Uneven Cutting

firmwareengineer
Posts: 26
Joined: Thu Aug 10, 2017 6:05 pm

Uneven Cutting

Postby firmwareengineer » Mon Aug 28, 2017 5:57 am

I upgraded my system to the T9 with Z table. I have realigned my mirrors so far so good. But, for whatever reason the lower left corner of my material which I am trying to cut is unable to cut through the material (acrylic). The rest of it cuts perfect, with one pass. But in this one area consistently, it doesn't cut all the way through.

I have also measured the distance of the last mirror (the one with the air assist attached to it, I'm sure it has a name...) to the Z bed and it is even all the way around.

Any ideas what's wrong?

Tech_Marco
Posts: 4328
Joined: Mon Jun 15, 2009 3:00 pm

Re: Uneven Cutting

Postby Tech_Marco » Mon Aug 28, 2017 8:13 am

Theee possibilities popped up in my head: 1) the level of the Z table and 2)the position of the lens and 3) the lens quality


Check the level of the Z table with a leveler. Make sure the distance between the laser tip and the bed is equal. If you are using our air assisted laser head and a 12mm focus lens, make sure the lens is set to the center of the laser hole or beam will be deflected. If the polishing work was not good on the lens, will may come out non straight or deflected side way

Hope this can help you to solve your problem


Marco

firmwareengineer
Posts: 26
Joined: Thu Aug 10, 2017 6:05 pm

Re: Uneven Cutting

Postby firmwareengineer » Tue Aug 29, 2017 5:29 am

Thanks for that. I ended up printing out a holder for the lens, it was not centered. But looks like I may have another issue. But this is with the bed itself.

1) If I tighten all the nuts on the ztable which affix the metal plate to the threaded rods, then attempt to move the table, It will move a little then just start making a grinding sound. I then have to loosen up the nuts to use it, which in turn eventually makes all the nuts come lose and makes my entire bed not level. When I looked at the threaded rods when they spin, it looks like one is slightly bent. Which may be the cause of the entire issue. I can contact support for a new one, but wanted to know if I was doing anything obviously wrong before doing so.


2) For whatever reason, when I hit Z+ or Z- the bed will stop moving before it gets all the way to the top. Its like it gets stopped out in firmware? I have to hit Datum in the software for it to go all the way to the top. But since there is no feedback it just begins to make a grinding sound when it hits the top. Then I press Z- to make the bed go lower. That is the only way I can get the full range out of the table. Am I missing something?


Thanks.

Techgraphix
Posts: 475
Joined: Fri Jan 20, 2012 1:39 pm
Location: Appelscha, the Netherlands
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Re: Uneven Cutting

Postby Techgraphix » Wed Aug 30, 2017 7:41 am

That grinding sound you hear can have a few causes: or you table gets stuck. This can be that de screw-spindles (if you have) are not exactly parallel and perpendicular. or there is something that obstructs the movement of the bed.
As long as you don't have closedloop motors, the controller won't notice anything of this and calculates the traveled distance as it should be.
If your range is set close to the actual range it will not reach the end as a few mm's are lost due to loss of steps.
As you wrote that loosing some screws fixed it, i'm quite sure it needs some more alignment.
Another cause can be is that the motor is not suitable for this task i.e. to weak.. If you're sure this motor should do it, check the motorcurrent, Startspeed, accelerationand max.speed
Not sure if you use homing for Z. Normaly it's not neccesary when you use autofocus. It will stay there untill you move it on the keypad or let it move up to trigger the autofocus-sensor.

Kees

Tech_Marco
Posts: 4328
Joined: Mon Jun 15, 2009 3:00 pm

Re: Uneven Cutting

Postby Tech_Marco » Wed Aug 30, 2017 9:43 am

After Techgraphix , you need to install a Z limit switch to tell the controller where is 'home' Plus, you need to lose those screw a little bit to avoid chock up. Remember that those screw rods were not the professional grade ball screw and the frame is small and soft. If you locked those screw up, chance is that the Z table won't move or move slow and less lift capability. Grease the screw rods will help.

Marco


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