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cheers no worries i have been advised that its been better to drive the ball screws with separate motors but then wired together so id there is any interference on start up the same goes to booth so not to sure now. I liked the idea of just bolting the motors straight up to the ball screws without having all sorts of belts and pulleys but having just the one motor would make some things easier. Another job this week is figuring out the x axis drive and what ratio i need to gear the stepper to.
Well who ever told you that is wrong.!! Problem comes from Mid band resonance and how the drive works out compensation and correction. When you have 2 motors connected to one drive it doesn't know which motor to apply the compensation correction to so it can throw the other motor into resonance.
I can tell you from experience that screws connected with belts are by far the best option and most accurate with least hassle other than attaching pulleys.
ok cool i will try work that into the design. is there a standard method for doing the belts i couldn't find much when looking last week?
No real standard way regards laying out as it's often machine dependant but regards sizes etc then there is kind of standard in that most use in HTD 5mm pitch belts and either 15 or 25mm wide. Pulley sizes will depend on if your having a ratio but from experience between 18-20T for 1:1 ratio is best. If you go too small you risk excessive wear and jumping teeth due to fewer teeth being engaged. Equally don't go too large on pulley size as the extra inertia will have a negative affect.Quote:
Originally Posted by charlieuk
Really this is something you should have worked out before ordering the ballscrews as you could have had the screws machined in such away that they suited pulleys and made life easier.
ok many thanks for that. is it best to drive one screw direct with the motor and then take a belt of that to the other side or have the motor central and run two belts to ether side or is there another way? i could do with keeping all the motors and belts down to the one end if posable.
This is useful, http://www.mycncuk.com/forums/machin...html#post43225
found this on google turns out i was searching the wrong name
is this the sort of thing i need to do? I only have 265mm between the centres of the ball screws ether side so the belt wont need to be that long
Ah ah think I drew that for someone on here long time ago when I used Rhino.!! . . . If not I've done something very similair for someone.
But yes that type of thing thou in your case I'd just offset the motor to one side for ease of build and neatness. Doesn't matter if it's offset with such a short belt.
cool that should be fairly simple then as i can get a pulley straight on the shaft and motors, i may have to put a extra pice of extrusion across anyway to take the motor mount so not sure go off centre is going to make it to much neater, i think i have a little ocd on things being symmetrical as well.
What i will also do is try and get the bk and bf blocks in line with the top of the alli so the stepper does not drop to far bellow the gantry. I would have loved the belt and motor to be all inside but that doesn't look possible with this design.
Jazzcnc, thanks for that, I've been thinking what's best for this kind of setup, too.
Helluva build, eh?
started to draw things up the hole y and z bit is proper complex and proving a bit of a head spinner but slowly making progress. just ordered a few bits from kjn to replace the main beam on the z with 80 x 80 and a hole load more t nuts. (You can never under estimate just how many you will need!) The aluminium while expensive is really good if you are not 100% sure on what you are doing as its so easy to go back a step or two if you forget something.
I have all so ordered a number of triangular corner plates to go on the table to give it belt and braces as there is the tinniest bit of movement if you hang from the arm.
While this is a huge machine and a bit of a different design im not sure it that much different to anything else except the x axis is very long!
im allso working on idea for the x axis rack and pinion set up/gear box. I have done a very very crude mock up, i have been told that it is probably safer to go for a fixed pinion setup rather than spring loaded as it is a lot less likely to go wrong and it is very hard to get enough pressure with out a very big spring. I am going to try and work some way of making a manual tensioner to help press the pinion up into the rack before bolting it up tight.
I Started to read the what motor threads and got to admit im wondering if i will ever figure it out myself! im not a great one for maths.
............
Hi Charlie,Quote:
Originally Posted by charlieuk
From the diy machine builds i've seen/read, i think they all used the spring loaded method when it came to the R&P. The build is coming along nicely, good luck with the rest.
