30"+ work space low cost diy CNC router parts kits?

[louieatienza]

Just to repost the directions for resistor sizing, copied from the GeckoDrives website:

STEP 4: CONNECT MOTORS

Wire your motors to the included DB9 solder cup and secure the backshell connectors. If your motors are rated below 3.5A you must use a current set resistor across PIN 1 and PIN 5. The resistor is calculated by taking the current in amps and multiplying by 1000. If your motor is rated at 2.8A per phase you will have to use a 2.8K 5% 1/4W resistor. If your motor is rated at 3.5A or above you can safely not use a current set resistor; however, your G540 will not go into current standby mode which will result in increased motor heating.

I would go as far as to test the resistors. f you set the current lower than that rated for your steppers, you will lose torque proportional to the current you're running them at. It does not take much electronics skills to set this up other than soldering a few wires to the lugs of the DB9 cup. I probably would NOT use a DB9 breakout board if it won't fit in a back shell; all you need to do is have some metal swarf flying around, and shorting the leads to one coil, which will hose your drive, or at least the fuse on the motherboard of the G540...

[ger21]

You need to use the DB9's that come with the G540. Most others can't handle the 3.5 amps of current.

[Goemon]

Just to repost the directions for resistor sizing, copied from the GeckoDrives website:



I would go as far as to test the resistors. f you set the current lower than that rated for your steppers, you will lose torque proportional to the current you're running them at. It does not take much electronics skills to set this up other than soldering a few wires to the lugs of the DB9 cup. I probably would NOT use a DB9 breakout board if it won't fit in a back shell; all you need to do is have some metal swarf flying around, and shorting the leads to one coil, which will hose your drive, or at least the fuse on the motherboard of the G540...

Will any 3.5k resistors work or does it matter how many watts and ohms it states?

[louieatienza]

Will any 3.5k resistors work or does it matter how many watts and ohms it states?

Dude, do you not read my post?! I re-quote:

"...will have to use a 2.8K 5% 1/4W resistor"

Should be obvious, that since this is a resistor, 2.8K refers to 2.8KOhm. So 3.5A motor, 3.5KOhm resistor, 5%, 1/4W.

[Goemon]

Dude, do you not read my post?! I re-quote:

"...will have to use a 2.8K 5% 1/4W resistor"

Should be obvious, that since this is a resistor, 2.8K refers to 2.8KOhm. So 3.5A motor, 3.5KOhm resistor, 5%, 1/4W.

I did. Just trying to understand if I can use any of the resistors in the box I already have or if I need to buy new ones. None of the resistor thing is obvious to me as I have never needed to use them before. If it was obvious then I wouldn't be asking for help.

Thank you. That answers my questions on that.

[louieatienza]

I did. Just trying to understand if I can use any of the resistors in the box I already have or if I need to buy new ones. None of the resistor thing is obvious to me as I have never needed to use them before. If it was obvious then I wouldn't be asking for help.

Thank you. That answers my questions on that.

You can Google "resistor color codes" and get a chart like this, which you can use to see what the values are on the resistors you have. Not sure? Check it with a multimeter.

[Goemon]

You can Google "resistor color codes" and get a chart like this, which you can use to see what the values are on the resistors you have. Not sure? Check it with a multimeter.

Thank you. That helps as not all of mine were properly labeled.

[Goemon]

Ok I think I now have (or have ordered) almost everything I need to finish my build. Looking at the quality of the parts I have, I feel confident that it is going to be a robust machine that will exceed my needs, (or if it doesn't, I can't blame the parts). I can tell that I got some good advice here and as a result, the quality of the parts far exceeds anything I would have found in an equivalently priced kit.

For around $1500 I'll have a machine with good THK rails and bearing blocks, industrial quality lead screws, a frame made of steel and aluminum with a carbon fiber and aluminum gantry.

Now that I have started assembling the frame, I'm not sure I'm happy with my decision to wait on ordering a CNC spindle and using a regular router in the meantime. I have seen my router cut through some aluminum alloys like butter but most of what I have read suggests it is a bad idea to use it on a CNC machine (as it's not designed for continuous use).

Unlike almost every other CNC part, I have been unable to find any good deals on high quality used CNC spindles on eBay or Craigslist etc. I don't have the budget for a high quality new CNC spindle (I would be limited to the $300 Chinese ones off eBay). Is there anywhere else I should be looking for a deal on used CNC spindles? I found a few other sites that deal with used industrial CNC equipment but nothing where people are selling used spindles at that high quality desktop CNC machine level.

