback would be of benefit is if you had the drives disabled and the axis was moved then Mach would know, also if you E-Stopped then as long as your feedback was still active Mach would know the axis position, so it saves you homing but really that seems to be about it.
Of course this is just my understanding of my talk with Brian so it may be slightly different.
Hood
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You might want to look at EMC instead of Mach3 as your controller software. It closes the loop in the PC, and there are pretty inexpensive interface boards available to connect directly to +/-10V drives.
Regards,
Ray L.
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I do like the Smooth Stepper's output rate does it need an opto isolated breakout card between the Limit switches?
My drive manual states the drives have opto isolation on the Step/Dir inputs so I should be good their.
Also the motor data sheet states they have Multi-turn High Resolution Encoders but does not states pulses per revolution in the manual.
Would I loose position resolution if I setup say a 4:1 gear ratio on my Mill with the encoders of the motors that would be around 250IPM ?
Thanks for the help as usual
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I use a breakout board with my SS on my machines, more for the convenience of connection but also as a bit of added safety. I use the PMDX 122.
One thing I will recommend is that you convert the single ended step/dir outputs of Mach to differential, it makes them much more immune to noise issues.
Increasing the gearing mechanically will give you better resolution, think of it like this, if your encoder was 10,000 steps per rev and was direct coupled you would have 10,000 steps per screw revolution but if your gearing was 4:1 then it would be 40,000 per screw rev so a 4 fold increase in resolution.
Ok your encoders are sine/cosine and the default is 1024 counts per rev, you can multiply this in the drive to get over 1 million counts per rev if you wish but no need for anything like that ;)
I have these kind of encoders on my lathe and mills spindles and I just have them set for 1024 but if it was an axis I would probably be looking at multiplying by 8. If I recall you can multiply by 2, 4 , 8, 16, 32, 64, ...... up to 1024
Hood
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Heres a pic of the setup in my Beaver NC5 mill, the line driver is the board I made up to convert the single ended step dir to differential, I made it so that it hooks directly into the PMDX breakout without wires.
Hood
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Hood
Are you using an a negative voltage supply with your single end to differential Driver?
I have some chips here that have 55mv to 4.95v single to different on a single 5v supply but 0 to 4.95v with a negative supply.
What are the Chips you are using with your line driver?
I have on hand some LT6450 from Linear Technology but they only have on channel input.
I was just going to use short shielded cable to tie mine together but I am open to try anything to help with reduce noise.
I will look into the PMDX boards thanks again for the help.
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The drivers I am using are SN75172N http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=630-875
The way I look at it is the DSD drives can accept differential input so its best to supply it. I know quite a few people that have tried the drives recently with single ended inputs and have had problems, once they made up a line driver circuit they disapeared.
Hood
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Hood
Do you have a schematic for your interface or do you use a particular on from the app note?
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I should have a drawing somewhere for the PCB I made if thats what you are wanting?
Hood
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Do you have the Circuit diagram for it?
Yes the PCB layout would be great to have.
Thanks again
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I just downloaded the pdf from RS and used that for connection diagram.
Have looked here and cant find the drawing or code but I have given it to a few people so I must have it somewhere, it should be at the workshop, I will look tomorrow.
Hood
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Hood
Do you use any type of balance resistor between your Diff signals?
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Nope, not an electronics guy and I think someone once mentioned a resistor may be required but as it had been running happily for 6 months without issue I didnt bother.
Hood
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I just read your Balding Beaver thread and I like the servo for the spindle you are using that is what I plan to use on mine I think I will use a 5kw motor for my spindle it has a 7 HP motor now.
As far as the balance resistor I believe the reason we use them on RS485 communication is that is balances the load out over the long wire length.
I have found some 1398-009 drive amps and some J-4050 motors which are I believe overkill but are a good price the motors have 6.9nm of torque and 4000 rpm max speed.
I also have found a 1398-030 drive that would be nice for the spindle motor but have not found any motors for the spindle yet.
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Have attached the code for the PCB I made, it says .5mm dia cutter but I actually used a 60 degree engraving cutter in the end.
Have also attached an iges of the board, just have to make sure you make it the right way round ;)
Presume thats H-4050 motors? They should work 1:1 but you may need to get some active shunts for the drives. I think the 009 drives are micro drives so no shunt circuitry in them. I have 020 drives and I still needed the active shunts to get the best accel I could, see pic.
Hood
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Sorry file was to big, if you want the actual file, PM me your email and I will send it. Also say what format you need, IGES? DXF? etc
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Hood
Sorry typo on the motors they are F-4050 ferrite magnet motors.
The 1398-009 are very much the same as a 2098-010 in size just older.
I was worried about needing active shunts and I will be on the look out for them.
I have been looking for the proper cables for my motors and they are quite pricey.
Did you use allen-bradley cables or did you make your own?
PM sent DXF is fine
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Ah ok, thought it more likely it was the H series as J is nearest to H or at least on our keyboards.
Yes have had a few of the DDM's but some of them were full sized drives, cant recall the exact model numbers of them though.
BTW the Giddings and Lewis DSM drives are the same just in case you find some and are wondering.
I made most of my cables up myself, on the mill I actually took the motors connectors off and made up a connection board as the mil spec connectors are very expensive, then a few weeks later I bought 3 motors from eBay and the guy sent a load of cables and connectors that he had ;D
Hood
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Hood
I also found that some of the reliance drives are the same as the AB drives.
Yes same thing here on the cables connectors are expensive and cable from AB are real expensive.
I will find some from some of the surplus guys around here eventually or make my own.
I did find a cable manufacture that makes cables for around 100 us dollars each.
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Yes, Reliance and also Electro-Craft, they were I think swallowed up by Allen Bradley who are now part of Rockwell Automation. If you see reliance or ElectroCraft drives be careful as there are ones that predated the DDM drives, think they are just DM and they are analogue only. I have a few of them but badged Osai who were also once part of Allen Bradley, they are a PITA drives as you need to get a motor and drive matched, there is a personality chip you can get programmed to match the motor but obviously that costs and when I was testing them out it just suddenly died and the module was wiped, was going to cost me £50 plus to get it reprogrammed but luckily the DSA drives turned up so I gave up with the step/dir to analogue idea :)
I bought a 25m reel of cable for around £50 I think from RS components and made all the cables up, I bought a load of the 45pin connectors for the drive from a place in the UK called Rapid, they had a clearance on and I think they were 10p each so the cables ended up quite cheap. For the power cables I bought some SY cable from eBay.
Hood
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Hood,
I have found the connectors for my drives they are made by 3M and some online suppliers.
I am still looking for the motor AMP connector part numbers for the F-4050 motors when I find them I will make me up some cables.
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I got mine from Allied. Amphenol I believe.
About $35 for the 19 pin encoder, $25 or so for the motor power.
I think I searched these #'s at Allied and found them.
Yup ... http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=MS3106F20-29S
Russ
Edit: I see Mouser has them also.
http://www.mouser.com/Interconnects/_/N-5g3y?Keyword=MS3106F20-29S&FS=True
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LOL you guys get them cheap, I was £70 or so for two, thats about $100 or so :(
Hood
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Thanks Overloaded for the parts #s is this for the F series motors?
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Yep, but there are different F series sizes.
4000 is listed in the pic.
3000 series uses a smaller MOTOR power connector but the ENC is the same on all (I believe)
Looks like the 6000 series might have a larger one thant the 4000.
All above are F series.
Good luck !