New Machine Build- First CNC - 50% Finished

[Trucks]

Hey guys, well been asking questions and lurking around, basically building a decent sized 3' x 5' table, everything so far has been bought at the local ACE Hardware, Home Depot and True Value Hardware stores. Basically i used mainly 3/4" MDF, and the skate bearing design with a few modifications of my own, the gantry has 2 sets of bearings on each side, the top set is bolted into place, and the bottom set can be adjusted to allow for some tension to be applied to the rails, and the gantry is really solid, and doesn't seem to rack, and it moves very freely.

Here is my next question. I am at the point where i need to order my ACME rods and motors, controller, ect.

Can i get away with a Nema23 sized motor, say something that puts out 425 oz-in of holding tourque, its a dual shaft bi-polar motor from kelling, (they are super close to where i live), for the X-axis, and something similar for the Y-axis. The reason i ask is because it would save me some cash if i could get away with a single motor on the X. I plan on using ACME Rod, with a .500" per Turn, ect.

Any info or wisdom is always appreciated.

[Crawler374]

What did you use for the X axis rail?

[freecncplans]

I am not familiar with MDF machines, but my first machine with a 4 foot Y had many issues and was extremely hard to keep running. Often it would lock up in one direction just by holding it back with my little finger (going away from the X drive motor) and the other way would push me with no problems.
The other problems I had with the machine were the fact it would be off a bit on the sides because of the forces from the router when cutting (racking).
I now run a dual screw machine and I am much happier with the setup and the cost was well worth it to me.
Sean

[Trucks]

To answer the first question, the X-axis rail is 1.5" x 3" 1/8" wall rectangular tubing, with 1" Angle welded to it on both sides.

Okay thanks for the info, so far i have not had any issues with binding, on the bottom of each of my axis slides, aka - the X-axis bearing carriages, and the Y-carriage which i now have completed (as shown below), i have the ability to adjust the tension on the bearing carriage, i can easily push the whole machine around with my finger, i will be purchasing my motors from keling on Monday, i just received all my backlash nuts and couplers from dumpster CNC today, and i am very impressed with the quality. If the single screw doesn't perform well, it will not be too hard to add a second motor and lead screw to my setup, as i am using a G540 to control it, although i really hope it works ok because i would like to used the 4th axis for a rotary table, although i did look into the one motor driving a belt setup that drives twin screws. Since its my first attempt, we will see how it all pans out.

[Crawler374]

thanks for the answer! Got any close up pics of the X bearings?

Machine is looking real good. I like how clean it is

[Trucks]

It isn't the best picture, but it will give you an idea of what i am doing. Basically all my steel angle pieces that i used for the carriages, have 3/8" square nuts welded into them on the back side, so i could bolt to the steel, it works really well. So for the bottom carriages on both the X and Y, i used a 3" piece of threaded 3/8" rod and locked it into the carriage and then i have a jam nut that i turn with a ground down wrench, and then there is a locking nut on the opposite side, so that when i get it set, i can lock it down. I think it works out really well, i can adjust the tension on each end of the carriage since there are two bolts per carriage.

[KOC62]

Hi trucker.

I've looked at the joe2006 and he uses a stepper motor in the 200oz-in range. Your design appears to me to be of similar category. So I would conclude that a 425oz should be ok.

I plan to use Keling's KL23H286-20-8B steppers which are 425oz-in, and bought 4 of them.

[FandZ]

Originally Posted by Trucks Can i get away with a Nema23 sized motor, say something that puts out 425 oz-in of holding tourque, its a dual shaft bi-polar motor from kelling, (they are super close to where i live), for the X-axis, and something similar for the Y-axis. The reason i ask is because it would save me some cash if i could get away with a single motor on the X. I plan on using ACME Rod, with a .500" per Turn, ect. Any info or wisdom is always appreciated.

When I was building my machine I thought 425oz steppers was the way to go. Like you I got a g540. It's not. The g540 will not be able to power those at their optimum range so you'll end up with very slow rapids/ weak rapids. Hopefully someone can stop by and explain it better. From Keiling, you want the 280 oz range ones. Trust me, it's plenty of power and you'll be able to get most of the usable speed.

Now, the best steppers I've read about for the g540's are the ones Ahren with www.cncrouterparts.com has. They are 380 oz and pre wired with the resister. At $52 a pop, they are completely plug and play for the G540, No soldering. I wish they were available when I was building my machine. He just got them in a week or two ago and he is updating his website so I don't think they are listed yet. You'll have to PM him or send an email if your interested in them.

Chris

[FandZ]

Here's some good advice on picking out steppers to go with the G540.

http://www.cnczone.com/forums/showpo...20&postcount=8

[KOC62]

fandz,
You may be confusing me for trucks. I don't have the g540, but did buy the 425oz-in kelings.

I was responding to trucks question in post #1 whether a 425oz-in motor was sufficient and I mentioned that a joe2006 uses a motor in the 200oz-in range. You have confirmed that a 280oz-in is sufficient so the answer for trucks is yes, the 425oz-in is more than sufficient.

fandz, your experience regarding the g540 being inadequate to drive the 425oz-in was unknown to me. So trucks is now faced with finding a controller to match a 425oz-in motor or find a motor to match the g540 controller, -whichever is cheaper I suppose.

[FandZ]

Originally Posted by KOC62 fandz, You may be confusing me for trucks. I don't have the g540, but did buy the 425oz-in kelings.

My bad... I quoted the wrong post. I meant to quote his first post but somehow quoted yours. Corrected now.

But in conclusion, matching the Keiling 450oz to the g540 would be like having a car with a V6 that only had 4 spark plugs. You may be able to get it to run but you aren't going anywhere fast.

[Trucks]

Thanks for the info fellas, i was planning on purchasing the 387oz motors from keling, but i will look into the ones from ahren's. I just finished putting the second coat of polyeurethane on my table, it looks really nice now that its sealed. I am waiting on a nice linear stage assembly to come from ebay, its got 4.5" of travel which is plenty right now. Well my G540 is sitting on my desk, and no soldering would be super sweet.

Andy