Loseing torque

[ger21]

You need to check it with everything connected.

[grahamshere]

I ran it with every thing hooked up and it stays at 24.1 volts.so what do you think ?
thanks for your help Ger. Graham

[grahamshere]

Well I bought a new dig multimeter and checked every thing, verf was 3.52 changed it to 3.6. made no difference,rechecked the volts and its 23.9, don't think the .1 difference will make a difference , changed the computer but made no difference. don't know what else to check? Graham

[ger21]

Try lowering the Vref to 3.3 or so. But that's all I have for you. Try asking on the Xylotex Yahoo group.

[grahamshere]

?, wouldn't that lesson my torque?

[braidmd]

Hey Graham, I've been following your thread on the Xylotex support forum. I'm really starting to suspect a mechanical problem related to binding of some sort. Has the change in performance come about after a hardware change? Do you have a build thread that we can reference? The problem could be something as simple as a mild-alignment problem that only manifests under load, a loose bolt or two, or perhaps the gantry is a bit too massive for the multi-start screws? (gasp!). I think a few pics of your machine would be very helpful...

Mike

[ger21]

Have you lowered the acceleration, or just the velocity?

[grahamshere]

HI Ger, I lowered the acc from 50 to 20, seems to be the same,

Mike, The change did happen after the rebuild, But its all three axis, even the z
I,ll lower my velocity some more, I use y as my main raster so that,s the most important axis I guess, I added some pict,s. do you really think there might be to much weight there? I know 425 oz motors have more torque at lower speed,s that's why I got the faster screws. Ill change the velocity from 100 ipm to 80 imp and see what happens. Thanks guys

Graham

[grahamshere]

hmmm I lowered the velocity and used a lower cutting speed but it still missed,it seems to be pulling to one side. I know the machine is squared cause I spent all night last knight squaring it up. so I ran the code and cut air for 10 min. it ran fine plus i grabbed the gantry and there was no way I could hold it back. so Im wondering now if the couplings are the cause, there as tight as they will go, how would I check to see if thats the problem?

Graham

[braidmd]

So it sounds like you are only having issues on the X axis... when you apply force to the gantry alone, not the movement of the Z carriage side-to-side or the spindle up & down. Is this correct?

If so, it leaves me to wonder if your gantry is not square with the frame. I recommend you try loosening the timing belt on the X axis' lead screws, select one screw to work with, and try turning it both directions until you feel resistance. Count the number of turns total, then split the difference to bring that side to "center". This equates to the "best" alignment of the screws with their respective bearing trucks. From there, you'll need to check the squareness of the gantry with the frame. If it is off, then you'll need to readjust the gantry's mounting on the trucks to bring it back to square. Avoid using the screws to adjust squareness, if at all possible.

This is a bit of a shot in the dark. But I'm building my own dual lead screw-type machine. I'm using a stepper on each screw, but have the two X screws synchronized with a timing belt, similar to yours. I have found it easy to unknowingly-change the rotational-alignment/positioning of the screws while fiddling with the belt, which can result in drag/binding in the gantry if it gets too far out. A bit of slippage in the belt on one screw, vice the other, can do the same. I've also found that over-tensioning the belt may induce a slight bend in the screws, with the bearing behind the timing pulley being the pivot point. That can also induce friction in the screws & lead nuts, as the screws have a bit of a bow to them and are mechanically "wider" in the center of the frame. Not sure if any of the applies to your situation. But it might be worth considering. Food for thought...

Mike

[grahamshere]

Hey Mike, no I,m having is issues with all axis but my x is the worst and ya it's the belt drive. The machine is squared up, I carved a square that came out perfectly square. when it,s cutting it seems to be pulling to one side, wondering if that's the coupling that's causing that. Graham

[D.L]

The xylotex handles 30 volts, there is a tiny pot on the power supply.
Crank it up to 29 volts, more volts equals more amps.
Max the vrefs below 2.4volts? 3.6 was the old type / that setting makes smoke.
Keep the heat sinks icy cold with plenty of fans. (3 or 4)
Tune the motors on the bench till 'growling' stops.
You got 2 start threads with direct drive so you will need every drop of torque available.
Failing that I would put a reduction pulley, or realise the motors full potential with a GeckoG540 and a 50 volt toroidal transformer.
Its all price relative, pay for what you get.

NO SMOKING !