[Paul90]

Hello

oh I am so glad I found this forum

i am new to this forum but have had some experience of Chinese laser cutters. However I don't know what to do with my most recent issue with my Chinese laser 50 w cutter.

Basically i I am finding cuts on the x axis are clean but cut on the y axis are almost like as if they are jagged (like as if the firing of the laser isn't as often so it results in Slight jagged edge). It's not easy to notice except on anything cut small.

So for example a small piece of Laserboard cut square ends up with very clean x cuts but the sides (the y axis cuts) have a slightly jagged edge to them, so not smooth.

The make of this (I am sure I am spelling it wrong) is Shenui. I am using the software that came with it RDWorks 8. When cutting I use the cut option (not dot option).

Does anyone one know what I need to do to fix this?

Thank you

Paul

[Labmaster]

Welcome to the club.
I guess every one of us with a cheap shensui 50w has this problem, some more some less.
The problem is the whole mechanical y axis.
The linear bearings do not work as smooth as they should and this is mainly caused by very bad manufactoring of some base components.
In my case the black steel frame where the linear rails are mounted on are not in one flat plane, togehter with the problem that both y axis rails are not fully parallel this causes a very bad and rough movement that gets oscillated by not rigit enough y axs belts.
This is simply bad build quality and on some points bad engineering, but to be honest what would you expect for such a price.

best regards,
Walter

[Paul90]

Welcome to the club.
I guess every one of us with a cheap shensui 50w has this problem, some more some less.
The problem is the whole mechanical y axis.
The linear bearings do not work as smooth as they should and this is mainly caused by very bad manufactoring of some base components.
In my case the black steel frame where the linear rails are mounted on are not in one flat plane, togehter with the problem that both y axis rails are not fully parallel this causes a very bad and rough movement that gets oscillated by not rigit enough y axs belts.
This is simply bad build quality and on some points bad engineering, but to be honest what would you expect for such a price.

best regards,
Walter

thank-you Walter for replying so quickly to this.

I examined the the laser last night and found exactly that issue in the the y axis is not at all as smooth. I greased both y rails and tried again but little difference. I even played with the stepper motor switches to see if that would help but ended up with a shorter y cut.

So I then decided to slow the cut down to half with half power and thankfully got a much better result. I guess these machines can't go fast or you lose quality but I sure am pleased with it compared to my k40 which even with an controller upgrade had it issues, especially along the lines of best of reliability.

Regards

Paul

[Brogmoid]

Does this machine come with the Y stepper motor between the 2 side rails and belt pulleys on either end, it might be worth checking if both gears are clocked to the exact same position on the shaft with the beam sitting at 90 degrees, could be that there is slight difference and the belt jumps over the leading or trailing edge of the gear teeth.

[Paul90]

Does this machine come with the Y stepper motor between the 2 side rails and belt pulleys on either end, it might be worth checking if both gears are clocked to the exact same position on the shaft with the beam sitting at 90 degrees, could be that there is slight difference and the belt jumps over the leading or trailing edge of the gear teeth.

Hi Brogmoid

Thankyou for for getting back to me so quickly as on this. Awesome feedback.

Discovering the other evening that slowing things down gives acceptable results but of course takes a lot longer to cut something now.

The motor is in the middle and it has belts going to left and right y axis. I am not sure what you mean by both gears being clocked at exact same position with the beam sitting at 90 degrees. Do you mean with the laser head sitting exactly in the middle position and then to look at the belts at the end of each rail or motor. Sure sounds worth checking.

This is forum is so useful as I have tried to get support from the seller but unfortunately, and no disrespect to them - I think the Chinese make great budget laser products for those of us that can't afford much more expensive products -, but they often do not understand my questions no matter how simply I explain them.