.Me
cheers lee i will have to see if i can come up with something then as a few people have said it can be more effort than its worth as you need to have it under very high tension otherwise it can slip out the rack and then you get even bigger problems. I have been wondering if it is almost posable to get a pice of sprung steel that could work like a leaf spring that you could tension right up.
many thanks
i also spoke with cnc4 you and zapp regarding motors and drivers cnc4you recommended for the y and z axis ball screws there nema 23 3.1 with there cw6060 driver and zapp recommended there SY60STH86-3008B motor and DM856 driver.
from my very basic knowledge it looks like the motors are the same ? can any one give me any advice on the two drivers that have been suggested on which is better?
DM856 Digital microstepping driver
Stepper Motor Driver 6.0A 20~60VAC or 24~80V CNC Microstepping CW6060AC
many thanks
There's nothing between the motors. I would definately go with the digital drives thou in My experience I'd go with EM806 rather than the DM856 as they are worth the extra. They have better resonance handling and stall detection and just seem to run motors that bit smoother than the DM856.
With the rack I'd go with sprung loaded as it keeps backlash to a minium and lowers rack wear. Problem with fixed is you need to be very precise with rack alignment and pinion tension/engagement otherwise it wears quickly and can stick or bind causing motor stalls.
Sprung loaded is more work but more forgiving and if done correctly gives better backlash and longer life.
Cheers thanks for that, are the digital drivers cnc4you good alternatives to the em806 only that they have been super helpfully through my build andQuote:
Originally Posted by JAZZCNC
offer great backup and support from them so far.
I will do a little more searching to see what I can find for the rack and pinnion and come up with some sort of design unless zany one knows of something avalable for mod 1 rack? Many thanks
I understand what you mean regards supplier being helpful and it goes along way in my book too but you have to remember with any supplier they are always going recommend and Big up what they sell for obvious reasons. Helpfullness does also needs to be factored in but must say from folks I help and my own experience Gary and staff at Zapp are not unfriendly or awkard.!Quote:
Originally Posted by charlieuk
Regards the drives then Honest answer is I haven't used those drives so can't comment on them. What I will comment on thou is the things they don't have compared to the Leadshine EM806 or DM856 which can become a major issue in some machines, esp large steel machines and machines with slaved axis.? . . . Resonance handling and stall detect.!
Most decent drives, inc the CW6060AC will have Resonance handling features built into them and some like the CW6060 will have more advanced algorithms to deal with resonance than others but essentially they still do the same in that they use a fixed frequency range or field of view along the motors speed curve.
The Leadshine drives come with a COM port so you can connect to them via software and adjust the drives resonance parameters. This can be priceless if you have a machine that is resonant and happens to be producing resonant frequencys outside the drives compensation field of view or dipping in and out so causing irratic or rough running motors.
If this does happen on fixed range drives then your stuffed and stuck with it but with EM806 drives you have full and fine control of the resonance handling.
If your thinking does this happen.? Then yes it does, esp on large steel framed machines or machines running resonant drive systems like R&P. It's just that often people don't know they have resonance problems as the drive is doing some compensation whick masks it and they just accept that the speeds or way machine runs is just how it is.!! This is Because unless resonance is really bad it doesn't stop motors running it just makes them run rough or lowers the speed you can get from them before stalling.!
Does it happen Often then again some times yes, esp on cheap drives but people don't know it. In most cases then folks won't have a problem but if you do have a resonance issue then you'll be highly pleased you bought the EM806.!!
This takes us nicely into the Stalling motors.? The EM806 as a nice feature in that it detects motor stalls and provides a Fault signal which can be used to E-stop the machine. This for machines running slaved motors is Vital to me and after using these drives I wouldn't run any slaved axis machine without this feature.
There are other nice features the EM806 offers like full Current tuning control and fully adjustable Micro stepping and fine adjustment amp setting 0.1A but they are secondery to the other 2 features which IME are worth that little extra.!!
Between these features if you have any issues you can deal with them and tune them out rather than just having to Live with them.!! . . . Priceless.!!
