PT425 48" Brush Hog Broken Bolt Removal Tip

[ponytug]

Big blades = big energy. Great for reducing 4" oaks to chips. Also great for sending 10lb chunks a couple hundred feet. My wife now spots me from at least 350' away after one particularly large branch nearly hit her. Guesstimate was that she was 200' away at the time.

I think that the smaller blades may have impaired brush cutting performance, but might be somewhat safer to be near, rather like flails on a flail mower.

Just idle speculation...

All the best,

Peter

 

[MossRoad]

Moss, on your PT how do you reach these nuts? Do you have to drop the Spindle?

I am not sure if I reported this but last year I cut a bunch of holes in my deck (3 to be exact plus 3 drain holes) These holes allow me to use a rig I made (A nut welded onto a long bolt with just a bit of thread hanging out). I rotate the spindel so that the broken bolt is visible through the hole in the deck. I then thread the long bolt with welded nut onto the existing nut. Slap on my impact wrench and down it goes. I then lif the mower and grab on with vice grips and spin the broken bolt out. Right now I am averaging around 5 or 6 broken bolts a year (I am continuing to push back the blackberries and brush and there is always something noisy and sparky and fun to hit buried within). I have to get a metal detector.

Oh, as for spacers on my machine I am just using 3/4" black pipe. Seems to work fine for my system.

Reviving an old thread....

After a couple more broken bolts, I, too, gave up and drilled a 1.5" hole through the top of the deck right in front of the hydraulic motor, in-line directly above the arc of the circle that the blade mounting bolts make, and use forceps to place a nut onto the back of the broken bolt and drive it out with the impact wrench. When I have time, I'll weld a nut to a bolt and do it that way. Much quicker. :thumbsup:

I'd still like to find a real 3 point hitch 48" brush hog and either adapt its guts (with better spindle and blade mounting system) to my PT brush cutter, or just remove it's 90 degree gearbox and drive it with my hydraulic motor from the PT brush cutter.

While the PT brush cutter is an absolute beast, I'm averaging one broken bolt for every 4 hours of operation, and its getting old.

 

[woodlandfarms]

My neighbor whom is a mechanic has a different solution I am considering. He wants to cut some wedges out of thick steel and weld them to the hub, so mini stump jumpers just before the blade. A wedge before each blade. Lots of physics I need to thing about on this.

I am not sure on this whole thing for a myriad of reasons. But I too am done with breaking bolts. Yeah, I would say one a day (so once very 8 hours of mowing) at the least.

 

[SpringHollow]

What size bolts are these? I know you can get button head up to 1/2" diameter, I am not sure about larger.

Ken

 

[ponytug]

Despite breaking a bolt every couple of hours before I changed my system, I haven't broken a bolt in five years.

I upgraded to Grade 8 shoulder bolts and sintered oil bushings. (McMaster) I remove the bolts, grease everything, and tighten it back up every eight hours. Greasing everything really improves the lifetime of my blades, as I am usually mowing in dry, gravel conditions that used to wear the bolt and bushing tremendously. An air wrench and welded steel sawhorses make quick work of it.

I gave up on trying to have the bolts in the holes 90 degrees from the blades. As Ken wrote above, I tried to find an oversize (buttoned) version that would match the PT blades, but I couldn't find one, nor could I find a set of "Brush Hog" original blades/bolts that would drop into the PT mower.

I'm on my fourth set of blades, though I am getting better at bending the blades back into shape. I just tried using my welder to fill the elliptical wear hole in one, and I think that I can rebuild most of my older blades by welding and grinding them. (Fun and games with a welder- I'm learning about what you can do with a TIG welder on a copper or aluminum surface.)

All the best,

Peter

 

[MossRoad]

Peter,
I would like to see some pictures if you have any. I also have two sets of bent blades somewhere (maybe I scrapped them already). I'm on my 3rd set in 15 years. And I only replace them because of the egg-shaped hole.

 

[woodlandfarms]

I made my own blades (or have them made I should say) by the local machine shop. they are 1/2" hardened steel. Not cheap, but I think comparable to PT.

Going to get a new set this year....

 

[ponytug]

MR- I just took a tip from a welding video (thank you youtube!) that used an aluminum plat to back up a weld. That gave me an idea to try. I put an aluminum plate below the blade, and then put a slightly undersized aluminum tube in the hole and worked my way in with a couple of layers of TIG. I originally tried tacking the bushing in place in an elliptical hole, but I didn't like the way it came out. If you are better than me with MIG, you could probably do it with MIG. It is way beyond my stick welding skills to try it, at least with a tube in the hole. I could imagine filling the hole in a couple of passes and then drilling a new hole.

I will need a drill press to get the hole back to size.

I used the same trick on the blade edge to lay down more material, and then ground it back down. I tried to be quick about it to not heat up too much of the blade.

Let me try to get photos.

All the best,

Peter

 

[MossRoad]

So the aluminum did not melt? It just acted as a form or guide for your steel welding?

 

[SpringHollow]

Copper and graphite work well for that purpose. For relatively small areas, you can just flatten out a small piece of copper pipe.

Ken