It's The Little Things That Make The Biggest Difference

[machinist@large]

About 2 weeks ago, I noticed all the "nylon" bushes holding the engine plate to the frame of the mower were all but gone, only one survived almost intact...

I started investigating & found that the cheapest I could replace them was over $40 (cheapest in AU was $4.85 each plus postage & I need 7 of them); I found a place that sells polyurethane rods for around $30 so, I ordered one then set to work on the lathe to carve out the desired size & shape; one tool (parting blade) did the lot in a lottle over an hour...

Polyurethane comes in different densities, which can seriously affect the lifespan of the part in a given application. And without a durometer, comparing type's can be a .

Since you said it takes 7 of them, I'm guessing that the load is pretty well distributed. The only concern I have is from the appearance of the shavings you wound up with. That suggests that they sold you a pretty soft grade. If it compresses the same as the original using a pair of plier's you'll most likely be good to go. Just keep an eye on them.

If you need to machine polyurethane (or any grade of soft plastic), the colder you can chill it, the better. The freezer is a good start, a cooler full of dry ice is better. My personal favorite is liquid nitrogen; now you have something that machines like aluminum until it starts to thaw out.

The downside is you have to have the protective gear and the experience working with the stuff. Liquid nitrogen is not something to play with.....

Hmmmmm.....does that mean it took somewhere between a little and a lot?

Your ADHD is showing again Doug.......

 

[OzFab]

Hmmmmm.....does that mean it took somewhere between a little and a lot?

Sorry Doug, typo; edited...

Polyurethane comes in different densities, which can seriously affect the lifespan of the part in a given application. And without a durometer, comparing type's can be a .

The only concern I have is from the appearance of the shavings you wound up with. That suggests that they sold you a pretty soft grade. If it compresses the same as the original using a pair of plier's you'll most likely be good to go. Just keep an eye on them.

That's the best part, I didn't just jump in blind, I did my research

All the parts catalogues (local & international, including the MTD home site) list the replacements as "nylon" but, even I know, nylon is a lot harder (as in density)...

I first called & discussed the situation over the phone, then went & saw the same guy in person who was armed with a durometer; he measured the only original bush, which measured a little over 90; taking age & constant heating/cooling into account, we decided 90 duro polyurethane was the way to go

Since you said it takes 7 of them, I'm guessing that the load is pretty well distributed.

One corner has a steel locater bush under the plate, I machined a flat spacer with a smaller ID to match that corner...

The other 3 corners have one spacer under & one above the plate (as seen in pic 1 below), with a 1/2" tall & 1/2" diameter anti crush spacer in the centre (as seen in pic 2 below)

If you need to machine polyurethane (or any grade of soft plastic), the colder you can chill it, the better. The freezer is a good start, a cooler full of dry ice is better. My personal favorite is liquid nitrogen; now you have something that machines like aluminum until it starts to thaw out.

The downside is you have to have the protective gear and the experience working with the stuff. Liquid nitrogen is not something to play with.....

That would've been helpful yesterday, thanks Pat

No, seriously, it wasn't too bad; the hardest part was drilling out the centre but, again, once I figured out how, it was relatively easy...

I don't think I'll be using liquid nitrogen any time soon

 

[machinist@large]

.......I don't think I'll be using liquid nitrogen any time soon

That would be great. While I'm glad that I have the knowledge to use it, I'm still seriously not happy about the way I had had to learn it....

 

[OzFab]

looks like it's back to the drawing board; while mowing my grass last week, I noticed the chute was clogging around the low point so, it appears the existing chute needs some tweaking to allow for better flow... any ideas?

The biggest issue is the top of the chute needs to be low enough to sit under the axle casing when the cutting deck is adjusted all the way up while the bottom needs to have adequate ground clearance when the deck is all the way down... which leaves a rather small scope...

 

[OzFab]

Well, after completely rebuilding the chute with a wider exit, the same issue still exists the grass is still collecting in the red area in pic 3...

Once I discovered that, I decided to take another look at the original chute which is used without a catcher & noticed a "deflector" so, I though, "it can't hurt"... but, it didn't help either...

Then, while discussing the issue, I mentioned the possibility of maybe adding "wings" to the blade to create more wind, to push the cuttings harder & thought "the blade should already have such wings, which led me to check the blade...

Now to find a new blade...

 

[machinist@large]

Well, after completely rebuilding the chute with a wider exit, the same issue still exists the grass is still collecting in the red area in pic 3...

Once I discovered that, I decided to take another look at the original chute which is used without a catcher & noticed a "deflector" so, I though, "it can't hurt"... but, it didn't help either...

Then, while discussing the issue, I mentioned the possibility of maybe adding "wings" to the blade to create more wind, to push the cuttings harder & thought "the blade should already have such wings, which led me to check the blade...

Now to find a new blade...

You need a bagger/self mulching blade... I thought that that point had already been raised?????

 

[OzFab]

Not that I recall...

I've done some research & I have a guy on the job hunting down the necessary blade; I should know either way by tomorrow (Monday)...

