I just completed beta testing Andrej's backlash fix. I am estastic to say that it is working well!

I don't think the beta version is online yet but expect that it will be very shortly. I just sent Andrej the results of my testing and it works as well as Mach 3. Can't ask for more than that!

THANK YOU Andrej :fantastic:

Now maybe I can give my wifes computer back to her.


The photos of the 2" circles show the Mach 3 cut on the left and the USB board cut on the right. Both were set to compensate .014" which is the amount of backlash I have after fine tuning my Phlatprinter . Attached files

 

It will be published in beta 2.10.1101.2601 little later. I need to finish and test some other things first.

 

I was about to send my response, but Marks response covers it pretty well.

One thing you need to do is zero your X axis before you start each move. This was not mentioned and it will cause erroneous readings if you forget to do it.

If you don't have a dial caliper, you can always guess. Start with .010 and see if that helps. If not, double it and check again. Trial and error should get you there within a few tries.

 

By the way... I use .1 moves when checking with a dial indicator. I cut 1" circles to test the results.

You cannot expect to see 1/32" backlash in a 10" circle. It is the little circles, 1/4", 1/2", etc that show up backlash the worst.

You can input the move values in the text window at the lower right of the display.

Example G1 X .1 F10 to move forward and G1 X -.1 to move reverse. Just be sure you zero the axis each time.

 

Beta 2.10.1101.2601 is published.

 

Great News !!!
Can't wait to try it out this evening !
Thanks Andrej

 

Andrej,
We now have Round Circles !
You Nailed it !
Many Thanks
Bob-n

 

I don't think calibration will cause the X not to return fully to its home position, especially if circles are true and you are tracking well. I would tend to guess that you just lost a few steps. Could be you are accelerating too quickly which could cause slippage.

I would not be too concerned if all you are getting is 1/32nd over 30 passes. This is not going to show up in most anything you will be cutting. Most parts are going to be two passes typical. If you can go from one end of a sheet of FFF a couple times and return back to home position, you should be just fine.

I have my settings set to ramp up the X axis slowly. Think of it as stomping the accelerator on your car and spinning the tires.

What we want to achieve is accurate cuts, not see how fast we can do them. If you want to try to improve your accuracy, try turning down the acceleration property and let the X axis startup very slowly and gain speed then ramp down. You should be able to hear the difference.

Other things that might cause this are the material itself. Try the same test with different material and see if the results vary or remain the same. I have several different materials I run thru it and some have a tendency to drag on the table top or just have more flex to them than others.

I would say you have your machine dialed in pretty well as is.

 

WOW! So many changes and updates, when I get back "up" to working on my PP, I'm gonna hafta relearn everything! Great stuff!

 

Aircraft ply is another story... I would recommend putting masking tape at least along the edges. Ply is so hard that it is very easy for slippage to occur.

Depending on size of material, use enough tape to permit rollers to have something solid to grab onto.

You could also tape the ply to a sheet of FFF as a carrier, but the other thing to watch out for is where the rollers meet the ply. They must be centered over the ply or you will get skewing from uneven pressure on the upper rollers.

Feed rate and spindle speed also comes into play with harder materials. If the bit cannot cut the material as fast as the drive train wants to move it, something has to give, and it is usually the ply that will slip.

Guide rails of course will help keep minor skew/slippage under control, but push comes to shove, the path of least resistance wins.

 

I will do a video later, but just to give you a quick tutorial, You need to move the X axis in one direction in .1" increments, measuring the amount of actual travel each time. Do this at least 4 times. Average those values. Now reverse the travel again by .1" and measure the actual travel. It will most likely be less than your forward values.

That is the value of your backlash.

Go in reverse a few more times .1" at a time. These values should be close to your forward values.

Reverse again, the next .1" increment will give you the backlash in the opposite direction.

Average the two backlash values. Enter this in the control software.

It is best to use MDF or something solid to get a good reading with your calipers. I have even used a cutoff yardstick...

Hope this helps.

 

I don't know for sure that different material will give different readings on backlash, but I suspect it could simply because some material is so much softer than other. 1/2" foam comes to mind, or EPP.

Your best bet is to cut a 1" circle and see what it looks like. That will tell you if you need more correction.

I did a video this morning showing the process. It is kinda rough but should help if it is still unclear.

 

There are so many variables which come into play it is hard to know what is causing what. For balsa, you need to center the wood in the machine and try to get the upper pressure rollers to evenly apply pressure, as this will skew balsa very easily.

Try taping the balsa to a sheet of FFF as a carrier. This may be a quick fix if you are tracking FFF just fine.