I will do a little more searching to see what I can find for the rack and pinnion and come up with some sort of design unless zany one knows of something avalable for mod 1 rack? Many thanks[/QUOTE]
Hi, first of all let me say that I am a machine user(converter) and have never built a machine. I think that your giant will be awesome for the uses you plan. With regards to tensioning the R&P, I think the most simple way would be to pivot the drive and have an extended arm with an adjustable slide weight to let gravity do the tensioning. Perhaps this is just too easy, I'm sure I will soon hear why its a stupid idea, but I do love simplicity!!! G.
i was wondering about that but i from what i have been told it need to be under pretty high tension which would require a lot of weight or a very long arm to hang it from i guess.
Many thanks for that jazz although i am only just strating to learn about this side of it it does make sense what you are saying.
cnc4you have been super helpful and even dropped in to see them and they spent ages going through everything and offered full support on getting it all wired up correctly and running and even offered to switch parts over if for some reason i needed to so seeing as this is my first build that was quite reassuring. Im not saying zapp dont offer the same but i just have only spoke very briefly to them but they we very quick at giving me advice on the motors.
this was the digital driver i think cnc4u have added recently, i have no idea if it is suitable or similar to the EM806 you recommend
Digital DSP Stepper Driver 7.2A, 80VDC or 60VAC CWD872
when you mention slaved motors are you talking about two motors on one axis or one motor driving the two screw like i am having?
im happy to get the product from were ever but feel it would be nice to support kevin and brian if they have a suitable product as i could do with as much help as posable when it come to getting the motors and electronics up and running.
They are similair to the EM806 in that they use PID technology and can tune them selfs to the motors but they still lack the abilty to go in and tweak thru software in the avent of resonance problems. Now in practice it's likely won't have any troubles but if you do then you still can't do anything about it other than alter the Micro stepping which is less than ideal.Quote:
Originally Posted by charlieuk
To be honest IMO Leadshine lead the way when it comes to this technology and the others are either cheap copy's or better quality copies playing catch up. My gut feeling is these drives are ok Copies of leadshine technology but can't use the Software option for legal reasons.
Don't get me wrong I'm not saying these drives are no good because I've not used them before but they don't give the same flexabilty or features as leadshine drives. That said, it could be said, they don't cost the same either so your not paying for the features either and if you don't need them why pay for them.? . . . Which is fine if you can be sure your not going to run into resonace problems but like I pointed out before if you do you'll wish you'd payed £15-20 more to be able to tune it out.!
Being in business I applaued your attitude regards supporting helpful business or people and Having help and advise on hand is also valuable but hey you have a Forum full of help and I've offered my number so you have experienced phone support if you need it so I wouldn't compromise my machine just to carry favor.! . . You can still support them by buying other items from them, like there motors which are Ok.
I mean 2 motors working same Axis that need to run in sync. Imagine the carnage that happens when one motor stalls but other keeps going when 2 motors slaved to the same axis.!! . . . You need some way to tell the other motor to stop as well. The stall detect and it's fault signal provide this abilty.Quote:
Originally Posted by charlieuk
While the stall detect is mostly of benefit to slaved motors it is also useful to stop the machine when using single motors on each axis in case one axis stalls. This can often save the job if a stall does happen and your not around or quick enough to E-stop the machine before too much damage is done.
(Often Stalls happen at higher feeds, like rapid speeds, when torque is at it's lowest. So you can recover from stall before damage is done because rapid move stalls tend to just mean positional loss and are not engaged in the cut or material.!)
Many thanks for that info again, i will most likely then go for the EM806 drivers from zapp as it does sound like a worth will benefit as the machine is so big in the x axis.
cnc4you nema 23 were as zap call them SY60STH86-3008B, will they in fact be exactly the same? i will most probably get those and the rest of the little parts from cnc4you.
Zapp mentioned that it may be worth running a nema 34 on the x axis with possibly one of there 3 to 1 gearboxes which would allow a direct drive which may simplify things but not sure if i will be able to fit it all in like that without having to mount the motor up top and still have the belt that i was originally planning.
Does any one have any experience with the quality of the zapp gearboxes for the nema 34?
Many thanks again for all the help sorry for so many questions but i just want to be double sure on every thing as it is all totally new to me and obviously a lot of money involved in it all that is extremely tight.
Looking forward to seeing this beast up and running.
