Buying Advice Building a front-hoe for my PT-1418 - Advice?

davesisk · Apr 5, 2004

Hey Folks:

I hope everyone's doing well!

I finally decided to get with the program and build the front hoe (aka mini-hoe). I had all the parts except for a piece of plate and some big square tubing (which I picked up a few days ago), and it'll be too useful to just not do it.

So, far I've cut the triangular plate from a piece of 1/2" 30 x 35 or so piece of steel plate. Used my plasma cutter (Thermal Dynamics CutMaster38) and it's slow with something that thick, but it cut it like a champ. I've got enough plate left for 2-3 more attachment plates. I just finished welding the attachment tabs onto the plate (my old 1418 uses 3 pins rather than the slick quick-attach you guys have).

I'm using a 160 amp ESAB Heliarc welder to do the welding. With only 160 amps I was quite concerned that I might not get sufficient penetration with 3/8" tabs, 1/4" walled tubing, and 1/2" plate, but I think it's going to come out quite well. You just have so much control with TIG...I ran initial beads with no filler, then went back and layered filler until I have about a 1/4" or so bead. Not all of them look as pretty as I'd like (you know...the stacked dimes TIG look), but I'm pretty sure they'll hold.

Next step is to attach the square tubing to the front of the attachment plate. I've got a 32" piece of 1/4" walled 4"x4" tubing. Isn't that what the mini-hoe's are made with, or is it smaller? (In fact, I'm thinking someone mentioned that the mini-hoe arm was 1/8" walled tubing?) Anyway, what size is the tubing PT uses for the arm? And, how long is the arm? The bucket I have is a little larger than the PT bucket (I think)...I might cut it down a little to remove some weight.

Do you guys think the arm made out of the tubing I described will be strong enough? I'm trying to balance strength with weight...I don't want to make the hoe so heavy that I can't dig with it, but I also don't want to make it so lightweight that I destroy it the first time I use it.

Any suggestions appreciated!

Thx,
Dave
/forums/images/graemlins/grin.gif

J_J · Apr 6, 2004

Dave

I am currently building a backhoe for the front of my PT-1445. The people that cut out most of the parts in the kit recommend 1/4 inch thick wall tubing, but I am going to use 3/16 seamless steel tubing. I also extended the reach on both legs for more reach. but now I have to get the cylinders to match the extra length. I bought one 12" bucket from Ebay, and made the 6" and the 12" from the kit. The kit is very useful if you don't have access to a precision cutter , either plasma or laser for the smaller parts. They have the swing cylinder pushing and pulling from the back, and therefore, the swing is limited to 150 degrees either side. I am trying to figure out how to get the full 180 degree swing. I will post some pictures soon.

see cdp-backhoe.com

Sedgewood · Apr 6, 2004

I've got a 32" piece of 1/4" walled 4"x4" tubing. Isn't that what the mini-hoe's are made with, or is it smaller? (In fact, I'm thinking someone mentioned that the mini-hoe arm was 1/8" walled tubing?) Anyway, what size is the tubing PT uses for the arm? And, how long is the arm? 

Yup, Dave, my bent mini hoe tube was 3 x 3 x 1/8 wall! It just came back from the welding shop with a new 3 x 3 x 1/4 wall tube. I'd have to go measure the length but 32 inches seems about right. Here is a link to my description of the bent hoe and thumb. One day soon I'll get a picture with the new tube but there's not much to show. The welder did a great job of removing the old tube and glueing in a new one - you can hardly tell it's been touched except for the lack of paint.

Do you guys think the arm made out of the tubing I described will be strong enough? I'm trying to balance strength with weight...I don't want to make the hoe so heavy that I can't dig with it, but I also don't want to make it so lightweight that I destroy it the first time I use it.


Your tube should be plenty heavy and I think a bit of weight might be a good thing and give you more digging force. You only have to lift the weight of the hoe and a bucket of dirt - unless of course you add a thumb. /forums/images/graemlins/tongue.gif

In the middle picture on the above link you'll see an old crane post I picked up that one day I might to build a longer, heavier mini hoe. I was going to use it in my repair but just welding in a heavier tube turned out to be much simpler for now.

Good luck,
Sedgewood

davesisk · Apr 6, 2004

Thanks Sedgewood. That's what I thought. And yes, I do intend to add a thumb so I can pick up tree trunks and branches, etc. That's the primary reason I want to keep the weight down as much as reasonable. My old tractor will only lift about 600 lbs or so...I don't want to make an attachment that's 500 lbs!

