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Discussion in 'The DIY Tool Shed' started by BluesBlooded, May 13, 2015.
Thank you friends, I appreciate your kind words.
It's been a full year since I used my CNC last. I moved twice in the last year. IN one of the moves, the CNC was dropped from 3 feet to the floor. At the time I inspected it and it all seem fine.
A couple of weeks ago, I had to do a project, so I started it.
When I started it, moving along the Y axis was painful. The first half of the movement was free of noise, but the last half was horrible. A project I tried failed miserably.
It lost step on both x and y axis.
After investigating, I noticed that 3 bearings supporting the lead screws were seized.
I replaced one of them with a spare one, cleaned the other two, grease them and was now moving freely.
I also replaced the brushes on my bosh router.
Also had issues with the y homing switch. Replaced that too. After squaring it I was ready to start a project.
Started a cribbage board. This was a 25ipm with a 1/32 end mill making a 1mm deep pass.
Stuff that I used to do without any issues in the past. Probably made a dozen of such cribbage boards.
The tracks went smoothly. This is two passes. So the CNC tracked perfectly. The second pass was right at the same place
Then came the signature. This is when things got bad.
Still 25ipm 1mm deep two passes.
the t, e and s of the first pass were fine, but then you see that at the second S it started losing step on the Y axis. The "work" is all wrong, lost step on every letter.
The second pass over the W is all crooked. It lost step on both axis.
I stopped the program. I was fully angry at that point.
Shutdown everything and left the shop.
After a good lunch and a nap, I was back at it.
Wanted to run something and check what was going on.
So I ran this file which was not putting a huge load on the CNC.
What you see here is another signature, a little more movement on both axis, but only 0.25mm deep still at 25ipm with the 1/32 end mill
You can see that the second pass was offset starting at the W by 2mm on the Y axis and 1mm on the X axis.
I ordered new bearings that I will put on all axis, but I have problem believing that this is caused by bearings.
One other issue I have is my bosh router speed is varying throughout the job. It did that before I changed the brushes, and thought that the new brushes would fix this.
I don't think that the change in speed on the router could cause the CNC to lose steps. The bit is so small it would break before forcing the motor to lose steps. Furthermore the cuts are so shallow I cant imagine they would have an impact.
Could this be some kind of interference. The dust collector is sitting close to the CNC.
I'm about ready to quit on this machine and sell it as is.
If you have suggestions as to what to try next, I'm all ears.
Andre, I’m so sorry to hear this. Those photos are terribly discouraging. I don’t have any ideas to offer other than you were bright and sharp enough to build it in the first place, and I know you can fix it, the question is do you want to spend the time and effort necessary to examine the whole thing step-by- step, or would you rather just start over?
I can hear the frustration in your words, maybe walking away from it for a while, just not even think about it for a while, relax and unwind, then come back to it with a systematic approach-not to find and fix what’s wrong, but go through it every nut and bolt, and make sure each piece is right, properly aligned, and functioning as it should.
Hey Rick, You are right, I'm frustrated.
I've been fighting it for the last two weeks. I thought I went over everything that was wrong, but apparently not. I wanted this to be fixed and operational and spent most of the last three days determine to fix it.
Thanks for advice, I will try to forget about it, but it keeps nagging me in the back of my head.
Sounds very frustrating Andre . To lose steps something is binding , could well be the bearings , but could also be other causes such as static also . The speed fluctuation on your router might be the variable speed dial/wheel , I do remember reading somewhere that the Bosch's were susceptible to dust in the variable speed mechanism , could just use a cleaning maybe .
Like Rick said just walk away for a while , relax and come back and go through it one thing at a time .
I’ve yet to work on a CNC, so I’m not really qualified to speak on the subject. But, to me, it’s interesting that it cut the large part of the cribbage board correctly. Were the signatures that you were having difficulty with cut in the same area of the table? If they are, what happens if you try cutting them at the opposite end of the machine?
Andre', I can't help with the CNC, I wish I could. I totally understand your frustration, I've been there a few times, something that should take a couple hours turns into three days! Step away from the router... Hide all the hammers, before you do something irreversible. Have a Moslen's and relax, it will be there tomorrow, or next week. Good luck! Let us know how it turns out.
