Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Gropper on September 19, 2012, 03:38:10 PM
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I got a Model BR2J Vertical Milling Machine with 1 - 1/2 HP that my dad left me, I was advised not to use the 3 steppers (1.8 degree - 1600 OZ/inch ) that I have, due to lack of power. Can this be right, the motors really look quite impressive with a little over 12 pounds each. I really would like to hear what the more successive combinations have out there ?
Leif
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1600 oz-in should be more than adequate for a BP. That won't be enough to move the knee without retaining the bevel gear drive, and adding another 4:1 or greater belt reducer. But it should be quite adequate for X, Y and quill.
Regards,
Ray L.
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successful combinations .... not successive combinations.... could that be the spell checker ...probably not . Thanks to Ray for the fast reply, Ill start make the stepper mounts then, and set the thing in motion HUH......
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I used 1200 oz in stepper on my 9 x 54 Knee Mill. It does not
have ball screws yet. My power supply is 72 Volts with Gecko
201's. Not a rocket ship but very stable.
olf20 / Bob
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Hi,
Well...do you think the ”reduced” speed was due to lack of torque or just too few impulses per minute from the controlling soft / hardware Bob ? Maybe you used micro stepping in some form which can really reduce speed a lot. Can you give an estimate on the table speed in feet per minute with those 1200 OZ/in
Leif
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Steppers are not fast on this type of machine when you compare to servos. It will be however fast enough for most, the downside to me of steppers is the low acceleration when compared to servos.
Ok what I had, on the first mill I did, a manual Bridgeport converted to CNC, was 916 ozin steppers geared 2:1, I then got the CNC Bridgeport and used the same steppers but it already had 2.5:1 reduction so I kept that.
Both of these had more than enough torque and rapids achieved were 2500mm/min @ 40mm/s accel or 2200mm/min @ 100mm/s. I settled on the latter as accel is much more important than rapids. If you have servos of the correct size then you can have both for example I can get in excess of 6000mm/min @ 800mm/s acceleration. So steppers are fine for most but doesnt matter what size you will nt get lightning rapids or acceleration.
Hood
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Hood,
I only intend to use the mill for smaller items ( 5x5x10 inches ) so the speeds you indicate are fine…. Anyway I can se the servos is necessary for professional use when time matters. Ill give those 1600 OZ/in steppers a chance now that they are at hand my friend. Did you get a huge improvement in accuracy with the second machine ( Bridgeport CNC ) I guess it had real ball spindles ?
Leif
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I'm don't know the ft / min but the motors were 1:1 via timing belt.
I'm not getting much speed from the motors (rpm low) so I
purchase pulleys to give me a 2:1 reduction.
I talked to several vendors and posted on here on the forum
before the conversion and all agreeded that the 1200 would
do the job. I'm not dissatisfied with the setup just fine tuning.
I have not had a chance to install them yet due to building a
new building and moving our business.
Hope to get back to this soon.
olf20 / Bob
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Both mills had balscrews as I fitted them to the manual mill when I retrofitted it.
BTW you do want to use microstepping, Gecko say 10 is optimum.
Hood
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Hi,
I don't really know if Ill microstep the BP Hood, Ill lose speed and who knows.... Probably also a bit of torque, and that ain't good in this setup, but Ill try it if the resolution is to coarse.
I'm looking forward to hear about your project olf20
All the Best
Leif
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What RPM are you expecting to get with these motors?
I have not used steppers for a long time but I would say if you got 1000rpm you would be doing extremely well. At 10microsteps that would equate to 2,000,000 steps per min, so 33.333KHz which should be easily achievable on nearly any computer.
Losing torque due to microstepping is a new one on me but as said I havent used steppers for a long time and have forgotten the little I dd know about them.
