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anyone willing to look this over and let me know if anything is drasticaly wrong?
total width of machine is 800mm so i'm wondering what the chances are of using a single screw??
and also is there any advice on what size motors to use on each axis? as everything is steel am i best just going for 3nm on all??
It's hard to give a definitive answer as it depends on so many factors, what you need to cut and how often, how fast, required accuracy, personal preference... etc
It's borderline, you'd probably get away with one screw as the distance between the bearing blocks is fairly small, but if you're going to be cutting metals at all regularly or just generally want to be able to cut at a good material removal rate accurately then get two ball-screws. You certainly wont regret it.
brilliant thanks for the reply... is there anything else that looks out?? i did wonder if the gantry would need any triangle/cross bracing from top to bottom outer corner?
what i might do to start with is use one screw and then if i find myself cutting or want to start cutting metal on a regular basis i'll upgrade to a second screw.
the chances are if i get the bug i think i'm going to get from this machine i'll end up re-building and making a bigger machine anyway as i originally wanted a 4'x4' machine but cant justify the cost until i can get this machine to prove itself.
thanks again for the input i'll work on locating motors, mounting plates and anything else thats missing, i can also start to work out screw sizes so that i can get a price for my missus from chai
I forgot to answer the motor question...
You could use less than 3Nm motors in places without reducing the performance, but 3Nm motors are by far the best price per Nm so it's hardly worth getting anything smaller, especially since the 3Nm motors would be good for the 4'x4' machine if you decide to make it. Currently the cheapest place I know of to get them is here:
Nema23 3.1Nm
Remember to ask Chai to make the end portion of the screw longer (25mm is good) to make it easier to fit and align the pulleys. This will of course mean adding a little to the length of the screws you buy.
The gantry is currently quite tall so it look like it could bend 'backwards' (parallel to X) relatively easily. It would be a good idea to add in some diagonal pieces as you said to combat that.
that site is now bookmarked than you for that.
i'm happy slapping some diagonal's in that wont be a problem...
i had already thought about the extra length on the end of the screws as i've seen u mention it a few times but thanks again for the reminder.
i'm quite surprised there's not much else to pick at tbh, now i just have to get prices and try get my missus to agree to part with some cash :D
electronics wise.. is this everything i am likely to need for my machine??
Upgraded Smooth CNC Standard 3 Axis TB6560 Driver +Box & 3Nm Nema 23 Motor & PSU | eBay
would it work out cheaper if i split them down and got the drivers from the place you recommended.. i'm not sue what size drivers to get and what size psu where as the above package seems to have it all included..
Nooooo... those are terrible drivers and bad motors!
The TB6560 driver only reliably accepts up to about 24V and you want to drive the motors from a much higher voltage to get the best performance. Ideally around 75V, so three times as much. For example:
Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com
(But shop around, that may not be the cheapest.)
The motors in the listing you linked to have a significantly higher inductance than the CNC4You motors. This will limit the torque you get at higher speeds since a high inductance means the current takes longer to reach the rated value, so at high speeds the current doesn't reach the rated value and hence you get less torque. That is also the reason for using a higher voltage - the current rises faster when a higher voltage is applied.
Edit: Just remembered, I posted a much better explanation here.
ok without wanting to annoy you i need to ask this for my own peace of mind..
what is wrong with running the motors slower? why cant you cnc at the speeds your equipment can cope with if it ends up being that you buy the cheap crap stuff??
i understand you are looking out for us and dont want us to make mistakes and end up needing to buy the better stuff anyway, and for this i thank you... but i just wanna know why not if it's easy enough to explain it in simple terms.
just from a rough guess i'm looking at around £100 more than i expected to pay for the electronics, so i just basicly wanna be able to justify it..
also i will look in to finding a driver i presume aslong as i get any driver around 80v and 7.8A they will do the job?? any pointers on a PSU?? and is that all i need to buy.. motors,drivers & psu? the kit i linked seemed to have other stuff
If it's sufficient to run your machine as efficiently as you need, then there's nothing wrong. It's just hard to know if it will be..Quote:
Originally Posted by wilfy
The motors from England and the drivers are cheaper than the kit you just linked to, so I see no reason not to get the better ones. The TB6560 is generally so unreliable I wouldn't even consider it an option as I guarantee you'll only end up getting better drivers a few months after buying that.
