Hi,

I have an "X2" (Harbor Freight 44991) I purchased to convert to CNC.

I have read a mountian of posts on the subject and am still unsure on the answer to this question:

What is the best of the best for both electronics and hardware?

Here is what I have gathered:

1. CNC FUSION makes an exelent hardware conversion kit and the "#4" kit can be had for $550.00 (Anything Cheaper?)

2. Nema 23 425 oz steppers should be good for X, Y, and 4th axis and can be found for $49.00 each. (Anything Cheaper?)

3. Nema 34 640 oz stepper should be good for the Z axis and can be had for $90.00 (Anything Cheaper?)

4. A model #7212 - 72VOLT 12Amp power supply should be good to drive these steppers. $150.00 (Anything Cheaper?)

5. C11G controller should be good to go for a 4 axis setup of this type. $110.00 (Anything Cheaper?)

6. Geco G203V STEPPER CONTRLLERS = $140.00 x three!!! (OUCH!!) (Anything Cheaper?)


I am chomping at the bit to order the right parts at the right price but in these tough times am taking extreme caution and asking around before making such an important purchase.

Please respond with sugestions pricing and where it can be found for purchase please.

Thanks!!!!
(nuts)

I would think that you could easily use a Geckodrive G540 and a 48v power supply. I don't remember for sure but I believe that Hoss26 uses a Nema23 stepper for the z-axis as well.

Alan

I also have just bought an X2 mill and have been looking around at CNC options. There is lots of good info in this forum about CNCing the X2. What I found so far:

Use a gecko G540 and a 48V supply. (Already ordered!)

Motors. NEMA23 for XYZ but there is some difference of opinion as to what the necessary torque rating should be. Anything from 285oz-in to 425oz-in have been mentioned. Trying to find an affordable source of these.

Not sure on a CNC kit. The $A is not that strong at the moment and freight from the US is a killer. This also makes the motors an expensive exercise.

Look forward to seeing what you go with for your conversion.


Belt drive. While not part of the CNC requirement, it's certainly rated as a 'must have' accessory.

1. Yes CNC Fusion makes a great kit I have one my self. I recommend that you purchase the Helicals at the same time. There are cheaper kits out there. Some have a little diy in them and some have a lot. Hoss I think sells 2 different kinds of kits. One that you have to machine yourself ( He provides plans and stock) and another that requires some machining but the screws are already cut and threaded. Dont qoute me though I havent been to his site in a long time.

2. 425oz is a little over kill but is not to bad. 50 dollars sounds about right. You can check out Keling and Xylotex for motors. Beware of crap on ebay.

3. Completely over kill. I should tell you I have 269oz on all 3 axis and have no problems. I can jog at 45ipm, rough cut at that speed and cut at 20ipm.

4. I have a 24v power supply on mine.

5. I dont use a breakout board. My controller has it built into it.

6. Overkill again for this machine. If you plan on moving up in the future and have the funds then 203v are the way to go. If this is the end of the line for you the Gecko 540 or its little brothers would be more than enough. I use a 3 axis kit from Xylotex. By the way you would need three 203 drives. So
$420


Most of what you are looking at should be for a x3 which is bigger and heavier. Im not saying that none of this would work, but I am saying it is overkill. I just posted a video of chip load and I am waiting for it to clear. As soon as it does I will post it here too so you can see what mine is capable of doing with the above components.



Belt drive. While not part of the CNC requirement, it's certainly rated as a 'must have' accessory.

+1
Made machining much more enjoyable. Worth every single red cent!!!!!!

Video cleared customs.

1/2 endmill @ 45ipm with a depth of .05 cut. Old HSS endmill with a chipped tooth that came in a china package set from Enco (all 12 for 20 dollars)

CNC FUSION CUTTING 6061

Regnar,

What was the model of your controller and can you give more details on you parts? I beleive you are running what I didnt know I should be running but am getting the drift. :)

Thank you!!!
:rainfro:

Is there a cheaper solution for Drive controllers than the GECKO'S G203V at $140 x 3 of them = BIG BUCKS!!!!?????????

It just seems like alot to spend for what it does.

IS this for real?

