Are we too wide if our bed is 10 feet from edge to edge?


#1

We just completed our build of the raised bed for our FarmBot Genisis XL.
The width from edge to edge is exactly 10 feet.
Do we have a problem? Are we too wide?
We understand that the spec states 3 meters.
3 meters = 9.84 feet.
What we need to know is if there is any “wiggle room” or should we start to think about how to adjust.
Thanks!


#2

So I just measured and,as I said, we are at 10 feet (3.048 meters) from outside edge to outside edge.

After looking over the docs, it seems like the max width is 3 meters.

However, I measured from the inside edge of the same sides and that measures 9’8” (116” or 2.964 meters).

So, my first thought on a fix is to attach the rail mounts to the inside edges.

Does this seem like a viable solution?
The only concerns I have are:
1). Will this impact the wire carrier or wire routing in any significant way?
2). Since we have 4”x4” posts at each end and in the middle, will we have problems there?

Thanks for any help, ideas or thoughts…


#3

I also sent a question to the folks at OpenBuilds to see if it would be possible to get the “V-Slot 20x60 Linear Rail” in a length of 1550mm. If they can do that, I think this will solve the problem.
FarmBot folks, do you think that they will be able to do this? Do you hold any sway with OpenBuilds that you could leverage to help me get them to do this? Any idea what my chances are?
Thanks!


#4

Another thought…
If we added a second Gantry Joining Bracket and then cut a short section (2” to 4”) of Gantry Main Beam we could join this to the structure and give us the needed extra width.
Thoughts?


#5

I found that MakerStore (https://makerstore.cc) offers V-Slot 20x60mm linear rails in a 2400mm length for ~$40 ea.

Question to FarmBot Folks: If I purchase, cut and swap out the 1500mm lengths for the 2400mm rails, will there be any other impact? (Thinking wire lengths, sw and such.) Otherwise, I think this is the best solution, as it maintains all other aspects of the install. This will also leave us with a couple extra rails for any R&D or in-class demonstration work. (nothing wasted!)
Thoughts?
@roryaronson @Gabriel @connor


#6

I built mine and I don’t see any wiggle room in making it wider. It might be a lack of imagination but it just seems like a ton of work.


#7

Thanks for the info @TroyD

Yes, I agree that there is no wiggle room - 3 meters does not equal 10 feet…
(I think I now know how the NASA scientists felt after their blunder…)
So, unless I get a red light from the FarmBot Folks, I will get at least one V-Slot Linear 20x60mm rail at 2400mm length and cut it to fit. If I get two, and cut both, I can keep the join at the center of the gantry, and have some spare rails for R&D.
Any red lights, FB Crew?
@roryaronson @RickCarlino @Gabriel ?
Any risk of not enough wire lengths?
Any structural concerns?
Will we then have the biggest FB in the world?
If so, I am calling Ginnuss!


#8

The spec states 2.98m maximum outer width for Genesis XL beds. Perhaps we need to make that more clear as there really isn’t any wiggle room going wider.

Here are some considerations for you moving forward:

Mounting the tracks on the inside edges of the bed - What you’ll need to look out for ahead of time is ensuring that the track end plates and track joining plates will be located such that the 4x4 posts of the raised bed do not interfere. Lay out all your extrusions on the bed and hand position the plates where they’ll need to be mounted to ensure there will not be interference. You might need to shift the entire track if your support posts were positioned at the 1.5m marks. If you shift a track away from where your toolbays will be, you might also need to shift the toolbays from the standard install recommendation so the FarmBot can still reach them.

Extending the gantry - extending your gantry this small of an amount (less than 50mm) will probably not substantially impact structural integrity or the ability for the FarmBot to function. But for other readers out there: this doesn’t mean you could extend the gantry even further without expecting larger impacts to performance. As mentioned in my response about bed tolerance, a modification like this will eat into the “distance” the FarmBot has from its natural limitations, which could be problematic depending on all the other factors of the installation.

Depending on the exact amount you extend the gantry, your X2 motor and encoder cables might not be long enough. This is probably your biggest risk going this route. There isn’t a lot of wiggle room here because we optimized the cable lengths for the maximum size of the device.

Last, do not expect the completed FarmBot to be able to utilize this gained area. To increase the distance the FarmBot can move along an axis would also require longer cables/tubing/cable carrier.