The classifieds on this site seemed to be for other countries. I am hoping that there is somewhere you guys would go to sell your old CNC equipment (other than eBay and Craigslist)? (Yes... I tried googling it....)

Or maybe one of you just upgraded to a brand spanking new 4kw spindle and have an oldy but goody 2.2kw or 1.5kw spindle sitting unused and unloved in a box in your basement? And... maybe you might be open to a good old-fashioned mutually beneficial exchange for cold hard cash?

[ger21]

I have seen my router cut through some aluminum alloys like butter but most of what I have read suggests it is a bad idea to use it on a CNC machine (as it's not designed for continuous use).

It's not a bad idea, and if you already have one, use it. Many people use hand held routers for years. Just be aware that they won't last as long as a spindle, and won't be as powerful, or as rigid.


There's really nothing wrong with the chinese routers, unless you get a bad one, which is pretty rare.
I bought two chinese spindles two years ago, and just recently got a VFD to test them. They are smoother, more powerful, and quieter than any router I've ever used.

I'd say that 99% of DIY builders are using chinese spindles, as it's hard to justify 5-10x the cost for a high end spindle

I'd be leery of buying a used high end spindle. Replacing bearings on a high quality spindle can be very expensive.


These are the ones that I have:
2.2KW Air Cooled Cooled Spindle Motor ER20 220V 400Hz 24000rpm for CNC Router

with this VFD:
2.2KW 220V VARIABLE FREQUENCY DRIVE INVERTER VFD 3HP 10A | eBay


This spindle is probably a little better, as it's made in Turkey:
CNC AIR COOLED SPINDLE 2.2 KW

Or, you can buy a chinese spindle that's tested and guaranteed from UGRACNC.com

[louieatienza]

Ok I think I now have (or have ordered) almost everything I need to finish my build. Looking at the quality of the parts I have, I feel confident that it is going to be a robust machine that will exceed my needs, (or if it doesn't, I can't blame the parts). I can tell that I got some good advice here and as a result, the quality of the parts far exceeds anything I would have found in an equivalently priced kit.

For around $1500 I'll have a machine with good THK rails and bearing blocks, industrial quality lead screws, a frame made of steel and aluminum with a carbon fiber and aluminum gantry.

Now that I have started assembling the frame, I'm not sure I'm happy with my decision to wait on ordering a CNC spindle and using a regular router in the meantime. I have seen my router cut through some aluminum alloys like butter but most of what I have read suggests it is a bad idea to use it on a CNC machine (as it's not designed for continuous use).

Unlike almost every other CNC part, I have been unable to find any good deals on high quality used CNC spindles on eBay or Craigslist etc. I don't have the budget for a high quality new CNC spindle (I would be limited to the $300 Chinese ones off eBay). Is there anywhere else I should be looking for a deal on used CNC spindles? I found a few other sites that deal with used industrial CNC equipment but nothing where people are selling used spindles at that high quality desktop CNC machine level.

The classifieds on this site seemed to be for other countries. I am hoping that there is somewhere you guys would go to sell your old CNC equipment (other than eBay and Craigslist)? (Yes... I tried googling it....)

Or maybe one of you just upgraded to a brand spanking new 4kw spindle and have an oldy but goody 2.2kw or 1.5kw spindle sitting unused and unloved in a box in your basement? And... maybe you might be open to a good old-fashioned mutually beneficial exchange for cold hard cash?

I've cut aluminum with my CNC router for probably close to 9-10 years now. Started off with a RotoZip (the plastic bearing housing melted, causing crazy runout), then a Craftsman trim router, finally settling on Bosch 1617 with PreciseBits collets and SuperPID. Think I changed the bearings once. The harder aluminums, 7075, 7050, 2024, even some 6061, cut well because they create small chips. 3003, 6063 can leave longer stringier chips that can cause problems., but nothing a little lubricant can't help. Endmill selection is also key (see my thread stickied in this section.)

I have a pretty high quality Chinese CNC spindle, 3kW (4HP), that I'm looking to part with and almost no run time (I dismantled my CNC when I moved.) Air cooled, so no need for coolant lines or pumps, 4-bearing, suitable for metalworking, and square frame, for easy mounting without buying a clamp. Let me know, will sell it pretty fairly. You just need a VFD.

[Goemon]

I've cut aluminum with my CNC router for probably close to 9-10 years now. Started off with a RotoZip (the plastic bearing housing melted, causing crazy runout), then a Craftsman trim router, finally settling on Bosch 1617 with PreciseBits collets and SuperPID. Think I changed the bearings once. The harder aluminums, 7075, 7050, 2024, even some 6061, cut well because they create small chips. 3003, 6063 can leave longer stringier chips that can cause problems., but nothing a little lubricant can't help. Endmill selection is also key (see my thread stickied in this section.)