Hood
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If you have not found this site yet, you might take a look at
it. Bob offers great service and is always free to give you
advise. http://www.homeshopcnc.com/index.php?page=shop.browse&category_id=1&option=com_virtuemart&Itemid=9999
olf20 / Bob
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If you have not found this site yet, you might take a look at
it. Bob offers great service and is always free to give you
advise. http://www.homeshopcnc.com/index.php?page=shop.browse&category_id=1&option=com_virtuemart&Itemid=9999
olf20 / Bob
Bob? His name is Rick LaLonde.
Regards,
Ray L.
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Losing torque due to microstepping
Yes you loose torque, but...............
You'll need to do some research,reading and digest, in the proper context of what is said by the experts, on that subject.
Not some generalized statement out of context being echoed . Since I am not an expert i will keep from saying that
you'll loose 19% or so. ??? ;)
RICH
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Been doing some reading on the losing torque with microstepping and one very interesting comment was made by Mariss
"The page a little misleading. The table shows how much torque is required to push the motor 1 microstep out of position. The motor still develops its rated when it is one full step out of position. This is the same point a full stepped motor develops its rated torque.
Mariss"
Hood
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The primary value of Micro-stepping is smoother operation, not necessarily higher precision.
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Oh no..... My Mach3 wont run no matter what.... I get the " External Estop Requested" message in the status line . right now I only run the application without any milling stepper controller or machine connected so I dont have any external Estop I can press.... how do one get out of this loop please ?
Leif
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Change the active state of the E-Stop setting in Ports and Pins, Inputs page.
Hood
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Thanks Hood..... It solved my problem.... :-) Ill nip a little Scotch Whisky ..... You really saved my day...
All the best
Leif
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You are correct Ray, I did forget his first name. He is a great guy!!
Helped me several times.
olf20 / Bob
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Hood,
Interesting when one starts reading about steppers.
Will assume that you are reading some of Mariss's postings on CNC zone. That is what i meant by digesting the info in the context it is written.
Must also say, same goes for a lot of info from manufactures sites. So it can get rather complex quickly and one needs to appreciate that it's dynamic, ie; not one static condition that a general comment will hold true for. It's interesting because the drive used makes such a big difference and that the other associated components also come into play.
Guess my learned saying "one dosen't know how lacking they are until they get into the expertise of another" still holds true.
Off to the sidelines,
RICH
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Rich , I read a few papers yesterday and most said that there would be a reduction in torque if comparing full step to microstepping but it was on holding torque. Throw actual motion into the mix and the torque may actually be better with microstepping as it lowers the torque sapping resonance which full stepping would suffer from.
So as you say it takes a lot of reading to actually be able to form an opinion and even then the conclusion will depend on many factors, especially the hardware used.
Hood
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Relative to the original 1600 in oz mentioned, then a few comments can be made.
1. Nothing beats having another users practical use of an similar rated stepper being used on a comparative machine.
BUT
That is a rather limited consolation. The power source ( voltage & amps ) available, appropriate drive, motor specs, and mechanics of the
axis come into play.
2. Next will be what the machine will be used for and the users desired performance. Then the compromises start and alternatives weighed
in for consideration
3. Then the money factor comes about and sometimes puts it into perspective or restrains desires.
4. Decisions then must be made.
Shoot...........all they guy asked was if his stepper was appropriate. :)
RICH
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I bought this set a couple of weeks before I saw this Newsgroup, so Ill really just have to put them on to see first hand if they’ll be sufficient before buying another package. I had hoped the seller would have spend a little time tuning the part to work within the same performance envelope, but as RICH says, its nice to hear first hand from guys who have a machine / stepper combination that assembles the one witch is going to be retrofitted into CNC right… Thanks for your inputs… really appreciated.
