Backhoe Thumb

[Jiles]

Anyone ever make their own Backhoe Thumb. I have priced them and they are grossly overpriced. From what I can figure the metal will cost about $150. I can do my welding.
Any advise or pictures would help.

 

[Anonymous-0]

Google Ritchie Bros. auctions. They have some pictures of thumbs for sale at the Edmonton auction coming up. I'm thinking of seeing what they go for cause I could use one. They're usually made out of better steel so they hold up better but do seem rather expensive. Dave

 

[mje171]

They are not made out of any special steel. They are all made out of A36 Hot roll. I have prints for many that I've built. If you give me the Length and Width of you bucket, width of your dipper and what machine it is going on I can email you prints. What I usually do is have the Jaws CNC plasma cut at a steel shop (relatively cheap) then do all the rest of the cutting and assembly myself.

 

[JF in MI]

I made my own and it "eventually" worked out. My advice is to make it out of 3 times thicker steel than you think you need. I also had to get a grade 8 one inch bolt for the pivot because anything else would bend. Now that I have one I can't remember how I got along without it before.

Jim

 

[Anonymous-0]

Maybe yours are made from mild steel but I've seen others made out of higher strength steel like T1 and AR400 which would explain the higher price. Dave

 

[mje171]

Just an FYI from an engineer that designs these things. Anybody that advertizes "alloy steel" or anything similar is just blowing smoke.... all steel is alloy steel. We have made a few out of 4140 OQT and similar for guys doing alot of concrete demo. Truth is they don't wear that much. What ever you do just pick a good ductile steel. Not to argue with you dave, but if someone made a thumb out of T1 and heat treated it (which is why you would use T1) it would cost half of what the machine does it would break almost instantly. I would be very interested if someone is advertizing thumbs made of T1 Steel. These things have a huge profit margin built in thats why they cost so much. With exception of the really cheap ones they are relatively all about the same. Afterall it's not rocket science

 

[Jiles]

(quoted from post at 20:32:30 03/04/10) Just an FYI from an engineer that designs these things. Anybody that advertizes "alloy steel" or anything similar is just blowing smoke.... all steel is alloy steel. We have made a few out of 4140 OQT and similar for guys doing alot of concrete demo. Truth is they don't wear that much. What ever you do just pick a good ductile steel. Not to argue with you dave, but if someone made a thumb out of T1 and heat treated it (which is why you would use T1) it would cost half of what the machine does it would break almost instantly. I would be very interested if someone is advertizing thumbs made of T1 Steel. These things have a huge profit margin built in thats why they cost so much. With exception of the really cheap ones they are relatively all about the same. Afterall it's not rocket science

Which steel would be better to use---Hot or Cold rolled?

 

[Anonymous-0]

The best heavy duty buckets and attachments use T1 and/or AR400 plate. A36 is a plain mild steel with no abrasion resistance or toughness. T1 and AR400 have superior abrasion resistance and toughness. A36 is used because it is cheaper, not because it is better. A36, 60,000 psi tensile strength. T1, 100,000+ psi tensile strength. AR400 145,000 psi tensile strength. A better thumb with better steel is going to cost more. Another poster said to make a thumb 3 times thicker than you thought. That's another reason for T1. Thinner T1 will have the strength of thicker A36 mild steel plate and wear a lot longer. Someone that advertises they use T1 or AR400 is not blowing smoke, they are advertising they use better materials to make a better product. If their product costs more is not because of a huge profit margin built in. It costs more to buy because it costs more to make. Whether it's a thumb for a hoe or a box blade for a tractor, they aren't all the same. The better ones cost more but will be heavy duty and give better and longer service. It's not rocket science. Dave

 

[Anonymous-0]

Plate is hot rolled. Round bar can be hot or colled rolled. Strength wise there isn't a big difference. How big is your backhoe? If it's just a small one and you're not using it all the time, you could use just plain mild steel. Welding some hard facing on the jaws wouldn't be a bad idea. Below is a reference to some better steels. Dave

Abrasion Resistant AR 360/400/450/500

Abrasion Resisting Steel was designed to satisfy the demand for a grade of steel that would give prolonged service life where abrasion is the primary cause of failure. The surface hardness of Abrasion Resisting Steel will usually be in the range of 360 to 544 Brinell.