I have a pretty high quality Chinese CNC spindle, 3kW (4HP), that I'm looking to part with and almost no run time (I dismantled my CNC when I moved.) Air cooled, so no need for coolant lines or pumps, 4-bearing, suitable for metalworking, and square frame, for easy mounting without buying a clamp. Let me know, will sell it pretty fairly. You just need a VFD.

I would be interested. Please drop me a PM when you get a chance with the details.

[Goemon]

It's not a bad idea, and if you already have one, use it. Many people use hand held routers for years. Just be aware that they won't last as long as a spindle, and won't be as powerful, or as rigid.


There's really nothing wrong with the chinese routers, unless you get a bad one, which is pretty rare.
I bought two chinese spindles two years ago, and just recently got a VFD to test them. They are smoother, more powerful, and quieter than any router I've ever used.

I'd say that 99% of DIY builders are using chinese spindles, as it's hard to justify 5-10x the cost for a high end spindle

I'd be leery of buying a used high end spindle. Replacing bearings on a high quality spindle can be very expensive.


These are the ones that I have:
2.2KW Air Cooled Cooled Spindle Motor ER20 220V 400Hz 24000rpm for CNC Router

with this VFD:
2.2KW 220V VARIABLE FREQUENCY DRIVE INVERTER VFD 3HP 10A | eBay


This spindle is probably a little better, as it's made in Turkey:
CNC AIR COOLED SPINDLE 2.2 KW

Or, you can buy a chinese spindle that's tested and guaranteed from UGRACNC.com

That's good to know.

In your experience, how does the reduced power and rigidity effect the end result? I.e. Is it in the speed of the job or the quality of the finish?

I have mainly been using end mills rather than regular router bits (designed for wood). I have noticed that the diameter of the end mill and the depth of cut makes a huge difference to how well it works (or if it works at all). I chose my router in part because it could hold 1/2" shanks but, in practice, 1/2" cutting heads have been useless for anything except the shallowest of cuts or the softest materials. It does far better with 1/4" or less tools.

Does the 2.2kw spindle allow you to make deeper and larger diameter cuts in harder alloys without jumping?

[ger21]

Not sure what you mean by "jumping"?
In theory, the more power you have. the faster and/or deeper you can cut. Provided that the rest of the machine is up to the task. When cutting forces exceed what the machine can handle, it will flex at it's weakest point. This flex is what affects cut quality. The best spindle won't make any difference on a lower quality machine.

[louieatienza]

If you're referring to the speed fluctuations usually encountered with hand held routers under load, yes, having more spindle power will lead to almost no perceptible speed fluctuations, which usually means better finishes. A rigid, vibration absorbing frame goes hand in hand; as you use larger spindles, you need larger frames to support them.

Is faster or slower better? There is a proportion that must be achieved for each cutting tool and material. The tool should be made for the material. Tthe tool manufacturer has specific guidelines foe the tool; the better the machine the closer you'll get to matching said guidelines, and your tool will cut better and last longer. And if you employ constant engagement toolpaths, your machine will run better and last longer.

Another thing to note is that the advertised HP rating of the handheld router is peak, in practice it's a bit less, and the speed cobtrol lacks the sophistication of even a Chinese VFD or even a SuperPID ...

[Goemon]

Not sure what you mean by "jumping"?
In theory, the more power you have. the faster and/or deeper you can cut. Provided that the rest of the machine is up to the task. When cutting forces exceed what the machine can handle, it will flex at it's weakest point. This flex is what affects cut quality. The best spindle won't make any difference on a lower quality machine.

By "jumping" I was referring to that thing my router does when I try and cut a material that is too hard and it jolts back on impact instead of cutting. It happens when the depth of cut is too much or the diameter too large.

I understand what you are saying about how the overall build quality comes into play. This is why I took the advice you and others gave me about buying good steel rails and reinforcements. I can see how an inadequate support structure would render a more powerful spindle useless.

Is your point that, to increase the cutting capability for harder materials, you need to upgrade the whole machine and not just the spindle? I.e. You also need a gantry, frame and rails that can handle it, plus motors with sufficient holding torque to stop the gantry from moving when you don't want it to.

[ger21]

By "jumping" I was referring to that thing my router does when I try and cut a material that is too hard and it jolts back on impact instead of cutting. It happens when the depth of cut is too much or the diameter too large.