This is the set I have ....
http://www.ebay.de/itm/3-Axis-Nema-34-stepper-motor-1600-oz-in-Driver-CNC-KIT-/270714833922?pt=LH_DefaultDomain_0&hash=item3f07dc8c02
All the best
Leif
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Those steppers will work, but their performance, particularly in terms of rapid speed, will far well short of stellar. Those motors are VERY high inductance, which, on it's own, severely limits top speed. Further aggravating the problem is the fact that the power supply, at only 60V, is WELL below the ~150V required to get the best performance those motors are capable of. My guess is you'll probably be limited to rapid speeds well under 100 IPM.
Though the drivers allow micro-stepping up to 256X, this is essentially useless. You'll want to use the 8X, or at most 16X setting, to keep your pulse rates reasonable.
Regards,
Ray L.
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Hmmm......
Dint Look like I hit the gold then, but Ill try them out next weekend and see what it all ends up to Ray, if the performance is under par, they will be used for a plasma cut project I have in mind... yes I know, I have lots of things on my mind LOL.... A plasma must go fast but I could build it with 2 fast ball screws like 16X10 mm. I have one of those CUT 40 plasma cutters from China and that little thing really impresses me every time I use him :-)
Leif
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OH.... I can see in the specs. for the 3 drivers that they ll accept 80 volt DC input, do you advice that ill buy three additional 80 Volt Switchmode supplyes for the steppers or are we just talking marginal improvements here ?
Leif
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OH.... I can see in the specs. for the 3 drivers that they ll accept 80 volt DC input, do you advice that ill buy three additional 80 Volt Switchmode supplyes for the steppers or are we just talking marginal improvements here ?
Leif
Speed will increase, roughly, proportional to voltage, up to a point. So, 80V will buy you 20-30% more than 60V, but then you also have to be concerned about whether that 80V rating has any real margin on it. If not (which is common in Chinese designs), then an E-Stop when the machine is running at full speed could blow the drivers. Personally, I wouldn't throw any more money at it until I saw how they worked. You can easily swap out the motors later, and with a better motor 60V might be OK.
Regards,
Ray L.
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OK Ray..... I know more next Saturday, I guess Ill need a couple of days to dig that Bridgeport out of 5 years of collected "gold" in my cellar :-) Thanks for your advice on the subject .
Leif
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Those steppers will work, but their performance, particularly in terms of rapid speed, will far well short of stellar. Those motors are VERY high inductance, which, on it's own, severely limits top speed. Further aggravating the problem is the fact that the power supply, at only 60V, is WELL below the ~150V required to get the best performance those motors are capable of. My guess is you'll probably be limited to rapid speeds well under 100 IPM.
Though the drivers allow micro-stepping up to 256X, this is essentially useless. You'll want to use the 8X, or at most 16X setting, to keep your pulse rates reasonable.
Regards,
Ray L.
Yes, after making the adaptors I tested the maximum speed and I don't get more than 420 RPM on the steppers, so I guess the only thing one can do here is changing the pitch on the ballscrews or accept the speed that they are cabable of right... Maybe 3 new controllers will improve on things ?
All the best to you guys.....
Leif
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Those steppers will work, but their performance, particularly in terms of rapid speed, will far well short of stellar. Those motors are VERY high inductance, which, on it's own, severely limits top speed. Further aggravating the problem is the fact that the power supply, at only 60V, is WELL below the ~150V required to get the best performance those motors are capable of. My guess is you'll probably be limited to rapid speeds well under 100 IPM.
Though the drivers allow micro-stepping up to 256X, this is essentially useless. You'll want to use the 8X, or at most 16X setting, to keep your pulse rates reasonable.
Regards,
Ray L.
Yes, after making the adaptors I tested the maximum speed and I don't get more than 420 RPM on the steppers, so I guess the only thing one can do here is changing the pitch on the ballscrews or accept the speed that they are cabable of right... Maybe 3 new controllers will improve on things ?
All the best to you guys.....
Leif
Changing the screws will likely not help, since faster screws will require more torque at ALL speeds. High voltage controllers *might* help, and might not. Your problem, as pointed out earlier, is those very high inductance motors. Replace them, and you should get dramatically improved performance.
