Useful attachments adapted to PT ?

[ponytug]

I greased the bushings once at installation, but not since then say 19-20 hours before failure. Now wondering if I need to grease them before every use or 6-8 hours?

These bushings are tight inside the hole in the blade and don't spin inside the blade. They do spin around the bolt shaft. Are yours free to spin inside the hole in the blade, too?

They should only spin in the bolt, but I grease both. (Same friction on both surfaces, and the bolt area is smaller, so it spins there. Make sense?) I have some large diameter washers over the bushing, but I couldn't tell you if that was from the factory, or something I got from McMaster-Carr. I would have to check my stock.

Based on a very small set of conditions here, I think that grease intervals is dependent on mowing conditions. Observationally, mowing in cool, wet grass/brush, less grease comes out of the bushing area, and dry, dusty/sandy conditions seem to drive the grease out.

Wow. I good day for me is not blowing a blade off hitting a rock! I always find the blade, but the bushing is gone. I'm down to my last few bushings. I'll have to order another piece of DOM tubing to cut some more.

I have to head out to our property in the next few weeks. I haven't been out there with the brush cutter since probably COVID. I went out last weekend to clear the road entrance with a chainsaw so I can get the Suburban and trailer off the highway. Everything is 6' high on my road. It will be an adventure, for sure.

Sounds like fun! Videos? I will hope that nothing sharp gets a tire.

I don't think I have ever lost a blade, except from a bolt that worked loose, and that only happened once. I grease the blades and bushings and then tighten the bolts before heading out. I seem to hear when the bolts loosen a bit, and stop to tighten them while it is still on the hub.

I do sharpen and balance the blades each years because it makes such a difference to the mowing speed/HP and the performance (clean cuts, small pieces) when the blades are sharp. These days most of my mowing is bull/milk thistle or 6-8' mustard, both of which seem to have pretty tough stems, but they are nothing to the scrub oaks that I had to mow initially. PT brush mower for the win.

All the best, Peter

 

[MossRoad]

They should only spin in the bolt, but I grease both. (Same friction on both surfaces, and the bolt area is smaller, so it spins there. Make sense?) I have some large diameter washers over the bushing, but I couldn't tell you if that was from the factory, or something I got from McMaster-Carr. I would have to check my stock.

Based on a very small set of conditions here, I think that grease intervals is dependent on mowing conditions. Observationally, mowing in cool, wet grass/brush, less grease comes out of the bushing area, and dry, dusty/sandy conditions seem to drive the grease out.


Sounds like fun! Videos? I will hope that nothing sharp gets a tire.

I don't think I have ever lost a blade, except from a bolt that worked loose, and that only happened once. I grease the blades and bushings and then tighten the bolts before heading out. I seem to hear when the bolts loosen a bit, and stop to tighten them while it is still on the hub.

I do sharpen and balance the blades each years because it makes such a difference to the mowing speed/HP and the performance (clean cuts, small pieces) when the blades are sharp. These days most of my mowing is bull/milk thistle or 6-8' mustard, both of which seem to have pretty tough stems, but they are nothing to the scrub oaks that I had to mow initially. PT brush mower for the win.

All the best, Peter

No videos of the blade flying off. Plenty of videos of the brush cutter destroying stuff!

I've never had the blade bolts back out.

Somewhere, someplace, on my old computing devices I have a video of me mowing a really, really tall and thick patch of thistle. It was so tall, that I stopped the machine, climbed up on top of the canopy, reached up to grab a thistle plant next to the machine, and the top was 2' above my hand.

So I did the math...
I can rest my nose on the top of the canopy when standing next to the machine.
I'm 6' tall, so guestimating the canopy height at about 5.5' high.
I can reach 8' above my head.
The thistle was 2' above the top of my extended reach....

2+8+5 and change is a tad over 15' high thistle.

I was very impressed with not only the weed's height, but the ability of the little PT425 to handle it without any noticeable strain.

 

[MossRoad]

I will say the brush cutter earns the most respect of every dangerous tool that I own, slightly topping the chain saws. It will just destroy anything it comes in contact with, and has no problems flinging debris/rocks well over 100'.

Always wear eye protection at the least, preferably a face shield, never drive towards structures/vehicles with the cutter running, and keep all other people very far away when operating.

Once, I hit a 2" ish branch, a couple foot long piece of wood went spinning out away from me up into the air about 20-30', and my mind immediately said "wow, that looks like a lot like a boomerang". The thing made an arc and came flying right back at me! Missed but YIKES!