That would be a machine rigidity issue, and have nothing to do with the spindle.


Yes, the spindle is one part of the chain, and the weakest link in the chain will always be exposed.

Is your point that, to increase the cutting capability for harder materials, you need to upgrade the whole machine and not just the spindle?

Probably, but that would depend on where exactly the problem lies. But unless the spindle is stalling, or slowing down, the problem probably lies elsewhere.

[Goemon]

If you're referring to the speed fluctuations usually encountered with hand held routers under load, yes, having more spindle power will lead to almost no perceptible speed fluctuations, which usually means better finishes. A rigid, vibration absorbing frame goes hand in hand; as you use larger spindles, you need larger frames to support them.

Is faster or slower better? There is a proportion that must be achieved for each cutting tool and material. The tool should be made for the material. Tthe tool manufacturer has specific guidelines foe the tool; the better the machine the closer you'll get to matching said guidelines, and your tool will cut better and last longer. And if you employ constant engagement toolpaths, your machine will run better and last longer.

Another thing to note is that the advertised HP rating of the handheld router is peak, in practice it's a bit less, and the speed cobtrol lacks the sophistication of even a Chinese VFD or even a SuperPID ...

I have read this point about how the specs on regular consumer routers lean more towards the realm of wishful thinking whereas the specs on dedicated CNC spindles is more of a reliable engineering spec. I can certainly believe that there would be an element of marketing plus a pinch of salt on the consumer router specs. Especially in America where there is no real laws to prevent this liberal use of the truth in advertising.

How do people know that the specs are more believable on the CNC spindles? Is it because you can see what the real performance is on the inverter display?

[ger21]

How do people know that the specs are more believable on the CNC spindles? Is it because you can see what the real performance is on the inverter display?

You set the voltage and current at the VFD yourself, so you know exactly what you have.

[Goemon]

You set the voltage and current at the VFD yourself, so you know exactly what you have.

That makes sense and I can also see why they would leave that functionality out of the consumer models.

[1Jumper10]

Carbon fiber (and all woven composite reinforcements) are strongest in the direction of the weave. If you laid all your fabric in the same direction then most of it's strength would be in that direction but.... nobody who knows what they are doing would lay all their fabric in one direction if they expected multi-directional strength.

When I make cf plates, I take a number of steps to increase the multi-directional strength. First, I switch the direction of the weave for each layer. Second, I add some layers of biaxial and triaxial carbon fiber. Third, I thicken the plates with layers of recycled no-woven carbon fiber mat which, instead of a one-directional weave pattern, it has the fiber laid out in a random matrix which adds rigidity in every direction (as well as reducing cost as this material is very thick on it's own). Fourth, I add carbon nanotubes to the resin which increases rigidity by approx 30% (depending who you ask and if you are buying or selling).

The choice of weave also also makes a huge difference. When I want the most rigid parts possible, my preferred fabric for the outer cosmetic layers is a 4x4 twill which comes out noticeably more rigid than the more common 2x2 twill and plain weaves.

There is also the type of resin to consider. I don't just mean epoxy or polyester resin. There can be huge differences in the physical properties just between epoxy resins. And... don't get me started on the curing schedules

All this makes accurate strength comparisons extremely difficult. Carbon fiber, as a general point is stronger than steel by both weight and volume. But... for reasons described above, you can't say by how much unless you have the two parts side by side to compare.

You also have the added complexity of people using alloys rather rather than pure metals these days. I read about a recently created aluminum alloy that is stronger than steel and titanium. I've had bars of T6 that felt stronger than some low quality stainless steel products I've seen. Plus, the strength of steel is also somewhat dependent on how it's made and prepared too. There is a world of difference between, for example, the differentialy tempered, folded and laminated steel on my old martial arts practice sword and the cheap nasty Chinese stainless steel on the kitchen knives I got as a wedding gift from my distant relatives...

Anyway, net net, if made properly, my cf parts will be stronger and lighter than equivalent steel ones. That's the part I know. The part I am assuming (based on what I've been told) is that a lighter gantry will increase speed.

Also, carbon fiber is less sensative to heat distortion than steel so it should be a generally more stable material for this purpose. It doesn't rust either, which is a plus because I want to put this machine in my garage.

Goemon - When you get around to making your gantry please post pics. In my opinion, Carbon Fiber is the holy grail of materials for a CNC gantry. I'm in the process of building a steel CNC router right now. I would have used CF for the gantry but I'm aware of my talents and limitations and, making CF parts is not in my skill set. Good luck with your machine.