There is no problem using one motor I think most would use a nema34 in this case. You can buy the belts made to measure it might be an idea to have the belts lower down so as to be able to put long lengths of stock through the back etc.
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There is no problem using one motor I think most would use a nema34 in this case. You can buy the belts made to measure it might be an idea to have the belts lower down so as to be able to put long lengths of stock through the back etc.
Cheers, Just noticed your build seems to have a long belt on, Does it whip much on change of direction and whoa, there big pulleys, do they need to be that big? I was going for minimal?
Sorry, that last post was to njhussey, You posted to quick, I know I can get a belt long enough but I don't know if the flex/whip will cause issues such as catching the inside of the box section which I plan on using just because that is whats left from my cut plan :-) If theres a problem then I would rather rectify it now rather than buy stuff that won't work...I'm tight like that ;-)
The problem with big pulleys I am led to believe is the inertia that they have. I have no idea on how much the belt will sag but you can always add the belt cover when you have it up and running.
You will need to run a 70V power supply for the motors.
I'm running my Nema 34 on a 230V Kinco driver and at the moment it's running on 10 m/min rapids and very happy, had it on 15 m/min and was still happy but don't need that sort of speed. I got the 40 tooth pulleys as the Nema 34 has bags of torque and I wanted as much tooth engagement as possible...
I've not noticed any whip on change of direction...
Neil I thought you had used 230V but when I looked at your schematic I saw three drives connected to the PS did you originally go with nema 23 all round?
I've got an AM882 driver for a 4th axis as well now but did originally plan to use a Nema 23 on all axis as the calculator showed I'd be able to use it on the X axis but I decided to play it safe and go up a size.Quote:
Originally Posted by Clive S
Ah! that fooled me :beer:Quote:
Originally Posted by njhussey
Attachment 15966
On the schematic it only showed the two AC wires that were going to the driver, don't think I even put a representative box on it....:surprise:
I looked here http://www.mycncuk.com/attachment.ph...797357&thumb=1but didn't notice the 230V drive. That will teach me to assume. http://madmodder.net/Smileys/default/BangHead.gif ..CliveQuote:
Originally Posted by njhussey
I have been looking at the nema 34's and I am confused about the specs..
They all seem to quote a recommended voltage of about 2v, whats that all about? Would one nema 23 just not be able to move the mass because the 34's are quite a bit larger and wont fit in the location I have put it, which means putting 2 nema 23's one on each ballscrew which then also means a controller which supports slaved drives and controllers with error detection which means £££ ! I am trying to sell this to the better half as a bit of additional income but when I mention a couple of hundred pounds extra on top of my ever increasing budget she doesnt seem very impressed, I don't know why:stupid:
Charlie, what's the weight of your gantry complete with the spindle? If you put that weight into the motor calculator spreadsheet you'll be able to see if one Nema 23 will do it. On my gantry it was going to be only just ok (I've got more plate in mine than you have as I believe from the drawings you're using alu box sectio to mount your rails to?) so I went larger to be on the safe side. If you're borderline all it will mean is that you won't get the higher speeds of velocity and acceleration.
Well I have attempted to work it all out and this is what I came up with?
Aluminium on gantry 31kg
800mm rails+blocks 5.8kg
400mm rails+blocks 3.6kg
4 blocks on x axis 1.6kg
Z ballscrew+mounts 2.5kg
Y Ballscrew+mounts 3kg
x axis ballnuts 1kg
2 nema23 motors 3.6kg
CapScrews? 2Kg
Total weight 54.1Kg
Does that sound about right? have I missed anything. I suppose I need to look at the calculator now.
Cheers charlie
How about your spindle? You'll also need a bit extra for cable tray, cables water tubes etc....
Doh! I completely forgot about the spindle, Won't do much without one will I :thumsup:Quote:
Originally Posted by njhussey
Just had a look at spindle weight and it looks like 5.6kg, maybe another 1kg for cable and pipe so total weight comes in at 60.7kg
Quick answer to your question about "2 volt motors". Ignore motor voltage ratings. For all practical purposes, they are irrelevant. The control electronics are driving short pulses through the motor windings and include some clever controls on motor current, which is the important bit. The motors work using magnetic fields; the higher the current the stronger the field and the more torque you get out of the motor. However, the motor windings are coils of wire which have inductance. In this situation inductance is a bad thing because it slows down the rate of increase in current at the start of each pulse so you lose power. To get round this, you drive the coils with many times their rated voltage - maybe 60-70V for a nominal 2-3V motor - so the current builds more quickly. Then the current limiter in the driver reduces the applied voltage automatically during the pulse so the motor isn't over-driven. This all happens like magic and all you need to know about is the current limit setting in the driver module which should match the motor.
Neale Very good explanation much better than I could have done it:encouragement: ..Clive
Well, I've gone and done it, no turning back now....
Chester champion 20v milling machine ordered
steel for frame ordered
aluminium for gantry/frame ordered
welder borrowed
wife prepped
Bit lighter in the plastic pocket now but feel like it's something I need to do otherwise I will never get started!
I will get the frame and gantry started before I order the ballscrews and rails, I wont be making any fixings for them until I have them in hand just in case and once they are done I will then decide on the motors,drives and controller at which point I will need a lot of help :-)
Here goes, my steel and aluminium have arrived. My mill is installed and I've had a play with my evolution saw... It's bloody loud when cutting steel but I'm really impressed with it. I feel like I need to make a new build log and close this thread off now? Just one question though, how do you lot measure your large beams (eg. 1350mm) after machining, do you just rely on your machines açcuracy, I've only got a tape measure!
