Homemade Backhoe for LS Tractor (XG3140)

polemidis · Mar 31, 2019

Hello guys, I was thinking to make a backhoe for a while now and I was always postponing it, but I read Bfreaky's post last week and I decide to go ahead and do it. I will definitely need your help because there are so many stuff I do not know. For the history, I have my homemade 4'x8' CNC Plasma cutter, so I can cut steel up to ｽ" thickness.

Here is the preliminary design. Its a rough outline. No time was spent on details (nice curves etc) as these will be added as soon as the main geometry is final. I haven't work on anything below the king pin or the mount (tank, swing, sub-frame details etc). But I am pretty close on the geometry on the boom/ stick/bucket, and the Prince Hydraulics cylinders (Wolverine line) fit perfectly. (If later on I found cheapest cylinders I will adopt for them, but I thought its a good idea to use a common size cylinders)

The width/profile/thickness is just an estimate, I will try to make a rough analysis on the stresses now that am leaning towards to use 3.5" diameter cylinders.
One thing that I do not really know is the pin/bushings fabrication. Where do I find these? I tried Mcmaster but I am not sure what I have to look for. One possible scenario that I am thinking is to get 1.25" cold roll round steel for pins, and then for use DOM 2" OD with 0.375" wall for bushings. Any other ideas?

The grey box except the main mount, it will double as a reservoir as a PTO pump will provide flow to the BH.
I am not rushing with this project, as I am working on it on my free time, and it has a lot of details to be filled in, but I couldn't wait and I wanted to share it with you guys!
Bfreaky its all your fault man, you infested me with that virus!!! (Of course I used your post as my "research" to Backhoes, many many thanx!!)

I am open to any feedback and criticism of course

EDIT: The files are open source for personal non commercial use. Once this project is done, I will be glad if you replicate it for your own use and save some money. You can access them here. Any contribution to this project is appreciated (feedback,comments, ideas, mistakes to be avoided etc)

BFreaky · Mar 31, 2019

I'm very happy it's my fault

. One thing I have to comment...your lifting cylinder geometry is bad..it will lose alot of force at the highest point. Pull out your lowest point of the boom at the swing mechanism. Angle between lifting cylinder and boom is way too open

polemidis · Mar 31, 2019

BFreaky said:
I'm very happy it's my fault . One thing I have to comment...your lifting cylinder geometry is bad..it will lose alot of force at the highest point. Pull out your lowest point of the boom at the swing mechanism. Angle between lifting cylinder and boom is way too open

Do you mean this one? Its 4" horizontal distance now

BFreaky · Mar 31, 2019

Yes, that's what I mean

ptsg · Mar 31, 2019

Having built a backhoe myself knowing a lot less than I do nowadays, I definitely have an huge consideration and respect for everyone who builds this. I will be following this thread for sure!

So far looks very nice. And I agree with BFreaky on the lift cylinder. I will also suggest that you make the bucket close a bit more either adjusting the linkage or redesigning it, because if you try to dump a full scoop of dirt into, lets say, a dump trailer, it might fall quite a bit when you lift the stick.

Again, looks very nice so far. Looking forward for more updates.

polemidis · Mar 31, 2019

Thank you guys. I forgot, the project is open to anyone for non-commercial use! You can download the CAD files from here You need Freecad to open/edit them.

BFreaky · Mar 31, 2019

Ptsg, I agree. Bucket has to close all the way, movement angle of the bucket is almost 180 deg. Otherwise you spill alot of material when lifting high

Stimw · Apr 1, 2019

Find a local dealer with an attachment, go there, take lots of pics and measurements then build it.
Or you can just reinvent one.
Someone else has done the R&D and it is much easier to copy it.
Check out Surplus Center for hydraulic supplies, they are a sponsor here with great prices.

ruffdog · Apr 1, 2019

I would be more apt to start with something like this smaller Case attachment for less than $3k.

Backhoe - farm & garden - by owner - sale

BFreaky · Apr 1, 2019

Stimw, where's the fun if you copy everything?

polemidis · Apr 1, 2019

If you put a little thought, philosophically, we are all coping someone else! Maybe we put 1% of invention, but the majority has reinvented before!

