Why did this handle break?

If you make the link work we are more likely to look.

As you write your message, highlight the word you wish to become the 'link'. Click on the link icon just above the message box (globe and chain symbol) type or paste the actual link address into the box marked URL: and then submit.

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Hmmm I'm too lazy to cut and paste your link, but kind enough to type out all this..

What a strange, but kindly cat I am

Del

If you make the link work we are more likely to look.

As you write your message, highlight the word you wish to become the 'link'. Click on the link icon just above the message box (globe and chain symbol) type or paste the actual link address into the box marked URL: and then submit.

Alternatively post the pics direct by clicking on the camera icon.

All good suggestions, if one has a PC, but I'm using a Mac, consequently, I'm forced to use the intermediary site... flickr. Sorry.

Ok I'll get off my furry ar$e and have a butcher's.

Del

Sorry to hear you fell for the whole MAC thing.

Had a look, typed a reply, it dissappeared so here's a shorter one just in case the real one comes through.

Focusing on the RH side beside the bolt, looks to be a progressive tear.

If you look at that break closely, is there any evidence of corrosion on the break surface? If so, then there has been a progressive failure at that location.

Otherwise it's either cycle fatigue from being "loaded" each time the cater was emptied or excessive force. (maybe your grass clippings are heavier than the neighbours.)

Hope it's not too expensive to replace.

[p[]If you look at that break closely, is there any evidence of corrosion on the break surface?

Thanks for your reply.

There appears to be rust on one side of the break, indicating that it was the first to fatigue and fracture.

I won't bother to replace the handle/lever. I'll just redesign the method of attachment of the handle to the lever, and make a unit that will never fail again (which could have and should have been accomplished when the bagger was manufactured).

It just looks like bad design to me..

There is very little meat left on that rod once the hole is drilled through it, and there is a lot of leverage.

It could have been better made of plate or laminated plates to give a bigger area wher the hole goes through.

If I got a replacement part I'd weld a pice of bar or plate up either side of the hole to beef it up.

(Or maybe replace the hole with one made of stonger material )

Del

For all the lazy cats out there!

There's not a lot of meat on that! What was the orientation? Looks like bad design to me! Is that the hole it passed through in the handle? If so, that bell end will localize the stresses directly at the point it broke!

There's not a lot of meat on that! What was the orientation? Looks like bad design to me! Is that the hole it passed through in the handle? If so, that bell end will localize the stresses directly at the point it broke!

Thanks for grabbing the photo... wish I could do that!

Yes, the bolt passed through the hole in the handle, securing it (ha, ha) to the lever. The bolt was aligned in the direction of travel of the handle. I assume someone thought it a good idea to make those slots in the handle, so the two sides would be drawn together by the bolt to produce a nice, snug fit.

You are right, in that there is not a lot of meat on the lever. Drilling a slightly oversized hole in the 9/16" diameter lever for the 1/4" bolt to go through doesn't leave much left with which to couple the 20" long handle tube to the lever.

Apparently, the designer or assembler thought a 1/4" bolt was needed to secure the handle to the lever, so if one wanted to lift the rear end of the mover by the handle, they could simply attach a hoist to the handle and lift away.

These kinds of little failures just drive me bananas, and they happen all the time. Without the handle, dumping of the bagger becomes impossible. So, mowing becomes impossible. I slipped a square tube over the broken end of the lever, still attached to the bagger, and finished the yard.

Bad design really pisses me off.

We just bought a new dishwasher..the old Bosch one had given up the ghost and had some real design flaws..

You know what? We bought another Bosch because every design flaw I'd spotted had been rectified . Plus a couple of other improvements.

It is nice to see product improvement in action.

Del

I bought a Bosch fridge freezer and within a week the fridge handle broke off! They replaced it free of charge after about three weeks! Great I thought! Wrong, a few days later, the same thing happened, It broke! Now I have a fridge without a handle but with some cleverly placed fridge stickers to cover the holes! Bosch in my book means Botch! Sorry Del, Bosch don't cut the mustard with me any more!

