Hi.
Just to get back on claytons question . Get the spec on your blower and check what the pressure drop is on it with a 4 inch intake. Then ask the supplier what will the pressure drop be on a 2 and half inch pipe. If the blowers pressure drop is higher than the 2 and half inch pipe then it will work no problem. The upside for that is a higher velocity witch means you will suck up wood dust at a greater speed.

Paul

Very nice job and machine hope you make buckets of money and lots of fun;)

Thanks everyone.

So far I am having buckets of fun .. can't wait for the buckets of money.

Clayton

Been a while folks .... but have always been here reading and learning. My machine has served me well but I have had this pesky issue for quite some time.

At the start of a job, (usually an entire sheet of MDF from which I cut names, signs etc) I bring the gantry up to the hard stops to square the gantry. I always find that the X1 side will touch the stop first and the slave is approx 1/8" to 1/4" away from the stop. To square I give a good yank on the side that is not touching the stop. I proceed with the job and when complete I find the gantry requires squaring again. I have to repeat this squaring scenario several times a day.

I have checked the calibration in Mach3 to ensure the values are the same for x1 and the slave. I have checked the grub screws and all is good. The motors are the standard sg7.2 geared motors.

With power off, I unhooked the springs and dropped the motors out of the rack. Brought the gantry up to the hard stops and sure enough, the gantry toughed on the x1 side first with about 1/8" gap on the slave side. If I recall correctly, I ran the gantry of the rails at some point and believe that I could have caused it to go out of square from my original setup.

Is it possible that squaring a not so square gantry, can cause enough stress on the motors that they lose steps during cutting?

Well, the first question is whether the gantry or the stops are out of square.

Gerald has a procedure for that: http://mechmate.com/forums/showthread.php?t=231

If it's just the stops, you're all set. If it's the gantry, re-shimming the wheels is in order.

I believe the stops are square. When the gantry is brought to the stops and a rectangle is cut, the diagonals are equal (or at least within my tolerance for cabinet parts).

The problem arises when as cutting continues during the day, the slave axis tends to move farther away from the stop than the x1 axis. I realize that shimming the gantry is in order. However, I was of the opinion that these motors had enough holding power to keep the gantry square - within reason.

Is repetitive squaring during the day an expected task?

You should not need to square repetitively. However, since the gantry "naturally" goes out of square without the motors, I think you know what you need to do to solve this.

I use a couple different methods to address this issue. And it is common for many of the lesser priced gantry machines to have an out of tolerance when at rest.

With ShopBot control, I roll one side of the gantry into the prox switch, then back off. Then using a small ttl relay, I remove signal from that motor. Then roll the other side into its prox. I use a system variable to adjust that variable to square the gantry.

When using WinCNC, the "alt axis" feature is built in, in fact was the model for what I did for the SB control.

There are surely some here that can make that happen with Mach and UCCNC

Thanks for the help and suggestions.

I have adjusted the shim washers to improve the "at rest" squareness. I will evaluate the success of the adjustment over the next week.

I have the proximity sensors in position but just never found the time to complete the install. I'll add that to the bucket list.