Regards,
Ray L.
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HOW fast do you think you need to go ? That would be about 84IPM ?
Just a thought, (;-) TP
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Hi,
Id like to go from one end of the table to the other in about ten seconds, in rapid, but i m beginning to understand that Ill need servos for this kind of performance ......
Leif
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Hopefully you realize that BP kneemills were never designed to go that fast. You end up wearing out the machine in a hurry or possibly twisting the ball screws. Certainly you cannot cut that fast with a 1 1/2 hp slow spindle.
Sometimes you have to step back and think about what you are trying to do.
Just a thought, (;-) TP
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You are right TP .... Maybe I just expext to much after looking at those Utube videos shoving Japanese CNC machines :-)
Leif
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All depends if its a retrofitted manual or a CNC from the start. Not sure what the Servo Driven BP's do but my Beaver Mill was 8m/min rapids.
Hood
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Quite impressive speed ......1/3 of that would be nice on my oldie....
Leif
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Rapids are very nice to have but not when its at the expense of acceleration. With a servo system you can have both, with a stepper you cant, certainly not on a Bridgeport sized machine.
On my Bridgeport when I had steppers I could get over 2500mm/min( 100IPM) but the max acceleration with it was 40mm/s. I reduced the rapids to 2200mm/min and I could increase the acceleration to , if I recall, 120mm/s. There was a huge difference in machining time as acceleration is much more important for that.
I fitted servos to the same machine and could get 6000mm/min rapids and 1000mm/s, could have got a lot more if I had fitted active shunts but 6m/min is plenty for the wee table of the Bridgeport series 1.
Hood
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I have an old BP series 1 cnc. With the old stepper it maxed out about 85 IPM. Cutting was in the 20-30 IPM range. I put a set of 1kw ac servos on the girl. It would almost jump off the ground moving so fast .
STILL only cut in the 20-30 IPM range. It could move scary fast for an open machine. You could literally dance it across the floor
Point is it still is HP/RPM limited for high speed work so in reality it was a waste of resources to do the conversion based on work output and cost. BUT she was my baby for many years so cost be darned.
IF FAST rapids are your time saver then it is time to look for a better CAM system(;-) IT needs to spend more time cutting than ZOOMING around the table.
I would try what you have first THEN after you have mastered the process look into FASTER.
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Well BR549.....lots of good sense in those words, Ill stay with the steppers for now and see how they work and forget about the speed for now. I know the Hp decides how deep and fast one can cut. but every little movement takes time as you know.. :-)
Thanks for sharing your first-hand experiences Hood :-)
Leif
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Unless you're using the worlds worst CAM, rapids will amount to a VERY small percentage of your total machining time - typically just a few percent. As Hood indicated, higher acceleration is of more value for most applications, especially for 3D work, where low acceleration can increase your machining time many fold. 100 IPM is a perfectly reasonable rapid speed for a BP, and you'll gain little by going much beyond that. As Terry indicated, you start going too fast, and the machine will start shaking, and walking all over the shop. Plus, of course, when things go wrong with fast rapids, they can go very wrong, VERY quickly - before you have time to hit the big, red button. I have servos on mine, and it's quite capable of running 350 IPM, but I run at 200 IPM, because there's just nothing to gain by going faster, and the chances of a destructive accident are much greater.
Regards,
Ray L.
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(;-) Yes EVERY movement takes time BUT that is what CNC is all about when it is running it is NOT your time. You can be doing something else while it runs.
Add all the rapid times together and it will STILL be just a minor fraction of the total time to cut. Spending time to optimize the cutting is WHERE you save your time(;-)
(;-) TP
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OK Guys... Ill stay with what I have and try it out. Thanks for you advise on the subject. Ill probably be back with a little news on the project.
