Out of square PRS Alpha

[sidofengland]

Hi All,
Help required please.. I recently purchased a new PRS Alpha and followed the instruction manual to letter. However I have cut a series of rectangles and measured across the diagonals and I am about 1.5mm out of square.
I have read in the manual something about adjusting the gussets on the Y carriage but i'm not sure how to do this.
Anyone who has had "out of square" issues and resolved them may be my saviour.

And to all those people who have helped to develop this forum - A huge well done - So many fantastic ideas out there.

Regards
Sid

[Gary Campbell]

Sid...
We also experienced a minor out of square condition. The instructions in the manual are not the best, but do give the proper method. Here is the short and sweet version:

Clamp one side of the X car to the rail near both wheels. Loosen the bolts on the angled gussets under the Y extrusion. Move the other side of the X car into the square position, clamp near both wheels, and tighten all bolts. Recheck for square, repeat if needed. In some instances, you may have to loosen the bolts into the end of the Y extrusion. If you need to do this to get your gantry square, always keep 2 bolts on each side tight to keep the Y extrusion from tilting out of plumb.
Hope this helps, Gary

[GlenP]

I had the same issue. I also removed my X motors and after adjustments to the gantry pushed it end to end a few times to ensure it still ran smooth and all v rollers made contact. Once I reinstalled the motors it has been right on since. Also if you are running a router check to make sure it is square to the table, mine was off just a little. Good luck you will get and love the machine.

[dray]

I havent read the latest prs alpha manual it in a while, but DO NOT use any sheet goods to square your gantry, all/any sheet goods are not square.
use this pdf

[dray]

woops heres the pdf.. works great and you will know for certain that your machine is EXACTLY square


squaring-19889.pdf (http://www.talkshopbot.com/forum/messages/312/squaring-19889-32233.pdf) (34.8 k)

[sidofengland]

Thanks for the advice - I'll keep you posted.

Regards

Sid

[bleeth]

When checking my gantry for square I cut a 1/8 D shallow groove in the spoilboard at least 4 ft long and then from one end of that groove I cut one in the y direction at least three feet long. The 3,4,5 is foolproof. (Go 3 feet out on one leg, 4 feet out on the other, and then measure the hypotenuse. If it isn't 5 ft then you are out of square.)

[Gary Campbell]

This was written for squaring a machine during assembly before power was run to the router/spindle. Instead of scribing, you can cut a fine line with the Vbit. A powered machine would not require clamping prior to scribing the lines.

Due to a non standard mounting location of my control box (big surprise?) I needed to come up with a better way to make sure that the X car was square without doing the pull on gantry and reset method. I decided to insure that it was square when at rest. The following assume very straight, very level, parallel rails at the proper distance apart:

With the X car and spindle set in place I placed a 60 degree v bit in the collet. I clamped the Y car in a location so that I could use the tip to scribe a line at around an inch from the Y=0 edge of the table, full length. I then did the same by moving and clamping to the other extremity of the table. Then I moved the X car to the far end – 2” and clamped it in place. I scribed a line from one side to the other.
Then move the X Car to the Min. X end, clamped and scribe a short line at the min Y (home) side and the max crossing the 2 long lines. Measure these cross corner dimensions. If they are exactly the same and all your wheels are down tight on the rails, then you are good to go. If you just have a wheel that occasionally seems loose on the rail.. Return to the instructions for the adjustments.

If not… or you want to really square and true up the X Car then:
On the home corner I clamped the X car wheels down to the rails with 2 rubber padded bar clamps with the v bit over the scribed short line. Using a calculator, with the length between the 2 scribed on the home long line as a base, the distance between the 2 long lines as the leg and Pythagorean Theorem to determine the hypotenuse, I made a mark on the far side line that would make a perfect right angle. I then moved the Y car to the opposite side saw that I was off over 1/16th inch.

Loosen all the bolts on the gussets under the Y extrusion. Loosen all the bolts thru the end brackets that go into the end of the Y extrusion, then resnug to just past finger tight. The V bit should now be able to be moved to the square mark with only minimal resistance. If needed, loosen the bolts on the end of the extrusion further. I made sure I could move the bit past the mark, and then back to it. With the bit over the square mark I used 2 more bar clamps and clamped the wheels hard to the rail & extrusion.

At this point I put the digital level on the Y extrusion to make sure that it is plumb. Loosen the end bolts, adjust extrusion to plumb and resnug. Retighten the bolts in 3 stages. Lightly snug the bolts from the gusset to the end plates. Then snug the bolts from the gusset to the extrusion. Then resnug the end bolts in the extrusion. Tighten all in that order.

Now it is time to pick some new spots and repeat scribing lines on the ends and checking cross corner distance. If they are exactly the same, recheck all bolts for tight. And go back to instructions. If not repeat as needed.
Gary