For the PSU a 500VA toroidal transformer, 25V(*2) or 50V is the best option, with a rectifier and capacitors.
Wilfy I have spent many many hours talking and helping new people to DIYCNC on the phone and via email and THE MOST COMMON (by a long way) single mistake they make is buying the wrong drives and PSU. The TB based boards are one of THE easiest ways to waste money and more importantly time, mainly resulting in frustration and disappointment.
To answer the question regards speed and what's the correct drives PSU to buy then the Honest answer is CAN'T ANSWER.!! . . . . .Until more information is known about the machine and what materials your going to machine.?
I help loads of people either on here on via the phone etc and When I ask folks what they want to machine they generally say "Oh nothing too difficult just MDF, wood, plastic and the Occasional bit of Ali" . . ERmmmm is my reply.?
Whats wrong with that you may think.? . . . . Well it mostly boils down to cutting speeds.!
Given the TB based board and 24V has a crude example.!! . . Out of all those materials you'd think the hard ALi would be the challenge.? BUT in reality given the machine frame is strong enough it will be the most suited to the slow TB based board.? Ali only requires low feed rates and the 24V will probably be ok. This is also why lots of small milling machines and lathes use 24V.
But Wood, MDF, plastics etc require high cutting feed rates so in general require the motors spin faster for longer. There are other things that affect feed rate like screw pitch but in general in these softer materials the motors are working faster. To enable this speed you need voltage and 24V (Excuse the pun) just doesn't cut it and available speed is low and therefore feed rates. Too low feed rates wears tooling out very quickly and leaves a poor finish.
Then you have the workload of the drives.! They are constantly MAX'd out and eventually this takes it toll and in the case of the cheap TB based stuff results in either poor performance in form missed steps etc or has often happens they die quickly by frying themselves.
The extra £100 is worth every penny and will enable a very wide range of cutting capability with the least amount of stress.
your right acctually.. i didnt look at the prices correctly
so PSU - 480W High Power CNC Stepper/Servo Motor Driver Switching Power Supply 48V10A PSU | eBay
i cant find anything that relates to the 500va i'm guessing that is supposed to be 500w?? other alternative is 600W PSU 48V 12A CNC Power Supply Stepper Motor Milling
drivers - Best Selling! Wantai Stepper Motor Driver DQ860MA 80V 7.8A 256Micro CNC Router Mill Cut Laser Engraving Grind Foam-in Motor Driver from Industry & Business on Aliexpress.com
motors - Nema23 Stepper Motor 3.1Nm x 3
total around £255 is that everything i need or do i need a breakout board aswell for pc connectivity??
thanks for that you replied while i was posting my previous post.. thats explains everything and kind of fills in the missing blanks that i couldnt get my head round.. as it happens using the info jonathan has given me i've pretty much match the earlier price but with the better componentsQuote:
Originally Posted by JAZZCNC
Wilfy, I've put this on your build log rather than hijack the other one. If your looking for a local steel supplier try doing a google search. I have just done a google search for "steel stockholders wigan" and up popped about 4 quite big companies. Probably more if I looked harder but there's a start for you. Guessing any one of them will offer you a better price if you actually go & see them rather than phone up.
yeah thats on my list of things to do, i did email one company to find no reply, but i'll work out how much steel i need over the next few days and then i know how much i need to order, the other problem is getting someone to deliver it
wilfy, I'd offer to get the steel for you but by the time you've either courriered it to you or come and collected it (5 hr round trip) you could probably buy it for the same price locally. Plus I can buy the odd thing through work but if they see my buying lots of steel then questions will be asked :concern: if you can wait until wobbly orders then I can tack it on, but still got the problem of getting it to you....
You will get a better price if you actually go there rather than email, that's always been my experience so always try to speak to people face to face if I can.
