Aluminium Profile Type Router - Initial questions

Thanks for the encouragement all, looking forward to having a moving machine soon..

Andrewg - I plan to keep the log going until the end, I'm sure there are much better build logs out there than mine, but I'm trying to show some of the smaller details/photos which made no sense to me when I started this process, and if it helps a few people along the way, then great as this forum has helped me loads so far.

As you say without seeing the fruits of someones design/pitfalls you can't be sure if it's a good one. As Andy mentioned though there are certainly more, like his which do continue.

On the dual plate, to be honest I did think of it earlier on, but at the time I was going in circles with the design and if I could physically make it so opted for a simple single plate. Jazz - I see what you are saying, essentially the ballscrew is fixed square with the frame, but the gantry may need slight squaring.

I'm hoping I can get slight adjustment if I have to go there, from shimming either ballnut or the gantry side/ballnut fixing. I have built in a very slight tolerance by using a 1mm thick piece of rubber between gantry side and ballnut fixing, which can compress 0.5mm ish to accomodate a slight twist.
So watch this space whether it works or not! If building new, I'd go for the 2 plate though.
Jazz - looking forward to your machine unveiling, maybe I can swap it with mine.. :beguiled:

So, wasteboard, just best to start with MDF and hold down clamps screwed into it to get started?

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Originally Posted by CNCRY

I'm hoping I can get slight adjustment if I have to go there, from shimming either ballnut or the gantry side/ballnut fixing. I have built in a very slight tolerance by using a 1mm thick piece of rubber between gantry side and ballnut fixing, which can compress 0.5mm ish to accomodate a slight twist.

So, wasteboard, just best to start with MDF and hold down clamps screwed into it to get started?

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I like the idea of deliberately designing with a built-in gap for a shim in certain places. There's no such thing as a -0.2mm shim however much you might want one when finally assembling the machine.

Having recently got away from just screwing clamps into an MDF spoilboard to using something a little more sophisticated I can honestly say it's worth the effort to do better from day one, even if it is just to get you started. One of the problems is the little dimples that form around the screw holes which must be removed before you can put another workpiece over them and it's a pain having to drill holes for where you want to fit the clamps every time. Re-using the same holes many times over isn't too reliable either. I let my machine drill a grid of holes in the plywood base board and then put M8 T-nuts underneath. A sacrificial layer of MDF goes over that and then drill again. I also put a row of hand-drilled holes at either end of the base board to hold any pieces which cover the whole cutting area of the machine.
You can always upgrade to a slotted aluminium base in the future if you need to.

Quote:

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Originally Posted by CNCRY

On the dual plate, to be honest I did think of it earlier on, but at the time I was going in circles with the design and if I could physically make it so opted for a simple single plate. Jazz - I see what you are saying, essentially the ballscrew is fixed square with the frame, but the gantry may need slight squaring.

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Yes and no.
What you are doing when squaring the gantry is setting it perpendicular to the MASTER RAIL and NOT the frame. Infact forget the frame because unless you have built it perfectly square and aligned the Master rail perfectly parallel to it then you CANNOT measure from it. The MASTER rail is the ONLY reference point you work from.

So the ball-screw must also be perfectly parallel to the MASTER rail. Likewise, the Ball-NUT is set parallel to the gantry side.

So if you have set your ball-screws perfectly parallel to the MASTER rail, which you should have done. Then any angular adjustment on the gantry in respect to the MASTER rail means there must be an angular twist between the Ball-NUT and Ball-SCREW and this will cause excess wear and binding.

The goal is to get the gantry perpendicular in respect to the MASTER RAIL and the ball-SCREW perfectly parallel to the MASTER rail. This will then put the Ball-NUT perfectly parallel to the ball-SCREW.

When all this is done then this will show you how much Shimming and spacing is needed at various places around the machine in relation to the Frame. If you have built a perfectly square frame then it should be easy.!!

You may find the best place to shim to get square without impacting the screws/nut relationship too much is between the Gantry plates and profile at each side.
This is where building in lots of adjustment points comes into play and helps with setup and fine tuning, don't be surprised if this takes you many weeks to get right with lots of strip downs.

Edit: I've just done a quick sketch in SW to show how much just 1deg of misalignment translates across the length of a gantry or machine.
The measurement show the numbers except one and that is the twist of the ballnut in relation to the ball screw but the number is 0.70mm of twist which would wear a ballnut out in no time and cause lots of binding.

