[SCzEngrgGroup]

The G540 has no such limit. Each driver operates totally independantly, and is completely unaware of what the others are doing. If you're seeing limited current, you need to have a good look at your power supply, not the G540.

Is your supply the correct voltage for the motors you're using? Is the supply current capability adequate for your motors when all are running simultaneously? Have you properly configured the current limit for each motor? Have you properly tuned the resonance damping adjustment for each drive? Is your power wiring properly sized?

Regards,
Ray L.

[TiagoSantos]

the power supply is the typical 48V, 7.3A. The steppers are pretty high inductance and could most definitely use a lot more voltage, but I don't think the extra 2 volts that the g540 maxes out at would make a significant difference. The steppers are 3A and all have pots setting the current limit at the right current. The 7.3A of the PSU might be a limitation, but it is within spec according to the calculations on the g540 manual.

It could be a resonance damping problem, I tuned them by ear as best I could but it's definitely a possibility that they're way off.

Either way, I'm happy that I found what the limitation was and it should keep me out of trouble for the small number of parts left to do with the steppers. The new servos and the new gigantic power supply should suit the machine nicely. Like I mentioned a few times before, nothing wrong with steppers - but the ones I have were definitely not made for this purpose (they'd be awesome on the 3D printer I originally had bought them for!)

[SCzEngrgGroup]

With high inductance motors, you are likely never reaching max current when the motor is moving at any speed. Without max current, you won't have max torque. If you happen to be operating near the resonance point, so much the worse. So you are most likely just seeing the real-world limits of those motors with that power supply/driver combination. Not anything to do with the G540 performance, just poor matching of the drives and motors to the job needing to be done - a common problem with first-time stepper system designs.

Regards,
Ray L.

[TiagoSantos]

Yup, didn't mean anything about the g540 itself. And by the way, I've seen the current limiting idea floated around the zone before, for what it's worth. It certainly makes sense to me that each driver is independent, but since the power goes through the internal BoB, it's not such a nonsensical idea that the board could have a total current limit. Glad to hear it doesn't!

I don't believe it is the right choice for a RF45 sized machine, but it's a great device! It made the system almost plug and play and was a perfect introduction to CNC electronics. I'll most likely keep it and build something to make use of it - maybe a big arse 3D printer like I had imagined a year ago!

[TiagoSantos]

Got the pulleys two days ago, and suddenly I have no time to do anything! arghhh..

Been working late at night whenever I can and got the X axis motor mount done. Last night I took the measurements and started sketching up the Y axis mount. One of the problems with the way I'm doing things is I don't want to make new bearing mounts. I bored out the stock leadscrew mounts on both sides for the angular contact bearings and it worked just fine. The problem is, as you all know, every hole on these machines is drilled randomly. So finding ways to measure everything accurately and taking into account the hand drilled nature of the holes is quite a challenge I've found more ways to use a parallel than I ever thought possible..

Also worthy of note that almost every single machined part going into the conversion has some sort of machining error haha. But so far everything is functional and mostly hidden from view! Phew.. Wouldn't want people to know what a hack job I've done on this thing..!

[TiagoSantos]

Last year I bought a used 4x6" bandsaw from a local scrap guy.. It was cheap, but it looked like it had been well used and is probably from the late 80's or early 90's. The motor had been making funny noises since I got it and lately it had really been threatening to quit, until it finally crapped out two nights ago. It's probably just the bearings, which I happen to have a lot of, but, as luck would have it, I also had a 1/2hp Leeson motor that I didn't know what to do with. It was another of the handful of motors I got from the lab at work. Grabbed it from the garage and thankfully the specs all matched - same frame, same speed and 110v single phase! Sweet.. I love it when things happen like that! I guess I'm getting to the point where I have so much accumulated crap that the odds are somewhat in my favour of having what I need in the shop

[Dave [Swe]]

I love it when things happen like that! I guess I'm getting to the point where I have so much accumulated crap that the odds are somewhat in my favour of having what I need in the shop

LOL !
That´s not fair !!!
You actually got some good use of old crap.....amazing.....

I´d like to think since I have'nt been able to use any of my "good to have later" stuff, I just need more stuff....

[TiagoSantos]

No pictures (again) but I finished machining the X and Y motor mounts over the weekend. Incredibly, things fit around the stock bearing mounts and lined up with the holes while staying parallel. To give you an idea, the Y coordinates of the Y mount holes were something like 1.263, 1.287, 1.364. Also the left side hole was closer to the center of the ballscrew than the right side hole, by like 50 thousandths.. It's kind of a miracle (or a testament to my ninja measuring skills!) that I got everything to line up with a pair of calipers and a set of parallels :P

I did make a mistake (again!) on the Y axis mount and didn't bore a hole deep enough. Since the machine was already apart when I found out, this involved a particularly sketchy setup on the lathe. Basically, an 8" 4-jaw chuck with one jaw removed, the part lined up so it *just* cleared (actually had to dremel off one of the corners to clear the bed) and running the lathe in the slowest back gear. I actually put on my full on safety goggles and snowboarding helmet, that's how unsure I was of that setup. It worked, though!