Best regards
Leif
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Hi Gropper, How are the Chinese Steppers working out for you, I was thinking about doing the same thing on a Series 1
R2C3 I just got my hands on, ( SEM DC motors are there but drivers and controllers are shot) ( was going to use MACH 3)
I am not interested in speed, I just want to be able to mill shallow grooves in plate aluminum for urethane molds,
I am new to this group and CNC in general so any suggestions from group also is appreciated.
I thought about keeping servos and using Dugong drives but I also want to be able to repair quickly if needed in the future, and I am not sure how easy and expensive it would be to find a servo replacement if needed
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Hi,
After a little tweaking, the set has been a nice surprise to me, the speed and precision is more than I ever expected, so I`ll recommend the set to anyone who need a good performance without paying a kingdom...... Make sure you have ball screws on the machine OK, those acme screws need a bit of software compensation almost every time you use your mill. The Long set I bought is OK for a Bridgeport, that's my opinion on the issue.
All the best
Leif
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I have 870in/oz Pacific Scientific Hybrid Nema 34 single stack stepper motors on my series 1BP.
I retrofitted ballscrews and run a 3-1 reduction. PS is 70v 800W(IIRC) and I run G203V drivers.
I get 80 IPM rapids and regularly cut at 20 to 50IPM.
870In/OZ in this setup has been plenty! No need for monster motors!
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Hi Natefoerg,
I guess the higher voltage and a bit better drives make your setup performing close to the Long set
that I bought on Ebay .....
All the best
Leif
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I can say that good brand name steppers and Gecko 203V drivers have left me with nothing but good performance. I can run for hours at 50ipm and never loose a step.
Very happy with my setup, and it was affordable. (I bought the motors surplus- new take offs from demo machines, I cant imagine what they cost new...)
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I tried a test with my Bridgeport....... drilling ten 1 mm holes diagonal on a piece of alumina
and the machine was set to repeat the hole process 125 times, all holes were totally
perfect, so no lost steps here either, but the geckos are fine .... I tried a set last year on a
mill from Taiwan.
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Well, maybe this test needs a little explanation to be understood..... the holes where diagonal to the milling table and the mill drilled the same ten small 1 mm. holes 125 times, and all were still perfectly circular after the entire process , I guess that's a pretty good way to look for lost steps.
Leif
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this would be a better test: repeat your drilling. then without moving the part put in a 1.25mm 2 flute end mill and bore your holes with it using basically the same program 125 times. a drill can deflect and follow an existing hole a bit. the end mill will not. and by measuring carefully, check the location of your 1st and last holes, see if they match the programmed dimensions.
another good test might be to mill a square, say 1" or so, on an aluminum block on the left end of the table then another on the right end of the table. use rapid traverse to get from 1 end to the other. repeat the program many times. after a couple repeats, end mill spring would be eliminated, you should no longer see any shavings after that if things are repeating 100%
nice to hear good things about the geckos, i am considering them too, although i am trying to gather the courage to try a servo setup which is a little more complicated for an electronic noob like me.
.
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Yes, I can Se your point about the deflecting drill, but if yo have a setup that loses a step once in a while, defelection is no problem...... you will soon See new rows of nice little holes here and there.... :-) the test with the 2 squared holes could be OK though , but I really don't experience anything indicating that I have any lost step at all. edges looks like laser-cuts.
All the best
Leif
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my point was this, Gropper. if a drill misses hole center by a thou or 2 or more it will follow the existing hole due to the angled edges. an end mill bores the hole and makes it round as reasonably possible, drills do not always drill round holes. the end mill, especially a short one will not deflect, if you lose steps you will see out of roundness in your holes. the orientation of the out of roundness might well reveal which axis is mis-stepping.
and regarding squares, i was actually thinking about square bosses, although holes should work as well. rapiding from one point to another far apart as possible then milling i would think would expose dropped (or gained, can that happen?) steps, i would expect the step error to occur in the rapid move which is the fastest move, and would have the quickest accel/decel, i might even do the test with the rapid in 1st the x, then in the y axis. then maybe in both. truthfully i have not built a single mach3 thing yet and could be totally wrong about this.
it is this potential to lose a step that can affect long running jobs, kinda makes me lean servo, tho i would appreciate anyone chiming in that has run a stepper system for long periods of time, both in hours/day and also over months and years.