I was thinking about getting a 3 axis dro for my machine but connecting the 3rd longest scale to some round rail to make a large height gauge. What do you think?
Anyway here's a couple of pics and I'll see you all in my build log when I post it :-)http://images.tapatalk-cdn.com/15/09...7a557c43bc.jpghttp://images.tapatalk-cdn.com/15/09...0b377a8ae3.jpghttp://images.tapatalk-cdn.com/15/09...be8a3c226f.jpg
Tape measure is pretty accurate, more than you might imagine ;)
Very clean, where is all the mess from cutting!?
Not done much cutting yet, just facing the beams so they are square and using my tape measure for measuring ;-)
Spent about 3 hours today learning to weld...Think I need another 3 months and I might get somewhere! I kept getting the rod stuck , I managed to get it arc'ing probably 2 or 3 times and once it was arc'ing I could get it going again until I changed the rod and then it was back to square one :-( , am I using too low an amp setting? I am using 2.5mm rods and I tried the welders recommended setting of 80amps but the only time I got it arcing was at about 110amps. Is that too high or should I go higher still.
Better still, any welders in the Derby area want to help me out who needs the use of a mini mill :-)
Cheers, Charlie
Hi Charlie
I don't do a lot of stick welding as i have TIG but i do use it for rough jobs, you should be OK with the recommended Amps, what usually happens as you have found is the rod sticking to the job then you can't pull it off and it starts to get red hot so you have to release it from the holder. sometimes you can drag the rod across the job to initiate the arc but i prefer to peck it until it starts the arc.
if you get a sticky one that wont start just file a notch through the flux a bit further up and break the end off to expose the electrode and try again. you will get the hang of it.
Regards
Mike
Thanks for the reply, I have watched tons of YouTube videos so should be an expert by now :whistle:, I have tried the drag (strike a match) and tapping method but before I even manage an arc the rod seems to stick, maybe its in my technique, I will try again.
Cheers, Charlie
I'm not a welder but if you are having trouble getting it to arc, have you made sure the material is clean and a good conducive surface is exposed?
Charlie
Try practicing without the set set on, what you appear to be doing is not pulling the rod away to allow an arc to form, so tap the workpiece and pull the rod away about 15mm with the power on the arc should initiate, then lower the rod to get a stable arc.
re cutting to length, tape rule should be fine but i dont like the loose bit on the end so always measure from the 100mm mark and add 100mm to your required length, i clamp the rule with a rubber faced clamp.
Good luck
Mike
80 amps seems ok from my experience (a few 10s of 2.5mm and another so many 3.2mm). If between rods you cannot get it to arc, try breaking the flux around the electrode by hand. Careful, it is hot.
It really makes a difference when you have very clean metal both on the hot side as well as where you apply your grounding clamp. Also try to minimise the distance between the two.
Regards
George
how old are your rods ?
Warm the rods before using put them in oven or on radiator over night. Damp rods make a big difference has do cheap rods.!! . . . Damp Rods and cheap quality you'll always struggle if not experienced.
Practice on some scrap material of the same type your trying to weld.! Then When welding have piece of scrap at the side and strike up on this first to heat the rod.
I don't know how old the rods are cos my mate who lent me the welder gave me 3 full packs of different sized rods. I had another play today and I was able to strike the arc more consistently so maybe just a bit more practice needed.
I will try warming some rods in the oven and yeah I am practising on off cuts ATM. Wouldn't dare try it on my frame yet!
Cheers Charlie
It's definitely worth getting some nice new rods, they're not that expensive and make all the difference! I had some old rods and was struggling to strike an arc and I got fed up and bought a bix of new ones. You'll be amazed at the difference...now I'm not a good welder, in fact I'm pretty rubbish (bloody love my grinder!!!!!) but decent rods are a must :)
One oldschool trick is to strike the electrode and let it stick for a few seconds until it starts to "sweat". Then use it as normal. I would only use this method when emergency and out of good try electrodes...
Just a quickie to show my progress (Or lack of it!) My welding is improving now, still not great but better than before.
It seems I was upping the ampage to compensate for my complete inability to weld but now I have the hang of it the amps are set right for the rod size and the welds are starting to look like real welds [emoji3]
Cheers, Charlie
http://images.tapatalk-cdn.com/15/10...50dead5f3f.jpghttp://images.tapatalk-cdn.com/15/10...12d6bb08cc.jpg
http://images.tapatalk-cdn.com/15/10...8e5df54369.jpg
Getting there, welding still looks like pigeon sh*t but at least it looks like it will hold together now.
Cheers, Charlie
Sent from my XT1072 using Tapatalk
This welding lark is doing my head in! 4 weeks on and all I seem to do is weld, break of the slag and clean only to discover it welds on either the plate or box section but very rarely both together, my box section is getting thinner and thinner from grinding back :-( I am now also at the mercy of the weather so got knows when the frame will be finished but I need to make sure my welding's better before I start on the top rails. I keep watching youtube, playing about with different rods, amps and angles, bought a new visor with adjustable darkness so I can actually see what I'm doing but I think I just can't weld!
Cheers, Charlie
Stick @ it Charlie.
One of the reasons i opted for a TIG setup is that you can see exactly whats going on and you know the two bits are fused.
Frame looks good M8
Regards
Mike
Cheers, it's just so frustrating going over the same thing again, thinking you've cracked it only to discover its as bad as the last one!
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Charlie, my welding is the same as yours. I think I've cracked it and then lay a weld that's just attached to one piece...just keep at it. Law of averages means that although you might get through lots of grinding discs you'll get there eventually by having more goid welds than bad ones!!
I think it would be prudent to do some more test welds, try turning up the amps a bit and try to hold a short arc.
Good luck