If you can't get it in your own car do you not know someone with an estate or something like that? Just rough cut it on site if the supplier won't cut it for you.
I have a people carrier but all the seats bar the one I need have been removed so really it's small van size. Seats just clip in so if I do have to ferry anyone about I just stick them back in.
nah it's ok your right i'll find a cheap supplier near here, there is a few places around but i aint got a clue which one to approach.. i've never had to buy steel before :DQuote:
Originally Posted by njhussey
i have an estate so can fit 2.5m in one go seats folded down, but thats still 2 cuts needed
Try them all lol, take a list of sizes you need & ask them nicely if they will cut it to length for you, they may charge you a cutting fee but it may be worth it. Even if they won't cut it all to length you may get a couple of bits cut so it fits in the motor.
hmm been doing some thinking tonight dangerous i know..
looking at the size of the moving parts it now feels when i look at it that everything i've designed i should have a bigger work space.. what i mean is the foot print of the machine is 792 x 700 and yet this produces a cutting area of 385x385 and i'm starting to wonder should i bump up the length of the rails and screws to gain some cutting area... the only down side in this is extra cost which i might be able to come to terms with.
i suppose the biggest decider is at what point do i need to move away from 16mm screws and rails as this will be the limits of the machine for me
Attachment 7328
i've also added in the green bits for stability... with the above thoughts i'm also thinking of changing the 50 x 25 that supports the y rails to something wide enough so that the whole yellow section can slot in to the blue as at the moment it feels like wasted space that could be better used to shorten the ballscrew and the steel
infact just a quick look at getting the yellow section to tuck in to the blue i could gain 100mm workable width for the same size screw in just 100mm longer rails so i'm going to consider a slight redesign to make this happen
Edit: i've done it so it's the above with 100mm shorter rails or this one below with 100mm longer rails screw is the same length
Attachment 7329
Looks like you are starting to get the hang of trusty old sketchup...nice one !
How about 3Nm CNC Stepper driver Kit - 3 Axis for CNC. | eBay electronics kit from Zapp Automation?
Power supply is only 36v so I believe you wouldn't get optimum performance from the drivers & motors if some of what I have learnt so far is correct lolQuote:
Originally Posted by Nealieboyee
Yep Martin your understanding is perfect.!!Quote:
Originally Posted by martin54
These type of Kits are one of the worst Gotcha's I see new folks get stung with.!! Those drives are 50Vdc and the motors are easily capable of handling well above 50Vdc, 65-70Vdc is common. So the up shot is that any machine running this system with 36Vdc would be running motors working at nearly half the voltage they are capable handling. Speed of a stepper is proportional to voltage and very important for good performance so the system will be working minimum 48-50% less than motors are capable.
Also even if the correct voltage for these drives was used, 44-45Vdc then the motors are still working approx 35-40% less than capable.
Quote:
Originally Posted by Nealieboyee
while i appreciate you looking, i've found everything i need for £255 bar the breakout board and they are all recommended items by jonathan, so unless i find those items cheaper then i have no need to look at other things
oh and i got a sneak at the saw today.. its perfect for cutting the steel i need to create this build so that £50 really was a bargain
alright guys money for my project is here... i could order everything i need 2moro if i wanted to but i still dont feel condfident my design is 100% so i need to draw in the motors on my sketchup... is 5mm steel enough to mount a motor to the motor will be belt driving the screws on all axis
2 x SBR16 supported rails 700mm length with 4 SBR16UU bearing blocks
2 x SBR16 supported rails 754mm length with 4 SBR16UU bearing blocks
2 x SBR16 supported rails 260mm length with 4 SBR16UU bearing blocks
1 x RM1605-C7 ballscrew+ballnut 655mm threaded section add on end machining and extend dimension F to 30mm
1 x RM1605-C7 ballscrew+ballnut 754mm threaded section add on end machining and extend dimension F to 30mm
1 x RM1605-C7 ballscrew+ballnut 142mm threaded section add on end machining and extend dimension F to 30mm
3 SETS OF BK/BF12 blocks (with locknuts and cir-clips)
1 x 2.2kw water cooled spindle including VFD