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Gawd! Old myths just never die.... Steppers are every bit as reliable as servos *IF* operated within their capabilities. Exceed their capabilities, and they will lose steps. It seems everyone who's ever experienced lost steps on a stepper system wants to believe lost steps are just an inherent characteristics of steppers, but it is simply NOT true. Know your machines requirements, know the capabilities of your stepper motors and drivers, set them up correctly, and they should be absolutely reliable. Most people either don't design the system correctly (motors too small, power supplies not properly sized, drivers can't supply enough voltage or current, or setting velocity or acceleration too high), then blame the steppers. The fact is, steppers are used in industrial machines ALL the time, and they are EXTREMELY reliable. But you can't just pick a motor, pick a driver, find a cheap power supply on E-Bay, and expect it to work. And the same is true for servo-based systems.
Regards,
Ray L.
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Hi Ray,
Looks like a little China nerd had a pretty good sense when composing my set, I cant find any reason to make complaints, the set is running damn fine, so this time I didn't go wrong ...... :-) My set from Long is pretty low noise as well, nice when working near by ......
Regards
Leif
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"Gawd! Old myths just never die.... (regarding stepper motors losing steps)"
I agree with Ray on this, keep your acceleration rates, max speeds and cutting forces within the limits of your stepper motors and you will never lose a step.
I have a Bridgeport clone Mach controlled mill using steppers that I've run 1000's of parts on over the last 10 years and the only time I lost steps was when I crashed, and that's when you want to lose them. I kept the accel and max speed rates reasonable (60 ipm max speed) and the machine has been very reliable. It will bog the 3HP spindle before it loses any steps from high cutting forces, at least on 6061 which is what I'm usually cutting.
To be honest, unless you are doing complex 3D parts or fine engraving, servo's are kind of overkill on a BP mill, it doesn't make much sense to try to move them much faster than 60ipm so it mostly comes down to the faster acceleration you can get with a servo. For me the only time that's been an issue was engraving, to get square corners on small letters I have to go pretty slow but I don't engrave small letters very often so its not a big deal for me.
Paul T.
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Hi,
I'm at my Mom in the hollyday, so I want to use this moment to wish you all a Merry Christmas with or without the ones you love.... and remember,.... Be careful out there, in the snow and ice....
All the best
Leif
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Ray and Paul, thanks for the info on steppers, exactly what i was looking for. i am the noob here, a good machinist who has to (wants to also) retro his old fanuc control lathe to mach3, and knows not much about steppers. thats the direction i was leaning, i am not so sure now, i am getting some input that servos are not that much harder to do, and the concern i still have about steppers is heat and noise. perhaps these are also myths, i do not know. i am guessing steppers for my lathe would have to be in the 1800 oz in range, servos perhaps a bit smaller. i will disagree with Paul in 1 small aspect of vertical mill use. 90% of my work here at home takes place in a kurt vise, i bet steppers would drive my mill fine and be plenty quick enough (although it came with servos in the 1 hp range, i am not sure of this but its what others more savvy than i have told me) the other 10% might be noticeably quicker with the servos, that work can often span the 33" x 16" xy range of the table and includes many holes and features. my servo driven mill rapids at 120 or 150 ipm in xy, cant remember right now, and it accelerates very quickly. the beast horizontal i run at my day job rapids 1700+ ipm, and the advantage over my home mill running at less than 10% of this is obvious on jobs with lots of rapid moves.
