Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: tmccub840840@gmail.com on November 02, 2016, 07:57:07 AM
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Does anyone have any experience with any of these brands? Im fairly new to cnc. My machine is a kit with nema 23 steppers. I recieved no info on. Ive been using machine about 8months now with little problems until i did some test wood joint cuts and im losing/gaining steps. Could that be my drivers going bad? It seems im losing power to my motors. The electronics i have are all cheapos from china so maybe the bob not giving quality pulse trains? I increased steps per unit and seemed to be no help. I machine hard woods and some aluminum, what is a realistic feedrate/ cut depth for a spindle that spins 24000? Thank you all for any suggestions.
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Do not increase steps per in an attempt to fix - these figures once set will not change as they are hardware related.
Let me know what size and type of tool you are running and i can give a rough speed / feed for you, also spindle power, type etc
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Thank you davek. Right now Im using a 1.5kw huanyang but would like to upgrade this also down the road. I use these 6mm em i found on ebay and seem to work good for clearing. I have 4mm sinngle flute that work great on aluminum .06doc @30ipm spindle24000 and did nice but now it seems i lose in every axis. I use the amana tool 1/16 ,1/8, 1/4"ball em, 1/4" 90v bit. Thanks again Davek, much appreciated!
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Assuming they are carbide cutters, I would run a 6mm 2 flute end mill in aluminium at 24,000rpm, 1500mm/min 2mm deep and slotting or full-width cut. In hard wood something like 4000mm/min.
But you must clear the chips so air blast at a minimum really.
If your figures used to work and have now stopped, something is not right - maybe a seized bearing or linear guide?
It may be a failing drive - is it one or both axes that lose steps?
If one it may be possible to swap the connections to verify if the motor is failing or the drive is failing.
Is this an all-in-one drive board - all three axes on one board, I have not heard many good stories about them. Most builds and upgrades go for separate drives running from a breakout board.
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Yes, solid carbide.Going to do the look over and check the components. Had to shut it down and keep going the other day on another project. Just now getting time for investigation. Thanks man!
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It is 4 separate drives. 2 motors on y, 1on x&z. But seeing that it cost only 30$ for this breakout board and to top that i cant get any info on svt-3 bob (Ive ended searching for it), I must say im not impressed with the electronics that came with kit. I almost want to take it apart and tig weld up a steel base instead of 80-20
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Separate drives is good, may be worth trying another bob but first i would swap motor connections and see if the fault follows the cable(faulty drive) or stays with the motor(faulty motor)
If all axes are messing about it may even be PSU or the BOB or more.
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Im looking over machine all couplings are nice n tight, everything seems ok. Uppon startup I got lots of kerklunking on my slaved axis but now is moving along ok again. I dont hear any bearings sounding bad. I'll set up a test of cuts and have to run that to see.
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You have a slave axis - do you have homing switches and does it straighten the slave axis upon hoping?
Just wondering if that axis has become twisted somehow - this will put staring on the motors and bearings etc.
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I have homing switches but havnt figured out how to get it to straighten it. It should work if i figured out how to get both sides to touch and then back off. They just touch and stop. I tried adjusting all the homing settings but ended up not seeming to work with ul100 parallel to usb. I check the square after losing steps but its not precise cause i just manuallt turn ballscrew to make that side touch tge swith. Im probably going to invest in the next year or 2 into a quality prebuilt machine so maybe I will rebuild and improvise on my electronics. What is starring by the way?
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Ha, that was an autocorrect typo - it should say strain :)
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Haha, starring doesnt sound like a good thing if it existed. It drives me nuts to have the one side straining one side more than the other. Im at the point its like a window shaker ac for the motor driver and psu im using. I dont think im going to headache over it. Ill rebuild it better than it was shipped to me. Another thing that bugs me and I didnt realise but whoever put the bearings on the rails put all the grease fitting facing toward eachother making it impossible it purge out.
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You built this, what does your wiring look like? Shielded cables? Twisted pairs? Power wires routed away frm signal wires and only crossing at right angles? One ground point, no daisy chain of ground wires? Noise problems can make you think you have mechanical problems very easily.
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I ordered it as a kit. But for the most part i should have just built it myself cause trying to get ahold of the guy. My wiring is not the neatest, but its all sheilded 18/4 security cable. Thanks Gary, it is kind of a mess in my diy control box. I had no idea to run them the way you suggested.