 

[OzFab]

Well, because I'm impatient & needed to find out for sure before I lay out $40 for a new blade, I decided to get creative & weld new wings onto the old (existing) blade... with interesting results...

First, before anyone says "but the blabe is hardened steel", not any more it's not I wouldn't be surprised to know that this is the original blade, it's obviously seen better days &, with that in mind, I thought "what do I have to lose?"

I tried to make both wings as close to the same as possible & was surprised at how balanced the blade was; I also "sharpened" the leading edges as they were completely round

After fitting the newly "reconditioned" blade, I set off to cut some heave grass & it picked up just about every single blade The only time it faultered was when I hit a thick patch & was cutting a little low but, a second pass cleaned up that mess...

I'm now happy with the setup & would call it a success... at long last...

Oh, before anyone asks, yes, I do intend to buy a new blade, this just gives me a little time before I need to...

 

[machinist@large]

Well, because I'm impatient & needed to find out for sure before I lay out $40 for a new blade, I decided to get creative & weld new wings onto the old (existing) blade... with interesting results...

First, before anyone says "but the blabe is hardened steel", not any more it's not I wouldn't be surprised to know that this is the original blade, it's obviously seen better days &, with that in mind, I thought "what do I have to lose?"

I tried to make both wings as close to the same as possible & was surprised at how balanced the blade was; I also "sharpened" the leading edges as they were completely round

After fitting the newly "reconditioned" blade, I set off to cut some heave grass & it picked up just about every single blade The only time it faultered was when I hit a thick patch & was cutting a little low but, a second pass cleaned up that mess...

I'm now happy with the setup & would call it a success... at long last...

Oh, before anyone asks, yes, I do intend to buy a new blade, this just gives me a little time before I need to...

I'd get that new blade coming sooner rather than later. And keep the younguns away in case something let's loose. If you actually took the time to professionally rebalance it then you just upped the odds in your favor tremendously.

As for whether or not anyone mentioned mulching blades (I'm going to find your original build thread just to answer that question), I did reread what you've posted up in this one though.

Your post on 7/30/15, subtitled "Less is more", you added the part's diagram that you were using for reference. A more detailed read quickly answered a few questions. P/N's 52 thru 67 appears to be a four segment blade assembly, with #62 being one of the segments, with a clearly seen trailing edge lift wing. That fully back's your experiment, but begs the question of if the system is designed for double the lift and throw that you currently have with a one piece blade.

Right now, I need to go find your original build thread for this thing......

 

[machinist@large]

Well, after completely rebuilding the chute with a wider exit, the same issue still exists the grass is still collecting in the red area in pic 3...

Once I discovered that, I decided to take another look at the original chute which is used without a catcher & noticed a "deflector" so, I though, "it can't hurt"... but, it didn't help either...

Then, while discussing the issue, I mentioned the possibility of maybe adding "wings" to the blade to create more wind, to push the cuttings harder & thought "the blade should already have such wings, which led me to check the blade...

Now to find a new blade...

You need a bagger/self mulching blade... I thought that that point had already been raised?????

Not that I recall...

I've done some research & I have a guy on the job hunting down the necessary blade; I should know either way by tomorrow (Monday)...

Found it!!!!! In your original build thread for the mower,on 1/14/14, post #105, zbuck posted and described mulching blades, and how he felt that you needed one..... Now, if we had a tutorial on how to search, select, and post such link's for those of us who don't live our lives online, that would be great......

 

[OzFab]

I'd get that new blade coming sooner rather than later. And keep the younguns away in case something let's loose.

Will do...

There isn't usually any around when I'm using the mower but, again, will do...

If you actually took the time to professionally rebalance it then you just upped the odds in your favor tremendously.

By the time I pay to have it professionally balanced, I could probably buy 2 new blades

Found it!!!!!

You didn't need to do that, Pat; I wasn't doubting you, I simply didn't recall off hand but, then again, I sometimes have trouble recalling yesterday...

As for posting a link to a particular post (I assume that's what you're asking for), right click on the post # on the right (or press & hold if using a touch screen device) & select "Copy Link Location" then "paste" in your post I will look into creating a tutorial on the subject ASAP...

 

[machinist@large]

Will do...

There isn't usually any around when I'm using the mower but, again, will do...

That's a good thing. A ten inch diameter by 1/2 inch wide grinding wheel turning 3600 RPM blowing up in your face will scare the out of you with all the shields in place. That's being run by a 1HP motor. Add in your blade diameter × the deck RPM, and you can see why I might worry.....

By the time I pay to have it professionally balanced, I could probably buy 2 new blades

That was a minor jab hoping you had actually taken the time to try and balance it. It never ceases to amaze me just how people seem to fail to understand just what kind of forces are in play in these applications.....

You didn't need to do that, Pat; I wasn't doubting you, I simply didn't recall off hand but, then again, I sometimes have trouble recalling yesterday...

Tony, here's where I have to apologize for both of us. Whether or not you missed it, I remembered it in some form. If I had connected the dots sooner, I might have saved you some grief. The reason I posted that was as much to keep me honest as to give you information....

As for posting a link to a particular post (I assume that's what you're asking for), right click on the post # on the right (or press & hold if using a touch screen device) & select "Copy Link Location" then "paste" in your post I will look into creating a tutorial on the subject ASAP...