Leif, thank for letting me play in your thread, Ray and Paul thanks for the info. Paul your point on engraving was a good one, tho it shouldnt affect my lathe much. now off to research the myth? that a mach3 driven single pulse per spindle rev threading system may have its limitations and what they may be.
a very happy holidays to all !!
ken
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Ken,
1800 oz-in steppers are HUGE. I can't imagine you'd need anything that size. And, such large steppers will be SLOW, due to high inductance, and high inertia. With servos, the continuous motor torque ratings will nearly always be considerably lower than comparable steppers, because servos are nearly always geared down 3 or 4 to 1. Servos essentially constant torque, and are typically capable of high RPM, while steppers always lose torque at higher speeds, often precipitously. So, steppers are usually used direct drive, while servos will usually be geared down. As an example, my 9x49 knee mill uses DC servos rates at 850 oz-in peak, 140 oz-in continuous, and can run up to 4200 RPM. With 2.5:1 belt reducers, driving a 5-pitch ballscrew, I get 350 IPM rapids, and enough thrust at cutting speeds to break a 1/2" endmill without losing position. A stepper conversion on the same machine would probably use steppers in the 900-1000 oz-in range. It would not get the same rapid speeds as the servos (probably top out at 120-150 IPM, being RPM-limited due to torque fall-off at high RPM), but would be reasonably comparable otherwise.
To properly design a CNC conversion, you have to know the required torque to move your machine, the inertia of the mass to be moved, and the target performance you wish to achieve. Armed with that information, you can design a drive system, servo or stepper, that WILL perform as wanted. Most people seem to just ask "What motors should I use", then buy something close based on the recommendation of someone who may have never even built a machine, pick some drivers and power supplies based on what they can get cheap, they they're surprised when it doesn't perform nearly to spec. There is no substitute for doing the math. Trying to "over-design", by picking over-sized motors is just as likely to fail, just for different reasons. The screws, reducers (if any), motors, drivers, and power supplies all have to be designed as a *system* to work properly. If any one is poorly matched, system performance will suffer, often badly.
As for heat and noise - heat is really a non-issue. Yes, stepper motors typically run hotter than comparable servos, but they are designed to handle the heat, so it's not a problem at all. Steppers are typically a bit noisier than servos, with a characteristic "whine" when running, and depending on the specific driver used, they may "hiss" slightly when stopped. This is purely an aesthetic issue, not a functional one.
On most jobs, very high rapid speeds should not make a huge difference in overall run time, unless you're using pretty bad CAM software. Rapids should be less than 10% of the total run time on most jobs.
Regards,
Ray L.
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I'm just now bringing up a low buck CNC conversion of my Clausing 5914 12" lathe.
I ended up using a size 23 for the X axis, the one Geckodrive.com sells, its a 400 oz-in 2.6 mH (ie 52 volt, 5A) motor with a 3.1" long body and dual 1/4" shafts. I liked this motor because its small and fits nicely on the bracket type I wanted to use but it has good RPM capability so it should work well on this machine for the X axis. I'll be using gang style tooling so the good rpm range of this motor will hopefully give me reasonable rapids for that.
For the Z axis I needed more pop as I sometimes drill steel so I used this motor from Automationdirect.com:
STP-MTRH-34127 1292 oz-in, 6.3A, .49 ohm, 4.14 mH -> 65 volts
I chose these motors based on their good power but low inductance, this means they should work well with Geckodrive supplies and their 80 volt max voltage capabilities. I'm going to start out with a standard 48 volt supply to keep initial costs down, if that doesn't give me enough pop I'll build up a higher voltage supply.
I'll let check back in with info on how well the machine works when I get it up and running.
Paul T.
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Hi titchener,
Please give us an update on the project when you've tried it out OK......
Leif
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now off to research the myth? that a mach3 driven single pulse per spindle rev threading system may have its limitations and what they may be.
Ken,
It was found that multiple pulses provided no advantage over the single pulse. RPM measured and used for threading is
to three decimal places and and thus better than you can measure. I would worry more that the lathe system has required accuracy.
RICH