Possible Z Axis Issue? ~ Newbie to this!!

[TheSignStudio]

Hello Everyone,

So basically my knowledge of the this ShopBot that has been bestowed upon me is still very minimal. I have trouble shot a few different issues and so far everything has been great. To give you an overvue of what I am working with I have a ShopBot 4' x 8' With PRT Alpha Software. My Router uses a Spindle and Collet feature for the bits. I have just recently purchased a replacement Collet for my spindle and replaced the spoilboard for the first time. The reason being I was having quite a few problems with my Z axis. Today after mounting everything back to the table I went ahead and started to plane to spoilboard and well I seem to think im still having a Z issue.

There are pictures attached to this thread so you can get a visual of what I am working with. It seems as though when the router is planing it glides smoothly over the middle and towards each end of the board the cut tends to sink a little lower than before. The bit I am using is 2" in Diameter. I now have these ridges in my spoilboard and i'm wondering if they will affect the quality of my cuts. On top of the .75" Plywood Spoilboard I attach a .75" of PVC as well. (will I need to plane this piece as well?)

As stated I am still very new to this router and am learning alot as I go. I appreciate any help that I can get in regards to this issue.

Thank you all in advance for your time!

[jerry_stanek]

Make sure your spindle is plumb both ways. It looks like it needs to be adjusted to cut level. This can take some time to get just right. I use a dial trammel to get mine plumb.

[Brady Watson]

"Read the lines" and see which way they are angled. Get a rubber mallet. *Dink* the Z axis the direction it needs to go. Try clearing again & adjust as necessary. Looks like the top of the Z towers need to go towards the positive X side of the table...If my eyes serve me correctly in picture #1.

-B

[TheSignStudio]

Thank you guys for the suggestions, I will see if either of those help the situation. Would I need to resurface the board after these steps?

[ssflyer]

If you are covering the ply with PVC, you didn't need to surface this at all - only the PVC layer.

[Brady Watson]

On top of the .75" Plywood Spoilboard I attach a .75" of PVC as well.

I would strongly advise against the PVC. My reasons why are here: Post #5 (http://www.talkshopbot.com/forum/showthread.php?t=13883)

-B

[TheSignStudio]

After much recalculation and setting up of the machine I am still having issues with pocketing. As you will see in the pictures I am getting an uneven pocket all the way around. I am using a Single o Flute Upcut .25" Bit for these pockets and just cant seem to get a smooth surface. Any ideas? :mad:

[bleeth]

This type of job is done easier by cutting the letters and logo out seperately and making pockets in your field for them. Then you can cut your whole field flat in one go, then cut the pockets for the letters, and then drop the letters in. It also makes finishing easier by finishing the letters and field before assembly. I have found that no matter how perfect your z is the slight variations in height due to machine tolerance compounding over the lines of the file always will have some different levels in this type of thing. It is also a reason that many people use textures in a machined background.

[Rob Gunn]

Joshua, Your #2 photo clearly shows that your spindle is not square to your table. Check out You Tube and search for "tramming a head" or "tramming a mill". You will find many examples of how to tram a head on a Bridgeport mill and this will show the basics of what needs to be done on your ShopBot. Bottom line is the axis of your spindle needs to be 90 degrees form the table in any rotational orientation (not 89 degrees or 91 degrees). Think of the spindle the same as a clock face, you want to get the same indicator reading if you are in 12-o'clock, 6-o'clock, 3-o'clock or 9-o'clock. As a tool maker for over 25 years, I can tell you from experience that this can be difficult. The first few times you try it you will be very frustrated but it will start to make sense after some practice. I am surprised that ShopBot doesn't offer a video tutorial on how to do this. (maybe they do and I just don't know where to look?) Good luck!

[beacon14]

Part of the issue may be the lack of vacuum hold-down. If the material flexes or moves at all during your cut you will get ridges and uneven bottoms like the photos show.

[tallen84]

I too have had the same issues as Joshua. The problem shown in the first post is one I have had since day one, as expected it is more pronounced the larger the bit you use. I tried several times to adjust my Z axis to resolve the issue but I still have the same problem after over a year. I really need help and possibly someone more experienced to come out and take a look at it and get this resolved.

The second post with photos appear to show an issue similar to one I had that was due to a mistake that I made a few times (and thankfully learned from). The problem was a very very minute difference in the z location after changing from my clearing path bit to my detail cut bit. The minute difference caused the same affect around details and lettering. The issue was due to a bad Z-zeroing even when using the Z-zero plate. I am extra careful now to place the z-zero plate in the exact same place on the material every time, blow off any dust in that location, and I run the script 2 times. Since I have started doing this I found I don't get that problem any more. Hope that helps.