Yeh..that's what I thaught until I saw the latest one...the better quality stuff is almost twice the price...The packing order was basically.

1. Dirt cheap made in China with no jets in the top of the compartment.
2. 50% increase, European with jet in the roof for added cleaning.
3. 75% increase Mielle with additional rotating arm in the roof and built more solid.

The daft thing..the deal breaker was ... could Mrs Cat stack our cereal bowls in the rack! So one of the cheaper parts makes all the difference to the customer...maybe the marketing guys should take notes (nah that won't happen..they are too busy off on their junkets)

Del

These usually calm my cat down for awhile.

Ah, I see the problem.

The coin probably got stuck in there and widened the slot, causing the two sides to flare out.

I suggest you put the coin in your pocket.

The metal looks crystallised so the failure was from cheap metal or metal that was too hard for a poor design. Replace it with better metal and a smaller screw. Take a file and remove the sharp edges around the hole to un focus the stress. If you temper the metal temper it like a spring.

Tempering by color of .02 carbon or higher steel. Heat to a uniform light cherry red heat glow and quench. slowly reheat and at the first sign of straw color move back and forth until a light straw color is uniformly drawn over the part, keep heating slowly until the part is uniformly bronze(light straw→dark straw→to bronze color). Don't quench but let the part cool at room temp for an minute or two. While the part is still fairly hot heat beside the bolt hole so the area close to bolt hole turns to a peacock to a dark purple. When this color spreads over the hole area remove from heat and cool. It is now at a spring hardness at the hole area and should be very tough.

Brad

Someone who knows his colors in metal!

I lost my book (RN) on the subject years ago, and have regretted it ever since.....

Brad-UV, You have the temper colors right, But with no evidence that this was ever austenitized and Quenched, Tempering will do nothing.

.02 wt% carbon is insufficent to respond to quenching or tempering.

Nobody can make .02 C steel behave like a spring.

This is likely .18 wt percent Carbon if US manufacture- grade 1018. Very little machining, and low forces expected in application. Again, insufficient Carbon to heat treat. If the mower builder is a reputable company, it will be grade 1018; if its a cheapie cheapie, they may have gone even lower Carbon with grade 1008, out of rods...

If it 1045 or higher, could harden somewhat, but will not through harden.

You have the temper colors right, but they are not applicable to this likely cold drawn only no heat treated rod. Who would heat treat a handle? Why?

The failure is transverse to rod longitudinal axis and to the through hole, The circumferential groove is likely stress nucleation site.

Andy Germany, If you would like a temper color .pdf Send me a private email and I'll get one scanned for you tomorrow.

milo

Hey Milo,

I doubt it was ever anything but garbage cheap metal. I'd just fabricate a new one out of good metal, because the metal in the old one probably isn't worth the effort to repair.

Above I'm sorry I missed the percentage high carbon steel is 0.6-1.9% (I have a ref. for 0.2% but if I'd have thought about it I'd know that's not right). That's what I get for pulling the numbers out of my #$$, I mean head.

Also depending on the steel you use, what quenching medium you will need to use or vice versa.

I'm in the process of building a new forge, I'll take some pictures and when I'm done and post them. My Grandpa started me a the ripe age of nine at the forge helping to rebuild pitman arms. I still use some of his tongs.

Brad

Thats cool to have learned to forge from your Grandpa. My grandpa was a catcher on a two high hand mill and had tongs bigger than I was tall at age 9. Those guys had real strength!

I forged a couple of knife blanks once on a friend s outfit, it was definitely a different art than machining! A couple of my plant bracket hangers are still in use at my dads retirement home down in Florida.

I didn't decarburise the steel too badly, though, which was my only claim to success.

milo

Those guys had real strength!

