Vacuum Pump Blows


#1

Aloha Folks,

I’ve gotten my Farmbot assembled and moving. When trying a first round of seed planting, the needle picked up a carrot seed and lost it somewhere on its way to the first position. Subsequent attempts show the air blowing the seeds around in the tray. I took the rain shield off the pump and removed the hose and it appears that both the in and out ports blow air.
Has anyone encountered this behavior? Do I have a defective pump?


#2

Hi Makoto!
Good to know you are well and progressing in the world of FarmBot!

Our vacuum pump seems to both suck and blow.
I tested without any tubes attached. I set the pump to run, them placed my finger under each nozzle and felt suction at the “in” arrow and air coming out of the “out” nozzle. I did not try with tubes or needles yet. I did notice that in the instructions, the CAD drawing showed the tube connected to what looks to be the “out” nozzle, but I am connecting it (the tube) to what is marked as the “in” nozzle. But, if as you say, you have tried both, it may be a defective pump. I would guess that if the diaphragm (or whatever mechanism is used to force air) is defective, one possible symptom could be to force and suck air out of either/both.
Maybe take the vacuum pump off and feed it 3 to 5 volts at a workbench so you can better root cause.
I know it is not much, but hopefully this helps. If it is defective, I am sure the fine folks at FB will make it right!
Adding fine folks: @roryaronson @RickCarlino @Gabriel


#3

Hi, mine started doing the same thing! It’s weird because it WAS ok, and then half way through a seeding just stopped picking up seeds.
Did anyone work out the issue, beyond it seems to blow air instead?


#4

It might be good to get a diagram of the pump itself. I wonder if the vacuum mechanism may get jammed up if a seed or other debris enter the pumping innards. If we could see the way the pump actaually actuated, this might help.


#5

Hi, I had the same problem with two pumps a few months ago. I removed the screws and disassembled the pump and cleaned out the inside. There were some debris/soil on the diaphragm and surrounding areas. After reassembling it, it worked fine again. So I guess that was the problem for my pumps. Maybe you can give it a try, hopefully it will work.


#6

@Gabriel @roryaronson I ran our first seeding sequence this afternoon with students. The first two seed runs worked fine. The vacuum pump was drawing air in and successfully picking up seeds from the seed tray. Each time the z axis was lowered so that the end of the needle was a few mm beneath the soil surface and then the pump was switched off before drawing the needle out of the soil.

Upon initiating the third trip to the seed tray, the pump began blowing air outward instead of drawing air inward. It has been the same since even when turning on the peripheral switch in the controls panel. Please advise.


#7

I’ve seen this issue occur before when the diaphragm in the vacuum pump gets contaminated with particles such as soil or small seeds. As @Chiun recommended, you can take your vacuum pump apart and clean the diaphragm.

To get a better seal between the needle and your seeds (to help minimize contamination), you can also try using pelleted seeds. This will also generally increase reliability of the seeding system because pelleted seeds will be of a consistent, optimal shape and size.

In future versions of FarmBot we’ll look into using a different type of vacuum pump, one that can both suck and blow depending on voltage polarity, which will help keep the system clean and operational.


#8

This makes sense. I did in fact do as suggested and clean out the diaphragm which appeared to work but left me feeling a bit dismayed seeing how the system failed within the first 5 minutes of the first attempt.

I’m not much of a gardener (my thumb is digital, not green) but one thing I remember from grade school is that when planting seeds, you always put 2 or 3 in the same spot as there is no guarantee that every seed will germinate and if every seed does germinate, you separate and replant. That knowledge coupled with the (IMHO) cumbersome Farmbot way of planting, I decided I will start plants in seed pellets to assure germination and design a custom tool that hopefully will be able to excavate small portions of soil as well as pick up and drop off the seed pellets. I have a proof of concept working and will make a detailed post when it is completed.

I like that future versions of Farmbot will include Mega Maid style air pumps, this should help quite a bit.


#9

Anyone has tried to add a small air filter on the tube to avoid such vacuum issue ?
This would keep the vacuum clean from small seeds and particules.

Thanks.
Vince


#10

Thats an idea worth trying IMO.
Keep us posted, please. :slight_smile:


#11

I have used a fuel filter, that works great !


#12

Awesome addition @vroyer! Would you mind sharing what model fuel filter you used, with perhaps a link of where other FarmBot users could get one for their bots if they have similar issues?


#13

Thanks, this is a basic fuel filter like that one, found in a garden store close to my home.
Here is the same one from online stores:


https://www.rendcarparts.com/volvo/parts/1576741-3209422-464728/RD464728A


#14

Great! By the picture it seems to have collected quite some debris, didn’t it?