New Machine Build- chinese:rails/bearings/drives your thoughts plz

[vdoug]

hey all,
dont think everyone has seen my last build.i wanted to see if i could and learn some cnc action. for as cheaply as i could. and did it.
heres a link to my you tube:
‪cnc plasma $650 for driberif85 and cnczone good luck‬‏ - YouTubevideo's:
‪circlecut.wmv‬‏ - YouTube ‪cnc plasma‬‏ - YouTube ‪100_0169.MOV‬‏ - YouTube
I have cut alot of metal with that thing.and had alot of fun.my page has me and my dad building a saw mill with some of the parts i have cut.

so let me get to the point. i need more!!!
I have been looking into buying a machine from jcut,keling. and then said lets see if i can build another.
so here's what iam looking at:
4Axis Nema 23 Stepper Motor 425oz-in CNC Mill Control - eBay (item 130546325593 end time Jul-20-11 23:41:20 PDT) i bought my first kit from them and want to beef it up a bit. are those drivers better or a whole lot better. if you bought these i would love to here from you.

next:
3 SBR20 sets +3 ballscrews RM2005+3BK/BF12 +3 couplers - eBay (item 140575303403 end time Aug-08-11 23:17:59 PDT) has anyone bought this kind of rails and bearings and your opinon please.

Also: i looked at 2.2kw spindles on ebay. how are they or should i just do a porter cable router.

i know alot of you will say. depends on what you going to do with it.
it's going to be a 4 x 4 router build with possibly a plasma side kick. with water table. an all around general machine that if i wanted to do some aluminum. i could. but not on a full time basis.

opinons please. and if you have bought some of the things i have listed please pro's/con's.

[DonFrambach]

Originally Posted by vdoug next: 3 SBR20 sets +3 ballscrews RM2005+3BK/BF12 +3 couplers - eBay (item 140575303403 end time Aug-08-11 23:17:59 PDT) has anyone bought this kind of rails and bearings and your opinon please. opinons please. and if you have bought some of the things i have listed please pro's/con's.

I used SBR20 supported rails on one axis of my small router. Although I bought them from Glacern here in California, I assume they originated in China. The rails were extremely well packaged. The have worked flawlessly for me. I recommend them highly!

Here's a link to my build: http://www.cnczone.com/forums/diy-cn...ry_router.html

[vdoug]

Thanks Don,
I feel better about the rails now. I have heard good about the screws on another post so looks good to me so far.

your machine is awsome. I even love the cabinet. Cuts down the noise as well as the mess. and just roll in into the corner and let it do it's thing.. Sweet real sweet.

i did see one thing in the build about routers. your thoughts plz router vs spindle

and your rails were on the support of the bottom. do you think it will make a difference if mine are on the side?

[Walky]

I use SBR16 rails and they are very nice, so I guess SBR20 must be nicer. Stay away from SBR12 (yeah, even for the Z axis), they are quite difficult to adjust correctly. I think that for your needs SBR16 would be enough (I even did some light aluminum work on sbr12 with a MDF frame!), and that will save you a lot of shipping costs (and rail cost). I use RM1610 ballscrews on the X and Y axis.

I get my stuff from a chinese guy named Chai:
eBay My World - linearmotionbearings2008

Nice guy, good prices (and even better if you contact him directly).

There are a couple of issues that you could expect (you get what you pay for), but most of them easily fixable:

1) Ballscrews might need a little straightening (mine did) but I guess that's to be expected from rolled ballscrews because of the way they're made, and after the long way home and those evil mail guys sitting over them (not hard with a couple of wooden v-blocks and a straight surface, just a little tiring).

2) Bearing blocks might or might not need some shims to do some preload on them (easy fix).
About the rails, I always replace the nuts that hold the

3) Some the bolts that hold the rails to the extrusions sometimes are stripped; I always replace all of them for new ones each time I get a new set of rails, anyway. Not a big deal, really.

Even considering all of the above, the value for the money can't be beaten, and the guy seems pretty honest, which for me is very important (and believe me, I know what it's like to have a $2000 paperweight because some chinese guys would just play deaf about their crappy machine).