Another time I was clearing a lot for a good friend of mine and I told him to just sit in the truck and let me do the work. But he's a worker bee and can't help himself from picking up branches and debris. I was well over 100' away from him and WHAM! I hit a softball sized rock! He heard it and looked up, the rock was flying right at him. He ran and the rock flew right past his feet. I stopped the machine and looked at him.... he got back in the truck!

 

[ponytug]

No videos of the blade flying off. Plenty of videos of the brush cutter destroying stuff!

I've never had the blade bolts back out.

Somewhere, someplace, on my old computing devices I have a video of me mowing a really, really tall and thick patch of thistle. It was so tall, that I stopped the machine, climbed up on top of the canopy, reached up to grab a thistle plant next to the machine, and the top was 2' above my hand.

So I did the math...
I can rest my nose on the top of the canopy when standing next to the machine.
I'm 6' tall, so guestimating the canopy height at about 5.5' high.
I can reach 8' above my head.
The thistle was 2' above the top of my extended reach....

2+8+5 and change is a tad over 15' high thistle.

I was very impressed with not only the weed's height, but the ability of the little PT425 to handle it without any noticeable strain.

More like 200+' for my 72" brush mower, when it hits an oak or a rock just right. It is definitely not ideal for mowing around buildings or vehicles.

I wear a chainsaw helmet, with face shield.

I've never seen a thistle remotely close to that height. I'd be planting fruit trees, corn, something on that site.

All the best, Peter

 

[MossRoad]

More like 200+' for my 72" brush mower, when it hits an oak or a rock just right. It is definitely not ideal for mowing around buildings or vehicles.

I wear a chainsaw helmet, with face shield.

I've never seen a thistle remotely close to that height. I'd be planting fruit trees, corn, something on that site.

All the best, Peter

It's all trees now. Close to 20,000.

Forgot to mention on that friend's lot I was clearing, I also hit a few dozen golf balls and some softballs as well.

I know there's been discussion on TBN in the past regarding what is it with people wanting to got golf balls into vacant lots???

 

[ponytug]

It's all trees now. Close to 20,000.

Forgot to mention on that friend's lot I was clearing, I also hit a few dozen golf balls and some softballs as well.

I know there's been discussion on TBN in the past regarding what is it with people wanting to got golf balls into vacant lots???

Golfers that I have known consider it a good use for "old" balls that don't drive as well. Personally, I find it morally offensive, a form of plastic litter, and I can't say that mowing golf balls does anything positive for the environment.

All the best,

Peter

 

[2manyrocks]

There was a neighbor who used to practice his golf in the farm fields about 40+ years ago. Understood he was pretty good golfer because practice on rough farm fields made a real golf course look easy. Found a golf ball in the course of clearing an area of thorn trees a few months ago. Don't know if he hit it there or if some animal carried it there.

 

[2manyrocks]

Now I'm befuddled. The bushings I installed at 119 hours are worn down only 12 hours later. I'm not getting the life out of these that Ponytug or Terry have estimated which makes me wonder what I'm doing wrong or if something else is causing this kind of premature failure?

I've been running my deck with the rear down maybe 2-3" compared to the front. That might cause more stress.

I mow slopes cutting down or up, but try to also mow coming back down even though these blades only have a cutting edge on the front.

Not enough lubrication?

Not enough lubrication frequently enough?

?Something about my blades themselves causing premature bushing failures?

 

[ponytug]

Now I'm befuddled. The bushings I installed at 119 hours are worn down only 12 hours later. I'm not getting the life out of these that Ponytug or Terry have estimated which makes me wonder what I'm doing wrong or if something else is causing this kind of premature failure?

I've been running my deck with the rear down maybe 2-3" compared to the front. That might cause more stress.

I mow slopes cutting down or up, but try to also mow coming back down even though these blades only have a cutting edge on the front.

Not enough lubrication?

Not enough lubrication frequently enough?

?Something about my blades themselves causing premature bushing failures?

View attachment 5762402

I'm sorry things aren't working for you as well as you would like.

Well, my recommendation still stands, grease before use, and every 4-6 hours thereafter.

Leaving that aside, yes, I think that given the wear, you need to grease more frequently. How frequently? Well, if it were me, I would go to before every use, and see how it goes for you. If the bolts aren't tight when you go to grease the bolts and bushings, then I would say more frequently. You want to ensure that the bushing is tight.

