Tractor backhoe - homemade

[BFreaky]

Square tubing is the past. With curved boom design you get light but strong boom and it looks alot better. Well I could post cad drawnings, but the size of this machine would not suit your needs... It's not all that hard to draw it, these are simple 2D drawnings. First of all you need to determine boom lenght you want to build, then you can design everything else.

 

[Renze]

Bfreaky, how are you going to make the upper and lower plate of the boom in a curve ? have them rolled, or just clamp 4 or 5mm plates against the vertical, laser cut, curved plates with strong vise grips ?

 

[BFreaky]

Bfreaky, how are you going to make the upper and lower plate of the boom in a curve ? have them rolled, or just clamp 4 or 5mm plates against the vertical, laser cut, curved plates with strong vise grips ?

I will take them to a nearby shop and have them cold rolled. Then I will weld one end and clamp&weld them step by step.
Plates at dipper and boom swing connection will be made out of 25 mm metal. Similar to the drawning at the 1. page of this topic.

 

[Renze]

I will take them to a nearby shop and have them cold rolled. Then I will weld one end and clamp&weld them step by step.
Plates at dipper and boom swing connection will be made out of 25 mm metal. Similar to the drawning at the 1. page of this topic.

Yes, but the main boom profile, what material thickness did you take ? I would love to see how you end up tacking the boom profile together, i mean, what turns out the most practical way...

 

[BFreaky]

Yes, but the main boom profile, what material thickness did you take ? I would love to see how you end up tacking the boom profile together, i mean, what turns out the most practical way...

Vertical plates will be made out of 6 mm (maybe even 8 mm), and horizontal out of 10 mm. Maximum reach on the end of the bucket wil be 5.5 meters (measured from the center of king pin) so I think it's necessary to put thicker material. Also, sadly, it won't be made out of Domex because it's too expensive here...

 

[allen6634]

Another possibility is to offer the plans and all the parts as a complete do-it yourself kit. Similar to what EA has been talking about doing with their attachments. I would imagine with a well designed backhoe and website you would be able to sell a number of kits every year. I bet there are members here who would be interested in such a kit. I realize this would be a lot more work than simply selling your plans. You'd have to run the numbers and see what would be more profitable plans or kits or maybe both.

i know that i would be interested in a kit, because finding the steel and having it cut would make it more trouble than it would be worth.

 

[Renze]

Vertical plates will be made out of 6 mm (maybe even 8 mm), and horizontal out of 10 mm. Maximum reach on the end of the bucket wil be 5.5 meters (measured from the center of king pin) so I think it's necessary to put thicker material. Also, sadly, it won't be made out of Domex because it's too expensive here...

So you stick with St.52.3 (or S355 ??)

Thats half the strength of Domex 700 or Naxtra 70. So you need double the material thickness than a Takeuchi excavator boom made out of these high strength steels. Estimating from the bend radius of the boom of 3t excavator booms, i guess they are made of 4 to 5mm steel, so your 8 to 10mm should be about right...

 

[BFreaky]

So you stick with St.52.3 (or S355 ??)

Thats half the strength of Domex 700 or Naxtra 70. So you need double the material thickness than a Takeuchi excavator boom made out of these high strength steels. Estimating from the bend radius of the boom of 3t excavator booms, i guess they are made of 4 to 5mm steel, so your 8 to 10mm should be about right...

Yes, it will be St52.3, nothing less than that. I'm still negotiating about Domex 550 MC...there is one sheet which could go at a smaller price....but don't know yet...it all depends on the seller. The idea is to make the boom as light as possible...but not too expensive. Buckets will be made out of Hardox 500, that's already arranged

 

[dfkrug]

Square tubing is the past. With curved boom design you get light but strong boom
and it looks alot better.

I agree! A "box beam" of thinner steel can be made quite a bit stronger than a "dimensional beam",
and weigh a lot less.

I think you can make a very strong boom out of 1/8" (3+mm) mild steel, like A36, with laminated
sections around all the pivot points. You CNC-cut the sides out of a full plate, then stitch-weld the top and
bottom out of, say 4 or 5" wide plate. Easy to bend, manually, as you add each weld.

Keep up the good work.

 

[BFreaky]

I agree! A "box beam" of thinner steel can be made quite a bit stronger than a "dimensional beam",
and weigh a lot less.

I think you can make a very strong boom out of 1/8" (3+mm) mild steel, like A36, with laminated
sections around all the pivot points. You CNC-cut the sides out of a full plate, then stitch-weld the top and
bottom out of, say 4 or 5" wide plate. Easy to bend, manually, as you add each weld.

Keep up the good work.

That's true, but I think 3 mm is not strong enough...reach of the backhoe from swing point to the tip of the bucket teeth will be 5.5 m, that's 18 feet...
It has to be stronger or it could bend. Main boom cylinder develops a force of 20.72 tonnes at 200 bar of pressure. I can't go under 6 & 10 mm plates...