That's no lie. I must have been about twelve when my Dad and Grandpa had to turn the pins in Grandpa's Case caterpillar tracks because the pins were getting too worn. So Dad and Grandpa would drive them out while I held the drift punch, turn the pin over and drive it back in. It was an all day job, I was beat just holding the punch for 12 plus hours. Dad was giving Grandpa a hard time at the last cause he was getting tired. (go figure) As me and Dad were driving down the highway that night it dawned on my Dad that Grandpa had matched him blow for sledge hammer blow and he was 60 years old. I'm harder than most and I couldn't do it now. I still have a ways until sixty.

Brad

Yes please. Check your email sometime.

low strenght rod meets operator who wants to empty system only once when it would have been emptied 4 times?

Is this the possible winning answer?

I liked your answer as a completed scenario. I felt the drama of mowing the lawn. Sometimes I wonder if the designer of a particular machine has ever actually used it themselves. It is to be expected that the actual operator would not feel any need to empty the clippings bag until it was full, and the handle ought to be robust enough to match to the typical weight of the bag accounting for moisture. In my lawnmowing career I have never used a machine with a bag. I have imagined things to do with grass from a bag. Cows goats and sheep, eat grass. Would be cool to make a lawnmower that wrapped the grass up in bales they could sell to farmers, or other buyers. The calculated production versus income from a particular sized lawn would dictate worth of the project, though the distribution system indicates onsite use, considering lawns, as opposed to farms, which have machines to do this. Possibly it would be best all around if the lawnmower that has a bag or baler was run from the methane possible to make from the grass? This would be the Grass Gas Integrated Lawnmowing System. Soon from Sears!

P.S. I'm writing on my wife's MAC and for some reason my paragraph and line breaks are ignored, and I can't locate the spellcheck. The Lawn Powered LawnMowers Time Has Come!

On topic:

The gearstick on older Mercedes vans used a similar connection method - so after about 80k miles the stick would break off, leaving a stump on the floor which could only access 2nd and 3rd gears..... Now rectified:

Off topic:

Not had any problems with my Mac - using Firefox rather than Safari.

Thanks for the Firefox tip; I'll check it out.

Sorry, no win this time, dadw5boys,

Bagger only holds a bushel of clippings... grass was dry - not much weight. But, when the operator reaches back to dump the bag, it is impossible to see if all of the grass has evacuated, so it's necessary to bump the handle a few times to coax all of the grass out.

When we're done with this thread I'll post a rundown of why the handle/lever connection failed and the simple solution, which should have been used during manufacture.

It is easy to say why it failed.

They drilled the hole for the bolt too fast overheated the rod in that spot weaking the entire leverage design.

Well that is my take the whole thing.

Well, I don't get the arrangement yet, but the bar piece shows no signs of ductility, looks like a fatigue failure. (appearance of "beach Marks" On right side face)

The belling on the "pipe or handle" appears to be the result of that material having exceededd yield strength due to greater than design force to actuate the mechanism.

My guess is that some portion of the dump mechanism is not working (frozen bearings etc,) causing Handle to be used more like a "cheater" LEver arm Than merely actiuating function.

Fatigue crack on bar may have been initiated by the groove or scratch that seems apparent on the OD, though witness marks on the hole upper right side may also be pointing to origin. The distortion of the hole indicates again severe over force conditions/abuse.

milo

I feel (as many) that the 1/4" bolt needs a much too big a hole. Scroll pins take up far less space and are exceedingly strong, if needed, even two scroll pins, someway apart and at 90° to each other might be a good idea.

Thickening of that area is needed if a 1/4 " bolt is to be reused I feel, as others have already mentioned.

Better quality steel is a further option as well.

I know there's all kinds of fancy-pants explanations for the handle failure. But all of these beloved engineers are missing one important fact...you borrowed it from your neighbor. Otherwise it would never have broken.

Well... I didn't really borrow it. I was mowing the neighbor's yard with her mower, but I git yer drift.

of the forge mentions, My brother once said you can make a pretty good crucible from old brake drums.