Quote:

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Originally Posted by CNCRY

I'm hoping I can get slight adjustment if I have to go there, from shimming either ballnut or the gantry side/ballnut fixing. I have built in a very slight tolerance by using a 1mm thick piece of rubber between gantry side and ballnut fixing, which can compress 0.5mm ish to accomodate a slight twist.

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The Rubber is BAD idea, your basicly building in Back-Lash. The rubber will allow it to float even under compression. Don't underestimate the forces and the amount of inertia that will be applied to ballnut which transfers to the ballscrew which pushes on the Endbearings which will be sat basicly on rubber engine mounts.!!

Quote:

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Originally Posted by CNCRY

Jazz - looking forward to your machine unveiling, maybe I can swap it with mine.. :beguiled:

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Oh don't be getting too excited I've not re-invented the wheel and the design is nothing special or new. It will just be built properly and strong compared to all the Cheap offerings on Ebay etc.

Attachment 28070

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Originally Posted by AndyUK

That's just because people don't bother to post in the gallery thread..

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I was being a little provocative to see if anyone else might think to post their machines. Shoudl be a sticky, as it was a good idea. That some very capable people turn up with some great designs and get huge assistance here but fade away before getting a working machine does seem a pity.

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Originally Posted by JAZZCNC

I'm going to answer this Andrew because many won't realize the difference and why it's important.

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Thanks, I am beginning to understand how alignment and precision in the build process is hugely affected by these design details. However with a single under-table ballscrew design, this would mean ideally the gantry side plates are not a single part...or are you suggesting the adjustment come at the top of the gantry plate with its connection to the X Gantry beam?

But sorry CNCRY, lets keep focused on your final hurdles to cutting! You are almost there.

Quote:

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Originally Posted by JAZZCNC

What you are doing when squaring the gantry is setting it perpendicular to the MASTER RAIL and NOT the frame. Infact forget the frame because unless you have built it perfectly square and aligned the Master rail perfectly parallel to it then you CANNOT measure from it. The MASTER rail is the ONLY reference point you work from.

So the ball-screw must also be perfectly parallel to the MASTER rail. Likewise, the Ball-NUT is set parallel to the gantry side.

So if you have set your ball-screws perfectly parallel to the MASTER rail, which you should have done. Then any angular adjustment on the gantry in respect to the MASTER rail means there must be an angular twist between the Ball-NUT and Ball-SCREW and this will cause excess wear and binding.

The goal is to get the gantry perpendicular in respect to the MASTER RAIL and the ball-SCREW perfectly parallel to the MASTER rail. This will then put the Ball-NUT perfectly parallel to the ball-SCREW.

When all this is done then this will show you how much Shimming and spacing is needed at various places around the machine in relation to the Frame. If you have built a perfectly square frame then it should be easy.!!

You may find the best place to shim to get square without impacting the screws/nut relationship too much is between the Gantry plates and profile at each side.
This is where building in lots of adjustment points comes into play and helps with setup and fine tuning, don't be surprised if this takes you many weeks to get right with lots of strip downs.

Edit: I've just done a quick sketch in SW to show how much just 1deg of misalignment translates across the length of a gantry or machine.
The measurement show the numbers except one and that is the twist of the ballnut in relation to the ball screw but the number is 0.70mm of twist which would wear a ballnut out in no time and cause lots of binding.

The Rubber is BAD idea, your basicly building in Back-Lash. The rubber will allow it to float even under compression. Don't underestimate the forces and the amount of inertia that will be applied to ballnut which transfers to the ballscrew which pushes on the Endbearings which will be sat basicly on rubber engine mounts.!!

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OK so full honestly, in terms of the rail and ball-nut alignment, what I've done is to set the master rail using the thickness of the extrusion as a gauge and then use a fixed size block offset from the edge to ensure the rail runs parallel to the edge of the extrusion.
Then the "slave" rail is firstly set it the same way with not fully tight bolts, then run the gantry along it to ensure it runs smoothly along the rail and moves the rail very slightly to a final adjustment. (but in theory its the same offset from extrusion as master rail)
The axis runs smoothly with no ball-nuts attached at least!
Then the ballscrews were attached to extrusion using tooling plate spacer so in theory are fully parallel to the extrusion.
So yes clearly its not fine precision, and a fair amount is riding on the aluminium profile being to good tolerances which I guess is much harder on box steel build, but to see where I'm coming from I didn't know what a DTI even was was a couple of months ago!
So with that said, I'm hoping I can tweak things without any major changes to the machine.

