Advice please: Drives and steppers

[lukaspanic]

I am getting ready to build a 24x48 solsylva router for woodworking. I am a toymaker and I will mostly be cutting 1/4", 1/2" and 3/4" hardwoods, mostly poplar. I purchased a Porter Cable 690LR (1.75 HP 11 amp) router for the spindle. I was looking at the Xylotex drives but Jeff from Xylotex warned me that the drives are not powerful enough for what I would like to do. (Thanks Jeff, I appreciate the honesty)
I would like to achieve cutting speeds of 100ipm or above, after all this is supposed to be an entry level production machine and not just a hobby.
What drives should I use and what steppers? The plans are layed out for nema 23.
PS: Please keep in mind that I don't have unlimited funds or I wouldn't build the router myself.

Thanks in advance!

[crane550]

Here is an excerpt from my own build thread on the HobbyCNC vs. the G540. I wrote this less then an hour ago, so I guess the timing is good. Hope it helps! I am selling my HobbyCNC board, but I would give it the same review if I was not. It really has been great. PM if your interested.

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A few words about the HobbyCNC EZ board. It was great. It required a bit more setup work then the G540, but in the end it did it's job quite well. Where it clearly does not have the same holding power as the Gecko Drive, it was plenty for a table this size. I would be comfortable using it again. When making signs, and plastic parts the power was sufficient. When cutting hardwoods (up to 2 inches thick) with a 1/2 end mill it was sufficient. Even cutting Mic6 aluminum was no problem for it.

Thats not to say the G540 is not an improvement on that- it is.

I did some price comparison:

HobbyCNC EZ Kit comes with 3 steppers, wire, and most of the components for the power supply. All you need in addition is a box to put it in, and a transformer.

Price list:
$290 - HobbyCNC EZ kit
$45 - 12A transformer.
$20 - Enclosure
$45 - Radio shack connectors

$400 total cost

The Gecko solution is a bit more simple - just the G540 and power supply. No assembly needed. You still need to solder your DB-9 connectors.

G540 Parts:
$300 - G540
$160 - Power Supply (12.5A in my case)
$45 - Connectors
$150 (3x budget steppers)

$655 total cost

An enclosure is a bit more necessary with the HobbyCNC solution as the power supply has a lot of components. You could also use a regulated power supply, of course. It was just cost a bit more.

Anyways, hope thats helpful to anyone wondering what they need. Both solutions work great. The HobbyCNC is a great way to get started, plenty of power for smaller machines, and great value. The G540 offers a bit more power, is a bit more simple to get started, and has fewer components to worry about.

Alex

[ger21]

I have a Xylotex on a 30x45 machine, and can cut at 190ipm on the 30" axis, using 250oz motors and 1/2-8 2 start screws. At the time I purchased it, it was the best choice.

Today, the G540 is preferred by most users.

What drives should I use and what steppers?

Are you using leadscrews or rack and pinion? How much weight are you moving?

Most just buy a G540 kit with 380 oz steppers. This works well for most similar sized systems.
But ideally, for maximum performance, the motors, drives, power supply and drive system all need to be a matched system.

[Fish4Fun]

lukaspanic,

I am a CNC Newbie. I have a much smaller machine (9x12 inch). I can tell you only my own experience, the G540 is VERY EASY if your motors are <=3.5A each. I have all sorts of designs (open source and proprietary) that I could have built, but @ the end of the day I chose the Gecko because of the support and reputation. I just really wanted my machine to work on the first run; and it did.

Just my very in-experienced opinion,

Fish

[lukaspanic]

@ger21 I am using lead screws on all axis, at least that was the plan. I have not build any component of the system yet but I was thinking about building the aluminum version of the gantry. I don't know how much it will weigh. I guess I should wait until I have the gantry build to make a final decision on the steppers and drives.

@crane250 you mentioned cutting hardwood up to 2 inches. is that in one pass? Also: are you getting rid of the hobbycnc because you are upgrading to the gecko?

I am also not sure on what screws tu use. on the x I am planning on 1/2in diameter and 3/8 on the other axes. I would like to hear some suggestions or experiences there too. I have seen the setup ger21 mentioned, 1/2-8 2 start. The speeds sound promising.

[ger21]

I'd recommend 1/2" on all axis. Either 1/2-8 2 start or 4 start, or 1/2-10 5 start. The 4 or 5 start should get you close to 300ipm, and will keep the long screw from whipping. My 2 start on my X axis is 60"+, and whips badly at 150ipm.