Your not the only one! so long as i don't go broke before i get it done hopefully it wont be too too long. Almost got all the plates drawn up on cad for the y and z but now looking for two suitable pulleys to use for the y axis that go ether side of the motor like in the pic i posted on the last page
tried ebay but cant think of what search to do to narrow it down? any ideas it just needs to have a flat surface and barring for it to run on.
Charlie
Just use as many bearings as you need to cover your belt width
mount them on a bolt and place shim washers between each bearing( on the id)
if you use a bearing say 30mm od 10 mm id and width say 9mm thats a 6200 very cheap and easy way of making idler pulleys
Ian
It's hard to say how good the driver from CNC4You is, as the description doesn't state what algorithm they use - just some 'buzzwords' which appeal to those who don't know so much about the subject. We can therefore only speculate as to which is best - e.g. the lack of software tuning could be a disadvantage, or it could just mean the drives uses algorithms to automatically 'adapt and learn', so manual tuning is not required.
I have not observed a tangible different between the two motors from the measurements I have taken.Quote:
Originally Posted by charlieuk
You appear to have ballscrew on the Z-axis, so the mechanical advantage to the motor to lift the axis is already huge. You definitely don't need and therefore shouldn't use a bigger motor on the Z-axis as it is important for this machine to have quite high feedrates, which you certainly wont get with a Nema 34 motor, especially with a gearbox.Quote:
Originally Posted by charlieuk
Arrr yes i totally forgot about that im sure now i have seen pictures of that just totally forgot i will defiantly do that many thanks.
Quote:
Originally Posted by Jonathan
Many thanks Jonathan for that i will see if i can find out more about the cnc4you drivers if posable but it sounds like all you lot use the others so hopefully all your support will be sufficient to get me out of any problems im bound to have.
the z axis and y axis is a ball screw and will be the nema 23 3nm . The long X axis is what they suggested the nema 34 possibly with a gearbox for as the gantry weight will be some where around the 60kg area sorry i may have confused you.
best regards
Sorry, that was my fault - for some reason I read 'x axis' as 'z axis'. The gearbox is a reasonable suggestion for X - you need something there (be it a gearbox or belt) to get sufficient resolution and better acceleration.Quote:
Originally Posted by charlieuk
no worries yes im going to see if i can fit the gearbox in as it will be one less thing i will have to have made assuming they are good quality.
sorry more questions
i am trying to find out what motor size i need for the x axis and to do so i obviously need to figure out what speeds i want to obtain from the machine.
From the research i have done i am aware that there is obviously a optimum speed for each material.
surfboard machines looks like they are cutting at around 10-12 inches per min or around 15,000 mm min which is obviously very fast i assume because foam is soft and the cutting path is very long.
for plywood which will be most probably the hardest thing i will be cutting it looks to be a third of that at around 5000 mm per min.
will this huge range be a problem?
i asume to get the high feed rate it will require a larger motor with more gearing?
from what i understand you have the cutting speed and the rapid speed which is what i under stand as the max speed it can travel when not cutting. is the rapid speed something you just find out when you get it up and running and see how fast it goes under no cutting load? or is it something that would effect choice on motors and gearing?
while i am not going to be in a mega rush to get things cut i dont waiting hours and hours and hours for it to cut a big surf board if posable.
best regards
Good idea and I've not seen any differance between the motors either so your good to go there.!Quote:
Originally Posted by charlieuk
Yes thats what I've done in the past and they are nice units Italian made I believe.? Just be aware thou the Nema34 motors don't spin as fast Nema 23 motors unless running High voltage drives(240V ac) so if your needing certain feeds rates for cutting your foam etc then be sure to select the correct ratio but other than that it's a good solution. Also be aware that the gearbox does make the overall motor/geabox length quite long so check you have room.Quote:
Originally Posted by charlieuk
Yes but it will be worth the trouble, don't look at the extra expense as costing more think of it in terms of saving money.? You'll only be spending one time not replacing and regreting.! . . . . To quote My Guru Ger21 . . "The cheapest way to get a good machine is to spend more money."Quote:
Originally Posted by charlieuk
ok so for the long x axis to get the fast speeds zapp have recommended the nema 34 8nm motor SY85STH118-6004B Nema 34 High Torque hybrid stepper motor
but said that the EM806 drivers would not be powerful enough so it would have to be the 2m2280n driver which looses the functions we have been discussing unfortunately. 2M2280N Digital microstepping driver
from a users point of view is it worth reducing the speed requirement just to run the other drivers?
while i want to build the machine to a good quality i just need to be careful the costs down spiral out of control.