The rubber part is only on the dual Y (formally known as X :) axis) ballnut. As per below in red. The bolts are still coupled into the ballnut mount, but I can easily replace that with 1mm aluminium shim.
Attachment 28088

I've attached the motor mounts now so am going to run it tomorrow and see how it moves. Is it obvious it its binding , does it judder etc?
Then if shimming is needed use this on the gantry and Ball screw mounts.

How should you align the ballscrews vertically - I tried using a DTI on the rail touching the ballscrew but hard to where on the thread it sat. Or use a small block sat on the screw..?
Do people use the 3, 4, 5 triangle method to check square then adjust and set limits? As there are various ideas out there..

Will report back after running it - wish my luck :suspicion:

Quote:

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Originally Posted by CNCRY

The rubber part is only on the dual Y (formally known as X :) axis) ballnut. As per below in red. The bolts are still coupled into the ballnut mount, but I can easily replace that with 1mm aluminium shim.

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Dump the rubber it's a bad idea for the reasons stated before. Shimming with aluminium is the better way to do it.
What you have done so far with rails etc and screws is fine so with shims you'll get it pretty much spot on with a bit of patience. My point in all the other post's was to high light the difference and why the extra plate makes things easier and with less chance of messing things up in other areas when making adjustments to gantry.

Quote:

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Originally Posted by CNCRY

I've attached the motor mounts now so am going to run it tomorrow and see how it moves. Is it obvious it its binding , does it judder etc?
Then if shimming is needed use this on the gantry and Ball screw mounts.

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Be Very careful when approaching the ends of travel because it's here where most get it wrong and it's very easy to bend the screws. At slow speeds the steppers will quite happily bend those screws like it's liquorish sticks and not complain about it.
At higher feeds any error here will stall the motors but still damage will be done.

When jogging near the ends watch the ball screw carefully and if you see it lift or bend then you have some misalignment. I CANNOT stress this enough move slowly and watch carefully because it only takes a second to bend the screw.!!

If you see any movement then loosen the end bearings and jog slowly towards the bearing, this will give you some idea of what's wrong. Most likely either a Gap will appear between bearing and frame or it will lift up/down. However it could be pushing the bearing into the frame which isn't so easy to see so pay careful attention to what the screw does.

Quote:

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Originally Posted by CNCRY

How should you align the ballscrews vertically - I tried using a DTI on the rail touching the ballscrew but hard to where on the thread it sat. Or use a small block sat on the screw..?
Do people use the 3, 4, 5 triangle method to check square then adjust and set limits? As there are various ideas out there..

Will report back after running it - wish my luck :suspicion:

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It's difficult on a long machine to use the DTI because the screw sags so you need a combination of straight edge and DTI. However it's often easier to go by feel and just loosen the end bearings, then shim or adjust as needed.
Between adjusting the Ball-nut mount and end bearings you will get it spot on eventually but don't be surprised if takes several setups, but the effort will be worth it because any binding robs power and cause excess wear so the extra time spent here pays off BIG time.

Regards testing for squareness then if you haven't got precision squares etc just initially use a good set square off the master rail to get you close. Then just cut a Large square, nearly the size of your bed and measure the diagonals with a good steel rule, NOT a tape measure. Tweak and adjust as needed then cut another square by trimming the last one.

Very mixed day of results - finished most of the Z axis strengthen plates and connected the 2 Y motors up.
I ran each motor individually first with the ballnut uncoupled to check how it runs. The good part
The gantry motion on rails is very smooth and all good, and one ballscrew is running true (until squaring anyway!)
Using a digital square the gantry seems good enough to progress to cutting a square to determine further.
The bad bit - the other ballscrew is definitely bent, not 100% if it arrived that way but much more likely it's a result of drill testing or something else I did! Some swearing involved and am waiting to find out if Fred can amend my spindle order...
Advice for anyone in the research stage - plan some budget for screw ups!
I connected both screws up for a short time just to test the Axis slaving - and it was cool to see my creation moving via the laptop finally!

Now waiting on replacement parts I'm going to fit and wire in the limit switches. This should be simple but the diagram which came with the switch confused me..
Can someone tell me is this right? I thought I understood it until I see the black cable on the switch diagram shows 6-36V while "out" on the AXXB manual shows it at 0v?

AXXB manual image, switch diagram and my understanding of it.
Attachment 28105
Attachment 28106
Attachment 28107

The black wire is the output of the sensor. It is pulled up to the supply voltage by an internal 10k Ohm resistor until the output transistor conducts and pulls it to near zero volts. 'Normally Open' (NO) means the transistor is not conducting (output pulled high by the resistor) until the sensor is triggered. 'Normally Closed' (NC) means the opposite. Only NO types can be connected in parallel as shown in your diagram, any single output pulled low will pull the others with it and the input to the controller. NC types (which you have according to the diagram) must be connected in series since, if in parallel, all the outputs will be normally low and the ONE that tries to go high will be held low by the others. Unfortunately your AXXB manual image does not explain that but the text should.

