Workbee mech kit with Uno and DQ542MA

I have just received my workbee mechanical kit.

I have a set of wantai DQ542MA drivers and 1.9N-m motors, running from an arduino uno.

I didn't want to use the Xpro, as I'd prefer a more modular approach with separate controller and drivers. However this has cost me the convenience and documentation of the full kit - so I have lots of working out how to put it all together.

This thread is where I will ask lots of stupid questions and report my progress.

referring to this video: https://openbuilds.com/threads/uno-grbl-dq542ma-wiring-methods.8785/ I have understood how to connect the arduino to the drivers and motors, and have made a motor move from universal gcode sender.

my first questions are:

should the negative of the power supply be earthed/grounded? or just left floating?

what stepper microstep settings are appropriate for a screw driven workbee? The DQ542MA has 4 dipswitches that set this, but I'm really not sure what a good starting point would be. How do pulses per revolution relate to expressing microsteps as a fraction?

 

Thanks! Yes it seems this is what people do - but then what defines the relationship of the DC power to the environment? - if it is totally free floating then the voltage of either DC terminal to ground is undefined - is that OK?

For example on a 24v power supply then the voltage between the DC output terminals is 24v but the voltage to ground could be 5v and 29v, or any other DC offset...

I'm not that familiar with switching power supplies, they are a black box to me. On a linear supply you would ground one terminal, usually the negative.

I will start with full steps, it makes sense to only increase it the minmum amount necessary for smooth operation.

 

So, I finally got around to assembling my workbee...

I'm trying to get the steps per mm set right with UGS and GRBL - buit I was getting unexpected results, i'll try again and try to be clear about exactly what is wrong.

with no microstepping , 1.8deg motors and a 2mm per rev leadscrew I would expect 100steps per mm.

it is moving too far though - so is the workbee leadscrew more than 2mm/rev? seems like this should be stated somewhere but i've yet to find it...

 

thanks - I had just worked that out! Strange how few places that is actually mentioned.

I am getting very weird behavior from the machine though. Changing the steps per mm in UGS doesn't make linear changes in the distance it actually travels. Also the motors seem noisier than I would expect.

I think I must have misunderstood something about the stepper driver configuration....

 

On the DQ542MA I assume the 400 pulse/rev = no microstepping (although why is it 400 not 200? is it assuming 0.9deg motor or what?)

so then if I set it to 1600 pulses/rev that should be 4x microstepping and I should be able to up my steps per mm to 100 - is that how it works?

off to try it it again...

 

I got correct movement - not sure why it didn't work earlier - I'll post details later.

 

so it works correctly with 200 steps/mm and the DQ542MA set to 1600 - which looks fine on the numbers.

motor is 200 steps per rev
8mm per rev.
1600 is 8x200 so 1600 must be 8x microstepping

but there is no 200 setting on the DQ542MA - the lowest is 400 which implies that there is no setting without microstepping...

anyway it works so onwards.

 

I wondered that too - it's a sensible guess since that's the only configuration not listed. I haven't seen any actual mention of it anywhere though.

It may be yet another case of important information missing from the manual/instructions because the maker thought it was obvious.

I guess I should try it. though since 8x is often recommended i'm happy with the setting I now have.

 

I got the workbee to draw an outline with a pen with the hoped-for results.

now I'm trying to work out speeds to try actually cutting something.

no doubt I'll find that info eventually but an hours searching indicates it's complex and there's a lot of options that don't apply to what I want to do.

so if anyone would like to chime in with suggestions for speeds and depth etc that would be great.

I'm planning on carving wood in 3D with 3mm and 6mm 2 flute upcut ball nose cutters

also cutting ply 2D (18mm mostly) with 3mm 2 flute upcut endmill

and aluminium 2D up to 2mm thick with 3mm 2 flute upcut endmill

if anyone has favourite settings that work for these on workbee please share!

 

There's also a tiny UGS niggle, on Linux Mint 19 it doesn't communicate with the arduino unless run as root. That's obviously a permissions issue and I haven't looked into it yet, but if anyone happens to know the fix please share.

