x axis slipping during cut

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hedmunds
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Joined: Wed 20 Feb , 2008 3:16 am

x axis slipping during cut

Post by hedmunds » Mon 07 May , 2018 7:40 am

Hi,

We have a router 2600 Pro which has worked fine for many years now. I started it up this morning and did a few cuts and it was working fine. The forth cut I did came out as if the x offset had moved 50mm half way through the cut, half the design was in the right location and the other half had moved over 50mm. Also when it returned to home at the end of the cut the x stepper motor continue to try to move the x axis after it had reached home, ,making a rattle gun sort of noise. I cleaned the rails and home sensor on the x axis and then ran the same code again. It did the same except it was only offset roughly 3-4mm this time rather than 50mm. I also noticed that during cutting you could occasionally hear/see the the x axis stay stationary for a second and hear the stepper motor making a bit of a crunching noise, bit like a rattle gun. I'm assuming this was something slipping or jumping as the x axis was trying to move but for what ever reason couldn't. After this I turned the whole machine off and left it for 20 minutes then came back, ran a spindle warn up code which worked fine, then ran a different code from before hand, cutting a circle 2mm deep on pine, It got 3/4 of the way round the circle then the x stopped and the y continued. At this point I stopped the machine and homed it. At home I noticed that the x axis I could move by hand although it was notchy and you could feel some resistance. I checked the screws that attach the x stepper motor to the threaded shaft and they were tight. I'm thinking it is a failing stepper motor because it is only happening under load. I have lubricated the threaded shafts and guides with silicon spray recently and I did leave it over night when I did it. Any help would be greatly appreciated. I only work two days a week so my response time may not be fantastic, sorry in advanced.
Cheers,

Josh

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Re: x axis slipping during cut

Post by TDIPower » Mon 07 May , 2018 21:54 pm

Sounds like its time to strip the rails/feeds, clean all the gunk out lube up and away you go.

Just try sending it from end to end on all its x y z travels, if it starts to stutter then def time to clean up. I have literally had to do that to 3 microrouter pro's in the last couple of months. I believe they all use the same screw/nut drives. If you unscrew the 'nut' on the closest X feed(has 3 allen bolts holding it in the Y axis frame) and wind it out of the Y axis frame you will see how bad it gets in there. Fine dust clogs it up big time and then when you silicone it up that seems to bond it together.

My 1st one took me about a day to sort in total but the next way quicker and so on. Just take a slow methodical approach and photo stuff.

The easiest mistake to make is when re fitting the x nuts, the screws have 4 helix running along them so it is (75%) possible to fit the second nut out of sync with the other. What you end up with then is the travel binding up towards one end and loosing position.

Pete

hedmunds
Posts: 6
Joined: Wed 20 Feb , 2008 3:16 am

Re: x axis slipping during cut

Post by hedmunds » Mon 21 May , 2018 7:48 am

Thanks for your respond. I tried that, it worked for a day and then the same problem came back. So I stripped the nuts again and cleaned them again and it's still doing it. I checked that the nuts were in the correct orientation when I put them back on but I am going to double check when I'm in next. Any other ideas? Does it usually require very much force to stop the x axis from being able to move because I've tried by hand and I'm putting very little force on it to stop it from moving. Thanks in advanced.

Josh

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Re: x axis slipping during cut

Post by Martin » Mon 21 May , 2018 17:23 pm

When you have the nuts disconnected try moving the slide by hand.

If it's tight there are a number of things you can look at.

1. release the 2 cap head screws holding the Y axis assembly on to the front tower & see if that frees it up.

2. Release the 2 end bearing supports from the end of the X axis lead screws.

Let me know how you get on.