EDIT: Your controller software should include a configuration for selecting whether your sensors are NC or NO. If you get continuous limit alarms then that my need to be changed.

Ok so they are NC type to cover the issue of broken wires etc.
So the black wire will normally be at supply voltage until limits are hit.
I'm planning on wiring each to its own limit input on axbbe as there are 6 available, leaving a couple for probes and future use.
So imagining just one switch in my diagram above , l1+ will always be 24v and l1- would be at 24v normally unless switch triggered.
Is that right ?
Thanks !

Other way round! NC will normally be at ground voltage (Normally Closed to ground) until triggered. "Normal' means you have NOT driven the machine to it's limit and it is continuing to cut material as intended. This gives you protection against broken wires as an open wire shows up as a high voltage if your controller has it's own pull-up resistors and the machine stops. Failure of a NO connection only shows up when the limit switch fails to make the ground connection required and your gantry crashes through both the limit switch and the end wall of your shed.

My personal preference is for one switch per input as you are planning. NC is best as explained above but NO is more commonly available, presumably because of the ease of parallel connection.

Thanks kitwin , think that makes sense now , will connect one up to UCCnc and test.
Looks like too late for replacement ballscrew from Fred , can any 1610 ballscrew work with the SFU nuts ? Or is the fit not right unless factory paired ?
E.g if I get a gten machined one will it work with SFU ballnut from Fred...

Replacement ball screw ordered now, so will report back if SFU nut fits well.
I tested the limit switches and all working as they should - they even light up:) Thanks Kitwin !
The final piece of the wiring puzzle (until I add things!) is the spindle, while I'm awaiting delivery I want to make sure I know what I'm doing and this is the bit I've been avoiding:)

High level, do I connect up power and the spindle, then go in and set the PD* values , power down and wire up to AXBB-E , then go in and test?

Wiring
The wiring I have based on CharlieRams thead is

Attachment 28148

Does this look correct ? In that thread Charlie couldn't get 0-10v to work so stuck with 0-5v. Any issue with just leaving the jumper on AXBB on so its 0-5V and setting PD070 to 1 to match the 0-5V control?

Also I'm thinking why is FOR/REV needed, I can't think of a use now for reverse so can I just link DCM and FOR ? Or will I lose the ability for UCCNC to turn on/off the spindle and e-stop?

I'm planning to use 1mm CY 4 core cable - seems like there are differing opinions here, but I'm trying to minimize cable size and 1mm should sustain a max of 8Amps rating and the spindle will use 5A or less in use as Jazz has measured, so gives so overhead for voltage drop etc.

PD Values
This is where I'm a bit stumped, maybe the manual will explain more (probably not) but some blogs etc people set only a couple of values while the sticky here suggests loads.
Is the sticky still correct as of 2020?
Control:
PD001/002 = 1
Frequency:
PD005 - 400
PD004 - 400
PD003 - 400
PD006 - 2.5
PD007 - 1.20

PD008 - 220
PD009 - 15
PD011 - 120
PD014 - 5
PD015 - 10
PD044 - 2
PD045 - 3
PD072 - 400.00
PD143 - 2
PD142 - 7
PD144 - 3000, factory setting is 1440 ->3000 gives correct RPM of 24000 at 400hz

PD070 (optional to 1 for 0-5V rather then 0-10v)

Thanks !

One of the most important parts of installing your spindle is soldering on the connector properly. I have a sneaking suspicion that many of the 'my VFD blew up the first time I switched it on' complaints have their roots in this having been the first time the relevant person had soldered a plug onto a cable. This is a very expensive way to learn from your mistakes!

Quote:

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Originally Posted by CNCRY

High level, do I connect up power and the spindle, then go in and set the PD* values , power down and wire up to AXBB-E , then go in and test?

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Doesn't matter really you won't hurt anything either way. I just connect everything up then set the settings but I've fitted 100's and confident so just do what you feel most comfortable doing. There's no right or wrong way provided you DONT wire it when powered up.! (like I often do.:cower:)

You can actually power up the VFD without the spindle connected and enter the settings on the bench if you prefer, I often do this before fitting into the control box's on machines that are fiddly to access or I'm waiting for other stuff so do it to save time later.