EbAY Item: "4 AXIS CNC Router or Mill Stepper Motor complete kit"

Complete kit with everything for $290 +S&H or $325 with BuyItNow

http://cgi.ebay.com/4-AXIS-CNC-Router-or-Mill-Stepper-Motor-complete-kit_W0QQitemZ160313393645QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item160313393645&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

It looks like a good deal but seems to good to be true.

Anyone have the skinny on this???

Is there a cheaper solution for Drive controllers than the GECKO'S G203V at $140 x 3 of them = BIG BUCKS!!!!?????????

It just seems like alot to spend for what it does.

Do you NEED 7 amps at 80 volts?

If not, then the G540 is only $299 for 4 drives. 3.5A at 50V.

The Chinese stepper driver in the kit is based on a Toshiba TA8435H Driver IC, it only has a 1.5 amp output or 2.5 amp peak.

It would be marginal with the stepper motors suggested for use with the X2.

You will be taking a very big chance purchasing cheap drivers off eBay, most likely they will not provide the power needed and you will have to spend a second time to get what you really need.

Be very careful you don't $crew yourself in the process.

Reinventing the wheel wont be pleasant, many of the members have already been down that path.

Jeff...

IS this for real?

EbAY Item: "4 AXIS CNC Router or Mill Stepper Motor complete kit"

Complete kit with everything for $290 +S&H or $325 with BuyItNow

It looks like a good deal but seems to good to be true.

Anyone have the skinny on this???


It would depend on just how good the drive controller is. $290 for 4 stepper motors and a power supply is a lot of money :)

If you want an inexpensive kit that will work well take a look at this:

http://www.kelinginc.net/ThreeXCNCPackage.html

$379.00

Hoss2006 runs the same system and it works very well.

http://www.hossmachine.info/

Jeff...

What about this:

at $55 its cheap as hell but is it for sh#t?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=120372436003

Add a cheap decent 5-12-24volt PW supply and 3 NEMA 23 -264oz steppers and stick a fork in it!

My rough math says that this whole setup could be as low as $200 for the electronics.

I realize this would be a bottom of the line system but would it work good enough to function correctly for a very part time hobbyist working with metal fabrication???

Thoughts?

Are you reading the posts?

I bought this systems a few years ago. http://www.xylotex.com/3AxSysKit.htm

If and when I do have to replace the driver I will go with the Gecko 540. I dont think you would be disappointed. Built in breakout board and the same feature as the 203v. Just not the same power.

One more thing I forgot to mention. If you have a signifigant other that doesnt enjoy metal working as much as you. You will want a enclosure. I seemed when the carpet started to turn sparkly the complaining about everything got turn up a notch. New enclosure no complaining :D

Video cleared customs.

1/2 endmill @ 45ipm with a depth of .05 cut. Old HSS endmill with a chipped tooth that came in a china package set from Enco (all 12 for 20 dollars)

CNC FUSION CUTTING 6061 (http://video.google.com/videoplay?docid=3518469489970451444&hl=en)

I wonder what your tool life is like doing that kind of cut. Even at 4K RPM, you'd be running a 0.006" chipload, which is 2-3X most manufascturers recommendations for a 1/2" HSS endmill. I would expect you to end up with chipped teeth pretty quickly. Or is this a 4-flute?

Regards,
Ray L.

Is there a cheaper solution for Drive controllers than the GECKO'S G203V at $140 x 3 of them = BIG BUCKS!!!!?????????

It just seems like alot to spend for what it does.

CNC74,

Several of us have told you that you could save a lot of money by using the Geckodrive G540. It costs $299 for a box with 4 drives and built in BOB. What is the point of trying to help you if you aren't going to read the posts carefully.

Alan

Thank you all for your detailed and guided input.

I asked about other less expensive options to draw comparison to the Gecko product. If you want to jump down my throat for asking about other products I would rather you not reply at all.

Is there a detailed comparison chart of the different controllers that can handle an X2 in 4 axis configuration floating around somewhere?

If not

Would anyone be willing to draw a comparison between the gecko 540 and any of the other less expensive boards?

Thanks to all!!

(nuts)

I'm no expert, just a beginner really... From what I've seen the biggest 2 factors you need to consider when buying a driver are the voltage and amperage ratings.

That last driver you posted can only handle 36 volts (about ~72% of what the G540 can do) and I don't see any amperage rating. The lack of an amperage information is worrying - to me it suggests that driver doesn't have a very good rating.

