New Build, Ziggy's Onefinity Modification

[ShawnM]

I have to ask, why on earth would you want stall homing? I’m guessing it’s not at all accurate or repeatable. If that matters to you. That seems like “poor man’s homing” to me. If you want repeatable and accurate homing use home switches.

As Keith stated the G540 does work but there are FAR better choices for the same or less money that are MUCH faster and more powerful. The G540 also has too many limiting factors in my opinion. You could do way better with a more modern drive.

You can use g code to turn off and on other appliances through the relay board and its outputs. You have 8 outputs with Acorn and you can buy/add many more if needed.

You can easily run 110 through the relays up to 10A if I remember correctly.

[cnckeith]

"You can easily run 110 through the relays up to 10A if I remember correctly."

related reading.

https://www.centroidcnc.com/centroid_di ... asheet.pdf

and

https://www.centroidcnc.com/centroid_di ... _guide.pdf

[Ziggy]

I have to ask, why on earth would you want stall homing?

As Keith stated the G540 does work but there are FAR better choices for the same or less money that are MUCH faster and more powerful.

I am new to all of this. My only experience has been my stock machine which used stall homing. It seemed to work well on my original system. I may not know much about CNC but I calibrate things for a living. The machine was accurate over 30+ inches to a thou or two. I liked the idea of stall homing because mechanic switches seem like they could fail and thy would also entail quite a setup with more wiring. I have seen some proximity switches but I haven't read about their accuracy. Plus.. to be honest, the little I read about setting up the Y axis just seemed bizarre; specifically setting one side to trigger before the other. I may have that wrong. It has been a while since I have read it. I am attacking this learning curves on several fronts at once.

All this being said, the machinest that reccomended the Acorn/G540 combo doesn't use switches either. He just manually homes the machine.

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Regarding the better choices: What are they? I looked at various sites for alternatives and wasn't able to see very many direct comparisons. If you could list a few, maybe I could look them up and learn the differences. I am open to change. I don't know that speed or power will be much of an issue... but again, I am ignorant. However, accuracy is what I am most looking for. My BB controller was very accurate. But, like I said, it didn't support arcs. That was a dealbreaker.

Yes, if you could make some suggestions I would certainly take a look.

Thanks again for your response.

[Ziggy]

"You can easily run 110 through the relays up to 10A if I remember correctly."

related reading.

https://www.centroidcnc.com/centroid_di ... asheet.pdf

and

https://www.centroidcnc.com/centroid_di ... _guide.pdf

Thanks Keith!

I will be using the relays. These look just like the ones that I used on my original setup.

I was just inquiring if there was another feature outside of the relay board that would accomplish the same task.

[Ziggy]

Here are a few pictures. Everyone likes pictures I think.

It may not be "right" but it is mine.

[ShawnM]

Machine looks great and I'm sure you are happy.

I apologize but my comment about not being accurate was that your "homing" cant be that accurate using stall homing. Not the machine. I'm sure the machine works great and cuts well and is accurate. I just was commenting on stall homing. If you use a fixed tool touch off or it it was a machine with a tool changer or a machine with multiple fixed work coordinates programmed you would NEED accurate homing every time. It's critical so you must have accurate home switches or some motor/drive combos that come with built in homing.

As for homing switches, proximity switches are preferred I think and there are very accurate and repeatable. And very simple to wire up. That said, there are also some very accurate mechanical switches as well but they don't come cheap. But then again, CNC isn't a cheap hobby. You don't NEED two switches on your gantry like you read in the manual. That's only if you do auto-squaring and in my opinion the small machines don't need this. I feel that's more for larger machines where the gantry can rack out of square. Some people manually home their machines and to this day I still don't understand why but that's another discussion for another topic.

As far as alternatives, if you are happy with the G540 by all means use it and make stuff. Alternatives will vary by your budget and there are some very good ones. You stated "I don't know that speed or power will be much of an issue... but again, I am ignorant." I believe that speed and power on a CNC is everything. Good rapid speeds between cuts will cut down on machine time and power (or torque) will determine your cut speeds and depths. These can of course also be limited by the chassis of the machine and build quality as well. There are many other factors as well but I don't want to get off in the weeds on the subject.

Congrats on getting it completed.

[martyscncgarage]

Congrats on your build
A quick comment on the Geckodrive G540. There is nothing wrong with it. However the I/O on it is redundant to what Acorn has on it.
Recently CNC4PC developed a motherboard that plugs directly into the Acorn DB25 and uses very similar stepper drivers as the G540. So you don't pay for the IO on the G540 that you don't use.
Based on your application, provided you sized the stepper motors, power supply correctly, I see no real reason why it doesn't serve you well.
Keep us posted on how the machine performs for you.
Marty

[Ziggy]

Thanks for the responses guys! I really appreciate it.

I was told my original controller used a 36V Meanwell PS so that is what I bought.

This is the stepper I am using: It is a smallish Nema23 motor. I used a 2.8k Ohm resistor in the Gecko connectors

https://www.omc-stepperonline.com/nema- ... hs22-2804s

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Another quick question: I was reading in another thread about applying snubber circuits to the relays. I am well familiar with snubber circuits and I had already planned - and in fact built - snubber circuits for the relays that will be closing 120V contactors.

Would I also need these snubbers for the relays connected to my VFD? The connection diagram shows Out 4 for Spin Forward, Out 5 for Spin Reverse and Out 8 for VFD Reset. Do these need snubbers? (I attached the schematic)

Thanks again!!!

[suntravel]

You do not need snubbers on the Acorn relays.

Uwe

[Black Forest]

You do not need snubbers on the Acorn relays.

Uwe

Where did you buy your snubbers for 24v contactors Mr. Suntravel?