Quote:

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Originally Posted by CNCRY

Does this look correct ? In that thread Charlie couldn't get 0-10v to work so stuck with 0-5v. Any issue with just leaving the jumper on AXBB on so its 0-5V and setting PD070 to 1 to match the 0-5V control?

Also I'm thinking why is FOR/REV needed, I can't think of a use now for reverse so can I just link DCM and FOR ? Or will I lose the ability for UCCNC to turn on/off the spindle and e-stop?

I'm planning to use 1mm CY 4 core cable - seems like there are differing opinions here, but I'm trying to minimize cable size and 1mm should sustain a max of 8Amps rating and the spindle will use 5A or less in use as Jazz has measured, so gives so overhead for voltage drop etc.

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I find 0-10V gives better scaling and more accurate speed than 5V but both work ok and neither is very accurate but for most machines, a few 100rpm tolerance is perfectly fine.

Only connect FOR because these spindles are not designed to run in Reverse, they will run in reverse ok electrically but the collet system isn't designed to run in reverse and will unscrew it's self if put under heavy loads.


1mm/2 cable is perfectly fine provided you are not running very long lengths. Again I've built dozens of machines that are fitted with 1mm and never had any issues.
Like KIT mentioned it helps with the spindle connector because space is very tight. Take your time here and use heat shrink on the pins so they can't touch. Also and this is THE MOST IMPORTANT make sure you fit a Cable strain on the bracket or Z front plate to hold the cable so it takes the pressure off the connector. This is THE single biggest reason why spindles blow up which ties in closely to KIT's poor wiring job advise, fail to do both correctly and it's just a matter of time untill BOOM.!!

Vfd powered up on bench to check settings, most were factory set, such as 400 frequency and earth pin connected to body .
Quick question on pd007 , factory is set to 0.5 and 1.2 recommended , minimum frequency . Can anyone confirm this is correct as some forums etc use very different values here.
Spindle is a gdz80 2.2
Thanks

Quote:

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Originally Posted by CNCRY

Vfd powered up on bench to check settings, most were factory set, such as 400 frequency and earth pin connected to body .
Quick question on pd007 , factory is set to 0.5 and 1.2 recommended , minimum frequency . Can anyone confirm this is correct as some forums etc use very different values here.
Spindle is a gdz80 2.2
Thanks

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I use 1.2 on my 2.2kW 400Hz generic Chinese water cooled spindle.

Ignore the below sentence, I was remembering information about PD011, which is similar. Might still be the reason?
I believe the variation on this one is between if its water or air cooled. You shouldn't run the air-cooled version below a certain RPM (i'll probably miss quote it here if I try to remember) without it overheating, so that might be the cause of the variation in recommendations you see.

One thing Jazz recommended when he saw my settings which were mostly coppied from the sticky, was to increase the acceleration and deceleration times, PD14=5 PD15=10.

Thanks Andy, I'll stick with that value for now . I had pd014 /015 set to default of 60/90 ! I read somewhere that 015 is ignored unless you have braking configured but don't quote me on that ! I set pd014 to 10 to give a decent spin up time but may reduce in future if all goes well. Next to connect spindle !

No problem.

Been doing a little more reading, looks like PD007 and PD010 work together to define the minimum point on the V/F curve, so in essence it looks like its a way to tune how much torque you get from the spindle at different speeds? Either way, 0.5 or 1.2 should work to get you started.

It might just be paranoia, but when I turned on my spindle I had a second person around who knew how to isolate the power supply. Just incase I'd messed up one of those phases and was about to make the whole thing a bit sparky. I then checked the spindle body with a multimeter while it was running, and sheepishly tapped it with the back of my hand to make sure all was well.

Quote:

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Originally Posted by CNCRY

Thanks Andy, I'll stick with that value for now . I had pd014 /015 set to default of 60/90 ! I read somewhere that 015 is ignored unless you have braking configured but don't quote me on that ! I set pd014 to 10 to give a decent spin up time but may reduce in future if all goes well. Next to connect spindle !

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PD015 is ignored if not using DC braking and if you have it too low then you will get over current errors because the spindle cannot stop in time to satisfy the time parameter and dumps a load of current trying to do this.
The settings I gave Andy work for 99% of spindles, only if you have ATC will they need to be changed. Pd007 can be Zero if you like it won't hurt but just leave it at default.