I think the other people here are answering a question you didn't ask "is it worth it to buy a no-name driver?" It looks like the prevailing answer is "no".

Gecko drives are known to be reliable, you're taking a risk with a no-name driver. It's a tough call, but I'd say the "reputation" of Gecko drives is worth at least $50... to ME. Meaning if I found a driver with equal specs to the Gecko and it was $50 less I'd still buy the Gecko.

The fact that there are a lot of other people here using Gecko drives makes them more valuable as well, 'specially to newbies like you and I.

In addition to the anti-resonance feature jalessi mentions below the g540 also has a "charge pump". A charge pump is a mechanism that prevents the driver from turning the motors unless you want them to by detecting a special signal from your computer. If the signal isn't there the motors wont turn. "They" say that the parallel port can send out signals when the computer is booting up and stuff. It might also send out strange stuff if the computer crashes or something too. Those errant signals could cause the motors to do stuff you wouldn't want. The charge pump protects against this.

The $300 price of the g540 also includes connectors for your motors, which would probably save you around $10. Not the biggest selling point, but worth noting.

CNC74,

None of the less expensive eBay stepper drivers have anti resonance features built in.

Without anti resonance the performance will be greatly reduced.

The second issue is the current capacity and voltage output of the less expensive drives and again much less performance.

If you want to take a fifty percent performance hit buy any of the other products.

None of the less expensive drivers come close as far as speed and reliability.

If you also want lots of problems buy the cheap eBay stuff.

There are lots of posts here on the Zone that talk about what we are suggesting, do yourself a favor and take the time to read them.

The Keling KL- 4030, Xylotex and HobbyCNC are decent products, however still have shortcomings compared to the G540

http://www.kelinginc.net/KLDriver.html
http://www.xylotex.com/
http://www.hobbycnc.com/

In a nutshell there are no products in the price range that compare!

Have a most awesome day.

Jeff...

Guys feel free to flame me.

Jeff...

Guys feel free to flame me.


You're expecting to get flamed ?

Of the 3 products listed, I only have experience with the Xylotex. It's an honest product from an honest vendor and worked well on my X2 until blowing an axis after 1+ years of use. And that's the thing. The g540 will not only outperform brand X but is also much less fragile. All this plus the g540 has built-in extra features
Win-Win.

Guys,

Gecko 540 it is!

Next questions are:

1. What is a reasonably priced yet good power supply to match the 540 with?

2. I was thinking of purchasing the Nema 23-425's. (I could go smaller ???) Where can I get them at the best price?

Is there a place to buy everything at the same time at a good price?

Many thanks,

CNC74
:rainfro:

Bigger is not always better. You are all but certainly buying the wrong motors for X2 and G540.

I recommend Keling $39 60V KL23H276-28-4B 270s for X and Y and Keling $49 65V KL23H284-35-4B 387 for Z, along with Keling $60 KL-350-48 48V/7.3A PSU.

Keling has all of this (Including the G540--and 425s if you are that stubborn) and a discount on Mach3.

CR.

Thanks for the heads up onn the motors.

I have read many posts about the Z axis needing more torq that X and Y and all of chatter about going with the 425's to oleviate the issue which was where I got that idea.
If I am sacraficing speed and acuracy for torq (unnesasarily) then I will run the other way.


Keling is in the Chicago is it not? (??Local pickup??)

You guys are the best!

Yes, Keling is in West Chicago--And one of the BEST dealers for price/value. You will have to email about local pickup:

http://kelinginc.net/index.html

CR.

Crevice Reamer,

I took your advice verbatim. Although I probably could have saved the shipping with a pickup I put the order thru for delivery with the parts you specified with an additional motor for my 4th axis project.

Now I have to work myself up to spending another $300 on the Gecko540. LoL

Thanks again,
CNC74

YW! Keling 387s are out of stock until 2/10. You'd better email him for NO SUBSTITUTIONS or you may get something else shipped today.

If you can handle installing new DB9 connector screws, you can get a brand new G540 right now for only $225.

http://cnczone.com/forums/showthread.php?t=72628

CR.

CR,

You are very tuned in to whats going on with this stuff. Sales, stock levels, tech info..etc

I emailed Keling on the subsitutions issue and jumped all over the G540 @ $225 like it was a naked super model!!!!

