Shark HD4 stuck at front 6" of machine

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Shark HD4 stuck at front 6" of machine

Postby Janettx » Fri May 11, 2018 11:32 am

My shark HD4 Extended will not move to the back of the table. It is stuck at the first 6 or so inches of the machine. When I push away on the pendant it stutters and will not move past this point. I checked nothing blocking it. The cord is free.
TIA
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Re: Shark HD4 stuck at front 6" of machine

Postby jeb2cav » Fri May 11, 2018 5:09 pm

When you say stuck at 6" - is this the gantry carriage/location of the router - or when you look at the gantry where it is mounted on the bracket that runs on the metal tubes - that bracket is 6" away?

Did you look under the table to see if by chance something may be blocking the movement across those last 6" - or along the sides and on one side it is engaging the gantry, and stopping movement?
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Re: Shark HD4 stuck at front 6" of machine

Postby Janettx » Fri May 11, 2018 5:28 pm

What I mean is. That noise that you get when you push the Z axis up to far and the machine clicks and jumps a bit. Well when I am moving the gantry away from the project at the front of my machine so I can change the bit I am only able to go "away" about 6" from the front of the machine and then I get that clicking sound. I have looked under the machine cleaned it well blew it and vacuumed and used a dry oil on the Y screw drive. There is nothing in the way, and the cord to the router is freely moving and not lodged. The machine is acting as if it thinks it is already at the back limit of the machine but it is only at the front. Does that make sense. It's like I need to reset the y axis but don't see how to do that. Another note. I turned off the machine and unplugged and tried to push the gantry past this point going towards that back of the machine. It pushes easily to that point where it is stuck and I can't even push it past that point.
Thanks for your reply.
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Re: Shark HD4 stuck at front 6" of machine

Postby Rando » Fri May 11, 2018 9:53 pm

JanetTX:

Any chance we can get a few photos to give context?

Below is a somewhat boring bit about how I'd figure it out.

In the end, it seems like the "best" of the below is to jog about an inch in the "good" direction, and check for anything on the newly-exposed leadscrew; maybe there's something that was inside the anti-backlash nut (causing the problem) when you checked it before. If you see nothing, will the machine go back that full inch in the bad direction? If we're lucky, whatever's doing the damage will drop out. If you can't go back the full inch in the bad direction, that means the blocking chunk is still inside the leadscrew follower (anti-backlash) nut. (See the very end, under "you've now fully disassembled your machine....")

Or, you could have a truly, badly worn anti-backlash nut (they're made of plastic) that's been run into the ends far too many times, and it's days are now over :( . That's unlikely, but fits the symptoms.

But really, if the motor is grinding, and you can tell there are significant forces being opposed, then something is blocking or binding somewhere, or a bearing has failed really REALLY badly. There is just too much force involved for it to be relatively-small and relatively-soft things like wood chips. Even pound after pound of aluminum chips have never bothered my machine's movement, and I don't clean it until the chips stand about 2" deep. So there must be something significant being unkind.

Thom

----------------------------------------------
This is the longer boring part :roll:

Because sharkcutup will point at this post and roll his eyes if I don't say this (luv ya, man! ;) ) inspecting the machine, especially under the bed, while it is moving and you know it's broken somehow, is NOT a normal or safe thing to do. Be VERY careful the gantry doesn't clock you upside the head or break your nose or pull out a hank of hair!


To clean that leadscrew I use a light-oil soaked chip brush taped to a ruler. I chase the gantry assembly with the brush as I jog it. Maybe for next time when it DOES move again ;) .

It sounds like you've verified there aren't any tubes or wires anywhere being pulled.
It sounds like you're not hitting a broken limit switch, because that would make the motors stop pushing, and they're still pushing.
Like everyone else, it sure sounds like something to do with the undercarriage of the machine, under the extruded aluminum sectioned bed.
Any chance there's something blocking the movement of the vertical gantry arms along the rails? Like a screwdriver or a piece of wood
just out of visual range behind the slide rail? Outside? Like one of those thin steel rulers? Or a pen?

As the machine currently sits, can you jog it just a tiny bit in the NON-binding direction? Does it move okay? Can you go an inch?
If you can go an inch in the good direction, can you then go back that full inch in the bad direction? Or can you go LESS (or more) than that inch?

If it will only move a little bit back from the one-inch-to-the-good location, I'd suspect a REALLY loose coupler that's getting jammed.

Check under the aluminum top (get a flashlight, so you can get a really good look), that the end of the leadscrew looks like it's in the bearing pocket okay.
Check the four bolts holding the stepper motor on. If they're loose, this could be a pain to fix, since holding those nuts way under there might mean getting or making a really long wrench.
Or worse, taking the aluminum bed apart. :shock:

I don't know if your arms will fit underneath, but are you able to manually turn the leadscrew and watch it move? I suppose a long push-stick from each side, hitting on the exposed coupler bolts might work. See if you get the same level of resistance that the motor is claiming. If not, then a jammed or very loose coupler might be an issue.