The Z axis is mostly ready to go in the machine.. Since it'll be a pain in the ass to do anything to it once it's inside the enclosure, I'm taking my time trying to think of everything I'd like to do to it. I installed both air springs last night, adjusted the gibs one last time, and made a temporary Z axis limit switch housing. I think I'll redo the housing later on to give me a bit more travel for some extra bit of comfort, but this will work for now and since the holes are already in the column, it'll be trivial to change later. I had a nice piece of white delrin that worked great for the switch housing. Since the switches have an LED built in, it makes the delrin glow when it's activated Nifty.

[TiagoSantos]

Spent a few more hours in the basement last night, lots of heavy lifting this time.

Had to clear the way and organize things for the column swap.. Trying to do it without taking the machine out of the enclosure - hoisting the old column out, hoisting the new column in, fully assembled. Had to remove the old motor from the old column for ceiling clearance and BOY was that a joy to do inside the enclosure. I'm a tall skinny dude, lifting 40lbs with my arms stretched out and above my head isn't the kind of thing I'm built for haha. But with lots of swearing and a little sweating, it came off.

It was a little after midnight once the hoist was in place ready to lift the column, so I thought it was a good time to call it a night. Last thing I want to do is do something stupid, half asleep at 1am when no one will find me crushed under the hoist until the next morning!

[TiagoSantos]

Little bit more work last night, got the old column off easily.. But getting the new column in is proving a bit challenging as a one man job! The balance on the rigging job is precarious to say the least, and after several attempts, I realized I'll need some help. Need at least a person to crank the hoist while I help balance the column and then move the hoist around. Grrr...

[TiagoSantos]

I'm really trying to avoid taking the enclosure apart, but it would let me assemble the whole thing on the ground and then lifting the whole machine into place (much easier to balance than just the column/head combo).

Anyone got any ideas or tricks on how to balance this thing? Basically, the head is attached to the column, the motor is in place, etc. The only thing I seem to be able to wrap a chain around is the head itself, but since the center of gravity is somewhere near the face of the column, it starts tilting quite a bit. Not usually a big deal, but it was tilting enough that the chains started shifting and I got worried they slip out of the hoist's hook.

Maybe the trick is to work on the chain attachment and then let it tilt however it likes..

[hoss2006]

move the table to the rear and lower the head, that should be a close as you can get to the cg but it's still likely to tilt a little.
Hoss

[TiagoSantos]

that's the problem, though - there's no table or base.. I find that usually, when I lift the whole machine, it tilts a tiny bit forward, but not a big deal at all. But I'm trying to lift the column, head and motor out of the base. The head/motor weigh about 200lbs or a bit under, the column is probably about the same. So I think the balance point is right on the Z slide area, but I can only attach the chains around the head, so the lift point is sort of in the middle of the head - so the whole thing tilts BACK instead of forward.

Actually that just gave me an idea.. I'll see if I can feed the chain around the Z slide (through the column) and move the lift point back as much as possible..

[ninefinger]

Leave the head and motor for now, just put in the column and z slide. Then put the head and motor assembly in - you could even rest the head assembly on the table (on a crib) and use the x and y axis to move it into place (just be sure to keep the head supported while doing this so it doesn't fall over and out onto you! :nono:

Mike

[1HobbyMachinist]

I bought one of the permanent magnet lifting tools good for about 600lbs for about 250. With that and a harbor freight shop crane I can easily move my 45 anywhere with very little effort.

In pieces of course...

[TiagoSantos]

Well.. Shoot. Had a buddy over last night and after a couple tweaks to the chains, we managed to lift into place without trouble. But alas, my much lauded measuring fu isn't all it's cracked up to be. The bolt holes on the column and base don't line up, they're off by about .100" front to back and .050" side to side. Attempts to enlarge the holes with a dremel grinding wheel proved silly. I then turned the threads off the shank of two of the bolts (leaving enough threads to engage the base) and that let me bolt on two corners, but it won't work for all four.

Gotta figure out a way of enlarging the holes.. Only thing I can think of is taking it all apart again and taking the column to a shop with a horizontal mill. Or drilling a hole next to the current one and then step drilling up until it makes a huge mess of a slot.

[arizonavideo]

Why not use smaller bolts?

I don't see why 4 1/4" bolts would not work fine.

[TiagoSantos]

The stock ones are M14, I'm not sure I'd trust 4x 1/4" bolts to keep the column from moving around - the advised torque on an M14 bolt is around 100ft/lbs, versus 8 or so for the 1/4". It would also mean filling up the holes in the column and re-threading - not impossible, though!

[arizonavideo]

I thought you were talking about the bolts to fasten the mill to the stand not the column.

Hold down force for a 1/4" bolt is around 1000 pounds If you go to 3/8 it about 3000.

I don't understand how the column bolts could not fit. It came with them installed.

[TiagoSantos]

I don't blame you for not understanding, this has to be the most convoluted and confusing conversion ever!

This is the RF-45 column, on the RF-40 base.. So yes, the bolts holes line up with their respective bases, but not with the travesty of a machine that I'm building

The reason for this is I got the RF-45 for $500, missing a table. But I still want to use the dovetail column, and the RF-40's table/saddle doesn't fit the RF-45 base either (different dovetail angles).

Found a bunch of really nice silver & deming bits today, so I'm just gonna drill the holes a bit bigger..