Designing and Building a backhoe, Need Help!!!!

[firel7]

I am looking to design and build a backhoe for my Kubota B7500 over this coming winter. I am looking to model it after the woods 7500, and the Bradco 408, Rhino b75 and the kubota bl4690. I have looked all over for plans for such a creation and all i can find is the cad digger plans. Those plans seem ok however they are not that "pleasing on the eye", for lack of a better phrase. My goals for this project are as follows:

1) Create a backhoe that looks and performs similarly to the factory hoes.

2) Create or modify a subframe mount that will work with a MMM.

3) Need to decide on using tractor hydraulics or a pto pump.

4) Create a cad drawing and plans and source list, along with a picture documentary to make available to all members of this board!!! (Want to give a little something back)

What I need help with?

1) First I need to know of a good psychiatrist for taking on such and endeavor. /forums/images/graemlins/ooo.gif /forums/images/graemlins/grin.gif

2) I need help with dimensions, pin to pin lengths, angles, movement, steel dimensions including gauge, cylinder lengths extended and retracted etc. all info here will help!!!

3)Pictures!!!! I need to see pictures of every component of your hoe. The more detailed the photographs the better. I am going to save all of them and make a huge picture library for reference. If possible please include make and model for use in classification.

4)Information on the modification of the subframe assembly. I have seen a post here that some have had their suframes modified so as to accept the MMM simultaneously. (pictures and dimensions here would help tremendously as well as free thinking ideas.

5)As the project progresses I would welcome all ideas and forethought as well.

6) Any info on other available plans to incorporate into my own design.

I am not looking to necessarily build a better beast but I am looking for something to keep my attention over this coming winter, and maybe save a few dollars in the process and p[ossibly stumble upon some minor improvements or at least incorporate the best of all the worlds into my own design.

Also if anyone is in the western NY area, owns a hoe of this class, and would be willing to let measure and photograph it, I would greatly appreciate it.

I want to thank all who will come forward in advance and I cant wait to start on my design. I know together we can create one nice backhoe!!!! /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/smirk.gif

 

[keeney]

A key part of the design that is repeated over and over again is the pivot mechanism at each joint as well as each cylinder mount point and end-attachment point.

For the joints not involving the cylinders, you are free to design whatever you want. Here, the key seems to be finding a supply of precision steel pins with the right end features machined into them and then hardened. There are two key features required on the ends of these pins: something to keep them from falling out, and some way to keep them from rotating and wearing on the softer surface of the frame they are mounted to. The other half of the joint is some hard tubing with a precise ID to just slip-fit over the pins. These will also need greas fitting installed in them.

An idea that came to me when I was thinking about building my own was to use grade-6 or grade-8 1" to 1.5" bolts as the pins. The retaining/anti-rotating functionality would be obtained by tightening them into a nut tack-welded to the opposite side of the joint. The problem with this approach is that the bolts tend to be undersized for generaous clearance in standard hole sizes. For example, a 1" bolt is about .970 or so. Not a problem if the tubing it slips into can be chosen in a slightly smaller size, but for the hydraulic cylinder ends, the pin holes will only be available in standard sizes like 1", 1.25", 1.5", etc.

 

[TOMDUALLY]

I would go to your kubota dealer and ask him for a 'spec' sheet on this backhoe, it should have a diagram with all the measurements on it. Tell him that you want to compare it with a couple other machines before you makeup your mind wheather to buy or not. In fact you could go to a couple other dealers then compare designs to see which one you like the best. Never know you might end up buying one. /forums/images/graemlins/crazy.gif

 

[firel7]

I have a few models specs sheets unfortunately they do not show the lengths from pin to pin, they more show overall dimensions and capacities. I just want to make absolutely sure I get the geometry perfect as it can be a real critical factor in just how the hoe operates. As far as buying the hoe it is not to likely because I am doing this more the the "entertainment of it" than for svaing money. I am sure if I were to figure my time into the cost of making it I would be losing money for sure. /forums/images/graemlins/crazy.gif
As far as the pins mentioned in the earlier post I was thinking harded steel rod at about 1" thick. Cut a v groove around the diameter of the pin in its center, then just drill and tap a zerk onto the hydraulic cylinder end. Hold pin in place by drilling and bolting on outer edge. Picture if you will the setup on loaders, at least on my LA 352 it is done that way. Figure that should work well for the hoe.
I appreciate the thoughts keep em coming please!!!

 

[JimR]

You may want to buy your pins with holes already in them. Driling hardened steel is no picnic. Using the bolt method on the ends of the pins to keep them in is a good idea. I have seen that on many small hoes. Just make sure that there is a notch for the bolt to lock into to keep the pins from spining. You don't want to wear out your frame.

 

[Glenn1]

I just completed building a unit for by B7500 from cadplans.com. naturally it will not do the work of a full size backhoe but I am very pleased. Total cost of less than 2K.

 

[bobodu]

http://www.machinebuilders.net
You might want to read through the many posts here.These guys do some fantastic stuff. /forums/images/graemlins/grin.gif

 

[PILOON]

One possible source is aircraft AN,MS bolts as these are hardened and particually the MS are very tight tolerances.
Often local 'surplus' stores will have them hanging around and they are so specialized that nobody will want them and they'd be real cheap.
I have seen for example, 1" X 5" wing bolts go into the scrap box.
Some aircraft have mandatory bolt changes at predetermined hours. Maybe check with an aircraft overhaul or FBO if you have one nearby.
I also made pins using 'drill rod' obtained from a machine shop. A shop near me carries 1/2" up to 1 1/2" rod.
I welded a flat bar stock on one end and drilled the other for a small bolt or pin. They sold me this stock by the inch.

 

[firel7]

Was giving more thought to the pins and I realized the obvious, if they are found to be that dificult to make I could just buy the pins from www.tractorsmart.com but I really do like the aircraft surplus idea if I can locate some. I also thought last eve that if I do run into any real difficult to machine parts i would seek the assistance of my local machine shop and it seems that the pins may be the first subject to approach them on.
Anyways, I need to get back to the basics of the dimensions and basic design. I have to come up with some viable drawings. I think I am then going to build some templates out of cardboard or thin plywood to see if I can get the basics of the geometry and test it so to speak. What i would really like to start off with is some photos and some dimensions as mentioned.
Thank you for the link to the machine builders site, I am sure I am going to get a ton of useful info there. Like I said in my original post I am looking to avoid the caddigger design, I am not sure why i just want to, but I am sure those that have done those designs can help a ton with the nust and bolts of the project.
Thanks again everyone for the ideas and posts, lets keep them coming!!! /forums/images/graemlins/smile.gif

 

[bobodu]

I really like Machine Builders....they are listed right after TBN on my bookmarks.Glad to see you are an American ( BUT an ORANGE guy....sigh...) as the Canadians seem to be outnumbering us there.The plywood mockup sounds like a good idea.I think that a machine built from plans is more like "assembling" and nowhere near as satisfying as building from scratch outta STUFF!!! If I wanted someone telling me what to do...I'd ask the wife to help!! /forums/images/graemlins/grin.gif