CNC by trial and error!

[metalnwood]

It's interesting as your out of shape squares could be a mixture of different things.

 

Do you know the backlash on your machine and have you got backlash compensation set up?

 

I am not thinking things through fully as I have to go and dow something but it could be that the rounded off edge is a consequence of the backlash from the previous corner.

 

It doesn't look to be an issue due to leveling. Then again, backlash shouldnt give you such different results at different speed whereas CV could.

[ClayM]

Here is the latest test

 

 

This file was kindly provided by Warhog for testing. It may be hard to see in this poor quality pic but in my opinion the results are great! The x1000 ft per minute text turned out very good for being only .100" high.

 

This was cut at 10"/min. At 30"/min everything goes for s**t.

 

I have already fixed all the backlash issues. It was mostly from loose bearing fits and loose preload nuts. I know this is a pretty weak machine but I think this is operator error more than anything else.

[metalnwood]

That looks good.

 

Can you post a picture of your 'general logic configuration' screen and one of the motor tuning page for your x or y axis from mach3?

[Warhog]

Here is the latest test

 

[ATTACH]122748[/ATTACH]

 

This file was kindly provided by Warhog for testing. It may be hard to see in this poor quality pic but in my opinion the results are great! The x1000 ft per minute text turned out very good for being only .100" high.

 

This was cut at 10"/min. At 30"/min everything goes for s**t.

 

I have already fixed all the backlash issues. It was mostly from loose bearing fits and loose preload nuts. I know this is a pretty weak machine but I think this is operator error more than anything else.

 

Clay, do you mean you just now fixed those issues or you did this some time ago. If it was some time ago you should recheck you backlash. BTW, it looks as though the y axis is also problematic after a close look at the Romans font you cut. The vertical strokes on the letters M, UVand H are shorter on one side than the other. That's a typical indicator of backlash.

 

You should join the CNCZone forum which I believe has a section devoted to your style of machine. I'm sure there would be a wealth of experience to draw upon as it is a huge forum devoted strictly to CNC. I spent many a day on that forum when I first started into CNC some 10 or so years ago. I still frequent it when I need an answer to something new I want to try.

[ClayM]

Here is my config/motor tuning

 

MachConfig.bmp

 

Thanks for looking Metal ( x and y are identical )

 

John,

 

It was a couple of weeks ago when I fixed up a few backlash problems. I will check again.

 

I will also have a look at CNCZone.

 

Thanks

 

Clay

Edited October 4, 2015 by ClayM
Attachment

[metalnwood]

Your screen is a little different from mine, what version of mach3 are you running?

 

PS, are your units set up for mm or inches when I am looking at the velocity, accel values?

 

I was trying to see that you did have, for sure, CV off. In my version it is on that screen but not on yours.

 

You could try turning the acceleration down a little and see what happend, you can keep velocity the same.

 

Now, I know you said somethings were loose on your machine and you fixed that but did you do the backlash compensation to cater for anything in your ballscrew/leadscrew, whatever your machine uses. Did you use a dial indicator to properly measure the backlash to use the right figure in the backlash screen?

[ClayM]

I need to get another collet! all I have is the 1/8" AND I only bought 1/16" endmills! So I'm leveling 10" by 11" with 1/16 endmill. Pretty sad.

 

I will get out the dial indicator again tonight. I have a little over 1" stroke dial indicator. When i did this befor I put indicator inline with whichever axis I'm checking. I move using mach3 towards the indicator. Then i position indicator so it reads exactly 1.000. then i zero that axis in mach3 . then move away from the indicator in mach and compare the DRO to dial indicator. Or should I just push and pull everything by hand???

 

Thanks

 

Clay

[metalnwood]

No, dont do anything by hand, that will just show you flex etc.

 

move the machine towards the dial indicator and make sure you move it in a reasonable amount. Then go in to jog mode and set it to move 0.01mm at a time.

 

Hmm, I see you are dealing with imperial, I thought you canadians were metric?

 

Anyhow jog at the smallest increment and get the dial on one of the marks. Then move in the opposite direction using jog mode. You will probably have to jog a few times in the other direction before you see the indicator move.

 

So, if you were jogging in mm at 0.01mm and it took you 5 jogs to see the indicator start to register in the other direction then your backlash is 0.05mm and you can put that in the backlash setting with backlash compensation turned on.

 

Now, when you change direction mach 3 will turn the ballscrew enough to compensate before it tries to move the desired amount.

 

Do it for x and y.

[metalnwood]

What is the collet size btw? I have ER25 on mine, I realise yours will be smaller.

 

1/16" inches is 1.6mm, with a 40% overlap you will be there all day!

[ClayM]

Metal

 

ER11

 

 

Not much bigger than a Dremel!

 

About do to do backlash testing but...

 

ADVICE TO NEW CNC USERS!!

 

At some point and time you WILL need to put a dial indicator on your machine. It's not if but when. Many machines purchased today are ALUMINUM. So will need to clamp something to your work surface so that your magnetic base can stick to something, probably with your t-slots if have them. So DO NOT cover entire work surface with your sacrificial board! Leave a corner or something open to mount indicator. Also, if you do cover entire surface and you decide to use fairly thin plastic of some kind ( at least a 1/2" piece of MDF you can screw something onto it ) DO NOT spend half a day leveling it all off so its perfect because your just going to have to tear it off the next day to get to your t-slots!

