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GT2 pulley and belt

Posted: Sun May 05, 2013 6:00 am
by robotdigg
China Source of GT2 pulley and belt RobotDigg
You also can find your Z axis Anti-backlash Nut and Linear Stepper Motor with Acme Leadscrew

Re: GT2 pulley and belt

Posted: Sun May 05, 2013 1:06 pm
by WillAdams
Almost reported this as spam.

The site looks quite good though and has a number of products I haven't seen elsewhere (but obviously, I don't get out much: http://www.makerbot.com/blog/2011/05/25 ... available/ ), some of which could make a ShapeOko Mark II smaller, less expensive and more precise.

In particular:

Threaded Rod NEMA17, 280mm Tr8*8mm

http://www.robotdigg.com/product/8/Thre ... mm-Tr8*8mm

Image

Gets one an Acme screw upgrade which eliminates the coupler, spacers and shortens the bolts.

I think the specced motor is underpowered for our needs, but can be customized.

Re: GT2 pulley and belt

Posted: Sun May 05, 2013 1:47 pm
by robotdigg
Many thanks to your reply, WillAdams.
You could choose also Anti-backlash Nut which I think is very useful to avoid backlash. You may also have found that our standard Nut is POM, POM Nut can stand up to more wear and tear than a Brass Nut.
WillAdams wrote:Almost reported this as spam.

The site looks quite good though and has a number of products I haven't seen elsewhere (but obviously, I don't get out much: http://www.makerbot.com/blog/2011/05/25 ... available/ ), some of which could make a ShapeOko Mark II smaller, less expensive and more precise.

In particular:

Threaded Rod NEMA17, 280mm Tr8*8mm

http://www.robotdigg.com/product/8/Thre ... mm-Tr8*8mm

Image

Gets one an Acme screw upgrade which eliminates the coupler, spacers and shortens the bolts.

I think the specced motor is underpowered for our needs, but can be customized.

Re: GT2 pulley and belt

Posted: Sun May 05, 2013 4:28 pm
by Tom Smith
The site looks interesting, but the shopping cart doesn't appear to work, and communications are not using https for anything it should be, such as registration, etc. Might want to hold off the shopping sprees until they get their online store to a finished state :)

Boy, it' looks tempting at those prices, though!

Tom

Re: GT2 pulley and belt

Posted: Sun May 05, 2013 4:50 pm
by WillAdams
Yeah, in poking around I missed:

http://www.robotdigg.com/contact

which says:

>The shopping cart system ISN'T complete yet, so if you want to place an order with us, please write us email.
>Thanks a lot!

Re: GT2 pulley and belt

Posted: Mon May 06, 2013 2:59 pm
by fasteddy
WillAdams wrote:I think the specced motor is underpowered for our needs, but can be customized.
Assuming the description is accurate, this motor seems to be right on par for the shapeoko. 0.4nm holding torque is about 56oz-in (current nema 17s from Inventables are 62oz-in). If that's the case, it could work out very well indeed.

Re: GT2 pulley and belt

Posted: Sun May 12, 2013 10:44 am
by aymanme
Wish I'd seen this sooner, I just got back from Suzhou yesterday ... I go to often but normally to the Shenzhen/Zhuhai area.

Re: GT2 pulley and belt

Posted: Wed Jul 03, 2013 1:54 pm
by crashn_burn
I was going to start a new thread, but maybe this is a good opportunity to ask.

Confusion on motor voltage.

The motor listed above (with the acme rod), the specs list the voltage as 2v. Is that a typo? And I see bigger motors at 3.4 volts, but when you look at the torque curve, it says 40v!

Maybe I just don't get it.

crashn

Re: GT2 pulley and belt

Posted: Wed Jul 03, 2013 11:07 pm
by cvoinescu
There is no mistake. There are two things going on here.

The motor driver operates as a chopper. Together with the inductance of the motor winding, it forms a switching-mode power supply that reduces the high supply voltage to the low voltage required by the motor.

Secondly, the parameter to look for is the current rating. The motor can be driven with a higher voltage, if the current is kept below the rated value. Inductive loads oppose changes in current, so it takes time to build the desired current. A higher supply voltage means the current can vary faster, and, as long as it's limited, the motor will not be harmed. The ability to change the current through the windings faster means higher maximum speed and more torque at a given speed (but does not affect holding torque, i.e., torque when stationary). This also means that, everything else being equal, a motor with a lower impedance (higher current, lower voltage) is faster than a motor of equal holding torque but higher impedance.

Modern stepper motor drivers are both chopped and current-limited, so they work best with supply voltages in the tens of volts (24 V is typical for small motors, but 48 V or more is common for larger ones -- check that your driver supports that!) and low impedance motors (rated voltages below 5 V, and currents above 1 A).

Re: GT2 pulley and belt

Posted: Wed Feb 19, 2014 7:03 am
by tm america
I'm very interested in these motors..By my caculations the tr8*8 has a 1.5mm pitch which would give you 16.93 tpi..I'm interested in the tr8*12 which has a 2mm pitch.which would be 12.7 tpi.To me the tr8*8 would be an improvement but only like a 31% increase in speed.but the tr8*12 would give around 75% increase in speed.I know there are mods to use a 1/2-10 acme screw ..So this would be slightly slower but would have better holding ability?Has anyone used these motors for the z axis on a shapeoko?If so did you have any issues with running them?