Tiddy CNC.

[TonyD]

Thanks Jazz, I've halted all planned movement now until I sort the adjustment. I was worried I had damaged the screws so I stripped them down and thankfully they roll nice and even.

[TonyD]

<Do not pass go, do not collect 200 pounds>
So. Adjustment plates produced by laser and returned nicely, tapped OK in the laser hole but had to try 3 M4 Taps to find one that worked well. Adjustment plates assembled and fitted on one side, was getting ready to fit the other side when the movement of the gantry got my attention.

Several months ago I applied some light machine oil (3-in-1 I think) to the hiwin rails and ran the gantry on the X Axis back and forth a few times, was satisfied with that and thought nothing of it. Fast forward a couple of weeks and the oil had dried into an almost varnish like residue that was possible to remove with a scriber but left a glue like substance behind. Bottom line the oil had gummed up the rails and the linear bearings were not so much cutting through it as riding roughly over it. The gantry had become still to move and it didn’t feel smooth at all. So took one rail off today, checked the bearing block and it seemed OK. I spent about some time with light sanding paper on the frame where the rail has been bolted as there was a rim of hardened oil residue all around the rail, that done I took a wire brush to the back of the hiwin rail to remove the frame residue that was stuck there and then thoroughly cleaned the rest of the rail with degreasant and elbow grease. The rail came out really clean, the bearing I had removed ran rock solid and smooth over the rail and once bolted back in the gantry is noticeably smoother. I'll do the other side next day or so. I have already got the right type of grease for future lubrication but thought I'd post this as a warning to others of what not to do. Once that's done I'll work on the alignment of the second X Axis screw and bearings and then go back into Mach, check the connections, limits & homing and finish setting the soft limits which is as far as I got before I took several steps backwards.

[Jonathan]

[...] thoroughly cleaned the rest of the rail with degreasant and elbow grease. The rail came out really clean, the bearing I had removed ran rock solid and smooth over the rail and once bolted back in the gantry is noticeably smoother. I'll do the other side next day or so. I have already got the right type of grease for future lubrication

Just to be sure, did you put any grease or oil in the bearing before testing again and finding it to be 'smooth'? If not, then (at risk of stating the obvious) do put some in before going further as running without any lubricant (which is presumably the case if you've cleaned it thoroughly) even for a short time will reduce the life of the bearing. Hard to say by how much, but there's no need to risk it.

Edit: You might want to check the ballnuts for debris whilst you're at it.

[TonyD]

Thanks Jonathan, I havent moved it much at all but now the other side is done too I am much happier with how smoothly it moves. Thankfully I didnt oil the ball screws at the time so the residue isnt on them. I'll grease it all up again soon. Tony.

[TonyD]

Move to Go. Do not pass Go.
OK, so I'm about back to where I was before, when I was racking the machine and trying to bend the ball screw out of true. I've got the machine moving smoothly and I'm setting up homing prior to figuring out the limits and setting the soft limits and I've hit a snag, done some reading to avoid wasting the time of people and I'm not confident yet.

Problem is dual X axis homing, Z homes OK, Y homes OK, when I select X home, (thankfully at 2% speed) the maching starts to rack as one X axis motor is turning, the other isnt. The weird thing is that under jog movement they both move together, so now I'm into the Mach ports/pins and homing screens. Ports and pins I have X and B axis configured correctly I believe, they move on jog so I'm OK with that, Z,Y,X Home I have values and the diagnostics page in Mach confirms they work and Y and Z home OK anyway. I *do not* have a home input signal for the B Axis as I assumed that as its slaved to my X axis that would be OK, clearly its not so I suspect I need to add input signal values for the B Axis and copy the X Axis home port and pin setting to fool mach into seeing the same switch? Is that the answer? as always advice appreciated, thanks.

[Clive S]

Tony. I am off to bed now and had a small drink. But in the morning if nobody has responded I will check my Mach3 and let you know the settings for it. You need two homing switches as the way it works is that both motors should drive the axis back to the home position then one switch trips and backs off then the other does the same. Its also important to have exactly the same setup in motor tuning for both the motors. When it works it will work fine. ..Clive

[TonyD]

Thanks Clive, for now I only have one homing switch, can I/do I have to use the inputs for one home switch for both home inputs?

[JAZZCNC]

Tony you MUST have 2 switches on separate inputs for homing to work with slaved motors. The first switch can be wired in series with Y & Z but the second must be on it's own input.

Also in General Config you must UNCHECK "home slave with master axis"

[TonyD]

Thanks. I guess I need to figure out a way to mount the switches on both sides with enough adjustment they both connect at the same time.

[Clive S]

Thanks. I guess I need to figure out a way to mount the switches on both sides with enough adjustment they both connect at the same time.

Tony Jazzcnc hit the nail on the head I could not think straight last night. If you pm me your number I will run through the settings with you.
If you are worried about racking when testing take the belts or motors off both sides then you can see what is happening. ..Clive