JJ and others - Post Hole Digger

[J_J]

Whats a controlled interference fit?

Also, JJ you mentioned I would need to have a connector machined? Any chance they allready exist?

Carl, You could use something that PT already has, if the taper is the same. Most of the wheel motors I have seen use 1 1/4 tapered or 1 1/2 in tapered shaft. There may be some adapters out there to go from say 1 1/4 tapered to a 1 in female adapter to fit the auger shaft. I would at least take a drawing to a machine shop and get an estimate for the adapter. You may need a different adapter for each implement you want to use. In the picture I sent above, the hydraulic motor just happens to fit the shaft of the implement, which is a neat setup for 3PT implements. If you are starting from scratch, you can specify the hydraulic motor to match something you already have, be it tapered,straight, or splined.


http://www.northerntool.com/webapp/...=mode+matchallpartial&Dx=mode+matchallpartial

These are some adapters used on tractors. You would need to show and explain what you are trying to do.

 

[marrt]

Do you mean something like this.

Yes, exactly. I had a hydraulic leak once that I thought was the motor. A TBN member offered to sell me a spare motor. He had changed his motors to a larger displacement to better handle steep slopes. Anyway, I bought all 4 since he didn't need them. I figured to use a couple for attachments.

 

[marrt]

Maybe something similar to this?

 

[woodlandfarms]

Martt. I have looked into something like this, but I am not sure it will work in our application. First is that the quck atach gets in the way of the motor, the other part is that these type quick attaches keep the device too close, making odd angle PTO shaft lines. Either you have to back up a ways or direct connect.

If you look at the net, the ones I see for bobcat keep the implement far away.

I think you are looking at the QA from Harbor Freight to save a few bucks? Maybe we can make extending ears.

One other thing, I think you have to make the QA plate angled to accomodate PT's weird angle.

But we should keep looking on this. Has to be a cheap yet effective way to do this.

 

[Gravy]

I built my own PHD for my 425. It wasn't terribly hard. Description & pix here:

http://www.tractorbynet.com/forums/power-trac/91387-better-late-than-never.html

If I were to do it again, I'd use a smaller displacement motor, probably in the 9-10 inch range. The 14 inch doesn't spin fast enough to throw off the dirt.

 

[woodlandfarms]

I remember this link but was unable to find it. Thanks for reposting it.

So I have 3 questions on this build. Do you feel that you need the valve you put in still? I was going to just run this straight off my PTO circuit and use the engine speed to change the revolution speed of the PHD

Second, how is that swivel plate working out? I have mulled over a series of design ideas. First, is it necessary to have this swivel at all for your PHD use. i will be digging on slopes for sure.

Finally this tapered wheel that you used. How is that holding up?

 

[Gravy]

In my rocky soil, reversing is essential for backing out stuck augers.

I don't know that I'd bother with the side swivel. I virtually always position the PT directly up or down slope from the hole. The PT tends to slip downhill while drilling. It would be really hard to compensate for that sliding sideways. Consequently, the side swivel doesn't get used much. The front/back swivel allows the PHD to pretty well self level due to the weight of the auger but I'm not sure it's really needed. I've also found that precision leveling is a waste of time on my property. Most holes end up oversized and off center due to hitting rocks.

I haven't had any problems whatsoever with the tapered hub setup.

Gravy

 

[J_J]

I built my own PHD for my 425. It wasn't terribly hard. Description & pix here:

http://www.tractorbynet.com/forums/power-trac/91387-better-late-than-never.html

If I were to do it again, I'd use a smaller displacement motor, probably in the 9-10 inch range. The 14 inch doesn't spin fast enough to throw off the dirt.

After looking at the calculations below, I can see why you could not throw the dirt out of the hole. You did have plenty of torque


At 8 gpm, and motor displacement of 24 cu in, motor speed = 77 rpm

torque would be 9554 in lbs

If you went with a 12 cu in motor, you would double your speed, and half
the torque

 

[Gravy]

IIRC, my motor is approximately 14 cu in, so it spins faster that 77rpm (by memory of actual operation, closer to 120). However, it's still slow.

I sized mine based on PT's higher-torque "planter head" model because of the rocks. I've since figured out that the rocks are tougher than anything short of a drill rig. The PHD has rarely powered through any rocks. If it did, it would probably break augers. I suspect I would have done better to go for more speed to throw the dirt off. OTOH, it has successfully made over 100 holes of various sorts. That's about 95 more than I would have managed with hand tools, so I'm not going to complain.

Gravy

 

[Gravy]

Oops!

After JJ's comments, I took another look at my original post and my old notes. The motor I used really is 24 inches, rather than the 14 I claimed today. So much for my memory. If I were doing it over, I'd go with something like 18 inches. IIRC, that's what PT was using for the smaller PHD at the time I built mine.

Gravy