Do you really need 2.2KW? My router is 430W and it's enough for most of the stuff I do, so I guess the 0.8KW chinese spindle would probably be enough for most tasks (hard woods and stuff like that) unless you're really going to force it by cutting full depth and stuff like that. I even used the 430W router for light aluminum work! very thin passes (made some small parts out of 3mm plate), though, but it worked.

If a VDF + spindle is too expensive, you can use a router and get a SuperPID to control the speed without losing torque, I've got one and it works great:


BTW, I use the SBR16 rails of my X axis (1mt lenght) bolted on their side and it doesn't have any problem holding the aluminum gantry's weight (that includes the Y rails, ballscrews, blocks, Z axis and router). I guess it wouldn't hurt going with SBR20 for the X axis, but for your gantry and the Z axis I think SBR16 would probably be more than enough.


http://www.cnczone.com/forums/diy-cn...speed-102.html


About the drivers, I'd go with the Gecko G540 and some 400oz-in steppers. Match that with some nice ballscrews and we have a winner
Probotix drivers are nice, too (I use their Probostep drivers), but Gecko is known to be top-notch.


Hope this helps

[vdoug]

now thats what i'm talking about for info . thanks walky.
i worried about the rails. but after the last couple of post i feel better.

i wish someone has got some info on the that drive. i know you said gecko. but for the money and the look of a gecko. i wonder if they perform like a gecko.
also. is 4 wire or more wires better on the motors?
and i think i will go with a router. one reason is the collar. should fit most any bits i buy.
however i believe but dont know that the spindles are quiter running.

thanks for the info

[sirkossorg]

I agree that Chai is great to deal with. The prices are great and the end machining on the ballscrew is pretty good.

However, I just received an order from him and ended up paying an extra $50 on top of the shipping to get my items through Customs because he declares the items as having no value, which is not true. If you are willing to lie to U.S. Customs, which I am not, you can get around that I suppose. There are forms you have to fill out, sign and fax back to them declaring actual value. Also, you will need his physical address for the Customs forms, if your stuff gets flagged.

The Customs agent also told me that EVERYTHING Chai ships now is being scrutinized. Don't know if it's true, just what I was told.

That said, for the service and the price, I would still deal with him again.

[Walky]

Originally Posted by vdoug now thats what i'm talking about for info . thanks walky. i worried about the rails. but after the last couple of post i feel better. i wish someone has got some info on the that drive. i know you said gecko. but for the money and the look of a gecko. i wonder if they perform like a gecko. also. is 4 wire or more wires better on the motors? and i think i will go with a router. one reason is the collar. should fit most any bits i buy. however i believe but dont know that the spindles are quiter running. thanks for the info

As sirkossorg said, Chai's end machining is very nice, very professional and accurate (you can send him custom specifications for the screws' machining).

I haven't had to play any customs with Chai yet, it might be because of the declared value or maybe because of some chilean-chinese trade treaty, don't know for sure but I've never had to pay customs for anything from China, not only Chai's.

4 wire motors are always bipolar. 6 and 8 wire motors are unipolar but can usually (or always, don't know for sure) be wired as bipolar. The main difference is the way their torque curve is, here's some brief general info:

UniPolar vs BiPolar wiring schemes for 2-phase Stepper Motors

Motor datasheets usually show the torque curve under certain circumstances. Current will give you torque, voltage will give you speed (if you have enough torque, of course).

I would always choose a Gecko before getting any driver directly from China, even if Gecko were a little more expensive. Gecko is a renowned brand of high quality and great performance, and has a lot of protections to avoid frying it, while when getting from China you have the following situation:

1) You might get a great product or might not. Looking for reviews might help, tough.

2) If you have any problem, you might or might not receive help depending on the seller. If you don't... good luck trying to solve your problem. The forum's full of people using Geckos with great results, that's probably the best kind of feedback you can get.

I've got to say I don't have any Geckos, but I haven't read anything but good thing about them.