I am trying to compile the list of "dodads" I will need to finnish off the electronics for this project.
I read that I will need:
1. ESTOP switch
2. Resistors (2 types)
3. Relays
4. Motor wire
5. ???
6. A good set of instructions!!!! LoL

Regards,
CNC74

You will also need some other stuff:

You can use THIS wire for motor cables and home/limit switches. Ground the drain wire ONLY at the driver end.

http://cgi.ebay.com/Servo-Motor-Wire-by-the-foot-18AWG-foil-shielded-pair_W0QQitemZ300257182769QQcmdZViewItemQQptZBI_Connectors_Switches_Wire?_trksid=p3286.m20.l1116
You won't need any db9 motor connectors with the G540, as they come WITH it. The G540 also has circuitry for simple spindle speed control and outputs for dc relays to turn coolant pump on or off.

These inexpensive relays are very good :

http://www.surpluscenter.com/item.asp?UID=2008091210032758&item=11-3167&catname=electric

You WILL need 2.8K and 3/5K 1/4 watt current limiting resistors, one for each motor. You can get them here:

http://www.digikey.com/

If you don't already HAVE them, these are excellent home switches:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330302080650&ssPageName=MERCOSI_VI_ROSI_PR4_PCN_BIX_Stores&refitem=260298574976&itemcount=4&refwidgetloc=closed_view_item&refwidgettype=osi_widget&_trksid=p284.m185&_trkparms=algo%3DSI%26its%3DI%252BIA%26itu%3DIA%252BUCI%26otn%3D4%26ps%3D42

They are NO, so only for home switches. Limit switches need to be NC. the whole set of 6 switches costs less than ONE switch would cost at Radio Shack.

These simulated roller limits from Enco will do fine and only cost $2.95 each. Now you know what a deal the home switches are.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=1095&PMITEM=317-6325

You will also need an estop switch. This one from Keling only costs 10 bucks and works fine:

http://kelinginc.net/CNCPackage.html

On that same page are helical connectors. These are best for low backlash. I haven't tried Keling's, but they LOOK good.

The G540 is so small that many are mounting theirs INSIDE the computer case.

Camtronics has a case MADE for the G540:

http://s120220635.onlinehome.us/stepper-components.asp

CR.

Somewhere on this forum there are some neat instructions for using angle iron to make cheap but good mini mill X/Y motor mounts that use existing Acme screws. There also is a thread for Z drive through the quill fine feed.

I can't find them. Does anyone have these links? Please post them if you do.

Thanks!

CR.

Thank you all for your detailed and guided input.

I asked about other less expensive options to draw comparison to the Gecko product. If you want to jump down my throat for asking about other products I would rather you not reply at all.

Is there a detailed comparison chart of the different controllers that can handle an X2 in 4 axis configuration floating around somewhere?

If not

Would anyone be willing to draw a comparison between the gecko 540 and any of the other less expensive boards?

Thanks to all!!

(nuts)
CNC74,

I responded to the statement that you made about G203 drives being very expensive for what they do (even that is debateable) after several of us had suggested that the G540 was a cheaper solution. It seemed as though you were not reading what people had written before asking another question.

I am glad you finally got the info that you needed to make a decision.

Alan

Now that I am sorted out on the electronics for my X2 build the attention is turning to the mechanical converion equiptment.

I am told the the #4 kit at CNCFUSION is a real good choice but at $550 I have to do some more cost comparison before spending the funds.

C.R. mentioned another solution that I had not heard of previously that involved fabricating a few parts and the possible use of more "original equiptment" to asumably make it a far less expensive option. If anyone has further information on that topic please share.

I also read that there are benifits to going with a belt drive system but dont know any more than that at this time.

Lastly it would be very nice to maintain MANUAL FUCTIONALITY on the machine if its not to much of a trade off for price/performance with the avalible conversion solutions.

Regards,
CNC74

You can make the conversion parts yourself. The hardest part is turning the ball screws, it is very hard to do on a small (7x) lathe, but you can get the work done by a machine shop pretty cheaply. Cost me $60 for all three and could probably get it done cheaper now given the times.

