Wavy cut lines

[Ignas Kaz]

Thats the best i could do with a phone:

sWIPFAx[1].jpg

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[Tim Mellor]

My little one is exactly the same construction and material gauge and size. They have just increased the Y drive and gantry length and left the engineering the same from a 3020 to a 9060 frame.

Even with a single outboard roller you are very unlikely to be getting any issue from that toward your major issue as belt tension is what keeps the gantry square to the Y not the rail or bearing such as it is supporting it. There is a positive with this simple system in that apart from the belts being torqued up and causing misalignment of the gantry it will move freely with minimal resistance to motion. Belt tension from below will help gravity keep the roller on the rail any vertical motion in the case of a Laser will show as a Focus issue. A second roller under it however would have been a 'nicety'.

My engineering brain still says it is the Y drive that is your issue and a lack of power, as the mass of the gantry will be well over double mine with the same motor. The only other possibilities are as we have been talking about is settings and the drives. Check the CD for a file labeled Vendor Parameters or settings? and go back and restore them to factory and test again.

There is one thing you could test electrically just to tick it off the list is do a voltage test on the 24V power supply with the Laser in motion (load test) with even a basic multimeter.

If you are dealing with Ronny expect NOTHING and don't be surprised if he is wearing a T-Shirt with 'mei ban fa' (“it can’t be helped”) on it. I have not found a way past him to their technical department and have done my own thing since shortly after purchase.

[Doug Fisher]

I hope you paid with a credit card. If so, just threaten a chargeback. Make sure to keep documentation of all of your tests in case he tries to dispute it.

When buying your next one, make sure to ask about the quality of the rails. Mine has clones of the HiWin rails. The big problem with mine is the lack of a grease nipple/connector on the sliding bearing blocks. There is a divot there where a connector should go. On some clones, you can actually install your own connector there. Mine is just a "visual fake" which cannot actually make use of a connector. This means it is really difficult to adequately lubricate the bearings in the bearing block.

[Ignas Kaz]

@Tim Mellor: Problem with this setup is this - Belts are springy, gantry due to length is springy (to lesser extent, somewhat restrained by belts in Y), the roller doesnt restrain X axis gantry in vibrating in X direction, which in turn makes head assembly vibrate, the single rail on left absorbs all vibration and misalignment of the whole XY system. Essentially, the round rail is becoming too much C in x vibration and S in racking/Y misalignment.
Effectively a 1.7m long spring sitting on Y, supported by single ~60mm long bearing on a skinny 12mm rail.

I'm clearly struggling describing it in enginnering terms as i have no nomenclature of engineering terms. Clear in my head though.

I had to deal with harmonic vibrations, unbalanced part induced vibration and PID controller freakouts due to this in flight controllers for RC quadcopters. But those things SENSE vibration and can compensate to a degree. This laser thing is so dumb there is no way of correcting harmonics/disbalance short of making the mechanics of the motion to eat it. In case of 3020 its enough, but not for 9060.

I have tested 24v at rest, it is 24v, but yeah, will retest under load.

@Doug Fisher: Paid by debit card bank transfer within UK, met the seller personally, know his company, hes got VAT reg, etc. At this point i'm not worried about the money. All is within UK law. No international shenanigans (not for me anyway).

As for fake rails. Fair enough, but one big point, if i had PROPER rails on Y, even if they were fake, its only a matter of replacing them with proper ones. Holes are predrilled, located correctly. A matter of "unscrew-take off, put on, screw down, done".

Making tests every day, in speed scales and keeping evindence as you suggested.

[Jeffrey Aley]

Its not fixable in its current state. Fixing it means throwing out ALL of XY motion, which leaves me with electronics and super expensive sheet steel box.

Fixing it requires cutting out all unneccessary welded case elements, drilling, machining profile supports, fitting stuff together, aligning rails, etc, etc.
Might as well build one from scratch.

This kind of design might have worked for a machine quarter its size, but definitely not for 6090.

As for your offer of photos, can you do a detail walkthrough of your machines motion with a camera ? Belts, rails, motors, gantry, in detail ?
I'd really appreciate it.

Yes - but not until tomorrow evening. I have to laser-cut a card for our nineteenth wedding anniversary, which is today. Probably best if I spend less time w/ the laser and more time w/ the wife this evening.

[Pete Cyr]

After only 19 (short) years you have learned a valuable lesson.
Remember you have been married for 19 ALL TO SHORT years in all conversations with her.

[Ignas Kaz]

Congrats on anniversary.

At least you can cut card/paper. I, for damn sure, cant...

[Gary Thompson]

My machine has just developed an intermittent problem with wavy cut lines!

I've read through this topic, checked mirrors, lenses belts etc - all seem fine. Bizarrely, I noticed a 'gurgling' sound coming from around the laser head, pinched the rubber tube for the air assist and the gurgling went - as if there was a blockage in the tube and it popped through with the added pressure. The next cuts were fine.

The next time I switched the machine on the gurgling was back so I ran a small test and wavy cut lines were back (also not cutting completely through). Pinched the tube, ran the test again and fine. Silly question but would condensation in the air assist tube be causing this? Any suggestions on checking? I really don't want to start taking things apart.

Thanks

[Gene Uselman]

Gary- you should probably start a new thread, members may ignore a ancient thread like this. It sounds like something is vibrating in your air assist system for sure. I would be taking that apart first thing. I think that is a brand new problem- congrats. Gene

[Duc Chu]

My machine has just developed an intermittent problem with wavy cut lines!

I've read through this topic, checked mirrors, lenses belts etc - all seem fine. Bizarrely, I noticed a 'gurgling' sound coming from around the laser head, pinched the rubber tube for the air assist and the gurgling went - as if there was a blockage in the tube and it popped through with the added pressure. The next cuts were fine.

The next time I switched the machine on the gurgling was back so I ran a small test and wavy cut lines were back (also not cutting completely through). Pinched the tube, ran the test again and fine. Silly question but would condensation in the air assist tube be causing this? Any suggestions on checking? I really don't want to start taking things apart.

Thanks

Hi Gary I had this waving cut line with my new omtech (after some hour working) 2 weeks ago and after some day checking everything same yours, I found the issue came from the focusing len, there is no rubber o ring at the focusing len, just aluminium tube contact to the glass len, so it will be losse after some hour working.