Gantry not staying square

[Rocky Mountain Teardrops]

Trying to square the Y axis to the X axis per THIS thread.

Adjusting the shims and stop blocks so the gantry touches both blocks (A&B) evenly, then turning the motors on (gantry pulled against the blocks)

Cut all for sides of a 48" x 96" sheet.
When the router gets back to the origin, the gantry no longer touches the stop blocks evenly. (Joggins slowly towards the blocks, not crashing into them)

One end of the MDF (1&2 and J&K) is square and true to the under sheet when flipped, but the opposite end (3&4 and L&M) are not square and true.

Don't see any hint of the V-rollers riding up on the rails.

Any ideas?

Lee

[smreish]

Get corners J&M to match exactly, and get edges JM to lie exactly together. (If you cannot get lines JM to match exactly over the two boards, your x-rails are not straight - fix that before resuming the squaring process)

[Rocky Mountain Teardrops]

Thanks for replying Sean.

The J/M line is good (within .003")
The K/L line is exactly the same.

The top sheet is wide compared to the bottom sheet on both lines.

Here's what I've got.

J/1= +.000"
K/2= +.010"
(Out of square .010")

L/3= -.050"
M/4= +.030"
(Out of square .080")


EDIT TO ADD
Hmm...... The Z axis is a little bit out of square in the Y axis direction.
I wonder if this is hiding a bigger error in the J/M line?
I'll correct this tomorrow and post results.

[pblackburn]

This is a complex question with little technical information provided. A lot of things can cause a squareness issue. I would do the above from Gerald and I would also plot out a 345 triangle. I normally use a 0.005" tipped engraver and make a slight plunge into the spoilboard. But first is there any backlash that is adding to your problem. If there is any it will exaggerate your squareness checks. This leads to more stress and headaches.

[Rocky Mountain Teardrops]

Originally Posted by pblackburn

This is a complex question with little technical information provided. A lot of things can cause a squareness issue. I would do the above from Gerald and I would also plot out a 345 triangle. I normally use a 0.005" tipped engraver and make a slight plunge into the spoilboard. But first is there any backlash that is adding to your problem. If there is any it will exaggerate your squareness checks. This leads to more stress and headaches.

This was the problem.
One of the X axis motor drive gears had a loose set screw.

Thanks for the help.

Lee

[smreish]

...darn grub screws.
(I ground an extra flat on the motor shaft and use 2 set screws on my machines)
On one of them, I got so tired of the z working loose over time, I welded the pinion on....)...be mindful, this was a 48" Z slide with A LOT of weight, I was asking that little screw to do some holding

[Rocky Mountain Teardrops]

I think it was a burr left over from drilling and tapping the gear.
I used blue Locktite on it, so it was not loose.
I just didn't get it seated when I put it together.

Quite the relief.
I didn't get very much sleep Saturday night worrying about what could be wrong.

On the positive side..... I have the Z axis within .003" of perpendicular now.
Used a dial indicator at a 2" offset from center of the collet.

[smreish]

Lee,
I did something similar.
I welded a 1/2" drill bit to a 12" carpenter square and chucked it into my spindle.

Then, rotated the unit 360 with dial indicator to make sure I was plumb. I won't take credit...those blokes in SA keyed me into trying it.

[Rocky Mountain Teardrops]

12"

I thought that 2" would be just fine.

[Zouave]

I did about the same thing, with an 8" section of flat steel I had. First thing I did was cut a + pattern on my surface, then centered the Z over that, chucked up a 1/2" bar I'd welded the 8" of flat stock to, and had the dial indicator out at the end. Amazing how accurate you can get with that setup.

[Fox]

for pinions/pulleys working loose I have used another solution with great succes.:

http://www.maedler.nl/Product/1643/1621/827.aspx

and

http://www.maedler.nl/Product/1643/1621/823.aspx

No flats needed on the shaft, just bore our the pinions/pulley.

It's not THE solution though, as your motorshaft can be too thick/your pulley too small to use these. But if that's not the case it is really strong, self centering solution + you can disassemble and replace or adjust with ease. ( my gearboxes went apart 3 times already to change things, I was really happy with them then ;-) )

[Robert M]

"I welded a 1/2" drill bit to a 12" carpenter square and chucked it into my spindle."

Anyone ever tried the "steel wire hanger" method
Worked fine & fast for me....with in .005 as per my filler gauge

[smreish]

Robert,
The only reason I used a square was because my starret run out gauge had a magnetic base....I needed something to stick it to!

[KenC]

I tried the "steel wire hanger". I ended up with a nice Z-axis tilet of 4~5 degree.
Just stick with the set square.

[Fox]

Oh my...and I thought you we're the keep it simple&cheap advocate on the forum KEN ;-)
Operator error ? Cause I use the bend wire method al the time, on my drill press etc....works just as well as long as you don't start to BEND it when setting.
But if you want to make it a project, the square will make it foolproof of course ( that is, if you don't distort it when welding )

[KenC]

Fox, I take that as a compliment. LOL
Anyone can complicate things beyond imagination. I enjoy doing things as simple as its required, the "cheap" cae as bonus.
Everyone has a square in their tool box... I actually went out to buy a wire hanger to have a go... what a waste of time & money...
Go with the square, its idiot proof.

[Zouave]

Whenever something is deemed idiot proof... Do not underestimate the power of the world to produce a more talented idiot. :-)