That washer looks to me to have too large a diameter. The washers that I use are an oversize, heavy duty washer, but the inner diameter is sized for the bolt size. I checked, they are from McMaster, and it might not be what PT shipped, but I think that the size is the same.

Here is what I use;

• Oilite bushings from McMaster
• 5/8" oversize grade 8 washers (packet to the right of the oilite bushings
• 5/8" flange head bolts ("hi alloy"?)
• Split washer

They are all stacked as shown on the right. Note how tight the flange washer is to the bolt.

I moved to the grade 8 "hi alloy" washers, in the box, as the "std zinc" washers were just getting chewed up in the gravel. I haven't replaced a bolt or washer in 10+ years. (For the curious those are grade 9 in the bag, not yet in use...)

Mowing forwards or backwards isn't going to make any difference as the sharp side of the blade is leading and cutting due to the rotational velocity being so much larger than the mower velocity, either direction.

FWIW: I think keeping the blades sharp makes a noticeable difference to the mustard and thistle mowing that I do to keep the leading edges of the blades sharp, and I do try to keep the blades nearly identical in weight (less than half an ounce difference).

Does this help?

All the best,

Peter

 

[2manyrocks]

I was going to ask about the order of assembly. Not the best picture to illustrate, but there's a thick washer, then the bushing, and the oversized washer fits around the bushing. I thought the purpose of the large diameter oversized washer was to take up the space of the bushing being too long for the thickness of the blade itself? I didn't see any oil impregnated bushings in the McMaster catalog that were the exact length to match the thickness of the PT blade.

If you notice, the bushing isn't wearing inside the oversized washer, but appears to be wearing where it fits inside the blade itself.

Maybe I misinterpreted your instructions how to do this all along?

So I need to change what I've done to use the thick washer, the oil impregnated bushing and a 5/8 ID washer?

 

[ponytug]

I was going to ask about the order of assembly. Not the best picture to illustrate, but there's a thick washer, then the bushing, and the oversized washer fits around the bushing. I thought the purpose of the large diameter oversized washer was to take up the space of the bushing being too long for the thickness of the blade itself? I didn't see any oil impregnated bushings in the McMaster catalog that were the exact length to match the thickness of the PT blade.

If you notice, the bushing isn't wearing inside the oversized washer, but appears to be wearing where it fits inside the blade itself.

Maybe I misinterpreted your instructions how to do this all along?

So I need to change what I've done to use the thick washer, the oil impregnated bushing and a 5/8 ID washer?

What perhaps isn't 100% clear on the bolt assembly to the right in the my photo above is that it is a 5/8" flange head bolt, a split ring lock washer, and then the large USS oversize washer.

Given the way that your bushings are wearing, I think that your blades aren't being well confined vertically, causing them to move up and down, prematurely wearing the bushing (which does need grease). I could be wrong. The blades should be free enough to move easily 360, to get out of the way of fixed objects like rocks, stumps, and other obstructions, without too much vertical movement.

All the best,

Peter

 

[2manyrocks]

I agree there's too much vertical play, either due to the assembly I've used and/or premature wear in the parts.

To clarify the assembly I've used that seems to differ from what I now think you are using, the first photo shows the original blades that came with the PT and the bushings from McMaster. The McMaster bushing is longer in depth than the OEM bushing, and to make up for it, it sits inside a washer acting as a spacer.

The second photo is a side by side comparison of the bushing setup from McMaster versus a new bolt, washer, and bushing that Terry sent me from PT.

Third photo is same side by side comparison but with the bushings shown separately to show the difference in their depth and the difference in the washers. The PT bolt is shorter and therefore there is no additional bushing acting as a spacer.

The new bushing from PT will spin with some light resistance inside the new PT blade.

Terry didn't send any lock ring washers with the new PT bushings. Am I supposed to use a split ring lock washer? If I correctly understand the way you are assembling your parts, it looks like the split ring and washer are there just like a normal bolt/lockring/washer assembly intended to hold the bolt tight.

But if I am correct that you are using the same bushings as I am from McMaster, they are longer than the OEM so how are you compensating for the difference in their length?

 

[ponytug]

I think either my blades are thicker, or the bushings are thinner. In your photos, it does look as if your blades need an over sized washer to account for the thicker bushings.

All the best, Peter