order for that lot has gone to china, got a really good price from chai, there is nothing on any uk supplier or even any ebay supplier that comes close, have to say very happy, cant wait to order the other bits and get the thing built now
Other sellers are significantly cheaper for the VFD and spindle. It's hard to know if there's any difference in quality, but I doubt it from what I've seen.Quote:
Originally Posted by wilfy
whilst i agree as a single item it'll be cheaper i'd disgree that on a big order it works out cheaper.. chai has quoted me 389usd = £242 for the spindle, if you take in to account the postage is likely to be the same regardless of wether i get the spindle or not as the items i have ordered are big heavy and bulky (i think) then infact i'm getting the spindle cheaper than ordering it direct from ebay at around £252.Quote:
Originally Posted by Jonathan
given the fact chai has given me a better price on the whole order than i could have got anywhere else i'm happy to pay him for the spindle aswell
The spindle is still a significant proportion of the total weight of the things you have purchased, so the postage would have been a bit cheaper without it. Plus you can use best offer with some of the sellers on eBay to get the spindle for less than £252, so overall it's likely to work out cheaper. Even better, get the spindle on ali-express as there it is cheaper than any of the eBay sellers.
I'm not sure if Chai is still the cheapest for rails and ballscrews either since there are plenty of sellers on ali-express with them. Still, he's very easy to communicate with which does help.
What are you planning on using for the bed of the machine? In the drawing it looks like wood...which is fine if you're mainly machining wood and plastics.
i'd rather order from someone i know is trusted by a few guys here, even if it means paying a little more, it's hard enough parting with my cash for the drivers on ali-express i couldnt bring myself to send the best part of £500 to a web site i have never heard of to a guy who no one has ever ordered offQuote:
Originally Posted by Jonathan
bed of the machine isn't decided yet if i'm honest, it may start as mdf and progress to ali in future
Wise choice because the saving if any would be £10-20 and penny pinching can easily get you in trouble when things arrive broke,bent or faulty which can happen to vendor. Chai is very helpful when things arrive bust or wrong and to me this is worth paying him £20 more.!!Quote:
Originally Posted by wilfy
christmas come early for me today... too bloody early infact i didnt expect this lot to turn up till after crimbo.
Attachment 7581
is it normal for stuff from chai.. or infact anyone in china to come in 2 deliveries? i'm missing the bk/bf blocks and also the spindle and vfd.
also i've noticed a stupidly huge cock up today whilst re-looking over my design, i've really done myself short on the rails for the x axis, looking at the size of the screw i've drawn and ordered i could have got at least another 100mm out of it.
i'm now tempted to re-order my x rails as thats the only thing i'd need and gain the extra length
Yes normal to come in more than one package regards VFD but usually arrive at same time and usually the BK/BF will be in with the rails etc.? I'd email Chai and ask if sent in 2 packages and mention BK/BF blocks not in the package received.Quote:
Originally Posted by wilfy
it certainly says 1 of 2 on the package i have, but i too thought the bf/bk's would have come with the rails.. i was tempted to wait and see if the other package comes 2moro.
So what have you signed for.? The package may say 1 of 2 but did you sign for 2 packages.?Quote:
Originally Posted by wilfy
I'd still email Chai asking has it won't hurt and is unusual in my experience for the blocks not to be with the screws Etc.!!
i didnt sign for it my missus did, i didnt even know it was coming, it's only been 10 days since i ordered it
I've bought stuff from China and there ahave arrived from 3 diffirent places on the same order, sometimes stuff is either wharehoused or built in different factories,, hopefully its wasnt those tards UPS .. they suck big style !
it was fedex that delivered it thats all i know, i've emailed chai see what he says.. have to say though 1st dec i paid which was a weekend.. and the rails and screws are here on the 10th.. thats some turn around if you think about the shipping involved
I,ve had stuff in 7 days and been ordered on a weekend and 9-12 days is quite normal for Chai.. . . No matter how large or small the order.!! That's why I don't mess around trying to save £10 or £20 buying else where.