1 other question! my VFD has an earth terminal (pin9) next to motor UVW and 2 other screws not in the main block with earth symbol. I assume the pin 9 is for SPINDLE earth ? And the other one for incoming mains.
Edit - sorted pin9 to connect both incoming earth and spindle earth ,(pin4)
Plus shielding to separate star point outside vfd.
Thanks

If you do go for a slow speed-up on the spindle and let the G-code start it just before the cutting begins you may need to add a delay to let it come up to speed. I've found this necessary using CamBam and LinuxCNC (though I cannot remember exacltly what my acceleration setting is, I'm sure I took the advice on this forum). I manualy add a line 'G4 P6' just after the spindle start line to add a 6 second delay.

Spindle wired up and powered on, very carefully !
Press Run and it runs ok but for some reason goes straight to 24000 rpm and the front speed control does nothing?
I tried setting Pd002 to both 0 and 1 but made no difference. The "J1" jumper is also shorted pin 2 and 3 e.g VR not VI.
The spindle spec sheet also says pd070 should be at 1 which it is.
Am I missing something ? Otherwise 'll try UCCnc control instead and see if that works !

Still no speed control on the spindle when connected to AXBB-E
Cabled as above with VFD>AXBB-E
FOR > O2
DCM > 24V0
VI > AO1
ACM > 5V0 (power out)

Attachment 28197

When I enter in MDI M3 S2500 - the O2 pit diagnostic lights up and spindle FOR lights up and stops flashing, like this:

Attachment 28198

But Speed sits at 0!
I checked the voltage between AO1 and 5v0 at S2500 and it seems to be 0 so possibly the issue.

Here are my settings

Attachment 28199

I noticed "SPINDLE CW" light comes on in UCCNC diagnostics too.
Am I missing some config here or something obvious as I'm stumped!

Thanks
Ryan

Sorted it ! It's not obvious in the documentation but there is an extra I/0 configuration screen where PWM channel has to be set to 1 not default of 0.
Oddly taking the jumper off the Axxb-e still won't output 0-10v, so ended up leaving VFD PD070 @ 5V control too.

Nice catch. I did have a quick look through the AXBB manual buy didn't spot that (the port/pin config looked suspicious but I've had Chinese motion controllers that ignore port/pins before so not entirely unrealistic). Not got/tried the AXBB myself - just keep your jumper setting in mind - unlikely but possible it'll mode on a reboot (your behaviour might be different next time you power-up... or maybe not), Peculiar that it doesn't behave as expected. You've set the max-spindle speed correctly, of course?

For anyone's reference in future this is the setting:
Attachment 28204

Initially I set the spindle min to 5000, max 24000 which I assumed meant it would just not allow a command below S5000, but figured out that meant 5000rpm = 0v, so when I set 10000rpm I would get 7500ish instead! So set min to 1, max 24000 and all good (to the nearest few hundred anyway).

Playing around in UCCNC reminded me of a couple of other things
- is it worth setting max velocity and acceleration at this point, set to 2000 units, so 20m/m which I expect is faster then it will go.
- Is there any worthwhile tuning of steppers needed - these are the hybrid steppers so slightly less common. I see there are 4 switches which can be used to set pulse/rev but no idea if these are worth changing?
Or maybe I'm just thinking up ideas while waiting on parts:) Feels like I'm on the home stretch now, just need to figure out my workholding and spoil-board which doesn't eat up the Z distance.
I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

Quote:

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Originally Posted by CNCRY

Playing around in UCCNC reminded me of a couple of other things
- is it worth setting max velocity and acceleration at this point, set to 2000 units, so 20m/m which I expect is faster then it will go.

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2000 is the units ie: mm or inch value so if you want 20m/m it needs to be 20,000 not 2000. Read below and it will make more sense, if not just ask.

The velocity and acceleration are very important and you can't just womp them up and leave it at that because you'll just get stalling motors.
This is the bit that you'll see mentioned as motor tuning and it's a balance between velocity and acceleration, If you increase one it will affect the other at some point and you'll have to decrease one of them.

Every machine is different when it comes to tuning the motors because of friction and mass, voltages etc, so it's very much feel way your way thru and lots of little tweaks.
Start low on both at say 4000mm/min on velocity and 500 on acceleration. Then adjust just the velocity until the motors stall, then reduce the amount by 25%, then do the same with acceleration. This will give you a base line and nice stable machine, you can tweak it up from there but again only adjust one at a time and test.

Quote:

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Originally Posted by CNCRY

- Is there any worthwhile tuning of steppers needed - these are the hybrid steppers so slightly less common. I see there are 4 switches which can be used to set pulse/rev but no idea if these are worth changing?

