Mini excavator quick hitch

Jnasystems · Feb 4, 2012

Hello all,
I am thinking about building a quick hitch for my NH EC35 and have some questions about design and machining. First the design, the thought is to create a hook on the front and just pin the back, will this be strong enough to handle the stress? It will be all half inch steel and the tubes will have 5/8" walls. Here is my design:

The next question is how to machine the tubes. I can't find the right size exactly, but I do have a lathe that should be fine for the job. I found new stock that will need 1/8" removed from the inside diameter for $65 and solid 3" bar for $12. Would it make sense to bore the 1-5/8" hole for the pins? Or would that just take forever? Here is the lathe I have - http://www.grizzly.com/products/12-x-39-Large-Combo-Lathe-Mill/G4791.

Thanks,
Joe

Jnasystems · Feb 7, 2012

Well, I did some searching online and found several for sale, but none were anywhere near what I would consider reasonably priced. Here is the cheapest I could find
http://www.everythingattachments.co...er-for-4-5-Ton-p/am-q2-1-4-5ton-minihitch.htm
and at 10x my cost I figure I can spend some time on it. If I could find one for under $500 I would consider it, but this is just for use around the house so I won't be making any money with it and I spent less than $15k on the mini in the first place. Just can't justify the cost.

I think I do feel more comfortable about the design though. The one listed above seems far lighter than what I have planned, so I won't worry about that any more. I am going to make a foam model of it this weekend. I will use it to fine tune the design before I commit it to steel. I will take pictures of the model and post them here.

Thanks,
Joe

mjncad · Feb 7, 2012

Jnasystems said:
I found new stock that will need 1/8" removed from the inside diameter for $65 and solid 3" bar for $12. Would it make sense to bore the 1-5/8" hole for the pins? Or would that just take forever?

Thanks,
Joe

Assuming the steel is close to the same grade; I'd take the lazy way out and spend the bucks to start with tubing. You could easily spend more in consumables boring out the solid steel bar if something goes wrong and eats the cutting bits.

Jnasystems · Feb 18, 2012

Well the project is coming along. Built the model out of wood last week with the exception of the pin sleeves to check fit and look at how the thing will go together.

Today I machined the top set of sleeves and got the bottom 2 cut to 1/8" over. Now I have a problem - I don't know how to hold the bottom sleeves to bore them to the right diameter. I put them in the chuck, but they wobbled too much for me to feel comfortable cutting on them. Any suggestions? Here are some pictures of my progress.