Other than the screws you don't need a lathe for anything. A boring head would be needed to make the seats for the bearings but it's a good tool to have. It's a good project if you want to improve your manual machining skills. It will take some time though so you can hold off ordering all the electronic stuff for a while. If you choose to do this, you might want to order Hoss's videos since they might save you time. I didn't by them and ended up spending a lot of time on parts that didn't need to be anywhere near as precise as I made them. I'd also recommend tearing your mill down and reassembling it just to be familiar with how it all goes together.

OTOH, CNCFusion has a good name. If I was doing it again and had the money, I'd be tempted to buy the kit. But I think the 100% DIY build is a good exercise for newbies like me.

You can only have manual control with the original lead screws. Once you go ball screws, There is no friction to hold the axis in place anymore. (The motors lock the axes when powered) The cutting force will move it.

CR.

Good to know about the manual vs ball screw trade off.

Is there a "prefered" DIY specification/drawing or are they all the same thing?

Regards
CNC74

Ballscrews are typically right hand thread which means you'd have to turn the handles the opposite of normal and
with .200 pitch you'd get 3-4 times the movement per crank versus the stock screws.
You'd have to have power to the steppers off so you won't be able to use the DRO's in Mach either.
About the best you could do is mill the edge of a part by hand if you still have the locks in place to keep the other axis from moving.
Once you're cnc'ed, you'll find it easier to mill "manually" with the jog keys, MPG, MDI, etc.
It's more fun anyhow.:)
Hoss

Somewhere on this forum there are some neat instructions for using angle iron to make cheap but good mini mill X/Y motor mounts that use existing Acme screws. There also is a thread for Z drive through the quill fine feed.

I can't find them. Does anyone have these links? Please post them if you do.


You're probably thinking of members chukkie or blades. A member search here will find all their posts. An example;
http://www.cnczone.com/forums/showthread.php?t=51449

I can remember this stuff but not where I put the car keys ?? :confused:

Here you go:

http://cnczone.com/forums/showthread.php?t=50277

http://cnczone.com/forums/showthread.php?t=51449

http://cnczone.com/forums/showthread.php?t=68199

http://cnczone.com/forums/showthread.php?t=58908

Bracing X2 column:

http://cnczone.com/forums/showthread.php?t=57540

http://cnczone.com/forums/showthread.php?t=54743

cheap belt drive:

http://cnczone.com/forums/showthread.php?t=55239

CR.

Ballscrews are typically right hand thread which means you'd have to turn the handles the opposite of normal and
with .200 pitch you'd get 3-4 times the movement per crank versus the stock screws.
You'd have to have power to the steppers off so you won't be able to use the DRO's in Mach either.
About the best you could do is mill the edge of a part by hand if you still have the locks in place to keep the other axis from moving.
Once you're cnc'ed, you'll find it easier to mill "manually" with the jog keys, MPG, MDI, etc.
It's more fun anyhow.:)
Hoss

Actually, ballscrews and nuts are readily available in either LH or RH thread, for the same cost.

Regards,
Ray L.

Actually, ballscrews and nuts are readily available in either LH or RH thread, for the same cost.

Regards,
Ray L.

I said TYPICAL as in what most people use and everywhere Ive checked including Roton charge more for left hand ballscrews and nuts for the the same size and pitch, which would explain why right hand are more popular.
Hoss

CR,

Thanks for the links!!! It got me to thinking, I would rather not mess around and would like to go with the best of the best mechanical kit avalible within reason with regard to its price.

Is there a clear cut winner of pre fab mechanical parts kits (with ball screws)?

I just decided I dont want to mess around or wish I did something different later on.

Regards,
CNC74

:drowning:

Now that I am sorted out on the electronics for my X2 build the attention is turning to the mechanical converion equiptment.

I am told the the #4 kit at CNCFUSION is a real good choice but at $550 I have to do some more cost comparison before spending the funds.

C.R. mentioned another solution that I had not heard of previously that involved fabricating a few parts and the possible use of more "original equiptment" to asumably make it a far less expensive option. If anyone has further information on that topic please share.

I also read that there are benifits to going with a belt drive system but dont know any more than that at this time.

Lastly it would be very nice to maintain MANUAL FUCTIONALITY on the machine if its not to much of a trade off for price/performance with the avalible conversion solutions.