That would be awesome!!!!! Could you also add a free app full function 3D cad program that runs on the Android system that is fully compatible with whatever security protocols my employer uses??????

 

[OzFab]

That's a good thing. A ten inch diameter by 1/2 inch wide grinding wheel turning 3600 RPM blowing up in your face will scare the out of you with all the shields in place. That's being run by a 1HP motor. Add in your blade diameter × the deck RPM, and you can see why I might worry.....

Yeah, I'm always aware of situations like that; before my stepson or I cut my ex's grass I always tell my daughter to go & collect all the "bullets" from the jard

That was a minor jab hoping you had actually taken the time to try and balance it. It never ceases to amaze me just how people seem to fail to understand just what kind of forces are in play in these applications.....

I did my best & as I said, was pleasantly surprised with the result...

After making & affixing the first wing, I made a paper template to match the other end, I even used an adjustable square to match the angle correctly; then I did a quick, simple balance test before fitting it...

I realise that a few grams out of balance can create massive vibrations which can cause major damage to many associated parts...

That would be awesome!!!!! Could you also add a free app full function 3D cad program that runs on the Android system that is fully compatible with whatever security protocols my employer uses??????

Umm, no...

 

[machinist@large]

That would be awesome!!!!! Could you also add a free app full function 3D cad program that runs on the Android system that is fully compatible with whatever security protocols my employer uses??????

Umm, no...

Why do you insist on dashing my hopes like that!?!?!?!?!

 

[OzFab]

I discovered a small issue with the mower yesterday; the inside edge of the chute sits too low & drags through the grass, need to sort that ASAP...

Anyhoo, onto the next project...

Some time ago, I bought a bunch of "Little Wonder" lawn edgers & refurbed one for my brother, now it's my turn...

Let me be clear, this is not a resto, simply a build, piecing together & modifying various parts to make the unit functional, I may clean up various parts over time but, for now, that's not the main objective...

The main objective is to fit the existing engine which came with the edger (a Honda G100) back onto the base; this was made difficult as, to save time, I used the original engine mount on my brothers edger, now all I have are two pressed steel "brackets" to work with...

These machines have a brace which connects the handle to the engine, keeping the handle rigid to the base; this brace also acts as a metering device, determining where the engine sits; with the pressed steel bracket & handle brace mounted in place, I then determined I needed a further 1/4" between the engine bracket & the base, simple enough, a length of 1/4" flat stock will do the trick but, none of the holes in the engine bracket line up with the base...

The first thing to do was stretch the bracket by 1/2", elongate the holes where it mounts to the engine, then extend the tabs on one side & shorten the tabs on the other side; simply spinning the bracket 180° wouldn't work (I checked), the holes were even further off...

After around 6 hours of cutting, welding, grinding & drilling, everything bolted together almost perfectly... except for the thread where the handle brace mounts, the thread was stripped out so, I retapped it from 8mm to 10mm...

All it needs now is a new blade & it'll be just like a bought one... except for all the rust

 

[machinist@large]

If it run's like the one you put together for your brother, you should be in like flint. The only question I have is whether or not it would have been easier to fabricate the mount from scratch, rather than modify what you started with...

If you started with what you had, then you did what you had to; anyone claiming that I was dissing your work can take a hike....

 

[landuse]

Nice work Tony

 

[OzFab]

If it run's like the one you put together for your brother, you should be in like flint.

I have an old, worn out cutting blade; once it was all assembled, I tried it our, started first pull after sitting for months & cut as well as can be expected, considering the condition of the blade...

The only question I have is whether or not it would have been easier to fabricate the mount from scratch, rather than modify what you started with...

Honestly, I considered it, that was my original plan; the biggest issue is that the distance between the base of the engine & the base plate is almost 1", meaning the simplest plan called for 1/2" flat stock;
1. my small welder can't weld 1/2"
2. all the bolts would need to be replaced with longer ones, increasing the shear factor
3. ATM, I'm somewhat broke so, I had to work with what I had available...

So, all things considered, I concluded that this was my best course of action...

If you started with what you had, then you did what you had to; anyone claiming that I was dissing your work can take a hike....

All good, Pat, it's called "constructive criticism

 

[OzFab]

Well, I've been tinkering away for the past few weeks, I put the edger through its paces at home & then at a friends house, where it started surging; a quick carb clean sorted that issue...

While I was using it, I noticed the guard over the blade was... let's say, lacking in protection; it was completely open on the outside so, having another guard laying around, I remedied that situation by grafting the two together but, removing metal from each as to not make it too wide (although, it still is a bit wide)...

I also noticed that the shaft which holds the cutting head was somewhat worn, making the head move excessively so, I disassembled the whole assembly (that was fun) welded the worn area & machined it back down to original size as well as fixing a few worn teeth on the angle adjustment "gears"...

I also finally got around to making a new brake caliper bracket for my kart since my first attempt was destroyed...

The chute for the riding mower is still clogging though, I made a new deflector the other day, let's see how that works out...

 

[OzFab]

More pics...