 

So I have attempted my first cuts. It's rather frustrating.

settings were not much better than a guess - something like 10000rpm, 2 flute 3mm upcut endmill, 30mm/s feed, 3mm depth of cut, 150mm/s/s acceleration.

I tried on MDF and pine.

I have a daunting list of issues and questions to research:

* The upcut bits tear out really badly. My first attempt on mdf at 10000rpm the bit was more ripping the mdf than cutting it, with long swarfs of mangled mdf ejected along the edges but still hanging on to the cut.

Another attempt on pine at about 15000rpm was better, but still not OK. The cut was almost acceptably clean except for the tearout at the top. The upcut bit, despite all the tearing, wasn't actually clearing the slot very well, only ejecting maybe 60% of the material and the deeper slot (14mm in 3mm increments) ended up fairly clogged.

* where's the best place to buy a variety of bits in the UK? I want to try straight flute, downcut, and compression bits. and I haven't even started 3D carving yet - though I hope/expect the ballnose upcut bits will be OK for that. So far I haven't found a better source of bits than ebay... UK sellers I have found so far seem to have limited range, limited info, and high prices.

* I'm using the makita router with a cheap collet sleeve from ebay. it tends to jam and getting the bit out is difficult, especially as carbide is super brittle so no force can really be applied. Do I need to buy the £35 1/8" collet from ooznest? Should I have bought a proper spindle with decent collets in the first place?

* How on earth are tool changes mid job ever going to work if I have to take the router right off the machine and mess about for ages to get the bit out? There must be a better way.

* How do you change tools and set the depth the same on a router? or do you have to rezero by eye and hand? (inaccurate)

* There seems no sensibly approached way to calculate feedrates etc - they all start from chip load - but chipload, though important, is a step along the way it is neither the beginning nor the end point of calculating feeds and speeds.

I want to start from type of material to cut, and type of cutter and diameter and end up with speed and feed and overlap; chipload may well have to be calculated as a step on the way but a calculator that regards it as input (and that's all of them I've found so far) is useless.

* the makita router is quiet at its lowest 10000rpm speed but it gets a LOT louder very fast as the speed increases. I hope I don't have to use the faster speeds.

* the eccentrics nuts on the workbee are really inaccessible except on the Z axis. Adjusting the wheels to be in even contact is difficult enough as there are so many wheels, but having to do it while lifting the machine and/or holding my head upside down with my glasses falling off is near impossible - how do others do it?

(edited for correct router speeds I had left off a 0)

 

thanks, that seems consistent with what I'm finding.

do you mean depth or overlap? for a 3mm bit cutting at only 1.5mm deep seems very shallow. But for overlap it is plenty - i was testing at 40% overlap, so 1.2mm. but some cuts had no overlap as it was just a 3mm slot, ie cutting out an outline rather than a pocket. i guess that should be cut slower.

are your speeds for a 3mm bit? presumably a larger bit can cut faster?

are the straight flute mills better? I am also about to buy some. they are cheaper than downcut.

those elaire collets look good that's a much better thing than the cheap sleeve I have that fits inside the existing collet. Does anyone know of a cheap source in europe for something like that?

 

yes I've bought the 1/8 collet and some bits from ooznest, I didn't realise that actually is the Elaire collet. It arrived today and the collet looks very good. It needs to for 1/3 the price of the router!

I'm looking for good suppliers of other types of bits accessible in the UK.

I've ordered (from ebay) some straight flute for cutting ply and pine and some aluminium cutting short single flute that look like o-flute to me though they weren't described as such.

If the quality seems OK I might get some downcut and compression too. I want to try the various types of bits on different jobs using cheap ones before spending more.

 

thanks. I am having much less difficulty now. I got the Gwizard software for feeds and speeds which I kind of hate, as it is expensive windows-only adobe-air driven surveillanceware, and has a terribly designed GUI, but it is useful once you get used to it.

I don't use phone apps from play/app store, I barely use a phone in fact, but i see the Millright one is also available as a web app. It seems quite basic though, maybe the phone version has more options.

I'm not having jamming problems now I'm using proper collets. The router is very noisy though and I'm using it at speeds above its minimum most of the time. It will do for now. The cutter in the wood is as noisy as the router or more so reducing router noise may be of limited help.