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Well first hybrid steppers are common as muck, probably the most common stepper on the market and it means NOTHING. I see this a lot that people get blinded by jargon and think that the word Hybrid means they are something special when all it means is they can be wired in several ways making them an Hybrid of several types of steppers.

Again these switches are very important as they set the micro steps, infact THE most important bit because if you don't know this setting then you can't possibly set the correct Steps Per unit value in UCCNC and you won't get the correct amount of movement. It also affects the motor tuning because the higher these settings then the motor acts differently, going too high can give negative results as they are very close relationship with motor tuning and the system as a whole.

There will be a chart on the stepper case that gives different micro step options and will tell you the positions those switches need to be set for each micro step amount.
Set them up to give 1600 micro steps. There is no need to go higher as it starts to give negative results.
Now you take this figure and do a calculation for the steps per unit value that you enter into UCCNC. Divide 1600 by the ball-screw pitch and any ratio you may have. So if it's direct drive with 10mm pitch then 1600/10=160 for the steps per.

This will give the correct movement, the Steps Per setting is a none negotiable setting and you can't just use a random number, it must be calculated from the Drive settings. ball-screw pitch and any ratios applied to it.

Quote:

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Originally Posted by CNCRY

-I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

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You can use what ever you like, stick a pencil up it if you like. Also no reason why couldn't use a Lock mitre bit provide it's not like 6" and 3kg in weight. I regularly use a 70mm surfacing bit which is bigger than a lock mitre bit.

I often use my old worn out end mils that I've used on aluminium for cutting wood as they are still more than good enough for hogging out wood and often I've only worn the first 4-5mm out and I cut much deeper in wood. I then use a decent end mill for the finish passes.

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Originally Posted by CNCRY

I also couldn't find an obvious answer on this - can I use normal 1/2" router bits in the spindle or does everyone use endmills? Obviously something like a Lock Mitre bit would be a bad idea, but the simple 2 flute straight bits, chamfer etc..

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One way to look at this is, "Would I use this cutter in a handheld 1/2" router at 26000RPM?" Or even a 1/4" router. If the answer is yes, then go ahead with it in a more powerful spindle with much better control!

To be fair - a good many hand held routers are in a similar power band to the usual spindle, and similar RPM. I wouldn't sweat too much. Common sense applies, of course.

Thanks all - I did see people using them but just wondered if there was something I'd missed before using standard bits. Seems like a really obvious question now:)
The stepper drivers were set by default at 1000 according to switches so have changed the switches to 1600 in the table as recommended.
I was thinking the "units" referred to cm - as UCCNC defaulted to 200 steps per unit, I took this as meaning 200 steps @ 1.8 degrees to make 1 revolution which would equate to 10mm of motion, so a unit being 10mm. I guess I was calculating the wrong way round!
Does jogging use the same velocity settings - as jogging seemed to be about 10m/min which seems about right , even with microstepping on drivers set to 1000 and steps /unit at 200?
With the hybrid steppers I mean that many build logs on here and other forums use "standard" steppers without an encoder, and wasn't sure if mine having encoders that had any bearing on the tuning. Assuming it being a closed loop the controller never knows any different anyway.
Once I get the replacement ballscrew and right size drag chain I'll do some more testing and tuning.

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Originally Posted by CNCRY

The stepper drivers were set by default at 1000 according to switches so have changed the switches to 1600 in the table as recommended.
I was thinking the "units" referred to cm - as UCCNC defaulted to 200 steps per unit, I took this as meaning 200 steps @ 1.8 degrees to make 1 revolution which would equate to 10mm of motion, so a unit being 10mm. I guess I was calculating the wrong way round!
Does jogging use the same velocity settings - as jogging seemed to be about 10m/min which seems about right , even with microstepping on drivers set to 1000 and steps /unit at 200?
With the hybrid steppers I mean that many build logs on here and other forums use "standard" steppers without an encoder, and wasn't sure if mine having encoders that had any bearing on the tuning. Assuming it being a closed loop the controller never knows any different anyway.
Once I get the replacement ballscrew and right size drag chain I'll do some more testing and tuning.

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Regards 1000Ms and 200units in uccnc then even thou it's traveling at 10mtr/min doesn't mean it's moving the correct distance. The test would be to tell it to move 10mm, which in your case with settings above and 10mm pitch it would move 20mm.
The closed -loop won't make a jot of difference because it's been told to move 2000 pulses which dutifully does, it knows nothing about the 10mm and only does as it's told moving a set amount of pulses based on the Steps per unit setting.