So, check there's no debris stuck back into the motor-to-leadscrew coupler hole...Kinda grasping at straws here, since the coupler screws would normally be expected to clear that pocket.

If none of those things turn up something, I'm going to say: there has to be something stuck in the mechanism that's preventing movement. Either something blocking it physically. Even if the side-rail bearings had a broken ball, it would still slide, you'd just hear a grinding sound. To check for that means removing the gantry with those dozen bolts on the side.

And if it's not in the rails, then it has to be in the stepper / lead screw / follower. If you've gotten to the point that you've taken off the gantry and still nothing, then the aluminum bed will have to come off, so you have have some direct access to the ornery bits. Once inside there, there's not a lot. If you can't see anything in the leadscrew, the non-driven end is solidly in the bearing pocket, and the motor coupling is aligned and tightened properly with nothing in that pocket, then my guess would be something has lodged inside the follower (anti-backlash nut) assembly. That will be another heaping mess of disassembly, but once you find the chip, you'll probably want to just go ahead and put in a new anti-backlash nut, available on their web site. :roll: :cry:

Really, once you've gotten the machine torn down that far, there's nothing else to it, so you will have found it. Hopefully you'll find the blocking issue WAY early in the process.

Regards,

Thom

P.S. I know kinda how you feel with insane problems that just should not exist: when I first got mine, I tried to get it running on the dining room table before moving it to the basement, due to the narrow stairs. 4.5 MONTHS later it still wasn't working reliably, but was still occupying the dining room table! Only a replacement controller eventually improved the reliability enough to make it usable. It's NEVER been 100%, though.
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Re: Shark HD4 stuck at front 6" of machine

Postby sharkcutup » Sat May 12, 2018 7:13 am

Thank You Rando ;)

:D Safety First - Always!


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Re: Shark HD4 stuck at front 6" of machine

Postby Janettx » Sun May 13, 2018 8:37 am

I'm going to look at this again. this morning. The machine is fully functional within that 6-7 inch area at the front of the machine. I can move side to side and all the way up to the point where the problem is then back to the front 6 again. I'm going to see if I can get the molded metal bed to slide back for a better view. If there is something it is hidden very well. I have lubed the bearings and Y screw drive but only blew air on the screw. I'm going to blow some air on the bearings and someone told me to loosen them and see if they move from there. If I can figure out how to slide the bed back so I can see that would be helpful as you say could be something small and it is very short and dark under there. Thanks for the help
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Re: Shark HD4 stuck at front 6" of machine

Postby Janettx » Sun May 13, 2018 9:44 am

I've confirmed there is nothing blocking the gantry bearings or shaft. I'e used high pressure air on both the shaft and bearings. I am still stuck at the front 6" of the machine. I can run jobs there so it could be worse. Here is a video of the machine https://youtu.be/_hou6w4ICYE
Thanks
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Re: Shark HD4 stuck at front 6" of machine

Postby Rando » Sun May 13, 2018 5:25 pm

Janettx wrote:I've confirmed there is nothing blocking the gantry bearings or shaft. I'e used high pressure air on both the shaft and bearings. I am still stuck at the front 6" of the machine. I can run jobs there so it could be worse. Here is a video of the machine https://youtu.be/_hou6w4ICYE
Thanks


Well clearly whatever it is, it's NOT in frame. Any chance we can get an actual thorough walk-around of the entire machine? You gotta help us here...it's your machine after all, and clearly something is not right. I for one have not seen evidence it's not sitting right there in front of our noses. I know you say so, but I've overlooked things sitting in front of me too many times. So, that was a good start, but please....show everything. Whatever it is, it's STRONG enough to hold back the stepper, which means it's not a mote of dust.

Regards,

Thom
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Re: Shark HD4 stuck at front 6" of machine

Postby sharkcutup » Sun May 13, 2018 9:59 pm

Hey Rando,

From the video shown it looks to me like the first large rail bearing clears the lower black support but the second small one may not be clearing the lower black support for some reason. In between these two bearings is very difficult to see especially from the inside area adjacent to the lower black support.

This is just my guess because of the angle of the video but when I look at the opposite side bearing it sure looks like that may be the case.

It could be misaligned or there may be something caught in between the Large and small rail bearing that cannot be seen.

Just my Observation of the Youtube video.

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Re: Shark HD4 stuck at front 6" of machine

Postby rungemach » Mon May 14, 2018 12:49 pm

Sharkcutup may have spotted it. It appears that the aluminum trailing bearing housing on the far side may be hitting the black rail center support. Hard to see for sure in the video, but the axis is hitting a pretty hard stop, and it rocks slightly when it hits.

A conventional fully supported rail uses a much thinner and continuous aluminum web. The plastic piece that Next Wave uses at the center of the span to support the rail is much wider. The clearance between the black plastic support and the bearing housing may not be that great. It certainly would have helped if they would at least ramp the end of the support a little, or better yet made the rail support continuous so that the bearing housings would never have to "enter and exit" the support.

I would check that machine for interference at the center supports, it should be easy to find, as it is not buried underneath the table.
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