Thank you

Paul

[ACG]

I too am having an issue with the Y travel and would appreciate any help you gentlemen can shed on this matter. The issue that i am having is not so much jagged edges, but that i am losing steps when the laser head is moving in the Y directions. It would cut fine on the X but during Y axis cuts it would sometimes start to stutter (which throws off the entire machine). This does not happen all of the time, but it happens enough that I have doubts every time i try to run a project. During the times when the Y axis is acting up, pressing the RESET button on the control panel would crash the whole gantry into the homing switch. Ive tried playing the belt's tension to no real effect. I usually cut at around 8mm/s and 15% power (1/16" acrylic). Also of note is that i am unable to get perfect circles, which i was able to before all of this started happening. I am going to go through the steps outlined above, but do you guys have any other ideas that i can try as well? Thanks in advance!

PS..The irony is that the machine worked flawlessly straight out of the box (no mirror alignments needed, laser tube was perfectly positioned. wires were nicely loomed and organized, etc), but started becoming an issue after around a week's use

[handlewanker]

Hi....just my 2 penoth worth as I'm not into lasers but mills and as the moves in X and Y are similar perhaps the fact that there is no real cutting force like a machining operation on a mill means that the makers have decided the steppers can be the smallest and lightest for the money.....just as long as the slides move etc.

It would pay to see if the steppers are strong enough to push the gantry around as the Y axis stepper has to push the full weight of the gantry and X axis too......the X axis stepper only has to push the saddle across the linear rails in one plane.

If you only have one stepper and screw in the middle of the table with a belt coupling to the screw....test the freeness of the screw with the stepper belt off.

It is a characteristic of a gantry design that the gantry can get misaligned if one of the sides has more friction on the rails due to bad build or assembly etc than the other, and can cause a dragging effect to the side uprights which seems to be what you might have.

Certainly the gantry side frame alignment to the linear rails is a prime suspect as it is a relatively flimsy structure when it spans the width of the table.....the length of the bearing blocks on the rails gives it a very high aspect ration in relation to the width of the cross beam.

Perhaps a photo of the machine would also make things a lot clearer.
Ian.

[ACG]

Hi Handlewanker,
If you've got time, please take a look at this video I've uploaded. it shows exactly what the issue is.
I would love to get your take on it as i believe you may be onto something.

https://youtu.be/y_7IO6iOM8A

And here is the best picture i could find on the 'net that show the slides, and gantry.


thanks!

[handlewanker]

Hi......just to make sure we're on the same track with the axes titles.....the gantry cross beam is the X axis and the side rails are the Y.......no Z obviously.

I see the Y axis is carried on two Hiwin....whatever....linear rails......what is the drive method for the Y axis.......does it have 2 screws either side with 2 stepper motors or rack and pinion or something else?

The drive must drive the Y carriage evenly.....if there is any drag or a tight spot on one of the rails the gantry will slew.......with the width of the X axis being as wide as it is and a relatively short bearing length on each side of the Y, the slightest drag could cause the stepper motor on one side to miss a step.

I can only theorise how the drive works without more info......it's a pretty wide span so I think there has to be two drives, one for each side or most likely a rack and pinion driven by a long shaft across the beam to both sides.....that would be a logical design to ensure the X axis beam stayed square to the Y axis when traveling.

You might have some dirt in the linear rail Y track(s) that would cause sticking intermittently......so many variables.

BTW....the video doesn't appear to show any hesitation in the Y drive movement, but as the camera is also moving about a bit, it's difficult to see.
Ian.

[ACG]

Ian,
Thank you for your advice concerning the possible drag on the linear rails. I completely cleaned and lightly oiled it. The stuttering is gone.
-ken

[handlewanker]

Fantastic.......this may re-occur, so a bit of regular maintenance might be your chore.

it's possible that there may be dirt in the bearing blocks too which will be difficult to clean out without removing the block completely and washing with kerosene and re-lubing.

The least you could do would be to wipe the rails and run the carriage back and forth while cleaning and re-lubing each side.....wipe the lube off to only leave a mere film, or it will attract dirt etc, as there will be sufficient in the block between maintenance.......whatever it takes etc.

BTW.....the best cleaning rags are anything made form synthetic material that won't leave loose fibres like cotton wool etc.
Ian.