OmioCNC report

[bl775]

Hey guys, it's been a couple of months since we set up the OMIO and heavy use of the machine resulted in 2 problems that are dampening our machining time quite heavily.
First, whenever we rapid, wherever it may be to, if the Rapid FRO override isn't under ~20%, we get huge amounts of slippage or skipped steps (hard to tell) and the machine completely loses it's zero. These issues don't happen during G1 runs or anything that isn't G0. I suspect it may have something to do with our velocity and acceleration rates, but they were given to us straight from the OMIO settings itself. If you guys could help with this issue or give us your motor settings, that would be great. We have checked if it is mechanical and have tried to counteract any slippage by increasing the slot space on our collets and tightening them further. If the problem turns out to be mechanical, if you guys could point me towards a set of collets that are more reliable and not cheap that you may have used for this reason that would be great.
Second, we have been looking for ways to clamp our pieces more efficiently. We already have set up a row of vices that reduce our tubing machining by an incredible amount, but we still have somewhat slow methods of clamping other sheets/pieces. What clamps would you recommend that fit the extrusion requirements and are as quick as possible (we're going to be doing aluminum sheet most of the time)? Apart from that, we couldn't even find a set of clamps that mimic the ones that came with the machine itself. Would this type of clamp (below) work for aluminum sheet?

[Mmpie]

Issue one, sounds like what I had which was mostly down to a bad PSU. Does it happen all the time or what? What about when using one/two/three axes simultaneously.

2 - they'll be fine. Don't overthink it. The machine isn't strong enough to generate much force in a cut, what matters most is making sure you have the whole part held still and not free to vibrate around, you don't need much tension at all. I have used 3D printed clamps whilst milling aluminium which have worked just fine.


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[bl775]

It's hard to explain so I'll link a video later today once I have time, but the slippage normally happens at program start or manual MDI input (at times all 3 axes, but sometimes one axis will slip while the other doesnt). Whenever we run gcode, we have to manually decrease the Rapid FRO to 15% to compensate for a weird jerk that happens at every program start. Then, once the cut has started, we can increase the Rapid FRO back to around 30-40% and there's no slip. Keep in mind the G1 code at times moves the axes faster than our G0 would and have problems.

Edit: on the clamping subject, i was looking at this set of clamps but wasn't sure if it would be compatible, any ideas?

[extent]

I don't see why G0 would behave differently at the beginning of a program vs once it's already running. Can you reduce it down to just the gcode that's running up to the problem? maybe your CAM is doing something strange. You can reduce your rapid speed in the motor tuning settings, and if it's just having trouble getting up to that speed you can reduce the acceleration too, but chances are you'll see better cycle times from keeping a higher acceleration and lower max feed than the opposite. If you need to keep your rapid FRO down at 40% to have the machine run correctly something is very wrong.

Making sure the power supply is good sounds like a good idea.

[ronsand]

There is a modbus plugin written for the ones that has changed to UCCNC. I will try this out when I do the change in the near future. I have the UCCNC sw and hardware waiting for me when i get home from work in about a weak

[ronsand]

forgot the link http://www.cnczone.com/forums/uccnc-...gin-uccnc.html

[dharmic]

#1 I actually cranked mine UP from the OMIO settings because that worked. I'm running 5000mm/min, sorry don't know what the acceleration is but it didn't change much from factory.

I'd change it until you can do rapids with no skipping from the MDI as a matter of workpiece and job (as opposed to people) safety. If it ends up too slow then start looking at whether the skipping is happening in particular places on each axis which might point at dodgy lead screws, or anywhere anytime which points at crappy power supply.

Rapids (G0) should have nothing to do with the collet.

If you're going to be doing lots of sheet and the pieces aren't too small, look at a vacuum table.

Failing that, getting decent support might mean you need to look at double sided tape or spray adhesive onto a spoil board which is bolted to the table.

Before I swapped my deck out for a tooling plate, I was using coach/carriage bolts (round head with a square neck before the shaft) upside down in the slots and that worked pretty well plus they're cheap as chips. They'd work ok with the clamps in the photo but, bear in mind, you're then only clamping the periphery of the sheet so cutter torque in the middle may flick the workpiece etc if the remnants to the periphery aren't thick enough.

[jo_ky]

I got a message from OMIO that they're shipping me a new spindle!

Speaking of workholding, I've been thinking about how to set up my table. Just attach an MDF board and mill it down, right? I was thinking I'd put a couple T-tracks in, as well (from Rockler). Instead of MDF, using compression-molded acetal was mentioned, somewhere in the thread. Is it worth it, trying to get this material? If it means that I can do wood and aluminum on a single surface, I'd be interested, but I'm not sure about that. I'm planning to add a mister for working aluminum, brass, etc.