You won't be cutting 2" hardwood on that machine. I don't even do that on the $100,000 machine we have at work.

Imo, the Solsylva is not the most rigid machine out there, and rigidity will determine how deep you can cut in one pass.

[Crevice Reamer]

G540 Parts:
$300 - G540
$160 - Power Supply (12.5A in my case)
$45 - Connectors
$150 (3x budget steppers)

$655 total cost

My 2 cents:

1: Keling sells the G540 for $245

Stepper Motor, Stepper Motor Driver,CNC Router, Stepper Motor Power Supply, Stepper Motor Kit, DC Servo Motor, Stepper Motor, Stepper Motor Driver, CNC Router, Stepper Motor Power Supply, Stepper Motor Kit, DC Servo Motor, Keling Technology Inc, USA

2: Since steppers draw power differently than, for example a resistance heater, you don't NEED a PSU of greater than 7A with the G540. Amperage capacity of over 7A is wasted because any more than 7A actual load would blow the G540 internal fuse. So a PSU like the $50 Keling 48V 7.3A is more than adequate to power four 3.5A motors.

3: You don't really need connectors, since they come free with the G540. However, you DO need 4 conductor 22 gauge motor cable wire, current set resistors, (About 5 for $3 shipped from Digikey) and an Estop switch. (Keling, $10) So $45 is reasonable for miscellaneous supplies.

For the above reasons, I would put the G540 total cost estimate at approximately $490.

Also, don't forget that the G540 is optoisolated, fully assembled/tested/guaranteed ready-to-go and you are getting a future fourth axis controller included free, so there is that extra value to be considered. If your application can use it, there is also the added value of the G540 built-in motor speed control circuit.

CR.

[frige]

cncrouterparts has 3-axis kit with G540, 3 380oz, PS and cables for $519.
I bought this 3 months ago after doing the research. My machine is not assembled yet.
This was a good choice for me considering: ease of assembly (all matched parts there with minimal wiring), power of motors, customer support (all from one vendor), benefit+feature/cost ratio compared to other solutions.
-frige

[crane550]

The only reason I went with the G-540 is that I needed a 4th axis. Thats all. I would have kept the HobbyCNC board had it supported a 4th stepper.

I'd recommend 1/2" on all axis. Either 1/2-8 2 start or 4 start, or 1/2-10 5 start. The 4 or 5 start should get you close to 300ipm, and will keep the long screw from whipping. My 2 start on my X axis is 60"+, and whips badly at 150ipm.

You won't be cutting 2" hardwood on that machine. I don't even do that on the $100,000 machine we have at work.

Imo, the Solsylva is not the most rigid machine out there, and rigidity will determine how deep you can cut in one pass.

I would also recommend the 1/2. I started with 1/2-10 but ran into a TON of resonance issues. It was really bad. Nearly to the point the machine was unusable. Also my max speed was only around 70IPM, this was measly upgrade compared to the 3/8-16 all-thread that that I had before. I ran 40IPM consistently with the all thread. Thats with everything perfectly aligned, lubed, ect. Dropping in the 1/2-10 5 Start IMMEDIATELY changed the machine. Absolutely the single best upgrade I did to the machine. I am running dual motors on my X right now, and CANNOT stop the gantry at 400IPM. It is a TANK.

I have a tutorial here that will walk you thru selecting the leadscrews:

Leadscrew Pitch Tutorial

This will take you through the math of it all, and let you know exactly why you will get the results you will. My two cents is go with the 1/2-10 5 start. I am very glad I did. The Cncrouterparts.com nuts went really well with it too.

I cut 2" hardwood all day long with my machine. My machine is full on for guitar production, and I have no problems cutting even the hardest of woods. Oak, Paduak, Purple Heart, Cherry, Wenge, you name it. I will cut at 1/4" passes all day. Could go deeper, but there really is no point.

The Solsylva is not the most rigid machine, but it is adequate. My next machine is not a Solsylva, I am building 100% from scratch, it's got Nema 34 1500oz motors, a 300lb gantry, rack and pinion, and a 5hp spindle. Oh, and it's 6x10 feet.

Take a read thru my build thread. I learned a lot on the process, and ended up straying off the path quite a bit during my build (after I had the stock Solsylva built.) Now it is a completely different machine. It weights twice as much (NEVER NEVER avoid weight, weight is absolutely your friend, my gantry is pushing 70lbs) but also performs a lot better. It still resembles the original design but is a completely different machine all together. Then again I spend over $800 at my local machine shop machining various parts.