Regards,
CNC74

i don't want to be a "wannabe" so i will say now my mill is currently not up and running on cnc yet. It annoys me on other forums when i find out the "experts" have no practical experience :( so i dont' want to be one of these "experts"

so with that said, in all my reading i will summarize it for you- if you want a machine that can cut repeatable parts with ease and not a ton of maintenance, go with ballscrews.

I often make the mistake of buying the cheaper tool, and i always end up buying the nicer one. I was going to buy the ballscrews myself, buy a lathe and turn the or pay someone to turn them for me, make the mounts et cetera myself, but i quickly found i was overwhelmed by wthe work and the price. I figured about 75 hours to make the mounts on the x3 + i think it was $450 or so for ballscrews, ballnuts, couplings, metal, et cetera. I quickly learned to appreciate the price on the cncfusion kit, it seems so much but when you get individual prices on the kit, i think you will find its a good deal.

manual milling is tough once its cnc'd as the ballscrews freely rotate(er, at least without a stepper attached. once again lack of experience here), but the jog functions in mach should do more then you would ever want from the manual mill. if your like me, i plan to do this a lot as i refuse to dish out $1000+ on a cold saw when my $175 bandsaw is fine after surfacing it on a mill, once converted to cnc just using the jog to surface something after its rough cut will be fine.

Kiss a$$ to crevice reamer, its incredible how devoted he is to helping and how much time he will help you individually on your project! your the best dude!

Its alive!!!

Well almost....

I have the X2 Mill, the Fusion kit, steppers, Keling power supply, gecko 540, wires, Estop, limit switches, Box for housing everything, etc..

Still need my resistors and roller switches??

I need some clear details on the electronic connections with regard to resistor placement and all the switches.

Is there anything avalible?

Congratulations! You now are ready to put it together and make chips.

The resistor positions are printed right on the G540 case. They solder inside the DB-9 connector between pins one and five.

This thread has a very nice generic Home/limit switch diagram.

http://www.cnczone.com/forums/showthread.php?t=24432

Limits/Homes are attached to pins 1-4 of the G540 terminal strip and grounded at PSU negative.

CR.

CR,

First off thanks! Seriosly... thanks! ALOT!

You mentions roller switches also in an earlier post below the limit switches.. Do I need them? If I was looking at the right ones they were expensive ($25 each) Or is it that I can do with the home switches instead?

Lastly and I hate to ask but dont want to order the wrong resistors from Digikey, do you happen to have the correct Digikey or Newark part numbers for the resistors?

Thanks,
CNC74

Uh, What steppers did you get? What switches do you have now?

CR.

CR,

2x 270's and 1x 387 with a secondary 387 for future 4th axis project.

As for the switches:
I got the ones you linked to:

Quote "If you don't already HAVE them, these are excellent home switches:
http://cgi.ebay.com/ws/eBayISAPI.dll...%3D4%26ps%3D42
They are NO, so only for home switches. Limit switches need to be NC. the whole set of 6 switches costs less than ONE switch would cost at Radio Shack."

And do I need the relay? if so how many?
http://www.surpluscenter.com/item.asp?UID=2008091210032758&item=11-3167&catname=electric


Regards,
CNC74

CORRECTION TO PREVIOUS POST. I made a typo. The resistors solder into the DB-9 connectors NOT the DB-25.

You will need THESE 1/4 Watt 3.48K resistors for the 387:

3.48KXBK-ND

and THESE 1/4 W 2.8K resistors for the 270s:

2.80KXBK-ND

They only come in a pack of five, so about $1.

http://digikey.com/

what switches do you have now?

CR.

CR,


The switches from this auction are the ones I have now. (quantity of 6)

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=260360389286

"CNC Limit Switches for stepper motor systems N. O."


And do I need the relays you mentioned on page 2 of this post?

Regards,

(group)

I used 3 of those switches for home switches. It's more complicated, but those NO switches CAN be used as limit switches. I like to use NC limits and wire them in series as in the drawing. Enco has some simulated roller switches that cost about $3 each and can be wired either Normally Open or Normally Closed.

You COULD, since you're using stepper motors not servo motors, even forego the limit switches entirely and just set up the Mach3 software limits.

http://syilamerica.com/docs/Homing_Video/Homing%20and%20Limits.html

Relays are handy if you want to have the computer do things from inside the program like turn the spindle on or off, or control a pump for flood coolant.

CR.