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Workbee mech kit with Uno and DQ542MA

Discussion in 'CNC Mills/Routers' started by halfshavedyaks, Apr 26, 2018.

  1. halfshavedyaks

    halfshavedyaks Journeyman
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    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?
     

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    #1 halfshavedyaks, Apr 26, 2018
    Last edited: Apr 26, 2018
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  2. CNCKitCompany

    CNCKitCompany Journeyman
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    Hi @halfshavedyaks

    On the power supply, for the AC input, I'd attach the line, neutral and earth. On the DC side, you use the positive and negative. I wouldn't attach the negative of DC to anything on the AC side.

    If you are just setting this up and experimenting regarding the drivers, start with full steps. Once you get things operating and moving, you can then experiment with micro stepping.
     
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  3. halfshavedyaks

    halfshavedyaks Journeyman
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    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.
     
  4. CNCKitCompany

    CNCKitCompany Journeyman
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    This all depends on the power supply design. You will need to look at the data sheet.
     
  5. halfshavedyaks

    halfshavedyaks Journeyman
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    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...
     
  6. SugarJ

    SugarJ Veteran
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    The standard Openbuilds lead screw has 4 starts and 2mm pitch. That means it travels 8mm per revolution, or 25 steps per mm with no microstepping.
     
  7. halfshavedyaks

    halfshavedyaks Journeyman
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    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....
     
  8. halfshavedyaks

    halfshavedyaks Journeyman
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    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...
     
  9. halfshavedyaks

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

    halfshavedyaks Journeyman
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    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.
     
  11. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Just guessing, but would all switches (5-8) set to ON be no micro stepping?
     
  12. halfshavedyaks

    halfshavedyaks Journeyman
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    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.
     
    #12 halfshavedyaks, Jul 27, 2018
    Last edited: Aug 6, 2018
  13. halfshavedyaks

    halfshavedyaks Journeyman
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    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!
     
  14. halfshavedyaks

    halfshavedyaks Journeyman
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    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.
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Contest Winner! Builder

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    RE: Make sure your user belongs to the relevant dialout group (or its equivalent on your distro) so that the user has access to the port.


    Serial port permissions

    Similar to the instructions on Arduino Playground - All
     
  16. halfshavedyaks

    halfshavedyaks Journeyman
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    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)
     
    #16 halfshavedyaks, Aug 7, 2018
    Last edited: Aug 7, 2018
  17. Giarc

    Giarc Master
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    I have the Makita and I just take the collet all the way out for tool changes if the bit does not easily drop out. If the collet is so jammed that you need to remove the router, then you need a better collet adaptor. I bought the set from Elaire and have never had that issue. It contained a 1/8", 1/4". and 3/16" collet. I have had problems removing cheap Chinese endmills from the 1/8" collet sometimes. But if you ever check them with a caliper, you will see their sizes vary quite a bit (no pun intended).

    When I do a tool change, I use the probe and touchplate to re-zero to the work surface. Usually, if I have to use multiple tools, I run a gcode file for each tool. It is just easier for me. After all, I have to stop the router to change the tool anyways. The only change would be the Z0, so I just re zero the Z.

    I have not had an issue with clogging, but I use a dust shoe connected to a vacuum. However, for the noise averse, this may not be an option. I just wear headphones and listen to music while it cuts. For feeds and speed for woods, I use 2500 to 3000 mm/min and 10000-15000 rps. I usually cut at 1/2 the bits diameter, but sometimes a little deeper. However, my machine was a custom design I did, so that may not work for you. Recently, I purchases two flute straight flute endmills to try for wood because I get tear out as well with up cut.
     
  18. halfshavedyaks

    halfshavedyaks Journeyman
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    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?
     
  19. Gary Caruso

    Gary Caruso OpenBuilds Team
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    Yes the Makita collet can be a real pain to get the bit out, I've found that if it's stuck i can take the nut off and using the wench apply some side force on the small part of the collet that sticks out, sometimes tap it with a screwdriver. Some hard wax on the tapers might help, also make sure the collet is good and de-burred with some 600 or 1000 grit paper.

    Pine is fuzzy, when you cut oak or other hardwoods the difference is huge. Most times even with pine you can just hand sand the surface and get 90% of the fuzz off.
    Ooznest has the makita collet from Elaire and some bits.. The shipping from Elaire is stupid.. I'm a five hour drive from them and the shipping was $23 if I remember right.. for a <2oz part should have been $5 tops.
    Look for endmills on ebay and amazon..
    Cheers
    Gary
     
  20. halfshavedyaks

    halfshavedyaks Journeyman
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    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.
     

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