I got a chinese machine with a defective board and got no help at all from the seller, so I know about that kind of thing first-hand.

Usually, for low screw leads (how much the nut advances with one turn of the screw) you'll want the motor to go faster while keeping torque (unipolar, or even better; bipolar parallel). For higher leads bipolar is a good choice because it has good low speed torque.

Don't get me wrong, unipolars can usually still get the job done, but you need good motors/drivers/voltaje/current. My ballscrew lead is 10mm, and my unipolar motors and drivers can get me some nice speeds while keeping torque. I'm sure a Gecko with a 48V power supply would get even better performance with such a high lead. Most people seem to use 5mm lead for their ballscrews, though, I just like fast rapids.

Oh, btw, if you're going with a gantry design, It's a very good idea to use double X screws/motors to prevent side play. Not absolutely necessary, but helps a lot. If you go with a single screw, try to get the bearing blocks from each rail apart from the other as much as possible to minimize side play (more distance between them means less effective travel, though)

[vdoug]

Thanks for your input,
well just for fun i typed in sbr on youtube. a couple videos came up. and as you said before. the rails were bent in the video. but for the money i'm going to give them a try.
i might be throwing my money away.
i took the plunge. i bought that sbr kit and a 4 axis kit from longsmotor99.
the sbr guy said he would change the coupling size for me and throw in some wire chians. and longs told me that the 4 axis kit has the upgraded drivers that work more like servos. digital. dm542a not the older dm542ma. 128 micro steps.
has anyone out there tried the new driver?

[Walky]

I've never gotten a bent rail (and I've bought a lot), only the ballscrews were bent. I don't know anything about chinese drivers, but 1/128 microstepps sure seems overkill (if that's really one step pulse per microstep, you'll be very limited on your max speed; my 1/16 microstepping actually limits me to about 350 IPM, since the computer just can't provide pulses any faster trough the parallel port).
I would have gotten the rails and screws from Chai since there's more feedback about the seller, but since you already got them from another seller there's not much to do until you can and want to cancel the order.

How many ballscrews did you get? As you got a 4 axis driver kit I'd assume you got 4 ballscrews (2 identical for the X axis, to prevent side play which would be notorius with a long gantry). Who got that stuff from lmb2008 or from the other seller you mentioned? What lenghts did you buy?

By the way, and if you want and are still on time to cancel the order, I insist that a G540 would be a far safer bet than getting chinese drivers, and might save you a headache in case of a defective driver, bad documentation, driver lost in transit or any other problem. I'm actually considering a G540 for a small hobby level machine I'm building, knowing that there are sub-$100 TB6560 based chinese boards (which are crap, lie shamefully about their specs and burn just by looking at them).

Is this the kit you got?:

http://cgi.ebay.com/4-Axis-Nema-23-s...item4158cb4cf9

The included PSU is crap, your motors would crawl at 24V. If the motor's data is right, the maximum/ near ideal voltage for those motors would be about 96V (by using sqrt(inductance) * 32).

Also, check the forums for info on Longs Motors, that's the first step to know if you'll get support or a good product (I do that kind of research with every single crucial part you get). If you have doubts about anything just ask, there's full of people you'll nicely guide you in the right direction. You could start here: http://www.cnczone.com/forums/cnc_pl...ngs-motor.html


This is another nice alternative that might be cheaper than getting a Gecko, and their support is great:
http://probotix.com/index.php?view=p...&product_id=45
That probotix kit matched with a 40V or so power supply would performe quite nicely.

Believe me, change the drivers, you'll happier in the short and long term.