A514 High Strength (T1)

This structural and pressure vessel plate is for general use where higher strength permits reduction in gross design weight. Offers exceptional strength, toughness, corrosion resistance, impact-abrasion resistance, and long-term economy.

Typical Applications
Fabricated bridges · Components for earth moving or transport equipment · Penstocks · Unfired pressure vessels

 

[2x4]

at Ritchie Bros. auctions, $400 for Cat 307 size, up to $800 to $1000 for larger machines

 

[MattE]

Wow....
who would have know a post like backhoe thumb would get people fired up.

My 2cents is this. I've built quite a few and I've bought a few.

Look at your use. If you have a large excavator and are going to use it daily then just buy one at auction. You can't make one that cheap and you would have to buy alloy steel weld it up and have it heat treated.

If your use is relatively light then mild steel will work fine and is readily available. 3/4" is plenty thick for a backhoe or small excavator providing it is braced properly. And if you want some extra wear resistance weld some hard face on the teeth.

It's not the best material by far. AR400 would be super, but again it would have to be heat treated.

T1 is a tool steel designation it would be extremely wear resistant, although not very tough. not to say it's not used.

To answer the HR vs CR question use hot rolled it has less internal stress and won't warp as bad when you weld and cut it.

again just my opinion
Using a high alloy steel which is expensive and most steel yards would have to order anything more exotic than 4140 won't buy you much unless you then heat treat it after you fabricate the thumb.

 

[MattE]

Checked my books. They did use T1 for earth moving equipment although not too much anymore. It is getting really hard to get.

Learn something new everyday. Thanks Dave..

 

[Anonymous-0]

I think a lot of bigger buckets are made from T1. Apparently there are different grades of T1. Using T1 allows a bucket to be stronger using thinner steel. The bucket will weigh less so it can carry more. For occasional use mild steel would be fine for a thumb. The only reason I posted about T1 and AR400 is because the other post that said all thumbs are the same and nobody uses T1 or AR400, which is false. Dave

 

[SARG]

I had a thumb attached to my Wood's BH6000 and while I initially regretted the $400. spent for a mechanical thumb ...... it has turned out to be remarkably handy..... especially for brush transport & the like.

 

[Jiles]

I have just a small lot that need extensive clearing. I recently moved here and still have all my equipment. This thumb will only receive light work such as brush and small tree moving. I have a Case 480D and a 364 IH tractor with five pieces of equipment. Relunctly---All will be sold after clearing. I was planning to attach the thumb on the pivit pin. The main arm will be 3/4" x 3" x 41" with 3/4 plated separating the 8 1/4" width. I plan to weld a 5x5 plate with ears to accept a 1/2" pin. I will use a top link for adjustment and the 1/2" pin will be bushed for 3/4" hole, to serve as a shear pin.
Any suggestions, especially photos, will be welcome.

 

[MattE]

email me and I'll send you some drawings I have drawings for a 48" you can just scale it down a bit and modify it as you choose. I made this particular one for a guy with a medium size Komatsu that only piddled around his farm with it. I used all A36 because that's what plate I had laying around at the time.
Matt

 

[Jiles]

(quoted from post at 22:18:46 03/05/10) email me and I'll send you some drawings I have drawings for a 48" you can just scale it down a bit and modify it as you choose. I made this particular one for a guy with a medium size Komatsu that only piddled around his farm with it. I used all A36 because that's what plate I had laying around at the time.
Matt

THANKS-------Private message is under construction. I don't have your email address.

 

[MattE]

Jiles just click on the send email link and fill out your info on the form that pops up