How to level out my cutting surface?

[BrMiHi08]

I got a K2 25x14 router a little while back and have been just doing some basic stuff like cutting foam and some other wood. I am needing to do some engraving on some acrylic plastic and when I try to do so I found that my table is not level, and this is causing me a lot of trouble. I have to use a V tipped bit, and when it goes across the X axis it tends to not be as deep. I contacted K2 about this problem and they were no being very helpful. So I took off my aluminum T-slot and the table still seems not to be level. I looked at the 2 rails for the Y-axis and they are not level either. I am pretty much stumped right now. I had a though of throwing a chunk of MDF on there and milling it across the whole board until the whole thing is milled and it should be level. If you guys have any ideas I'd appreciate it.
Thanks,
Brian

[ger21]

Originally Posted by BrMiHi08 I had a though of throwing a chunk of MDF on there and milling it across the whole board until the whole thing is milled and it should be level.

If the rails are not parallel and level, the MDF won't be flat, but it will be at a consistent height to do your engraving. Sounds like your machine has some quality control issues? Is there any adjustment to get everything lined up and parallel?

[InspirationTool]

Check out the Shopbot forums. There are a ton of discussions about this issue.

Basically, you should do everything you can to get your machine square, straight, plumb, trammed etc... Then as you say cut a sacrificial table surface at the same Z height so that the top of your work ends up at a consistent Z height.

If your machine is really screwed up you will need a vacuum to pull your work parallel to the reference surface.

-Jeff

[sploo]

Hi Brian,

As Jeff noted - you can cut a sacrificial table surface.

I found my 3925 was around 1mm-1.5mm out from one corner to another. I bolted a sheet of 3/4" thick plywood to the table and surfaced it.

I did this by hand coding some g-code to move a 3/4" diameter flat router bit up and down the table, across its whole surface (removing about 2mm). It took about 30mins, and the results have been good.

If you don't want to hand code, you could use your CAD/CAM solution to pocket cut a rectangle of the same size as your sacrifical table. Alternatively, I believe Mach3 has some suitable wizards.

You'd obviously need to cut and tap holes, or T-slots, for hold downs so that you can fix materials to your surfaced table top.

[ViperTX]

I was on one of the huge CNC router (Thermowood or someone like them)sites a couple of months ago.....anyway....one of the last operations that was performed on the machine after it was assembled at the factory...was to let the machine surface it's table by running a face mill of some type over the whole table.....this was a 5' x 10' table.....if I find the link, I'll post it.

[GuitarEng]

We use Fadal's at work and we do the same thing - face milling the table in order to machine it true to the spindle.

[todd71]

You could do a skim cut to see how far out it is by starting in x/y zero. Then make a cut around the perimiter of your spoil board. Measuring the depth of the cut with a depth mic to find your high and low spots. Shimming the areas to bring into a more consistant hight. Another thing you might want to check is your router "tram". Place an indicator on a swing arm http://www.mytoolstore.com/starrett/test05.html see attachment (K)
Then swing an diameter on a known flat surface to see if you router motor is perpendicular to the cutting surface.

Todd

P.S. Hey Jeff how's the telescope's coming along

[widgitmaster]

Is this the Router you have?
If so, it looks like a well designed machine!
I would suggest you get a dial indicator and a quality 6" level.

1st check the level of the whole machine by shimming or adjusting the feet at the corners
2nd check the y-axis using the dial indicator, then add shims under the top plate to get it parallel to the linear travel
3rd repeat the same process for the x-axis.

Shim stock is available in a multitude of thicknesses and materials, and I sometimes use the Mylar wrapper from a snack food as they can be as thin as .0005"

Using a sacrificial plate is ok, but for the money you spent on that machine, it should be within the manufacturers specifications when setup with a common 6" level! If not go Bark at the guy who took your money!

Also:
Do not move the machine from its working location, or you will have to repeat the entire process again!

Hope this helps!
Eric

[BrMiHi08]

Thank you guys for the help. I think I will try and get it as level as possible as you suggested, then go ahead and throw the MDF on. I might try and experiment and see what else I can do, but for a temporary solution it will due. I tried shimming it, but was a lost cause because I'd shim it one way, and it'd be off along the Y-axis. But thank you all for the help.
Widgitmaster- That is the machine I have. When I first got it it looked like a nice machine, but when it runs I am not all that happy. It took me about 3 email to get a hold of K2 and even at that the guy was telling me that is was all in my Gcode, and I tried to explain but the guy was dumber than a box of rocks.... He told me to use some plexi glass and run it across.

[widgitmaster]

I think he was trying to tell you to use PlexiGlas as a sacrificial plate!
Lexan would be better, as you can cut threads in it and they are stronger than in PlexiGlas!

Good luck
Eric

[widgitmaster]

Yes, shimming and indicating is a long tedious process, but you should be able to get the needle on the indicator to stay at zero across the entire surface, unless the t-slot plate is warped between bolt locations!

In that event, a sacrificial plate is all you can do!
Eric

[Les the Luthier]

Gosh I almost bought a K2 3925 machine! The advice given above by widgitmaster and others is good. The process is called leveling. It sounds like your machine has somewhat of a twist. The first issue that you need to resolve is to determine how much your X axis slides are out of paralell. The first thing you need to do is get both rails level. By rails I mean the ball slide itself, not the aluminum side rails. Not only do you need to get both slides level lengthwise, you also need to make sure they are level side to side. Once you have corrected for this twist. It would be wise to check that the slides are the same distance apart (paralell). With these issues corrected, you should then look at the gantry. Is the Y slide level? Is it perpendicular to the X axis slides. Most of these adjustments are a combination of shimming; loosening and repositioning misaligned parts; and rechecking untill you are satisfied that the movement of the machine is square and paralell to the X axis, then the Y axis and finally the Z axis. Not only must the Z slide be perpendicular to both the X axis and the Y axis, the router mount must be checked to verify that it too is true to the axis movement of the Z slide.
Sorry if I'm long winded, but I recently bought a Techno Isel 067 gantry router and had to deal with all these issues.
Now about the table. If you use a 1" travel indicator and move around the aluminum table, you will be able to map the distortion. Hopefully you will be able to shim or reposition the table to be mostly level. Then a sacrifice board will allow you to cut a reasonably level work surface. After that, you'll start to have fun with your machine.
I hope this has been helpful. Wishing you sucess in your journey,
Les the Luthier