[vdoug]

thanks walky,
i looked at so many kits. kit after kit after kit. size rails length reviews and on and on. i got caught up in size table more than anything. was going to do an 8 footer. then i said, man thats a alot of space taken up for a small garage. anyway there is no method to my madness. but thanks a bunch cause i lost track of how many screws.
i email him and hopfully he will fix me up one.
part of me wanted to go with the other guy. but he wasnt offering a kit like this one. and this guy seemed to have better pricing. so i thought if i could deal with someone else i would have a different opinon for the forum.
same reason i did the chinese drives.
actually for a driver aloan. the drives are not that far off on price.
thanks again walky

[longsmotor99]

Originally Posted by Walky I've never gotten a bent rail (and I've bought a lot), only the ballscrews were bent. I don't know anything about chinese drivers, but 1/128 microstepps sure seems overkill (if that's really one step pulse per microstep, you'll be very limited on your max speed; my 1/16 microstepping actually limits me to about 350 IPM, since the computer just can't provide pulses any faster trough the parallel port). I would have gotten the rails and screws from Chai since there's more feedback about the seller, but since you already got them from another seller there's not much to do until you can and want to cancel the order. How many ballscrews did you get? As you got a 4 axis driver kit I'd assume you got 4 ballscrews (2 identical for the X axis, to prevent side play which would be notorius with a long gantry). Who got that stuff from lmb2008 or from the other seller you mentioned? What lenghts did you buy? By the way, and if you want and are still on time to cancel the order, I insist that a G540 would be a far safer bet than getting chinese drivers, and might save you a headache in case of a defective driver, bad documentation, driver lost in transit or any other problem. I'm actually considering a G540 for a small hobby level machine I'm building, knowing that there are sub-$100 TB6560 based chinese boards (which are crap, lie shamefully about their specs and burn just by looking at them). Is this the kit you got?: 4 Axis Nema 23 stepper motor 425 oz & Driver DM542A CNC | eBay The included PSU is crap, your motors would crawl at 24V. If the motor's data is right, the maximum/ near ideal voltage for those motors would be about 96V (by using sqrt(inductance) * 32). Also, check the forums for info on Longs Motors, that's the first step to know if you'll get support or a good product (I do that kind of research with every single crucial part you get). If you have doubts about anything just ask, there's full of people you'll nicely guide you in the right direction. You could start here: http://www.cnczone.com/forums/cnc_pl...ngs-motor.html This is another nice alternative that might be cheaper than getting a Gecko, and their support is great: 4-Axis Monster CNC Stepper Motor Driver Kit - 4-Axis Monster CNC Stepper Motor Driver Kit That probotix kit matched with a 40V or so power supply would performe quite nicely. Believe me, change the drivers, you'll happier in the short and long term.

For the PSU we choose, the first one is the input voltage of the stepper motor driver, the second one is the diametion of the motor. Because the input voltage of the stepper motor driver DM542A is 18-50VDC, and the motor is Nema 23, usually we recommend to use 24VDC or 36VDC. Both are all ok. For what you said 40VDC, it is also ok. But i have to say that under this 40VDC, the motor's rising temperature will faster.
Best regards
Mary

[vdoug]

well the stepper kit came in, and i put it to the test. the motor size is the same size as my 354 oz/in. so i have to assume its the same and the driver must get them to perform better. the box came and was damaged. scratched a motor. and that was it. everthing else was in fine shape.
the wiring diagram (and mach3 settings. wasnt any.) paper work could use some tweeking. but i did get them running.

not much noise with them at all. that was nice but, the motors do get pretty warm.
i expected a bit more out of them. lost a few steps to lock up a thigh inchs per min. it preforms better than the tb6560 board type drivers. how ever for the price. its a close to a draw. a break out board gives you more options. but they cost more money to have. such as extra board of relays to turn on the spindle. the tb6560 has an all in one board. nice because of space and no extras to buy. but limited to what you can do. then again if you need more you have the option of putting an extra parallel port on your system to and more functions

over all i believe it will do what i need it to do. so thats what i was after.

i got your post after the purchase was done. i guess i got in a hurry.
it happends. thanks walky

next time i will buy geckos so i can compair the two.but, i will work with this kit and may get a higher opinon about it as i go along. it was not a long testing process. so far

still waiting on the rails and screws. he said he was getting them machined. no tracking number yet.

if anyone needs a "howto" on wiring and mach3 settings i will make a video.or anyother questions

this is just my opinon.