[crane550]

My 2 cents:

1: Keling sells the G540 for $245

Stepper Motor, Stepper Motor Driver,CNC Router, Stepper Motor Power Supply, Stepper Motor Kit, DC Servo Motor, Stepper Motor, Stepper Motor Driver, CNC Router, Stepper Motor Power Supply, Stepper Motor Kit, DC Servo Motor, Keling Technology Inc, USA

2: Since steppers draw power differently than, for example a resistance heater, you don't NEED a PSU of greater than 7A with the G540. Amperage capacity of over 7A is wasted because any more than 7A actual load would blow the G540 internal fuse. So a PSU like the $50 Keling 48V 7.3A is more than adequate to power four 3.5A motors.

3: You don't really need connectors, since they come free with the G540. However, you DO need 4 conductor 22 gauge motor cable wire, current set resistors, (About 5 for $3 shipped from Digikey) and an Estop switch. (Keling, $10) So $45 is reasonable for miscellaneous supplies.

For the above reasons, I would put the G540 total cost estimate at approximately $490.

Also, don't forget that the G540 is optoisolated, fully assembled/tested/guaranteed ready-to-go and you are getting a future fourth axis controller included free, so there is that extra value to be considered. If your application can use it, there is also the added value of the G540 built-in motor speed control circuit.

CR.

Actually, I just got mine for $225. I am good at finding bargains, and I did not want to advertise it at a wrong price.

As for the motor power supply current- I would seriously reconsider. A hobbyist would get away fine with the 7.3A but I depend on my machine not to fail. Running a small desktop machine would be fine, but anything thats made to cut aggressive and fast is going to need the extra juice.

Support

A good rule of thumb is .67 times the total amp draws of your motors.

I am running 4 motors at 4.2A, multiply that by .67 and I get 11.25Amps. It could be argued that the G540 will only draw 3.5, fair enough. This still puts me at 9.38. The question you have to ask yourself is "do I trust a 7.3A power supply thats made in China to carry a load of 9.38A while I'm cutting $200 guitar bodies all day long with it?"

All the sudden the 12A makes a lot more sense.

Then again my demands are a bit different. If my machine stalls my day is seriously F-ed up. I depend on it it to work.

The G540 is a great value, no doubt. But I would definitely use the more powerful PS if your going to be doing any type of production work.

[Crevice Reamer]

Good bargain at $225. You should share the source.

I know it SOUNDS better and all, but inside the G540 is a fast blow fuse rated at just 7A.

Digi-Key - F2318-ND (Manufacturer - 0251007.MXL)

All of the combined current of the motors must flow through this fuse. If your motors drew a combined STEADY current of 9.38A, this fuse would blow and everything would stop. But steppers draw current in pulses, NOT steady current, so the combined current of four motors does NOT blow the internal fuse.

So again I tell you, anything above 7A is simply wasted money spent on a PSU--Unless you also plan to run 12.5 Amps of resistive heaters or regular DC motors.

CR.

[crane550]

Good bargain at $225. You should share the source.

I know it SOUNDS better and all, but inside the G540 is a fast blow fuse rated at just 7A.

Digi-Key - F2318-ND (Manufacturer - 0251007.MXL)

All of the combined current of the motors must flow through this fuse. If your motors drew a combined STEADY current of 9.38A, this fuse would blow and everything would stop. But steppers draw current in pulses, NOT steady current, so the combined current of four motors does NOT blow the internal fuse.

So again I tell you, anything above 7A is simply wasted money spent on a PSU--Unless you also plan to run 12.5 Amps of resistive heaters or regular DC motors.

CR.

When it comes to amps, the driver is only going to pull as much as it needs. Going with a 12A power supply does not "force" it to run hotter. And a good rule of thumb for any industrial application is to only push a power supply 70 to 75% of its rated current. Once again, for me, this rules out the 7.3. We could argue about it all day, in the end it is what I decided to get, and then got. I have also had 0 stalls since I installed the system. Thats pushing 500IPM by the way with a gantry that is very overbuild and weights a ton, by the way. And I have my guides wrenched down tight.

A smaller power supply is going to work harder (and hotter) then a larger one. Period. I cannot take the risk of having a failure. That is why I run a larger power supply, and encourage others to as well. If this was a desktop machine, I would say different. The 6x10 machine I am building right now will get a bigger power supply yet. Probably a 22A or 3 10 A supplies. Not sure yet, have not got there. The machine will also weigh 3000lbs.

Alex