[signpro]

I finally got my Joe's 2006 running this past weekend. HCNC Pro Board, 305oz steppers, Mach3. No knowing much about cnc's and after spending hours and hours trying to set up the software and etc. I finally got some test cuts made. I noticed right off that a 5" x 5" square ended up around 4.875" x 5.125". Back to the software I went, adjusting this and that. I then slowed the machine down to a crawl thinking speed was the problem. Again, same problem replicated. I also noticed on some squares that the last corner didn't close. This only happened about 50% of the time.

It finally hit me that I never checked to see if everything was square, perpendicular, etc.

And so I ask.... what is the easiest way to check all this?

[atwooddon]

It sounds like your machine may have some flex or looseness in one or more axis. Can you push or pull on the cutting bit and see any movement? If so, you need to find out where it is 'loose'. It is interesting that your dimensions are off exactly 1/8" each direction. How did you generate the gcode? What size bit did you use?

You didn't say if your cut was a rectangle (one axis longer) or if it was off diagonally. I would start with checking the corners of your cuts to see if they are at 90 degrees. If they aren't, then the Y and X axis are not square to each other. Most of any misalignment can be adjusted out with the bearing tension. Caution, do not overtighten the bearings, you can ruin them easily if you overtighten the adjustment bolts.

Second, I would check to make sure the machine is moving the correct amounts for each axis. There is a stepper setup support routine in Mach3. You tell it which axis you want to test, tell it how far to move. Mach3 moves the axis then asks you how far it moved. Then it automatically resets the steps per unit value to match up your axis. I recommend doing fairly long movements which will show small errors better.

If your cutting depth is increasing, you may be missing steps as it raises the bit, or your bit may be loose in the router. This has happened to me a couple times, when the bit slips, it digs in a little bit each time gradually getting deeper. It never seems to get more shallow.

Don

[signpro]

Don,

I'm using a 1/4" bit and have generated the same test gcode from both Vcarve and Lazycam. After you mentioned it - I did notice that sometimes the corners were rounded, but it wasn't consistent. I've been doing a lot of searching and I think the bit getting deeper is due to losing steps with the current reduction on the Z axis. I'm going to try and disable it tomorrow night and run the same test.

I'm not totally sure how to measure the adjustments on the X & Y axis. I understand how to adjust with the bolts, but I don't understand how to measure it. Use a square somewhere? Any suggestions as to exactly how to do this? I don't see the obvious methods.

Thanks, John

[atwooddon]

There are a couple easy ways. First, mount a pen or pencil on your spindle mount and some paper on your waste board. Draw a large square, then use a carpenter's square or drafting triangle to do a rough check of each corner. That will tell you if the setup is generally 'square'. Next, as accurately as you can, measure corner to corner diagonally. The dimensions should be exactly the same if the square is 'square'....

This approach is general, there are more accurate or precise ways to do it but to start, this will be pretty close.

There is a thread or portion of a thread here on CNCZone about squaring axis. I think it was part of the Joes forum.

Don

[signpro]

I spent some serious hours late last night tightening stuff and making adjustments. I ran a bunch of test cuts and I think it's square enough for what I need! Thanks for the help!

[atwooddon]

signpro way to go.... Now that you have it 'squared up', you might want to go thru this thread about making center drive gantries solid. It is a good read and makes a lot of sense. I have not tried it personally but plan to when I finish painting my Joes 2006 and get it assembled again.

Don

http://www.cnczone.com/forums/diy-cn...ock_solid.html

[signpro]

Will do, thanks for the tips. When I grooved the table for the t-track I noticed that my X axis is a bit "shaky". I think it might have to do with the lead screw vibrating. Not sure what this is all about, but I need to figure it out.