Thx,
Dave

MarkStewart · Apr 6, 2004

Just curious. What are you going to do for the bushings where your boom and bucket pivot? thanks.

davesisk · Apr 6, 2004

( Just curious. What are you going to do for the bushings where your boom and bucket pivot? thanks.
)

The boom attaches in the same way that the dirt bucket and other attachments do, using 5/8" pins. Those are the pivot points for the boom. The 8" bucket will attach to the arm with 1" pins (came with the bucket). So, essentially, there are no bushings...when the pins wear down, I'll just replace them. It's less than ideal, but it's also simple.

Just FYI, the modern PT's don't use the 3-pin method to hook up attachments, so I'd imagine these newer machines have bushings, roller bearings, at least grease fittings...probably something a little more sophisticated that metal pins.

Dave

Sedgewood · Apr 7, 2004

so I'd imagine these newer machines have bushings, roller bearings, at least grease fittings...probably something a little more sophisticated that metal pins.


Ha ha ha!!! /forums/images/graemlins/laugh.gif

Think grade 5 bolts with pipe sleeves and a grease fitting here & there. After all, bolts make good shear pins and we (ooops, you) can buy them by the pound. /forums/images/graemlins/tongue.gif

As one of my guys used to say "good enough, we ain't buildin' a piano"
Sedgewood

J_J · Apr 7, 2004

I would highly recommend that you use 1 inch grade 8 bolts, or 15/16 pin stock inside of thick wall bushings on all your pivot points. This will give you more support and surface area for wear, plus you can also put a grease fitting in the bushing.

bottom swing arm 28.5 in
next arm up 26.5 in
boom extension 29.0 in

J_J · Apr 7, 2004

I tried to put apicture up but I failed. sorry

you can see the picture at cdp-backhoe.com

davesisk · Apr 10, 2004

Hey guys:

I got this contraption finished (except for maybe a couple of minor mods.) I'm out of town right now, but I'll post some pics when I get back, probably Tuesday.

My 19-month old daugther and I took the new contraption up the street in our neighborhood and dug a drainage trench in a spot where water always stands in the road after a good rain. Worked great! What a deal too...tried out the new 'hoe, entertained my lovely daughter, AND did something beneficial for the neighborhood. What more could a guy ask for, eh?

Anyway, a couple of thoughts:

1) I put a thumb on this front-hoe made from two triangular pieces of the 1/2 plate that I used to make the attachment plate, welded to a piece of 1/4" plate with 4 holes drilled in it. I bent two pieces of 1/2" threaded rod to make big U-bolts, and it's attached to the boom this way. (I wanted to make it removeable/adjustable, etc.) Anyway, the piece of 1/4" plate is just too thin...I've already bent it into a V-shape. I forget that these hydraulic cylinders can push with 6000 - 10000 pounds of force! So, I'll probably cut the 1/4" plate off and replace it with either some pieces of 2" x 1/2" stock, or I'll cut a square piece out of the remaining 1/2" plate stock that I have.

2) The cylinder base attaches to the top of the boom by a pin through a piece of 2" x 1" x 3-4" long rectangular stock (it stands up to give the cylinder a little distance from the boom for clearance). I realized that this is only a linear 6" of welded surface area to hold this piece of bar stock in place. Even though I stick welded it and am pretty sure I got a good (but not pretty!) weld, I'm still thinking that perhaps I should cut a piece of 2" x 1/2" stock with 45 degree mitered edges, and weld that in place as a brace for the big "tab" that the cylinder base attaches to. I didn't break it (or even deflect it) when I tried this guy out, but over time...still trying to keep in mind that that 2" x 1" piece of metal and it's welds have 8000-9000 lbs of force pushing against it. (It's a 2" x 8" cylinder...a 2x10 or possibly even 2x12 might would have given me more bucket travel, but since the bucket is quite long, I think I can live with 8" of cylinder rod travel...)

Anyway, it's not quite as good and capable as a traditional backhoe, but it's sure way better than no 'hoe at all! I used to mount this 8" bucket up and forward (just like the 48" bucket), and although I could still dig with it, I could only go down about 12", and I really had to spin the wheels some to make it effective. Turning it around and adding the 3rd motion of curling the bucket under (which appears to be the motion with the most force, apparently because of the dimensions) has made this much more effective.

I'll post pics my first opportunity when I get back home...

Dave