Also, does anyone use sacrificial mats? I see that they're often used with a vacuum system. I'm not going to have that, initially, but should I still get some?

[Mmpie]

Well I'll eat my bloody hat.


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[RCaffin]

Sacrificial base boards - all the time. I use MDF, chipboard, softwood and hardwood for this, depending on what I am machining.
Better note that chipboard and MDF do not play nicely with any sort of lubricant! But I can use hardwood with a mister with no problems.

For vacuum tables I use slabs of PE (ie, thick ones) and machine the top down every so often. You do NOT need a highly porous base for vacuum machining: just one or two small holes. Sure, you can use a porous base if you have a huge vacuum pump and don't care about the noise and cost of power.

Cheers
Roger

[jo_ky]

Sacrificial base boards - all the time. I use MDF, chipboard, softwood and hardwood for this, depending on what I am machining.
Better note that chipboard and MDF do not play nicely with any sort of lubricant! But I can use hardwood with a mister with no problems.

For vacuum tables I use slabs of PE (ie, thick ones) and machine the top down every so often. You do NOT need a highly porous base for vacuum machining: just one or two small holes. Sure, you can use a porous base if you have a huge vacuum pump and don't care about the noise and cost of power.

Thanks for the info. I haven't decided what to do yet. Earlier in the thread it was recommended to face mill a small amount off of an MDF board affixed to the table, in order to have a flat surface that's exactly parallel to the XY plane. This makes sense to me. Could I do that with HDPE?

[Mmpie]

Thanks for the info. I haven't decided what to do yet. Earlier in the thread it was recommended to face mill a small amount off of an MDF board affixed to the table, in order to have a flat surface that's exactly parallel to the XY plane. This makes sense to me. Could I do that with HDPE?

If I were you, I would just use good old MDF to begin with. Other materials are expensive and you're perhaps more likely to eat up your first board quicker than you need to. Use cheap materials and have some fun while you get a good handle on z heights and offsets.

It also depends what sort of stuff you're wanting to mill from aluminium and brass. You might be better off spending the money a big acetal sheet would cost you on a decent vice.


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[RCaffin]

Could I do that with HDPE?
Well, I do quite regularly. hint: you need a sharp cutter. A fly cutter works fine too.

I would just use good old MDF to begin with. Other materials are expensive
All good advice. I use scrap HDPE I got from the skip at a local plastics supplier ... Ask and ye may receive.

Cheers
Roger

[jo_ky]

Thanks. I'll start with the MDF and then try HDPE. One other question I have is, what if the piece is small enough to fit on the table, but larger than the area the spindle can move in? Is there a way to make it work?

[dharmic]

If your spindle can't reach the workpiece, you need to move the workpiece back within the spindle envelope.

Usually this means you'll need to do your job in multiple operations, moving the workpiece in between operations so you cover the whole lot. You'll need some kind of registration to ensure everything meshes together properly.

[RCaffin]

Lots of us move the job to get it within range. Very often two solidly-located precision pins in the base are used for this. Of course, what is a 'precision' pin is a good question. Sometimes the shank of a good drill bit is enough. Sometimes ... its a precision 6 mm shaft of carbide, otherwise known as the shank of a broken cutter. Eh - they are useful.

If you are doing a lot of this, a carefully-made metal base plate holding the pins with an MDF surface plonked over the top is viable.

Cheers
Roger

[jo_ky]

Thanks, that gives me a good idea of how to proceed.

Now, if I could just get my spindle working. The replacement arrived but it shows the same fault, E002, and I'm waiting to hear from OMIO again. Since there didn't seem to be anything wrong with my cable, It appears I need a new VFD. :/

[Mmpie]

Try a new cable first. Get some copper shielded CY cable, run it directly into the U V W terminals in the VFD bypassing the 3 prong connector on the back of the box. Before buying your cable pop the 4 prong socket off the top of the spindle, see if the earth wire is hooked up. If it is, use it and remove the need to ground your machine via the frame.


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[RCaffin]

I'm with mmpie here. Do a direct hookup from the VFD to the motor, bypassing everything. Just 4 separate bits of insulated wire would be enough for a TEST.

Faulty cables and faulty connectors have put more splinters under fingernails than you could imagine.

Cheers
Roger

[jo_ky]

Suddenly the spindle works! I pretty much did everything the same way, as far as I can tell, but who knows. If I have the issue again I'll start with the cable as prime suspect, but for now I can get going!

Oh and (edit) I want to add one thing for all the newbs to follow me. 5 meters of replacement PU tubing is not quite enough. I made it work, cutting the supply hose a little longer than 2.5 and having the shorter drain that needs help from gravity to reach the bucket.