Getting new extrusions - It is possible that extrusions from another source will be of a slightly different profile. Most likely this will not be an issue if they are marketed as v-slot extrusions and/or sold by OpenBuilds or one of their distributors. But if you do go this route, I recommend getting enough new extrusion to completely replace the gantry main beam so that the entire beam is of one profile shape from one supplier. Small variances in profile could cause edges at the joints that the v-wheels have trouble moving over.

I would also suggest getting two longer extrusions (1550mm for example) rather than a third extrusion. Less joints is always better, and you’ll save some weight not having to add another gantry joining bracket.


#9

@roryaronson
Thank you for your thorough and complete response. Much to think on and very good to hear. This is why I wanted to hear from the true gurus.

I want to make sure that you all (FB Folks & The FB Community) know that this is damage control, and I would hope that no one takes any of this info as an effort to increase the by-design specs, tolerances and capabilities of the FarmBot Genisis XL. I made an error. My concern now is salvaging the project. I would hope that folks do not take this topic as instructions or ideas on how to make their FB wider. I am not saying this should not be something people can do. However, if my goal had been to intentionally modify the by-design construction, my approach would be very different. I would have first gathered all the data, parameters, information, specs AND input from FB Team, User Community and any others prior to implementing any modification with the potential impact to so many aspects of the entire system.

I own this error and all this is me attempting to mitigate the impact & ensure that we can still install, configure and run the FB as it was intended.

Having said that…
About Rory’s statement about the spec (2.98 meters):
As Rory stated, and is clear in the documentation - the maximum width is 2.98 meters.
FB does not need to spend cycles making this more clear, in my humble opinion. It is stated VERY CLEARLY. (https://genesis.farm.bot/docs/building-a-raised-bed).
I needed to and should have paid closer attention.

About “Mounting the tracks on the inside edges of the bed”:
I think mounting the tracks on the inside edges of the bed is not the best solution.
True, it would allow us to set up the rails “as intended”, but, as Rory points out, it would introduce at least a few other challenges:

  1. Possible re-location of the tool bay (since the track may have to start forward of the short edge of the bed.
  2. Depending on where we are able to locate the track end & track joining plates, we may have to offset the entire rail support system.
  3. There is risk that we would not be able to use either the inside edges of the the 20’ boards and/or the posts if the plates do not match up to either both exclusively. If, say the end plates are mounted on the 4”x4” posts on each end, but the joining plates do not center on the posts in the middle. We could cut a 4”x4” block, screw it into the edge board and then attach the plates to this, but it would not be the best workaround, in my humble opinion.

About “Extending the gantry”:
I think this is our best solution.
I have, on order, two of the 2400mm lengths of V-Slot 20x60mm Linear Rail at a length of 2400mm. My plan is to cut both down to 1550mm each, making the gantry span 3100mm (increase in width of 100mm).
This will add the needed 50mm and leave me a bit of room, just in case. I can trim more after it is built.
I am taking Rory’s advise and swapping out both rails. I agree that using rails from another source is not ideal and there is risk. I looked at a drawing from MakerStore and a CAD model from FarmBot (on OnShape) and, while both seem to be very close, there were a couple measurements that may be off, albeit very slightly. Swapping both mitigates this, hopefully.

About “ Depending on the exact amount you extend the gantry, your X2 motor and encoder cables might not be long enough” and “ This is probably your biggest risk going this route. “ :
Rory (or other FB Team guru) - Do you think there is enough extra cabling and hoses to accommodate about 1” to 3” (25.4mm to 76.2mm) of extra gantry length? This is, as you stated, the biggest risk. This is my $1,000,000 question. Please just reply to this, and be brief so as not to take away from you day job. (I am already feeling guilty for the imposition and thrash I have created)

Finally, about “do not expect the completed FarmBot to be able to utilize this gained area”:
Understood. I just want to make sure we can have our FarmBot operate in the space it is designed for. Since this is damage control, to expect more would be silly.

I would like to say, for the record, that I am nothing short of amazed at the engineering, quality, professionalism, attention to detail (if only I could be so disciplined), and responsivness to customers and the FB User Community that all the FB Team Folks demonstrate. I know and REALLY aprechiate the amount of time that your (Rory) response took out of your day. To folks that think otherwise, I hope you, too, see how awesome this team is!

THANK YOU!!!


#10

Yes, I believe that will be okay.


#11

Thank you!
I will report back to this thread after I implement and let you know how it comes out.
Wish me luck, and slap the back of my head… :crazy_face: