Export thread

We change blades on two Tiger Cats daily. Some times more than once depending on the day and grass.........

We change them with a cordless impact and a floor Jack. On a few occasions we have had a blade that we can not remove. Impact won't break it loose. Cheater bar on a socket with a wrench fouled inside the deck on the bottom as a back up will some times get it to break. Yesterday we had to take a 1/8" blade on a 4" side grinder and cut the bolt off right at the bottom of the nut to get it out.

This was actually the second bolt we have had to do that to this year.

Have any of you had this problem? What did you do to rectify it.

Seeing you really don't want to use heat in that area because it would be bad for the bearing and seals. What I use is what they call a air chisel or air impact hammer. I install a very dull chisel bit and hammer on the side of the frozen nut. This will loosen the nut. It works for me but also remember you get what you pay for when buying a air impact hammer.

reynoldston said:

Seeing you really don't want to use heat in that area because it would be bad for the bearing and seals. What I use is what they call a air chisel or air impact hammer. I install a very dull chisel bit and hammer on the side of the frozen nut. This will loosen the nut. It works for me but also remember you get what you pay for when buying a air impact hammer.

Click to expand...

For us working in the field mostly it was more practical to just whack the bolt off and put a new one in. Those bolts are not that expensive and the cost of the bolt quickly offsets the down time. I am just curious what causes this to happen from time to time.

If the impact won't remove the bolt, how did you get the threaded portion out after you cut the head off?

If it comes out freely at that point, I'd say you're tightening them way too tight.

jekjr said:

For us working in the field mostly it was more practical to just whack the bolt off and put a new one in. Those bolts are not that expensive and the cost of the bolt quickly offsets the down time. I am just curious what causes this to happen from time to time.

Click to expand...

I am in the repair trade. You must be talking about the cap screw that go's through the spindle and the nut that holds the blade on style. Yes I have found some of that style very tight and hard to remove the nut. My self when that happens I use a 3/4 ratchet wrench with a long bar and have never found one that didn't come loose yet. Just how do you whack that large bolt off with? As I recall its a 5/8 or larger bolt. To me it would be easier just to split the nut or use the air chisel to loosen the nut. You have your ways and I have mine.

First, the bolt tightens due to the resistance of the blade going through the grass , the longer the grass the tighter the blade will become. I have to cut a few off each season so you are not alone.

I ended up with a 1500 ft lb air impact hammer to do this job.
Not cheap , around $ 600 Aus but worth it in time saved.
Even with this gun I still have to cut one off occasionally.
If you do this job daily then get some tools made to do the job.
A block of hardwood with a notch in one end deep enough so it can not easily fall off the blade which is the right length to brace the blade against the deck and a deep impact socket on a 4' breaker bar should do the job or better still a 6' breaker bar.

In the field van I keep a 3/4" standard socket set , a 4' breaker bar ( also 3/4" ), a few blocks of hardwood and a scissor jack.
The jack goes between the blocks of hardwood to make the distace correct to lock the blades.

A customer uses a block of hardwood with a slot cut into one end to fit the blade and a V notch on the other which slots over a spindle . This locks the blade against the adjacent spindle
To turn the nut he uses a podger ( slogging spanner ) and a very long bar, around 6' foot and that turns the nut with very little force.

Either overtightened on not tight enough.
75 FTLBs dry is the torque spec.
I understand your need for a quick blade turnaround, but this is when things can get problematic.

I am not a pro and do not handle more than one rider...But ignoring the tensile strengths of bolts and their required torque is asking for trouble. Unless you have an air hammer torque wrench with adjustable settings a la NASCAR you do not really know if you are properly stretching , or overstretching the bolts. This is further aggravated by any habit of applying anti- seize or even engine oil as a lubricant without making downward adjustment to the torque settings. A "dry" bolt as described by Mackie is the baseline torque called out in any factory manual. Spark plugs with galvanized threads are "lubricated" by the galvanize material and additional lube should lower the torque applied. Something like 70% of the torque applied is to overcome the bolt head shoulder. There is a chart in this forum with torque settings and lubricant adjustments.

motoman said:

I am not a pro and do not handle more than one rider...But ignoring the tensile strengths of bolts and their required torque is asking for trouble. Unless you have an air hammer torque wrench with adjustable settings a la NASCAR you do not really know if you are properly stretching , or overstretching the bolts. This is further aggravated by any habit of applying anti- seize or even engine oil as a lubricant without making downward adjustment to the torque settings. A "dry" bolt as described by Mackie is the baseline torque called out in any factory manual. Spark plugs with galvanized threads are "lubricated" by the galvanize material and additional lube should lower the torque applied. Something like 70% of the torque applied is to overcome the bolt head shoulder. There is a chart in this forum with torque settings and lubricant adjustments.

Click to expand...

Doing up is not the problem.
It is the undoing that is giving the OP grief.
FWIW I alway use a tension wrench for blades without fail.
It is my comeback should one ever come adrift & I get sued.
Even so most of the mowers from my commercial customers that I am the only parson who normally works on them require a massive amount of force to undo the blade bolts because they self tighten during use.
They are designed to do just that which is why rear discharge decks with counler rotating blades use a Left hand thread on the left cutting blade.

cpurvis said:

If the impact won't remove the bolt, how did you get the threaded portion out after you cut the head off? If it comes out freely at that point, I'd say you're tightening them way too tight.

Click to expand...

On a Scag the bolt goes all the way through with a nut on top.

When we run into this issue we take a 4 1/2" side grinder with a wafer thin blade and just cut it off. It probably takes two minutes or so to cut it off. A bolt is cheap compared to down time and/or labor. We have only had to do that twice this year.

Years ago works on a Ferris mower that had the same type of bolt all the way through the spindle with nut on top. Could put the nut on finger tight, and when it would come in 3-4 weeks later for blade sharpening it would take a 1600 ft/lb 1" impact to remove the nut. the 3/4" 900 ft/lb wouldn't budge them.

ILENGINE said:

Years ago works on a Ferris mower that had the same type of bolt all the way through the spindle with nut on top. Could put the nut on finger tight, and when it would come in 3-4 weeks later for blade sharpening it would take a 1600 ft/lb 1" impact to remove the nut. the 3/4" 900 ft/lb wouldn't budge them.

Click to expand...

Like I said some where above. We change blades on two identical mowers normally at least once a day. We use a 19 volt Craftsman 1/2" impact normally with great results. Probably once a week or so we have to pull out the breaker bar to get one to release. We have only had to cut two off this year. Cutting one off and putting a new bolt in is still cheaper than shutting my crew down for an hour or how ever long to get it out otherwise.

Use grade 8 bolts with antiseize compound on threads & a torque wrench & you should not have any more problems. Spindle bearings will be going sooner than later using impact wrench.

mechanic mark said:

Use grade 8 bolts with antiseize compound on threads & a torque wrench & you should not have any more problems.

Click to expand...

Beings we change blades daily, and it takes less than 5 minutes per mower with an impact, and we have only had this problem twice, verses what 15 minutes or longer per mower with a torque wrench I guess we will continue using the bolts we get from the dealer and if we have the problem again we will cut it off again and replace it.

For our crew time is $$$. Even cutting a bolt off once a month or two will only take 5 to 10 minutes longer.

It would not add 15 minutes to torque the blade bolts; you could torque a hundred bolts in 15 minutes.

The advice he's giving you would probably eliminate the problem entirely.

If you don't want to use a torque wrench, use a torque stick such as the tire shops use on lug nuts.

I don't change blades often, but I have had a problem getting the nuts loose even with a 600 FTLB impact wrench. I installed a flat washer under each nut and I haven't had the problem since. However I do have to replace the flat washers periodically.
The cordless impact tool will have an unknown torque output and the state of charge and battery condition will affect the torque output.
I don't recommend using anti-seize on the nut as this can easily promote an over torque condition.
I'm not sure why you change blades daily, but I have no idea what type of mowing conditions that you have to deal with.
At the end of your work week you must have one large pile of blades to sharpen!!!:confused2:

Mad Mackie said:

I don't change blades often, but I have had a problem getting the nuts loose even with a 600 FTLB impact wrench. I installed a flat washer under each nut and I haven't had the problem since. However I do have to replace the flat washers periodically. The cordless impact tool will have an unknown torque output and the state of charge and battery condition will affect the torque output. I don't recommend using anti-seize on the nut as this can easily promote an over torque condition. I'm not sure why you change blades daily, but I have no idea what type of mowing conditions that you have to deal with. At the end of your work week you must have one large pile of blades to sharpen!!!:confused2:

Click to expand...

we sharpen 10 or more sets of blades a week running two mowers and occasionally throwing a third in the mix.

I agree on the anti-seize. It has a place but not in this application to my opinion.

We change blades daily cause we run them a bunch daily. We cut 9 yards Friday and were home by 1:30 plus we had a lot of miles in between some of those.

We cut 70 or more yards on schedule from 15 or so acres down. We also cut numerous other yards for customers that want them cut them every once and a while when they can't get to them or have a mower broke down ect.

We live in South Alabama and cut a lot of Pensacola Bahia grass and it is brutal on blades. If you run a set 6 to 8 hours they are very dull. Dull blades do not leave a pretty clean cut......

Some times we change blades mid day also depending on conditions.

Gees,
I wish I could get you to talk some sense into some of my customers.
They ask me about sharpening when the cutting edge is about 1/2 the blade thickness then complain when I tell them they need a new blade.
After fitting I get "runs like new & cuts so much better" but when i suggest regular blade changes I might as well be speaking in Swahili.

bertsmobile1 said:

Gees, I wish I could get you to talk some sense into some of my customers. They ask me about sharpening when the cutting edge is about 1/2 the blade thickness then complain when I tell them they need a new blade. After fitting I get "runs like new & cuts so much better" but when i suggest regular blade changes I might as well be speaking in Swahili.

Click to expand...

I try to make ever yard look good enough that the person next door wants me doing theirs as well.

There are guys here that cut commercially that run them till the wings wear through without taking them off and then take them off and throw them away. When we are cutting the yard next door we often end up with their yards too. Then they get angry and wonder why.

I have not found anything sold LOCALLY TO ME that will cut with the quality of a Scag with fresh blades on it. Quality work and customer service makes a lot of difference on the lawn care service.

bertsmobile1 said:

Gees, I wish I could get you to talk some sense into some of my customers. They ask me about sharpening when the cutting edge is about 1/2 the blade thickness then complain when I tell them they need a new blade. After fitting I get "runs like new & cuts so much better" but when i suggest regular blade changes I might as well be speaking in Swahili.

Click to expand...

It is a proven fact that even duct tape won't fix stupid.

mechanic mark said:

. Spindle bearings will be going sooner than later using impact wrench.

Click to expand...

I just don't see your reasoning for this statement? over torqued? pounding on the bearing balls? must be a reason for saying it. I find the main spindle bearing failure is lack of lubrication.

I believe I first heard of the use of an electric impact wrench and anti-sieze on Zero turn mower blades on this sight but cannot be certain. Instead of speaking out of turn I decided to try it instead. The notion that an electric impact wrench incapable of applying the 75# dry torque would tighten them up mucho plenty if a little anti-sieze were applied made sense even though I have no way to measure it. And that they would still remove easily with the same electric impact wrench later.

Well, I have to sharpen my blades every 3rd mowing due to the sandy conditions here. Approximately every 18 hours of use and it has been much nicer since trying this. My far right nut (over the discharge) used to get so tight I needed a 3ft cheater on a 2ft breaker bar to get it loose. Now if yall could just come up with a way to have the underside of the deck get and stay clean. Tired of scraping and I have no vision of it ever being as clean as the day it was delivered. Should've waxed it then.

Junior, you've had some good replies and I'm going to add to the pile.

My son and I cut commercial for about 5 years. The last 3 years, we had a couple of Scags, a 52 inch V Ride and a Turf Tiger. My observations on blade bolts are:

1) You can torque them to whatever foot lbs. you want. When you hit that first patch of high grass, they are going to auto torque to 100 foot lbs. plus.
2) Some people like anti-seize compound, some hate it. I had several stuck bolts before I started using it. Since then, only one.
3) I like the idea of a slotted piece of wood to hold the blade in place if you need a breaker bar. I've never had a bolt that a half inch bar with a 3 foot pipe wouldn't loosen, but the 3/4 inch ratchet with longer bar sounds good also.