Newbie- cable and chain drives

[stepperhead]

hello there ,

I am researching all I can on these machines as I intend to build one soon. I have one nagging question that maybe some of you here can answer. I read the thread all about the differences with all the common screw type drives. I learned that ball screws are the best for no backlash and all the physics involved but what about cable or chain drive systems? It seems to me that a tight cable or chain would not have very much backlash and be a hell of a lot cheaper. do any of you out there have such a drive on your machine? I guess over time the chain or cable may stretch but that could be remedied by a spring and pulley and or a tightener. would this inevitable stretch make the machine inacurate? maybe I am off base here, I am just thinking out loud for ya.

thanks,
mac

[ger21]

acme screws can give you nearly zero backlash for a fraction of the cost of ballscrews.

http://www.dumpstercnc.com/

[CalG]

Ger21

There is a restriction with the referenced components, The "anti-backlash" is only as ridged as the spring force. That is not likely sufficient for machine tool requirements.

Now if the same spring force were applied to indexing opposed nuts, we might have something.

Correct me where I am wrong

CalG

Regards

Cal

[ger21]

What kind of machine are you building? The majority of router builders use the dumpster nuts with no problems. If you are building a machine for cutting metal, then they may not be sufficient for your application.

[dertsap]

I experimented with chain drive for my set up , and i was quite confident in the performance , it worked great and was a cheap and readily available setup , half way thru the project i found an incredible deal on some lead screws and i put the chain on the shelf , my son and i are currently building him a table and it is a toss up whether we use the chain or we go with a cable system .
the one thing that has to be taken into concideration is the resolution you will have , you will need to gear down some which will gain you torque but at the same time you will need to use microsteppers in order to keep the resolutions low .
you could get a .001" resolution if you use geckos or the likes with ten microsteps and you won't have to gear down too extreme as long as your drive sprocket is kept fairly small

[stepperhead]

ger21, are you suggesting that a cable or chain might be a tighter or stronger design than a spring anti backlash nut. I would guess that a cable may have some stretch in it depending on the metal used and the thickness. It may also stretch over time and use.
the machine I plan on building would be mostly for wood but I would like to also have the capability to do a little aluminum or brass as well.

Just thinking out loud on this.

thanks for the replies.

mac

[Weldtutor]

Originally Posted by stepperhead cable or chain. do any of you out there have such a drive on your machine?

My chain driven table is shown HERE.

It has proven to be very satisfactory for the application.