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  #241  
Old Sat 20 December 2008, 07:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Nils, you remind me that YOU were the bloke who started the nonsense on T-shirts/caps/whatever with MM logos. . . . . I must admit that I didn't have much hope of you finishing the build in those days!
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  #242  
Old Sat 20 December 2008, 08:31
Roadkill_321
Just call me: John #7
 
Wiseton, Saskatchewan
Canada
Nils,

Congratulations on the completion of your machine. It looks like a beauty.
John
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  #243  
Old Sat 20 December 2008, 08:43
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Just checked, Nils wasn't the only one pushing for caps, t-shirts and pocket protectors. Doug, Greg_J, Heath and GregA were also stirring the pot on GregA's thread. What happened to his build?
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  #244  
Old Sat 20 December 2008, 08:58
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

I am still pushing them.

I am experiencing a vibration or rumble on the X axis and gantry. If you are moving at 250 you can hear it and you can feel it if you put you hand on the gantry. At lower speeds you can feel it. It isn't along the complete axis but in spots.

I am concerned that this vibration will affect the quality of my cuts.

What do I want to try to fix it?

Thanks
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  #245  
Old Sat 20 December 2008, 09:11
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Some rumbles or vibrations will be completely normal, even if the machine is of fairly heavy steel. Yours might be abnormal, so the typical things to check are:
1. Are the geckos tuned to the motors?
2. Are the pinions and racks lubricated?
3. Do the V-rollers seat properly on the rails? (rails parallel)
4. Are the grub/set screws of the pinions really tight?
5. Accel values in motor tuning not set too high?
6. Thick ground wire run through all the moving parts to ground?
7. Motor tension springs not too tight?
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  #246  
Old Sat 20 December 2008, 09:35
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald
1. Are the geckos tuned to the motors? Yes, the motors run smoothly when they are loose.
2. Are the pinions and racks lubricated? Yes that has been done.
3. Do the V-rollers seat properly on the rails? (rails parallel)Yes they have been checked.
4. Are the grub/set screws of the pinions really tight?Yes
5. Accel values in motor tuning not set too high? 250 / 25
6. Thick ground wire run through all the moving parts to ground?Yes
7. Motor tension springs not too tight? Using the second holes and ordered the standard spring. But how do I know if they are too tight. Should I move them?
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  #247  
Old Sat 20 December 2008, 12:05
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
1. The motors will run smoothly when loose, but did you follow the procedure in the gecko manual and adjust the trimpots for smoothest running?
7. Motor spring tension
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  #248  
Old Sat 20 December 2008, 14:52
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Quote:
Originally Posted by Greg J View Post
Gerald / Mike,

I've lowered the accel. from 25 to 20 in/sec/sec and it seems to have made a difference. With accel set at 20 in/sec/sec, I haven't been able to reproduce the bad performance.

Always something to learn. Now, back to work.
Nils, sounds similar to what you are experiencing?
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  #249  
Old Sat 20 December 2008, 16:24
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Nils,

Did you get someone to help you with the motor tuning? Or did you do it by yourself? My arms weren't long enough so I had my wife help me.
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  #250  
Old Sat 20 December 2008, 17:00
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Nils,

Heath and Doug have good points.

I have all my motors on the 3rd hole for the springs. It did make a difference.

5 in/sec/sec was a hugh difference in my case. I don't think the vibration is associated with the accel. setting, but, experiment with it. If the problem is accel. then you'll hear a loud scream. Check out my Youtube video (I'm thinking of entering it at "sundance" in 2009. Hey, no body thought I could build a MM. )

Good luck bud.
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  #251  
Old Sat 20 December 2008, 17:03
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

I will look at your link about the spring on Sunday here. I will most likely move the hold to the bottom for less tension but I will read the thread first. I also will move the gantry after the springs have been removed to check on how things ride.

Heath,

Acceleration is the speed that gets things moving but the velocity is the speed that it continues at, I am saying this to insure that we both are thinking the same. I was trouncing around at 450 but Sean had me move back to 250. But I can control the rate with my shuttle and even at a very slow speed I am feeling a problem.