 

I'll let you guys know how the backlash test goes.

 

Thanks for the tips.

[ClayM]

I'm want to try and post a video of this somehow. I guess youtube then attach link here?

I have never tried the YouTube thing but i will give it a try.

 

Imperial measurements are what I typically use. Its kinda funny that in Canada we have the metric system. But our houses are still built out of 2 by 4's!

 

So I used .0005" as opposed to the .01 mm that metalnwood suggested which is .00039" due to the fact I only have an Imperial dial indicator.

 

I am confident in saying this machine has zero backlash on all three axis. The same results I got after repairing all the loose bearing fits and giving the bearings a bit of preload. By the way this is a ball screw machine. One of the reasons why I bought this model.

 

And before you say "this guy has no idea what backlash is" I deal with it 8 hours a day. Lots of old acme thread (typically 1/4" pitch) leadscrews with worn out bronze nuts that require an extra 1/2 turn or 2 to position properly.

 

If i move .0005" in mach in either direction i get .0005" movement. Mach DRO always matches dial indicator( Mitutoyo 2416S shes a beauty! ).

 

I thinking this might be a controller issue. According to CNCzone swapping out the controller is the first step to getting rid of most of the problems.

 

I also had a closer look at the RomanS font in Adobe Inventor. It seems like the actual font has errors. If I zoom way into the sketches you can see that some of the lines are short. Strange.

 

Clay

[metalnwood]

No problem, it's always worth checking though. I had a zero backlash ballscrew on one machine. It had backlash, very minimal but if the dial indicator doesnt move when you jog the other direction then it's not zero.

 

A bigger machine with rack and pinion had about 0.03mm backlash.

 

Only other thing I can think of but the pattern doesnt look exactly right is missing steps. I suppose you could do a quick bit of gcode to make it go to 0,0 and then a couple inches away, backwards and forwards a dozen times. Set up the dial indicator at home and see after the dozen movements if the dial is still on zero.

 

As I say the engraving has a little bit of the hallmark of it but I dont thing so. Still, if you have nothing to do, time to spare :)

[triise]

Imperial measurements are what I typically use. Its kinda funny that in Canada we have the metric system. But our houses are still built out of 2 by 4's!

 

Well, you are not alone. Over here in Norway all building materials are measured in inches... some things are not ment to change :music_whistling:

[Warhog]

@Tore... I think you are running the same machine as Clay is. You two should get together and talk as you both may have encountered similar issues.

[ClayM]

Warhog

 

I am still messing around with fonts. Slowly making some progress! I was checking ( again ) your photobucket page. Would mind sharing which fonts you used for CDU ?

 

I have played around with feeds and speeds and have been getting good results. now its just about the drawing details.

 

Thanks

 

Clay

[Warhog]

Hi Clay

 

I used Arial for the CDU keys and I pocketed them. They came out really nice but that coding for doing pocket operations makes for a huge fukin file. I seldom do that.

 

The buttons were made from white styrene, airbrushed grey then pocketed on the mill. The back of each button was also pocketed so in essence "its hollow". Thats how I get the back lighting into the button.

 

John

[ClayM]

Finally figured out what the problem was!

 

In the G-code options list there is " Velocity Mode". I guess I did not set this correctly during the setup. It was "undefined". I changed it to "Exact Stop" and all my problems went away!

 

Managed to get my CMSP panel finished (almost). I posted it on Lars panel thread since I used his drawings.

 

Clay

[Warhog]

Yes I saw it. Very nice Clay. I'm really glad you were able to resolve the problem. I know how frustrating it can be to trouble shoot a problem when you are not exactly sure where to start.

 

Looking forward to a whole wack of panels coming from you now.:thumbup:

 

BTW, I love the VFD. I bought one as well. Just haven't found a home for it yet.

Edited November 10, 2015 by Warhog

[ClayM]

Thanks John!

 

I thought the VFD had a more realistic look than other displays. I originally had green backlight lcd with black text and it just did not look right.

 

Eventually I would like to shift the digits one space to the left.

 

I am going to tear apart CMSP now and cut some pockets for backlighting. Should be an interesting task. I dont even know where im going to get the power from yet. Thinking old PC power supply.

 

And good luck with your CMSC project!

 

Clay

[ClayM]

OR

 

now that I can CNC some parts I should probably clean up my UHF. In its current state I must have 200 hours into it! First attempt was SN7407 drivers with individual resistors to run 7 segs. If you think its spaghetti now you should have seen it before I changed to MAX7219.

 

 

 

Clay

[Warhog]

Yah I think a rebuild may be in order :music_whistling: Now that your new found skill set is available you might as well take advantage of it.

 

BTW, you are doing extremely well Clay. You may want to think about adding a few accessories to your mill. ER11 collets are pretty small and there is not much you can do about that but what you should do is get the largest collet size they have (5/16" I think) and an end mill to match. Also see if you can find some end mills that are .375" (3/8") dia. but have a 1/4 shank. There will be quite a few times you need the larger diameter end mill so you should start thinking about it now.

 

I also sent you a file that you might be able to make use of.

 

John