Will these specs work well

[Huzzah]

Hi, I'm starting to narrow down the specs for my first CNC router. The unit itself will be based on plans from buildyourcnc.com

I already have a Gecko G540 on order and thought I would connect that to (3) KL23H284-35-4B 387 oz-in motors. For a power supply I was thinking of the KL-350-48 48V/7.3A unit.

For leadscrews I was thinking:
X & Y Leadscrew - 1/2"-10 dual start
Z Leadscrew - 1/2"-10 single threaded

What I plan on routing is mostly MDF and plexiglass and hopefully thin (.050") aluminum. Do you think these specs are good? Should I upgrade the power supply?

Also, looking around at various suppliers I see relays for sale, what are they used for and do I need to use them?

Thank you.

Steve

[revwarguy]

Your specs look fine, especially for cutting mdf and plastic. You get a better repeatability using 5 start screws, but with the 10 microstepping provided by the G540, you'll probably be happy with it.

If you're cutting mdf, make sure you budget for a good dust collector - you'll need it. That stuff is not fun, and will hurt your lungs.

Relays are used to control the router on/off, the dust collector on/off, or any other device the the program can control. A small signal from the parallel port, controlled by Mach 3 or EMC, goes to the relay to switch on 115v or 220v devices. Make sure that the relay is capable of carrying the current required by the devices being used, though, and is switchable by a parallel port signal.

[Huzzah]

Thanks for the quick reply. If I go to a 5 start leadscrew should I to that for all 3 axis or just X & Y?

[revwarguy]

Funny you ask that - I used a single start 3/8 acme for my Z and it works fine, and 5 start for the X & Y. Depends on the mechanical advantage of the belts and pulleys or direct drive you might be using.

Also, in my previous post about relays, I was assuming you were controlling the relay from the parallel port, but if you have a G540, definitely go through it. That way, when the computer boots, the router or whatever controlled device won't suddenly turn on because sometimes the parallel port comes up in an undetermined state. Using the G540, it won't turn on until the fault line is taken care of, which only happens after Mach3 or whatever is servicing its charge pump. Doing it the other way is an accident waiting to happen. Also, with the G540, if you hit the estop switch, everything shuts off.

[mlabruyere]

I use 1/2"-10 5 Start on all of my axis....it was easier to keep it all straight plus I used a drop piece from my y-axis screw for the Z axis....translation = cheaper. I have a 282oz/in on the Z axis and 628 in/oz on the x (dual) and Y.

[Huzzah]

Thanks guys. I think I will go with 5 starts for the exact reason mlabruyere says, it will be cheaper.

revwarguy - As for the relay explanation, your reply makes perfect sense - go through the G540.

[mlabruyere]

Originally Posted by Huzzah revwarguy - As for the relay explanation, your reply makes perfect sense - go through the G540.

Yeah, it's pretty straight forward with the G540. It has 2 outputs built in for controlling relays.

[Huzzah]

Okay, leadscrews, anti-backlash nuts, motors, power supply, limit switches, and e-stop button are all on order.

Next question, where's a good place to buy a coupler to connect the 1/4" shaft of the motors to the 1/2" leadscrews?

[mlabruyere]

I went here and got them:

http://www1.mscdirect.com/CGI/GSDRVS...IT4NO=78928203

You need to get 1 1/4" coupling, 1 1/2" coupling and a spider.

[mlabruyere]

Or you could go with this:

http://www1.mscdirect.com/CGI/NNSRIT...ber=3725Pmode=

One of the guys tried this and liked it much better than the lovejoy. I would have gotten this type had I known about them.....

[Huzzah]

I like the 2nd suggestion just because it's cool looking! Thanks, I think I'll go with that one.