Need help adjusting the spindle

[rgreever]

Hello ShopBotters!

First off, allow me to introduce myself...

My name is Ryan Greever and I am the 3D designer and drafter here at Glazing Management and Consultants, inc. where I will also be in charge of the CNC fabrication work on the ShopBot PRS Alpha that we have here.

I have plenty of 3D and graphic design experience under my belt, but I am brand new to CNC and the ShopBot. I am learning trial by fire, and please forgive me if my lack of proper terminology and knowledge offends you!

With that being said, here's my first question to this forum:

It is evident after the resurfacing of the spoilboard that the spindle is not vertically true (for lack of the proper term). Striations are clearly visible running down the length of the spoilboard (in the x direction). What is the proper procedure for getting the spindle back into being perfectly perpendicular to the table.

What is the correct term for the problem that I have here? I found the instructions for using a piece of bent wire or dial-indicator to determine vertical calibration. Is that what I need to go through? How do I go about adjustment of the spindle?

Thanks in advance!

[Brady Watson]

If the lines run parallel with the X, then you probably don't have the 2 lower V-roller bearings on the YZ car tight enough. They should just touch the bottom of the beam rail and you should not be able to spin them by hand. Snug is what you want...not king kong tight or you'll roll forge the rails. You have to remove the wheel covers 1st...and use the flat sheet metal wrench SB gave you in the tool kit.

If the lines run parallel with the Y, your gantry is twisted/canted. The only way to do this is to loosen the end plates and gussets from the beam and square it up with a big framing square. You'll need long clamps to clamp the beam ends down to the XRails...it's not for the faint of heart, but the proper way to fix the issue. Otherwise, you can shim the spindle plate until it is square.

-B

[rgreever]

Thanks for the speedy reply Brady!

It's definitely issue #1. I'll take a stab at it.

[rgreever]

Sure enough, the 2 lower V-roller bearings on the YZ car weren't even touching the rail. They were about a millimeter too lower. I adjusted them yesterday, but haven't had a chance to test it out yet. Today, if not, tomorrow, I'll give the spoilboard a resurface to test it out.

[rgreever]

Looking down the x-axis, this is what it looks like after adjusting the v-roller bearings. Better than it was before, but there is still striations in the spoilboard after resurfacing.
We also did a test resurface rastering in the y-axis, and it was a tad more noticeable.
27031

Any other ideas?

[Brady Watson]

A few things...

It appears that the tool used to machine it flat has a dish to it like a large ball end tool. Does it?

What overlap/stepover did you put in for flattening? I use 20% as this allows the bit to fully overlap the last pass, especially in the corners.

Feeling the table trumps how the lines look. Run your hand over the table and as long as you can't catch your fingernail on each pass, it is good. Any smooth dips etc are most likely the bit. Even if there are very small/faint ridges, you can live with that.

Flatness across the work area as it relates to the Z is the most important thing. Temp and humidity are going to fight you no matter what you do with a wood composite spoilboard.

-B

[rgreever]

Brady,
The bit I'm using is the 1.25" table resurfacing bit, and I do believe the stepover was set at 20%. The SB is a few warehouse bays over from my office, so I don't recall the exact settings we used and I'm not at that computer right now. Running my hand over the table, in 90% of the spoilboard, it feels pretty darn flat. There are some areas that just a hint of a fingernail will catch it, but overall, I would say it's pretty good ~. I'm just curious if striations are going to be visible when I do a pocket cut into a piece. Well, I guess there's only one way to find out, right? I was just over there running through one of the first jobs I created. Just an air cut above the table, but everything looked good. Maybe after lunch, I'll screw down a scrap and give it a go.