Author Topic: cnc6040 how to face the table?  (Read 9520 times)

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Offline ofg

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cnc6040 how to face the table?
« on: January 29, 2014, 09:08:26 AM »
I have been having tons of fun operating my Chinese sourced cnc 6040 router. Its a working nc machine, with some serious limits. Like many others, I have found that the supplied aluminum extruded T slot table is soo not flat that no precision cutting can be done using the table as a reference. So, I went about trying to face the table, with bad results. Lots of chatter, and steps generated resulting in a very bad finish. Also, the high spots seem to stay high even after cutting.  I know the tram that guides the y axis allows the bridge assembly( that literally is the x and z axis ) to rock back and forth about .1 inch! It rides on acetal, or nylon sliders on chromed tubes. Also, I dont have a large selection of end mills. So, anyway, Im wondering if some body can recommend some feeds and speeds, cutting depth and tool type to face my table. Also any way to tighten up the y axis guide sliders so it will not chatter? Writing the program and or using a wizard to create the code is no problem, but im quite sure my tooling is not ideal, and so everything else is not ideal either.


Offline budman68

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Re: cnc6040 how to face the table?
« Reply #1 on: February 01, 2014, 09:11:05 AM »
Hi, if it were me, I would actually install some sort of sacrificial top on the top of that, such as mdf, or abs or hdpe plastic.

Trying to face that aluminum table with the lack of rigidity setup you have is obviously not getting you anywhere.

Dave
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Offline ofg

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Re: cnc6040 how to face the table?
« Reply #2 on: February 01, 2014, 10:08:45 AM »
Yeah, I came to that conclusion too. I tore into the machine, and lubed up the y axis guide bearings, and ball nut, then used the built in set screws to tighten down the guide bearings. This has helped alot in terms of perceived rigidity. I gave up on facing the table though. The t slot table itself is 3 pieces, lengthwise, supported only at the ends where it screws to the frame. There is about 3/4" clearance underneath it for the Y carriage cross member(where the ball nut is mounted). So, Im going to fab up a brace for the middle of the t slot table so they are tied all together in the middle. This should also improve rigidity and reduce noise.

Problem is I need to use the t slots for locating fixtures and vises. For now, the solution will be to shim the vise and leave it set up .  I had also considered some kind of really thick and hard brushed on coating. If I could get probably 1/8 " layered on the table, then it could be faced satisfactorily.

Anyway though, these things arent meant for any kind of precision milling. Im quite sure the steppers and ball screws are capable of maintaining tolerance, but the aluminum frame is too weak and prone to vibration. The force of milling causes the axis to flex on its guide rods... Its a router. But, Im going to mill plastic with it anyway...