Y axis stalls throws off pattern

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Y axis stalls throws off pattern

Postby Hitch » Mon Feb 19, 2018 11:35 am

I'm making a spoiler board with t-nuts on a 24 x 24 mdf board. When the machine gets to hole #11 on the first column it gets jammed, makes some noise/vibration and carries on. The 2" spacing is now out of whack and a return to zero has moved past the original. I ran the router to this area with jog but everything is fine. I've lubricated the bars. I've also let the program do the entire board without another catch/snag. After all it's only the bottom. I've only cut the 3/4" part for the base of the t-nut. The holes will be off and then some. What's happening? Help would be greatly appreciated.

Ron
Hitch
 
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Re: Y axis stalls throws off pattern

Postby Hitch » Mon Feb 19, 2018 6:38 pm

Well, I took the air hose to the shark and tried it again. It did not get stuck, so, I tried again from 0,0,0 and the router stopped at the same spot as before. I can't see anything ubstructing the router. Solution was to make a 10 x 10 array for t-nuts. It's still a mystery to me, but I can live with it.

Take care out there.
Hitch
 
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Re: Y axis stalls throws off pattern

Postby Rando » Tue Feb 20, 2018 2:00 pm

Hitch wrote:Well, I took the air hose to the shark and tried it again. It did not get stuck, so, I tried again from 0,0,0 and the router stopped at the same spot as before. I can't see anything ubstructing the router. Solution was to make a 10 x 10 array for t-nuts. It's still a mystery to me, but I can live with it.


Hitch:

That IS weird as heck. In your case, is "Y" along the width of the gantry? Or is "Y" parallel to the slots in the t-slot bed? I changed mine so long ago...

If we're talking about side-to-side along the gantry, there are two places where I could see that issue happening:

1) if there was a hard piece of plastic/wood stuck in the lead-screw threads, that could jam in there. I run an old (okay, my brother's) toothbrush through the leadscrew threads when I'm lubricating and cleaning the machine, just to make sure.
2) If there was a piece of non-roller-bearing thing that somehow got into the linear bearings, or if somehow there were a shattered ball bearing in there, that might cause issues, but you wouldn't imagine it would be enough to stall the stepper. And normally our machines don't break bearings!

If I understand correctly, you're making a spoilboard to cover the bed. And you want to make countersunk holes for bolts that will hold it down, and in this case, countersunk holes for the locating T-nuts that your fixtures will bolt to from the top side. I'll make the giant leap here and guess that the spoilboard covers nearly the entire bed surface, if not EXACTLY the bed surface, correct? And, if you're like most of us, you want to have as wide a hold-down pattern as feasible.

If all those things are correct, I'm guessing the Y-axis can't really go that wide ;-). Although the bed is indeed 24" wide, the actual distance that you can get that router bit over to the side is somewhat less. I forget the exact amount (and it's snowing outside, and I'm a WA-state snow-wimp...I'm staying INSIDE), but if you were trying to get it to drill for one of the outside two tracks, my guess is that grinding sound you heard was the far end of the gantry getting in the way :D.

If not, and it really did just come to a freaking stall right there in the middle of the travel, then yeah, something in the leadscrew, the leadscrew follower, or slide-rails and linear bearings is binding up. It's easier to bind a leadscrew than a normally-working slide-rail, but not impossible.

Cheers!

Thom
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