[shiv15uk63]

So i have finally built my machine. now having a little trouble when getting a new arm made up i will explain so i have drawn up my design in solid works and saved it as a .igs file opened the file in bobcad sorted all the machining out in bobcad but when profiling the arm every pass it moves away by a few mill have attached a photo it is quite hard to explain at first i thought it might be the drawing so redrawn the whole thing but same thing happened don't have a clue been scratching my head past few days trying to figure it out will appreciate any help thanks


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[MikeTheG]

A Couple of questions first . Which toolpath in Bobcad did you use ? Profile ect. Does this occur in the Gcode or just at the machine . It this is not occurring in the Gcode program than it would be a machine issue. Movement in guides or part it self... Please posts bobcad file with toolpath and seperate posted Gcode file for us to look at.


MikeG

[shiv15uk63]

code

[shiv15uk63]

there's the code problem is on job 4 still doing the same thing

[jrmach]

WOW,you got some serious tool deflection issues.To better help you a few questions.What kind of endmill you using,and is it High Speed Steel or Carbide.Give us an idea of what kind of machine is being used here.Name,model,Horse Power.Also tell us your max. RPM

[Trotline]

I'm tempted to look at hardware on this one, as well. You say it's a new home-built machine? It frequently happens with new machines that things like shaft couplings aren't as tight as they should be, and slippage occurs. It's hard to tell from the picture, but it looks as though the actual toolpath is offset mostly in one direction. That's just what you'd see with a slipping coupling.

Not saying that's definitely the problem, but I'd sure check to see.

Luke

[shiv15uk63]

hey made the machine myself the endmill was a 6mm carbide and the spindle is a 2.2kw huanyang water cooled 220v Chinese spindles that are all over ebay have ball screws an all three of the axis was running the spindle at 12000 rpm
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[shiv15uk63]

hey Luke

checked to make sure seems everything is tight thing is it leaves the same amount of material on every pass so every layer is exactly the same size surely with slipping it will be all over the place? not sure

thanks

[jrmach]

If you got ball screws,you should be climb cutting.The .bbcd file you zipped,it had it set for conventional.But that ain't your problem.
One thing that for sure will do this is if your spindle is not Trammed in.It kinda of looks off,but it is a picture I am looking at.Do you know how to do this?
I do not believe BoB is behind this.It is a Machine thing.Tram the spindle,and let us know.


I think you should also try posting your question here http://www.cnczone.com/forums/diy_cn...able_machines/

[shiv15uk63]

not even heard of tramming just googled it would i need a tram tool or is there any other way of doing it?

[Trotline]

You'll need a way to clamp the arm for a dial indicator to the shaft of, say, an endmill. Basically, the dial indicator needs to be able to sweep in a plane that's perpendicular to the spindle's axis of rotation. The rig I've used consisted of a block of wood that was drilled for 1/4" in the top and 7/16, I think, perpendicularly through the side. I then sliced it through the axes of the two holes, allowing me to clamp it down over an endmill and the arm that held the indicator. Kinda ghetto, but it worked.

There are store-bought solutions, of course. You see ads for them on this site all the time. Looks like 2 dial indicators with a bridge between them, and a shaft going up. You can do it with just one indicator, though.

Once you have a way to hold the indicator out to the side of the rotation axis, then you can read the depths all around the spindle, to the work surface, and adjust the spindle until it's the same in every direction. Then, your endmill will be as vertical as you can make it.

I agree with Jrmach, you should post your situation over in the DIY CNC Router Table forum. It's not that we don't like you, but you'll have more people over there with similar machines and likely get more and better response from them.

Luke

[mmoe]

It looks like mechanical slippage on one axis. The steps don't look perfectly uniform, so I doubt it's an issue with the controller or other electronic hardware. Measure the steps with some digital calipers. If they are all identical, then I'd suspect the electronics are not set up quite right. If they vary, then I would suspect the mechanical components of the axis are either slipping or binding.

[mmoe]

If the angle of the spindle is off, the result will be a sawtooth on one part edge (which is still square overall, but with teeth). The opposite side of the part will have no sawtooth, but an angled edge. The photos do not appear to indicate the spindle is out of square, IMHO.

[Force]

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[shiv15uk63]

hey thanks that sorted the problem

[shiv15uk63]

you where right spindle needed tramming thanks

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shiv15uk63
i ran each pass thru tape to shape and they were all the same so it defenately is not the code maybe you could answer something for me how do you like spindle does it have good power at all speeds

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