If your going to run Nema34 motors then these are the drives you want. Kinco are good drives and while you won't have the abilty to tune out resonance they are still very good drives with advanced alogrithms for dealing with resonance and motor tuning so the chance of resonance being a problem is very very low. Also they provide a Fault output so you can use this to E-stop the system if you have stall just like the EM806.Quote:
Originally Posted by charlieuk
I wouldn't lower the spec to save money and these drives are 100% what you need with 8nm Nema34 if you want resonable speed from the motors. Also being 240Vac you won't need a power supply with these drives so you have to factor this into the mix. Obviously if your not using on all axis you'll need a PSU for the other axis.
Don't be tempted to try running smaller Nema23 motors with gearbox and heavy gantry running at high feeds because while the smaller motors may provide the speed and enough torque to move the gantry they will struggle to provide the torque needed to handle the slowing down and inertia of the gantry from higher feeds. The affect would be positional loss from steps being lost due to pushing affect.
Understand your point about keeping handle on the costs but The truth is that you can have high feeds but they do come at a cost. While 3.2 or 4Nm Nema23 motors run at 75V on the EM806 connected to correct gearboxs would work fine you would have to accept the fact they would be limited to what feeds/acceleration they can provide and the balance between working within an acceeptable motor tuning range and one that will cause miss steps etc will be a lot finer.
The High power Kinco drives and Nema 34 motors are the correct choice to deal with all the friction and inertia your going to encounter using R&P with gearboxs and heavy gantry and in the long run they will save you money by not needing replacing if you found the smaller setup just couldn't cut the mustard.
Unfortunatly if you want the best possible machine your just going to have to lube up Bite down hard and take it like a Man.!! .:dejection:
Cool that makes scene so will go with
nema 23 3nm for the y and z axis with the Em806 driver and the 8nm nema 34 with the 2M2280N driver
love the idea that the 2M2280N dont need a separate power supply as its going to be one less thing for me to worry about.
i dont suppose theres a driver that does the same for the other motors even if they were a little more, just thinking it would be one less wiring and things for me to learn wire and understand?
Just trying to sort out how i am going to do the x axis drive, i need to get about a 6 to 1 ratio. i was looking at the cnc router parts gearboxPRO Rack and Pinion Drive, Nema 34 | CNCRouterParts but they don't do it for mod1 rack is there anything similar available else were? Unfortunately i don't have any form of mill at the moment to make any parts so i am having to get most parts of the shelf.
Don't know of any that use 240Vac but I believe you can get versions of the Am882 and EM806 that will allow you to use AC voltage rather than DC so you can just use the correct size transformer without having to rectifie to DC and use smoothing Capacitors. That said building a DC toroidal power supply isn't difficult or rocket science.Quote:
Originally Posted by charlieuk
just to give you more of a idea on what i am planing to use the machine for
here is a hand shaped board hopefully the machine will do this hole process for me and give me much higher accuracy and control over the shapes
I have a helped someone in the past who lives near me with noise issues who shapes foam moulds for custom car body panels with a much simpler setup that what you have planned. See is video below of what he makes and the machine it's done on. (Which by the way I've had nothing to do with making the rough arse thing. . .lol)Quote:
Originally Posted by charlieuk
https://www.youtube.com/watch?v=cv-FrT0fA-c
https://www.youtube.com/watch?v=Vw1KXIgT96s
Thanks for those vids i had not seen them before if i can get that sort or accuracy on foam i will be more than happy i gess it comes down to the wood were the extra money spent will be noticed. I am hopping one day to make some moulds for boards and other things as well if it does turn out to be fairly accurate.