Thread: Making a new CNC machine

The Z axis is completed and installed. I have shown four different pictures of the Z so that you can see how I made mine. AND wonder of wonders, almost all the holes I had to drill and tap lined up perfectly. I like the job that I have done here and feel that it is about as good as I could hope to do.

I had intended to make the motor mounting on my old CNC machine. To do this I needed to modify the drawings that PsychoPig7 (Noel) had kindly drawn up for me, but I was having a bit of trouble resizing the drawing so I asked The Big Willy for help. He said to me "You don't have to make them on the CNC, you can just use a hole saw to cut the 65mm hole and then cut the rest of the shape out on your band saw." The first thing I felt was epiphanacious shortly followed by guilt as I remembered that Noel had put time and effort into making the mounting drawings for me. So, I am very sorry Noel, but the band saw way is so very easy for me. It only took me about an hour to make the whole thing and that includes going out to buy a 65mm hole saw.

Just the main screw underneath the table to go now, but before I can do that I need to get a cross member for it from somewhere. Back to the scrap yard?

Bob Willson

Bloody hell just put me in the crap with noel why dont you .
Good work bob good work but would have thought you would have had it finished today .

Looking good Bob

Great minds must think alike as my Y design looks a bit like yours.

Hi GWH74

Yes, the basic design is very similar indeed. You do realise that I have taken out a patent on that particular method and you will now need to pay me a fee for the use of my design.

What did you use for the transom? Whatever it is, it looks quite sturdy.

Bob

Hi Bob

I am using a piece of 60x60 AME profile with a 20mm rail top and bottom for the transom.
It is only a small desktop machine but I have over engineered most of the components so they can be used on a larger machine.
How do you find the rails and ball screws from Chai? My ball screw bearing blocks had a far amount of end float so i had to rebuild and shim them. Also they are only oiled with that burnt smelling Chinese oil so it is good idea to pop the seals out, flush out and re-grease.
I also have an about 0.25 run-out in my Y screw that i think is twisting the whole Y slide. It only has a MDF front. I will doing some more testing to see what I find.
I did measure the backlash and it just a little less then 0.01mm, so i am happy with that.

Gareth

Hi Gareth

I have not yet been able to make any definitive tests because I have just discovered a different problem.

The long axis (y?) kept losing steps even though it appeared to all be set up correctly. It is set at 320 steps * 3000 *200 accel. This is a very modest amount of speed and the motor appeared to therefore be binding somewhere. So I took the motor off and looked at the shaft to find where it was binding. I couldn't find anything wrong because despite all the odds and as unlikely as it is, I seem to have done a competent job of setting up the mounts in a straight line.

However, I decided to just see how high I could rev the motor with nothing attached to it and it just kept stalling. That's right, no load but stalls completely after a few seconds of start up.

This was completely unexpected as Willy had just shown me how to get heaps of speed out of the other axis and I was quite confident that I would very soon have everything running super fast.

I can run the motors slowly but that isn't nearly as much fun and I want to make this machine perform as I originally hoped it would.

Does any one have any ideas on this?

Bob

So the motor itself is stalling without anything attached at all?

Try putting that motor on a different driver see if it does the same.
I have to go to H&F in the morning and can drop in for an hour if you need.

Z= Spindle
Y=Gantry
X=Table

Yep. nothing attached but the motor stalls on the X axis (not that it matters which axis when it isn't attached).

I tried it on another driver with the same results. The best I can reliably get is 320 * 1800 *200.

Unfortunately I won't be here for much of tomorrow as I will be helping my daughter to move into her new place tomorrow. I could however just leave the door open if you just want to confirm that I haven't stuffed up something somewhere.

Bob

So anyone got any thoughts on this maybe the motor is stuffed anyway to check this.

Bob can you find the specks on your power supply for us as well may help.

What motors, drivers and PSU are you using Bob, I couldnt find any mention in this thread.

Is it the motor thats playing up? Do the other 2-3 motors work fine?

Hello Ch4iS

Sorry for not getting back to you earlier, but I have been a little ummm indisposed for the last few days.

The PSU is a KL-320-36 putting out 36 volts at 8.8 amps from Keling. He supplied this when I purchased the original motors.

The motors are also from Keling as are the drivers. KL23H286-20-8B motors and KL4030 drivers. It is using a C10 Rev8 parallel port interface card.

The other two motors are working properly now that Willy has told me how to use a simple calculator.

As I said earlier, the motor stalls under no load at all, no matter which driver I attach it to. I am inclined to think that it may have been faulty from the start and could be just one of the reasons that my previous build had such poor performance.

Bob

join the club I am now a dad since 0305 this morning mate I am going to leave a motor behind the screen door at my place come and pick it up see how you go I will also put the 48v PS give that a go as well should help with the speed as you really going to need the 48v I wont need it back for a week or two .

Have to go

Sean

Congrats to Sean and A

Bob,
The 4030 has a max voltage of 40vdc so you should stay with the power supply you have.