BasicPI

Finally got around to design holders for my Nema8 Nozzle head + I added a damper between the Nema17 and the head to reduce noise. I need to design tank-belt holders and I can start assembling pneumatic tubes and control system as I should have all parts by now.

I used FreeCAD to design these brackets. FreeCAD works, but it is a lot of bugs so you need some patience to use that in it’s current stage (version 0.20.2) – but, I am looking forward to new versions of FreeCAD + I need to learn more about it.

One of the things I want to do is to redesign the PnP Head completely. I work with Robotics as a profession and while this design is working I also see a lot of potential for mechanical improvements. As mentioned before I want to achieve 0201 quality and to do so I need to improve the mechanical accuracy/stability of the design. The white components above is PLA, while the black is PETG – a stronger type of plastic – but in the next design I want to avoid plastic on critical parts that will wear with movements. This is a machine with moving parts – it need to move fast and with some strength. The plastic design will work fine for a short period before it starts to wear out and not to mention that it will need constant adjustments. But, this is things you learn as you build one of these.

I also want a head with 4-8 nozzle tips on + I am very sceptical to the belt driven mechanism above – I suspect it will strugle with changing nozzle tips because you need some strength to click the on/off, but lets see. I will upload the changes I do to this machine, but contact me if you want them now.

I did notice that someone had dropped the adapter (in white) on top and made a non-turnable adapter – I will advice against that – that is 40.- USD that you do not want to save as the Nema8 will twist the pneumatic tubes and cause them to wear out fast.

Also remember that the z-gantry needs oiling from time to time.

The drawing above illustrate the current frame design with 4 x 2020 aluminum profiles (V type). I considered going up to 3030 or 2040 etc, but I do not have an issue with the strength of the profiles – I do hoverer have an issue with the entire frame moving a bit. So what I want to do is to double the width of the frame as follows:

This will increase the Y gantry to 1200 mm and stabilize the frame at the same time. To do so I only need to buy 3 x 2020 profiles that is 1200 mm long + 1 extra 600mm profile. I think this will do more for stability than adding larger profiles. Using the extra sis is an issue because I seldom need feeders – as most hobbyists I use strips and components in trays – I need the extra space to put this on and this is a low cost and very effective modification I think.

I ordered CNC belt driver wheels a bit quick and realized just now that their hold is 6mm while the shafts on my steppers are 5mm. The extra 1mm meakes a “hump” as the belt move and the combination is not a nice, smooth belt drive – so new belt wheels have been ordered. I am still waiting on tubes anyway so it will be february before the PnP is running. But, ordering parts from AliExpress used to be 8 weeks while it now is more like 2-4 weeks. Things have improved. I have to pay tax on everything, but all this is nicely organized from AliExpress. That said – some parts are cheaper on the local hardware shop.

This picture (above) show the PnP Nozzle head. (1) A Nuki 506 Noozle, but I have several noozles. (2) A noozle holder. (3) A Nema8 hallow shaft Stepper and (4) And adapter for rotating hallow shaft to vacum tube. These are some of the most expensive parts of the PnP design. I have received 501 Nozzle that is designed for 0201 components, so we will see how far off we are in mechanical accuracy.

This picture is the entire Z gantry lacking belt and camera. I had to repair one of the adjustment bolts as it did not hold and you don’t need much insight into mechanics to understand that this would be better as metal parts. But, they cost me ca 10.- USD and 30 hours in printing, so they will have to do as a start.

I have 3 cameraes and multiple lenses. I initially assumed that an expensive, high resolution camera would be better, but recommendation is to use 720P cameraes. The algorithm only focus on recognizing position and some parts and higher resolution will make the machine slower (need more time to compute).

These 3-Way peunmatic solenoids was cheap, so I ordered a 6V and a 12V. The 12V is the right size for the job and tubes. These are both small and cheap.

This picture is from LumenPnP (Opulo) that I use as base and show that they already have corrected the weak mechanical leg, but obviously not updated the open source drawing – or I must have downloaded the wrong ones 🙁

Never mind – I have glued the part that broke and they will do for now because I intend to change this design regardless. 3D printed parts have an obvious extra weakness in the direction they are printed, so if you print this laying down it will become strongeron that part, but notice that part that hold the motor – that would then be weaker and most likely break easier after some use due to vibrations over time.

I did notice that microsmt argue for having metal parts here due to this kind of problems with 3D printed plastic parts and I agree. This needs to be redesigned unless you want to repair your machine on regular basis. Sadly making metal parts is much more expensive. But, buying Aluminium plates are not – and one idea is to make hybrid parts – I want to redesign this part anyway because I want closed cabinets rather than a open dust collector.

The red arrow show both the slice/print direction I used and where this part broke off. This is a corner peace and I needed to print it in two parts – that worked perfectly, but as I put the 2020 frame parts in I also accidentally dropped it to the ground and the piece broke. The design is a bit weak here, but the real cause is because I did not realize that the slice/print direction needs to go the other way to strengthen this exact peace. I then get the exact same problem on the right side on motor fixings – so I will print this separate in the existing direction.

This was a 14 hour print-job and I am almost done with the 2nd part, so 28 hours more of 3D printing to come 🙂

I will also see if I can modify this part to strengthen it because the stepper motor will be on right and cause hammock due to vibrations over time.