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Re: x axis slipping during cut

Post by TDIPower » Mon 21 May , 2018 21:45 pm

Martin was a great help to me, I was convinced I had bigger issues on the 1st one I stripped and cleaned. I followed his advice, worked though things step by step and sorted it.
If you can post up a really descriptive report of what is going on it helps.
When you traverse X is it making a buzzing/grunting noise at about the same point or at any point? That's the stepper motors trying to drive it's but having a hard time.
With both the nuts unbolted from the Y frame you should be able to move it with a bit of resistance.
One thing I found that made life easier (if all clean) put the nuts back in the Y frame but keep the fixing bolts a little slack. Send it all the way left so the nuts are as close to the support/bearing blocks as possible then screws then tighten them up into the Y frame. There is an element of movement (bow) in the feed screws and this get to be less possible as you close up to the bearings at each end (more so at the left).

Pete

hedmunds
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Re: x axis slipping during cut

Post by hedmunds » Tue 22 May , 2018 7:10 am

Thanks for your reply. When I cleaned the nuts on the x axis I did check to see if it slid easily and provided that I was pushing evenly across the two rails it did slide easily. I've notice that it only happens when it is at least 400 mm away from the home on the x axis. I've had some stuff that needed machining pretty urgently so today I moved my mount so that the furthest part of the material was 393 mm away from the home and it worked fine, I managed to get through the rest of the machining which was about 20 10 minutes codes, so wasn't a fluke or anything. With the y axis test you're suggest can you confirm that you want me to move the gantry to it's furthest limits, loosen the 4 bolts that hold the y axis on, then home it and then tighten the four bolts back up? I'm not in till next week now but next week I can get stuck in properly due to the rest of the parts being finished. Also if you want me to film it or take photos or anything I can do it all just let me know what you want because I don't really know what would be helpful to you.
Cheers,

Josh

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Re: x axis slipping during cut

Post by TDIPower » Wed 23 May , 2018 18:28 pm

Undo each of the 3 screws that hold the X nuts in the Y frame (so the nuts that's run on the long travel front/back of the bed). Just enough so the nuts can wiggle a little in the frames.
See if you can send it all the way left then.
If you can tighten them up in that position of travel.
They are a bit like Ikea furniture, You never do each screw up fully until it is all in place, the point of least movement/bend/bow in the X screws is when the Y frame is fully left.

The 'gib' adjuster/runners that run on the bar under the feed screws are a 3/4 cylindrical section of plastic in a metal housing, there is the potential for dust to get inside them as well as the have longitudanal slots in them. The are a pain to get out and clean.

Where are you?

Pete

hedmunds
Posts: 6
Joined: Wed 20 Feb , 2008 3:16 am

Re: x axis slipping during cut

Post by hedmunds » Wed 25 Jul , 2018 5:46 am

Hi again,

Some personal stuff came up so I've been away the last two months. I've tried doing what you said withe nuts on the x axis. I've also pulled out those 3/4 Plastic guides and cleaned them. I tried running them on the rails before I put them back into the y frame and they were running smoothly. After I did all that the it ran 3 codes fine but then had problems on the forth. It gets to somewhere between 380 and 400 mm on the x axis and then it stops making the loud binding noise. It only happens when you are moving away from the home position, not towards it. We then recreated it just by jogging there and I noticed that while it was binding when you let go of the key that tells it move across, it will then move about 1-2 mm forward, past the location where it was binding. The other thing is if you jog to just before where it binds then stop then jog past it, it doesn't bind. I'll try to upload a video today. I'm in Perth, Western Australia. Do you know of any technicians local to me that could come have a look?
Cheers,

Josh

TDIPower
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Joined: Tue 29 Apr , 2014 18:38 pm
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Re: x axis slipping during cut

Post by TDIPower » Thu 26 Jul , 2018 20:50 pm

Have you tried winding the travel by hand? you need the power off to do so as the stepper motors hold the position/prevent you from turning the feed screws?
You could trying that and then you may be able to see/feel where the problem is.

Another idea would be to have the Y frame at home, undo one of the feed nuts and wind that by hand fully left. it should move easily. Now try sending the Y frame left by jogging it across to the left. If that works send it back and try the same with the other nut. If it travels with no problem then it must be a feed nut out of sink. Have you checked the feed belt if ok between the 2 screws? I wonder if that has jumped a tooth or 2 somehow.

Pete

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