Possible warped z table on 60 watt system

[Ron Burns]

Hello everyone,

I am the recent proud owner of a G Weike 60 watt Co2/engraving laser. So far I have had my spare mirror/nozzle milled down to accommodate a 38mm lens successfully from a 50.
I make frames and bulkheads for scale model kits so my hopes were to achieve a finer kerf as suggested by a few folks. Today I realigned and focused everything to near perfection
and did a run of frames. All I could say was WOW! The cut was near perfect...until we got to the top of the sheet. The cut width is almost double and the edges dirtier! I use 1mm card similar to mat board for the frames and tape down the corners. I tried to figure out where the problem was and for giggles I put a straight edge on my z table. Sure enough there is approx. a 3/64 inch bow in the table with the center being the high point. It does the same thing front to back as well. To me it might explain the symptom. Any opinions? I'm at the point where I need to start producing. Any suggestions on what to replace the table with? Its simply a 23.5 inch by 13 inch sheet of aluminum with 4 small notches cut out to accommodate the mounting brackets. Would it be feasible to have a table built that is perfectly flat? Instead of the rotary device I should have looked into other table options but I had no idea. If anyone is in Ottawa and needs a rotary device in swap for help making a table......

All the best!
Ron from Ottawa

[Ron Burns]

Wow! 137 views and not a response? I would have thought that those of us without the ability to mortgage a house would have been curious to find a solution to what seems to be quite a common problem.
Solution...1/4 inch aluminum tooling plate that is cut by band saw vs. sheer brake. I pick up a piece in the morning. I did see perforated plate online but it was from below the border and would cost body parts to bring it up here. As a new found friend just told me, when one buys a laser, regardless of brand, it becomes a long, long journey. I agree but damn it! I will make it a trouble free one! I'll post a pic or 2 of the process and final product in case it might help someone else down the long road

All the best
Ron

[Vicki Rivrud]

Trouble free . . . .:rolleyes: I don't think so friend, all the best, Vicki

[Ron Burns]

Hi Vicki!
Let me rephrase that... 'As trouble free as possible' :) I *am* very determined!

[Vicki Rivrud]

Hi Ron,
I am going to bump this subject in hopes someone here will answer the subject . .. .

I think that using a "solid" flat surface will cause a problem, trapping smoke under the substrate and/or causing damage to both the material &/or lens. Could also possibly start a fire.

IMHO the better solution would be a iron honeycomb (however this is subject to sag) or angle irons to raise the material off of the flat surface or use the solid flat but implement a pin table or the corian table posted at this forum. Sometimes I use golf tee's to lift the material off of the honeycomb to keep the backsplatter at a minimum.

Also keeping the project in perfect focus when attempting to cut an entire sheet - there appears to be a difference from one end of the table to the other end. There is also the subject of power inconsistenance the farther away from the tube, or so it has been explained to me.

What say you?

Vicki

[Ron Burns]

Just a quick update...
The plate I ended up with was perfectly flat 1/4 inch Alcoa 'Mic 6' cast tooling aluminum. It was a few dollars more than rolled sheet but very much worth the bit extra. It weighs about double what the original weighed so make sure your z table motor is up to snuff. When and if you decide to to take this on, make sure the folks that do cut it for you, make it square! I didn't check until I was marking out the cut outs and mine was off. I think it's a typical Ottawa thing....do the least amount of work possible for the biggest buck. I swear, quality of workmanship is lost in this town! I don't have access to many tools..your basic Dremel, a square, scribe and a file. Vicki, I see what you are saying! Thanks for the bump BTW :) I'm going over to my folks' place this weekend at some point and will use my Father's drill press to bore some holes (probably in the neighborhood of 200+). I plan on tapping every 2nd hole or so to accommodate a stand off of some sort as soon as I figure out what I will use.
The most difficult part of this little job was leveling off the table with only the depth gauge on my Vernier. Measurements were taken from the Y axis rail as it is probably the only true surface (other than the X rail) in the machine. As another new forum friend mentioned to me, sanding the heck out of the table will do well to diffuse and scatter any bouncing light. It was also mentioned that painting it, even with heat resistant paint would be a serious waste of time as it would only get vaporized by the laser. The end result you ask? I did both engraving and cutting on a 12 x 14 inch sheet. All scale 1:33 model parts (yes, 1:33) on 1 mm card. The lens was a 1.5 inch ZnSe. The kerf was as fine as can be and even on all 4 points of the table. No discernible difference! I own one of the newer removable honeycomb tables that rests on top of the laser z table. Removing the aluminum frame and loosening the nuts all around the honeycomb went miles to allow the individual strips to rest perfectly on the z table. No sense changing the table out only to add more error to it :) Bottom line, around $80.00, 2-3 hours of time and perfectly even cuts from top to bottom and left to right! Here's a pic of the table as it sits before the holes are drilled.

All the best!
Ron

[Vicki Rivrud]

I am glad that you are making headway with this major project.
I had 2 concerns when you started this

1- that Z axis your stepper motors would groan when lifting a heavier table; would need to upgrade to heavier steppers as I did.

2- preventing necessary airflow; which you will rememdy with all the holes :)

The honeycomb, even if iron, will sag in a short amount of time so your new bed should be great.

I received a clarificiation from the factory on the knife blades, always a problem with Chinglish or communication - it is wasn't painted-it was anodozided black - huge differance however they are pitted from over 6 years of use.

Keep posting your progress, this has been an interesting process.

Happy lasering,
Vicki