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I used a solid 14g wire from power supply to drivers, then sheilded 18/4 from bob to driver, from driver to aviation plugs for motors to connect (should I take these out (would these create noise?) I have the sheilding grounded to the box. Would I have to install a separate grounding rod for emi grounding?I will make some time to create a new control box and route the wires as you stated. Thanks a lot guys for the helpful info. It will be a few days before i gert another chance to go mess around with it.
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Personally, if it was working ok and is now losing steps and you have not altered wiring then I would not look at wiring apart from checking for loose connections.
Wiring would not suddenly go bad :)
Of course, if it has always been dodgy and lost steps then by all means modify. tidy, correct the wiring.
Unless its a plasma cutter I would not look at grounding rods.
The plugs should be ok as long as you have not created ground loops by connecting both ends of the shielding to ground :)
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I was very confused on this and grounding for emi. What i did is I attached the sheilding on the cable from driver inside the box to tthe nut that secures the av plug. Then from motor cables I attached the wire to the plug also. So it is grounded on one end inside the box and one end on the motor wires, grounded to their own plugs. I hope you can understand that.
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My wiring could be neater also.
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So you heavenly one end connected to ground but that point is at the plug/socket?
It should be ok like that, motor cables do not even need to be shielded really - they are higher voltage and current connections which are generally immune to interference and also emit very little as well, i don't think that area is your problem.
Has it always been dodgy/losing steps or is this new behaviour?
Even messy wiring can work, its not ideal but I have seen a complete rats nest of unshielded wiring in a commercial plasma table controller that even shocked me, and they were being sold like that!
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Its only lost steps when i have pushed the envelope. I can take some pictures of the last test cuts i did. I've been over the program in aspire and it is the way it should be. The problem that came up is new and has not happend. Ill update my progress, thanks for the help.
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If its only losing when pushing it , that sounds pretty normal to me, there is only so much the motors can do.
As you say, its a new issue so i would not be looking at wiring. ;)
By the way, the picture below is of a so-called commercial plasma table controller, a perfect illustration of how NOT to wire up :)
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Woah that is crazy they get away with selling that. I'll take a pic of my box when I get back this evening. Not nearly as messy
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This is the first test I did of a wood joint I made in aspire for cabinet door frames. Im losing steps in the pocketing successively and that would be from my y axis motors. Im kind of in belief that my gantry is too heavy for that kind of speed and accel but if this is the case im better off with a chisel.
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Test 2. These cuts are at 18000 rpm 6mm carbide 2flute 70 ipm and .06 on cherry wood. Seems sluggish to not be able to run a tool at the appropriate speed.
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This is test 2 the last one is hhow the parts should be, I would not place that tab on the dovetail like it is here in my test. The last one is showing how its losing in the x axis for starting the cut in the wrong spot and hacking both the parts too short. Same as the first chopping out the smooth part of the tail board. I can attach a dxf of my wood joint for anyone that wants to try. Dxf file and you just position your two 3" wide boards at a 90in your cam program and align a vertical guidline to the edge of the boards. Then useing layers separate the two sets of lines and the rest is quick trim tool and maybe some extend to common point. Just ask and i will get it posted up. i used a .3 radius for curves for a .25 or my case cheapo 6mm em Thanks a bunch Dave
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What is your acceleration set for in motor tuning?
May be worth trying the 1/10 rule - say speed is set for 5000mm/min then acceleration would be set for 500mm/s/s - its not a hard and fast rule, just something i have works great as a starting point.
How big is the machine? For some odd reason i was thinking small but it looks big :)
I see motors are Nema23 but what size 3Nm, 4Nm ??
Current settings in the driver?
Is it rack & pinion ?
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The machine has a cutting area about 37"x19" . Its kind of a beast as far as weight of the gantry. I have my motors at 1600 steps per, 5mm pitch ballscrews on all axis. Driver is set to full current. They are 425oz/in bipolar steppers.
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Ok, thats a 3Nm motor then, should be ok on screws, is that direct drive or belt drive with reduction ratio?
Any chance of a picture?
Is it skipping on the axis with slaved motors or the one with a single motor?
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Can you see with the pics whats goin on? The screenshot in aspore is how it should look. I had it set at 1800mm min and 150 accel. I had tried accel at 250 but it lost its smoothness if you know what I mean. I was lost with these settings without some kind of data spec sheet. Thank a bunch for all the helpfull input.
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Here she is, messy but.......
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Sorry the pictures are not rotating as should.
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Direct drive
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I got a chance today to get out to the machine. I re routed my ul-100 and i increased my velocity to 4k and 400 accel. Just did test 2 again and seems ok now.
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Thank you Dave you have been a great help!
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Theres the test 2 file cut successfully