I know how you feel Andre, just take your time and you will find what the problem is.
Just some thoughts.
Check if everything is tighten on the machine and square.
Try to cut your logo again with out the dust collector working.
Cut again the board to see if the problem is only at the signature ,if the board is not as good as at the first time this means that something get loosee and wobble on the machine .
Also run your router straight from the wall power supply to see how it runs.
Grease and oil everything.
I hope you find the solution fast.
Keep us posted!
Thanks Herb, I will check every single screw and make sure they are all tight.
Thanks for mentioning the issue with the speed control. I will clean it up and see. I've contacted Bosch as well to see where I can get a replacement speed control part.
One other difference from my old setup. I installed led stip lights inside the box to light things properly. I wonder now if they could cause some kind of noise/emf or something that could screw up the commands sent to motors
Thanks JB, I'll try to see at the other end of the table and see how it behaves.
Thanks Bill, no worries, hammers are out of reach. I slept it off and now am willing to fight it again.
I was pondering what if I get rid of it. What would be the upsides and downsides.
Upsides: Space saving. No more banging my head on the wall when it starts doing something it ain't supposed too, recuperate a part of the cash I spent on it and buy the drum sander I'm dreaming of.
Downsides: All that space saved will be used to store templates. Will have to recreate templates, will need a new router sled, will need to recreate all sorts of jigs for building guitars and necks, not mentioning how doing carved top will be painful again.
At that point I realized how much I liked my CNC. So fixing it is the only possible avenue.
Thanks Nick, All sound advises, I appreciate it.
So here's the plan when I get around to it. I'll do them one at the time to make sure that when things work I know what was the cause
Remove the bearings on the motor side. These are not required and may cause some binding.
Check every bolt and nuts make sure they are tighten.
Square the gantry
Grease the bearing at the end of the Z axis just to make sure everything is properly lubricated.
Run the same file at the same position.
Run the same cribbage board file at opposite corner. If I still have issues
Power off the dust collector and run the file again. If I still have issues
Close the led lighting and run the file again. If I still have issues
Play around with the debounce value in mach3 that is currently set to 2000 and index debounce is 2000 as well. This setting is to reduce electrical noise that interacts with limit switches. I don't see any relation to my problem, other than what I saw on the web was that both values were not the same. Something along 100 debounce and 4 for the index debounce.
By this point I hope it will run smoothly, otherwise I will suspect something mechanical, controller or motor or computer related.
Thank you everyone for your ideas, it did help sort things out and prepare a plan for the next steps.
I will for sure keep you posted of any progress I make.
Andre do you have a separate 5volt power supply for the break out board or you take power from your pc USB for the bob?
Nick, I'm not sure what you mean by breakout board.
I have a dedicated power supply for my gecko drive G540 controller and motors and micro switches.
The only connection to the computer is the parrallel cable to the G540
Sorry you said Gecko controllers earlier,those has the breakout board inboard so no need for an extra 5volt power supply!
Sometimes it helps to swap the controllers between the axis ,to see if a controller causes the problem.
Thanks for the info.
I'll keep this in mind if all else fails.
Andre is the slippage at the long axis?
Do you have two drivers for those motors or one?
Motors are connected with the balls directly right? Are the coupling tighten? Some motors has a flat point at the saft so the coupling's screw can grab the saft tight and do not let the motor spin and loose steps,if there is not a flat spot you can make one.
Also check if the couplings has any damage ,let's say a crack,this will make the coupling flex...
Ok I will stop posting now and let you do your job !
Stop Nick stop
I have two drivers for the long axis. One is Y, the other is A and is slaved to Y.
The slippage seems to be in both directions. It would be odd that I have screws loosening in both direction at the same time.
Nonetheless, I will take a methodical approach and start by checking every connection to motors, lead screws, couplers and so on. After I confirm the basics, I will start working on possible interference/static.
I will also move my dust collector unit a foot away. Maybe enough to reduce interference if any.
In a couple of hours I will start the checks and will report back.
Thanks for the support
Also do not forget to check the...
Dangit, Nick. We've not seen Andre around in awhile. Don't go irritating him and running him off so soon
I believe he struggles to fix his CNC now so he can get rid of us for good!