Question on Strength of Motors

[js11110]

Hey everyone! I will be starting to build my first router soon. I would like to build a moving gantry type. Because I am clueless on the electronic end of things I'm thinking of buying Xylotex control box/stepper motor package. The package comes with 270 oz-in motors. My question is how much weight will these motors move? I want to build everything out of aluminum and I'm thinking the gantry might be a little too heavy for these motors to move efficiently. What is a realistic expectation? Can I get beefier motors if needed? Or is this the largest motors for the Xylotex control box? If I can't use bigger motors, any suggestions on designs for a aluminum gantry that is very stable, yet light? Thanx for any comments!

[Bruggles]

What type of linear motion are you going to use? Ball screws, acme screws, rack and pinion or another type of linear motion.

[southernexplore]

I have an all aluminum home made machine and 265 Oz. In. motors and the machine runs fine. I just finished cutting a sign that came out really nice.

Tommy

[southernexplore]

Here is a photo of the Sign.

Tommy

[posix]

how long did the sign take?

[southernexplore]

The sign took about 2 hours and is roughly 11.5" X 17". While the sign was cutting I did see some things that could be changed in the programming that would speed things up a lot. The first thing is my plunge speed, second thing is depth of cut for the 60 degrees cutter. I told it to make 2 passes and it should have been 1, that alone would of saved a lot of time. Last thing I would do is pick up the feed rate for the roughing endmill and stepover amount.
The .250 endmill had no trouble cutting the full with of the cutter and the .250 depth. I noticed that while cutting out the profile around the sign. I will try deeper passes for the profile also, even though it did not take long to cut the profile.
Of course this is assuming you are cutting MDF. I will be cutting some Maple and Oak
soon and will get some feeds and speeds on that.
I am running the PicStep drivers and 48V PSU.

All created withVcarve.


Tommy C.

[js11110]

Bruggles- I'm going to use linear rails and ball screws. Would like to make a machine with 24"x24"x3" of travel. Would like to make something like the attached picture but with linear rails instead of thomson shaft. Southernexplore- that sign is awesome! How much travel do you have on your machine? Any chance you have a picture of your machine? I'm grateful for any advice!!

[southernexplore]

Cut size is about 24" X 38" with 4" travel in Z.
The photo you have there is a close machine to mine. I spent about 1 month drawing all the prints to carry to the machine shop and about 40 hrs. machining all the parts. I was planning on going with acme screwa but went with ball screws instead(glad I did). The big E provided the linear guides (used) and motors(new).
All of the electronics were homebuilt which include Picstep drivers, a mother board which is open source here a 12V power supply for the cooling, motherboard (works perfect with limits and home switches) and a nice fan control for a second fan when the case temp goes above 110(pot adjustable), all housed in an old table top computer case.
Everything worked perfectly while cutting the sign and that was the longest it has ran non stop so far.
southernexplorer

[sdantonio]

Can I get beefier motors if needed?

The simple answer is yes and no.

You should run your motors at roughly 4 to 20 times their rated voltage. Mine for example are 425 in-oz, 4 volt motors. For me to run them effectively I would have to run between 40 to 80 volts. More than the xylotek board can handle (the a3977 chip xylotek uses is limited to 35V max). In my case I will be running picstep boards (Once I build them).

Also, the footprint of your motors may change. Going to stronger motors you may end up with something bigger than nema 23's which would mean rebuilding or adapting the mounting (usually only a minor anoyance).

Also, running at higher voltages could cause problems with back emf and cause your board to screw up on it's step timing.

Steven

[js11110]

How much would you say your gantry weighs? If I did my math right, mine would weigh 60lbs without the router. Seems like too much for a 270 oz-in motor, but what do I know?

[sdantonio]

Hi Tommy,

I am running the PicStep drivers and 48V PSU.

You running into any back emf problems? I was told the PicSteps can run into problems over 40V and I should limit my system accordingly.

I assume you worked from Alans scematics. How did you flash the PIC chip?

Steven

[js11110]

sdantonio- you slipped in between my replying to southernexplore. See the problem I have is I am TOTALLY clueless about the electronic end of things. I would really like to get Geckodrives and do everthing right with say 450 oz-in motors. Being as clueless as I am, I'm not willing to spend hundreds of dollars on the geckos and then not be able to hook them up, or even worse smoke them. I've read hours and hours on hooking up the geckos, and still don't understand any of it. Thats why I went looking for something thats allready put together, and came across the Xylotex. Bummer they don't have something for beefier motors.