With that setting of 1000ms then you should enter 100 in steps per and it will move at 10mtr/min(or more) but only half the distance.

The velocity is the Max velocity of the machine and is used by everything, however you will see it slow down at times when 2 or more axis are traveling together because the controller will control the speed of the faster axis so all axis arrive at same time.
Jogging individually each axis will move at full velocity set in motor tuning if set at 100% jog rate.

So my replacement ballscrew arrived and it's 15mm O.D. it came with a ballnut but the screw is a different weight now . The existing one on dual axis is 16mm .
Seller is saying it's nominal diameter as it's a ballscrew . is it usable or will the weight difference and inertia etc compared to the other axis side make it not worth it...

Not ideal, but my gut feeling is if the pitch is okay, it should be workable.

It will make one motor work marginally harder than the other, but probably not even noticeable?

Thanks Andy , just trying to decide whether to try and straighten bent screw , use a diff weight screw or get an exact replacement from Fred ! Bit of a pain really but with the effort gone in so far I do want it to be right . Not sure I have the setup to straighten it but not much to lose on that !

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Originally Posted by CNCRY

Thanks Andy , just trying to decide whether to try and straighten bent screw , use a diff weight screw or get an exact replacement from Fred ! Bit of a pain really but with the effort gone in so far I do want it to be right . Not sure I have the setup to straighten it but not much to lose on that !

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Have you tried to run the machine with the bent screw yet.? If not you may be surprised how much of a bend can be tolerated. Esp on a machine that isn't massively long.!!

Did the 15mm screw come from Fred.? . . . I've never seen a 15mm screw that's sold as a 16mm.!

I did run it slow and seemed ok but worried it would wear the ballnut fast .
Nope that ballscrew was the only one not from Fred , I ordered it in the EU to save time but wishing I hadn't now!
The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...

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Originally Posted by CNCRY

The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...

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If you're still within 14 days very easy to turn around and tell them you don't want it if you've changed your mind. They've advertised as 16mm, so it isn't what you ordered... Doesn't matter if they think that is important or not.

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Originally Posted by CNCRY

I did run it slow and seemed ok but worried it would wear the ballnut fast .
Nope that ballscrew was the only one not from Fred , I ordered it in the EU to save time but wishing I hadn't now!
The seller is saying "For a ballscrew the external outer diameter is a totally unimportant dimension, because it connects to the ballnut with balls" which kind of makes sense but why call it a 16mm screw then. And Fred's are 16mm within 0.01mm ...

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Yes didn't think it would have been as Fred's screws are also ways within 0.01 of specified like they should be. Send it back would be my suggestion and fit the old one if it's only slightly bent. Then buy a new one from Fred if it gives you any grief.

Will post some progress photos soon, but have now pretty much completed the wiring and physical build.
Cable chain finally arrived from China so the (crazy) amount of wiring is now running back into the control box and 4 separate limits wired in.
I setup the limit and tested jogging into them and all good there. Machine is running at 4m/min currently as Jazz suggested, until I tune it further.
I ended up straightening the ballscrew mostly, using the advanced method of compressing between some hardwood and rotating it. But now it's back in the mount it seems to be running pretty well at 100% jog speed. I think my drill test made it seem a lot worse plus there was some slight misalignment of the motor coupler. I do notice the X axis is very smooth even compared to the dual Y.
My next test after jogging was homing.

So X and Z - moved along, hit the limit stopped and backed off - great.
Dual Y - both axis moved towards limit, one side hit limit switch fractionally before the other, then the one which hit the limit seems to keep going and the other side never hits the limit, so the gantry starts to go off square and hit the ESTOP before it breaks the gantry!

I have both axis set to have homing to the negative limit and 2 separate limit pins set so not sure what is going on here.
When I jog the axis slowly into limit it hit both pins and stopped, both flag up in UCCNC as hit.

Before I post on UCCNC forum am I missing something obvious here in the homing sequence for dual axis?

Attachment 28292

Sorted - the limit switches for each side of the Y axis did not match the drivers, so when one switch triggered it stopped the opposing side motor. Fine while I was testing limits, not so much for homing operations!
Homing all working now. Just waiting on some ER20 collets now and hoping to make first cuts very soon.
So far I just have a ply bed as I figure I'll probably have a few accidents, then thinking to use an MDF bed with threaded inserts fitted from underneath every X cm to allow fixing from above without using screws.
Need some practice before going for a more expensive material for the bed!
Still overwhelmed by the amount of settings in CAM around ramp speeds, lead in speed, plunge speeds, feed's etc and how much is OK to leave at default and how much to change.