[Mr.Chips]

I agree . There is no need for a breakout board if the inputs are optically isolated AND if the signal source voltage is adequate. The reason the BOB became popular was that the newer computers only put out 3.2V on the PP port. The BOB's had buffers to increase it to 5V . That was important on the G201's the G210's and the G320 because they required a minimum of 4.2V as I recall.
Breakout boards are also usesful for signal distribution. When you have a pc with a 3.2V output and a G251/203 then all you would need is a db25 on one side and screw terminals on the other.
The one advantage of the BOB's is where you need an optically isolated inputs from hopme/limit switches or other devices

Dan Mauch

Seems to me that you still should use a isolated BOB is to prevent stray voltage from getting back to the PC, and there is PS voltages going into the BOB and signals coming from your limit switches going back through the BOB an to the PC.

Having Driver cards and BOB both isolated won't cause any kind of conflict will it?

[David_Web]

Received mine today.
They are so cute!
I love the little gecko!
Too bad I could only get six but it's ok. I guess that means a G540 in the future.
I have no idea how you managed to get so good international shipping rates. Speedy too.

Now I have to wire up one and test it. I have a LOT of steppers and some looks like a really good match.
Then build a CNC thingey.

[CROSSHATCH]

OMG! Everyone is making me jealous, I'm going to buy my system this week! Thats it!


-Jason

[Greolt]

Bump

Parcel arrived today with my new G251s. Thanks Gecko.

I was a little surprised to find the two 2mm cap screws to be quite loose on all the drives. (wobbly loose).

And no sign of any heat transfer type material under any of the components.

On the G201s I have used before there is a white heat sink paste used.

Is this normal? Seems a bit strange to me.

Greg

[CoAMarcus]

Greg,

The G201s go up to 7A and create a whole lot of heat through their IRF540N's. Because of this we use a heatsink compound between the MOSFETs and the heatsink plate. The G251s use a .080" thick aluminum plate that is hard anodized; in hindsight the plate should have been .085" because currently the screws are about 1/4 turn too long for these plates. There is no problem with the plates being too thin aside from aesthetics. They will still transfer heat from the drive because of the low amount of heat being created.

Marcus Freimanis

[Greolt]

Thanks Marcus

So I take it there was not meant to be any heat transfer compound under them. This is normal?? Does not seem ideal for heat transfer. Especially being wobbly loose.

I will assemble them with some silicone compound and shorten the screws just a smidgin to prevent them sticking through and holding the G251 heatsink away from the larger heatsink they will be mounted on.

Greg

[LeeWay]

The 201's and 203V's don't even require heat sink compound when mounting if you run 3 amps or less.
I do use it anyway, just to help dissipate what little heat is there, but it isn't mandatory.

If you had use of a high powered electron microscope, you might even be able to add some under there yourself. Just program your nanobots to do the task.

[Greolt]

Don't know about the 203Vs but the 201s I have do have heat sink compound under the mosfets.

We are talking about between the mosfets and the ally base plate that makes up the drive. Not between the base plate and whatever you mount them on.

The G251s that I got have none under the mosfets. And the screws were loose. So that was what my query was about.

Greg

[CROSSHATCH]

You will probably be getting an order from me tonight!



-Jason

[Jay C]

You will probably be getting an order from me tonight!

-Jason

If they had $1 for every time you said that in this thread

[CROSSHATCH]

LoL, no this time i'm serious! Shut up! :P


-Jason

[CROSSHATCH]

Have a serious question here, I was looking at the manual. And it says for the 540 "Choose a motor that a 3.50 Amp or less" , My motors from Keling in a Bipolar Parallel are rated @ 4.2 Amps. So would it be safe to say that wiring it in this manner would not be efficient? Or would it be better to wire them so that they get the full Amps which my motors in a Unipolar will draw 3.0 Amps?



Please let me know.


-Jason

[ger21]

Depends on the application. Torque is proportional to current, so your holding torque when wired parallel will be about 83% of the motors rated torque. However, parallel will give you more torque at higher speeds, so if you need to spin the motor very fast, parallel may still give you more torque at the higher rpm than other wiring methods. It's a hard question to answer, without doing some actual testing on your machine.

[CROSSHATCH]

Because I want too Rapid the machine maybe near 30's or whatever and cut between 10-20 IPM.


I should still be ok though no matter what.


-Jason

[Mr.Chips]

Depends on the application. Torque is proportional to current, so your holding torque when wired parallel will be about 83% of the motors rated torque. However, parallel will give you more torque at higher speeds, so if you need to spin the motor very fast, parallel may still give you more torque at the higher rpm than other wiring methods. It's a hard question to answer, without doing some actual testing on your machine.

Spin the motors real fast? Hmmmm

I watch mine running at 20 IPM (1/2" 10 TPI Acme thread) and thoes motors are running at about 78 RPM (now you know how old I am)

What would you do gear them way down with belts to get them to run faster at 20 IPM?

I see Joe's Hybrid running a 5 start Acme thread, and that motor would really run even slower.

Could you shed some more light over here. Guess I'm missing something.

[LeeWay]

To get or even see faster speeds, you will have to have a pretty good machine or tune them sitting on a bench not hooked up to anything. They are pretty much all capable of some pretty good speed with proper PS, but can they do it hooked up to a machine?
It takes torque to overcome friction from turning the screw in the nut and to actually move the axis on it's bearings or ways. Without much torque, you can't see any faster speeds. You have to tune them to go as fast as possible on each particular axis without loosing steps and then back off that by maybe 1/4 to a 1/3 for insurance so that you won't miss any steps.

[dmauch]

I would wire them bipolar parallel and set the 540 to 3.5A. You will have more torque than unipolar. Wired half winding as in unipolar the torque is only 140 oz in if you have the 23H276-30-8 motor. Also with bipolar parallel you have get away with a cheaper lower voltage power supply since the voltage would be half of what it would be for bipolar series.

Dan Mauch
www.camtronics Inc
low cost cases for Gecko stepper and servo modules.

Have a serious question here, I was looking at the manual. And it says for the 540 "Choose a motor that a 3.50 Amp or less" , My motors from Keling in a Bipolar Parallel are rated @ 4.2 Amps. So would it be safe to say that wiring it in this manner would not be efficient? Or would it be better to wire them so that they get the full Amps which my motors in a Unipolar will draw 3.0 Amps?



Please let me know.


-Jason

[CROSSHATCH]

I will be using a 48 Volt 7.3 Amp PS; I'm afraid that if I set every axis to 3.5, I obviously won't achieve it's full performance.



Can I still see decent performance?


P.S. Dan, can you please fix your link so I can view your products, thanks.





-Jason

[kawazuki]

I will be using a 48 Volt 7.3 Amp PS; I'm afraid that if I set every axis to 3.5, I obviously won't achieve it's full performance.

Can I still see decent performance?

-Jason

I would have thought at 7.3A your power supply would be the limiting factor?
3 motors @ 3.5A = 10.5 x 66% is around 7A?. At full ampage (4.2) it'll really loose out. Just a thought?

[Jay C]

http://www.camtronics-cnc.com/