So today I made some progress. Here are some pics.
So far, the boom+stick+2 levers+bucket adaptor weights 350lbs. With a random 0.25 plate, for boom and stick, and 0.5" for the levers. These are just a basic thickness no analysis on stress yet.
Bfreaky I moved the pin you suggested 2" further away but I lost a lot on the digging depth, so I put it almost all back. The angle is very small but, still the a 3.5" boom cylinder, with 1.75" rod (because It lifts on retraction) at 2500psi, creates 18000lbs pull force, but because the angle is only 11ｰ, it will be able to lift 3400lbs. Still plenty i think? no?. In these pictures I increased the boom cylinder stroke to 20" to increase the digging depth with loosing power. We will see. Maybe it will be too slow to operate now?
Anyway This is what I have for mesurements:

BFreaky · Apr 2, 2019

It looks much better now. I changed that distance when it was already in use because I noticed it loses alot of power. Digging depth is good, there is a problem with digging deep holes near your machine. At one point hole tends to collapse. I had 2 close calls, almost ended up in a 4 m pit with everything. I managed to hold the entire machine with the boom and pushed it away from the pit. Lifting height is much more important then the digging depth

TMGT · Apr 2, 2019

BFreaky said:
It looks much better now. I changed that distance when it was already in use because I noticed it loses alot of power. Digging depth is good, there is a problem with digging deep holes near your machine. At one point hole tends to collapse. I had 2 close calls, almost ended up in a 4 m pit with everything. I managed to hold the entire machine with the boom and pushed it away from the pit. Lifting height is much more important then the digging depth

Agree, I was able to balance mine between depth and height but if I was to build another one I would favor height a but more.

Mines a bit smaller then the one you built BFreaky, one of these days I really should paint it.

Stimw · Apr 3, 2019

BFreaky said:
Stimw, where's the fun if you copy everything?

I have owned a fabrication shop and still have a lot of the equipment.
I bought my backhoe attachment for $3400. because I could not beat the quality of it for the price.
I would rather be digging holes than engineering something that has already been R&D-ed.
Good luck on the powder coating too.

BFreaky · Apr 3, 2019

TMGT it would be nice to paint it...color is not expensive

.
Stimw, each one of us choses his own way. I prefer to make mine because I just love to fabricate stuff and because I can't buy machine like this over here because no one makes it as an attachment. There are countless Volvos, JCB-s, Terex and Hydrema machines but they are 20x more expensive then this will ever be

TMGT · Apr 3, 2019

BFreaky said:
TMGT it would be nice to paint it...color is not expensive .
Stimw, each one of us choses his own way. I prefer to make mine because I just love to fabricate stuff and because I can't buy machine like this over here because no one makes it as an attachment. There are countless Volvos, JCB-s, Terex and Hydrema machines but they are 20x more expensive then this will ever be

Paints not cheap either! (Gonna do orange to match) I still have some odds and ends to finish up on it before paint.

I built rather then buy because I couldn't find anything I liked and would still have to modify it for a subframe and to make it fit like I wanted. Plus I enjoy expanding my skills by designing and building things when it makes sense to do so.

polemidis · Apr 4, 2019

Stimw said:
I have owned a fabrication shop and still have a lot of the equipment.
I bought my backhoe attachment for $3400. because I could not beat the quality of it for the price.
I would rather be digging holes than engineering something that has already been R&D-ed.
Good luck on the powder coating too.

Thats one option, even though I dont believe I could buy a backhow for the cost of manufacturing it.

BUT, and thats a big but, I am designing this, (as I did the grapple, and the firewood processors) to open source them. So someone that has time but no money will be able to build it for a fraction of the cost. For example the grapple that you can buy for $2200, you can build it for around $1000 in materials, if you have a CNC plasma or for 1300 if not. Or like my CNC Plasma, I could buy it for around $13000, I build it for $2500.
For this backhoe a commercial equivalent cost about $12000 (bradco), I believe I will built it around $3000.

Its about offering to humanity, and it feels good!

polemidis · Apr 6, 2019

I am wondering if I could avoid the huge unique king pin. As I am designing that part of the backhoe, it looks like I could use 2 pins. One on top and one on bottom (between the green and the light blue parts).
For the swing cylinders I couldn;t find affordable "trunnion" type mount cylinders, so I went with a regular tie rod.
I made little progress this week, but I have figured out the majority of the geometry. When this is done I will start figuring out the plate thicknesses for each part of the backhoe.

TMGT · Apr 6, 2019

I used 2 separate pins for the swing, without trunion cylinders I don't think you'll be happy with the degree of swing.

Surplus recently had a few trunion cylinders for sale that should work well for that size BH. Haven't checked recently to see if they are sold out.

Other option is make your own trunions.