Doug,

I did have some one help me. The Xs and Y seemed to be very smooth. Z is running a little rough and I will retune it but the only place I am having the problem is on X.

Sean things it is where the pinon meshes with the rack. That was before I greased my rack.

I think that Gerald might be onto the problem. It makes sense that there is too much pressure being applied to the rack because the springs are too tight. I will look at it Sunday.

Thanks to all for weighing in. You guys are great.
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  #252  
Old Sun 21 December 2008, 01:31
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Monday, I will make a trip to Skycraft and pickup a sping tension checker since I don't have a fish scale.
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  #253  
Old Sun 21 December 2008, 01:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Nils, at this stage you can just experiment by loosening or tightening the springs.

You say this problem is only on the X. Is it with both motors? You can disengage one motor from the racks at a time.
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  #254  
Old Sun 21 December 2008, 02:47
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Yes both sides of the X is making the sound. Sean thought it might be the pinon binding on the rack but after lubing and I also allowed the motors to float by loosening the bolts that hold the motor plate to the X. But these did not help. I think your idea that the spring is too tight is a good place to start but it is not happening along the full range of X.

I thought it might be the wheels binding but gantry moves easily with out the motors.

It is a pain to move the spring holder.
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  #255  
Old Sun 21 December 2008, 04:42
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

Here is what I tried today.

X1 and X2.

1) Removed the springs from each side, one at a time.
X1 it seems that there is less shudder on both sides when X1 is running alone.
X2 there is same shudder.

2) Removed both springs and pushed Gantry.
Gantry moves smoothly.

3) Moved spring holder to lowest level so there is less tension.
Same results but I think I will leave them their.

4) Checked the thightness of the bolts holding the aluminum and they are tight.

5) Checked the tighteness of the bolts holding the VWheels and they were a little loose. So I tightened all of them. I ran and I think the shudder was slightly worse or the same but I wouldn't bank on it.

6) I did set the acceleration to 20 but that did not do anything.

I am starting to think that it might be the wheels are causing the problem

What do you suggest I try next?

Thanks

Last edited by sailfl; Sun 21 December 2008 at 04:52..
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  #256  
Old Sun 21 December 2008, 06:02
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

I am having another problem. The machine is not cutting correctly. It will not cut the correct depth but I think that is a set up problem on my side. It will not cut a round circle.

I have included both the cut file and the ArtCam file.
Attached Files
File Type: zip Problem Cut.zip (11.4 KB, 55 views)
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  #257  
Old Sun 21 December 2008, 06:34
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Nils,

Can you make a short video and post on youtube?

A picture is worth ..... blah, blah, blah,
But, a video with sound may solve your problems faster.

Most digital cameras have video. Not good quality, but one more tool for troubleshooting.
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  #258  
Old Sun 21 December 2008, 07:14
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Going back through what's above, I think I read that this problem only occurs in certain spots along the X axis. I also read that the V roller / rail alignment was fine. Subsequently I read that the V rollers weren't as tight as they could be, and were tightened.

Based on a problem I had, I think I'd go back and look again at the V roller alignment both at the non problem spots, and at the problem spots. You may need to adjust the shimming of the the V wheels.

This doesn't account for your reported non-circular circle. Is the circle "squished" in a particular direction, like perhaps the X axis? What happens if you slow the feed rate way, way down, like 10x too slow?
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  #259  
Old Sun 21 December 2008, 08:51
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
I took these photos to see if they will show the bad cut. The wood is scrap and the lighting is not very good. The bottom of the photos are on the Y and the sides on X.

The first one is at 10 and the second a 5 acceleration.

You can see the machine jog at the two spots. But besides the jog spots the circles are not very round. I am using a 1/4" end mill. The bottom of the cut is very good. I sure have the Z and router set up good.

The outer circle is 2" Diameter and the inner is 1.5".
Attached Images
File Type: jpg DSCN1134.jpg (166.7 KB, 1458 views)
File Type: jpg DSCN1135.jpg (170.6 KB, 1460 views)

Last edited by sailfl; Sun 21 December 2008 at 08:55..
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  #260  
Old Sun 21 December 2008, 10:18
javeria
Just call me: Irfan #33
 
Bangalore
India
Nils did you clamp your work properly - I think you did.

think the motor is missing steps - if otherwise

I am myself not an expert.

RGDS
IRfan
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  #261  
Old Sun 21 December 2008, 10:36
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
IRfan,

Yes the piece is clamped well but thanks for the input.
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  #262  
Old Sun 21 December 2008, 11:13
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Yes, that looks like missing steps, in the vertical dimension of those photos.

Interesting that it's pretty consistent, location wise. Were both of those pieces clamped in the same place on the table? If so, I'd start looking for a mechanical issue. If not, I'd look for an electrical or software issue.
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  #263  
Old Sun 21 December 2008, 12:43
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Those wobbly circles are typical of a z-slide that is wobbling around inside its rollers. The eccentrics need to be tightened.
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  #264  
Old Sun 21 December 2008, 12:52
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

The Z slide is tight in the VWheels. I adjusted it the other day because the cuts were not smooth on horizontial. I just checked and they are tight.

What else can I check?
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  #265  
Old Sun 21 December 2008, 13:02
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
With the router switched off, and the stepper motors switched on, grab the router collet by hand and push/pull it with lots of force in various directions to see if there is any slop in rollers or the router bracket, etc.
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  #266  
Old Sun 21 December 2008, 14:09
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Gerald,

I think I have discovered the problem and once fixed it will fix both of my problems.

I did go out and shake the Z and Y and things are tight but I also pushed and pulled on the gantry and moved with out the motor moving much. I took off the X motors and discovered my pinon gears were slipping and sliding. I used the wrong size set screw when I first drilled the pinon gears. I discovered this on the Y but I thought I would wait until there was a problem before switching them out. I used 10-32 when the manufacturer calls out 1/4-20.

Monday I will replace all the pinon set screws and see if I have a problem.

I will keep you posted and thanks to all for your suggestions.
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  #267  
Old Sun 21 December 2008, 14:10
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Quote:
Originally Posted by sailfl View Post
Gerald,

I am having another problem. The machine is not cutting correctly. It will not cut the correct depth but I think that is a set up problem on my side.
I had that same problem at first but my daughter's boyfriend noticed that the Z axis motor wound up when I attempted to set Z. This caused the machine to think the tool bit was at a different depth than it really was.

Most machinists set the clearance between a bit and the work piece with a piece of paper. If you aren't using this method or don't know what I'm talking about, reply and I'll do my best to explain it.

In reference to your other problem, why don't you lower velocity and acceleration some more and see if it improves the situation. Also, are you setting velocity and acceleration for BOTH motors on the X axis in Mach3?
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  #268  
Old Sun 21 December 2008, 14:18
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Doug,

I am touching the wood to set my Z zero. I think the problem is in my software setup. I have 3/4 deep wood but it actually is less. I am not sure at this point.

I only have to set one X because my Xs are tied together. Both Xs are wired to the same output for the PMDX.

Fixing the pinon set screws I hope will take care of my bad cuts and shudder.

Thanks for the suggestions
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  #269  
Old Mon 22 December 2008, 08:41
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
I have replaced all the set screws on my pinons and cut another circle and it looks great. The problem with the X shudder appears to have not changed but I did not test that very much. I will look at it some more today.

I want to continue to work on learning how to cut stuff.

Thanks for every ones suggestions and help.
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  #270  
Old Tue 23 December 2008, 06:02
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
I don't believe I have included pictures of my controller box...

Fixed circle
Attached Images
File Type: jpg DSCN1138 2.JPG (90.3 KB, 1416 views)
File Type: jpg DSCN1140 2.JPG (103.4 KB, 1419 views)
File Type: jpg DSCN1147.jpg (167.3 KB, 1420 views)
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