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Didn't expect this: New FCF72
- Thread starter SamAdams
- Start date
seber
Well-known member
Hard to tell but I bet the undercut is 3/8 diameter. If so, there is no reduction in strength as the torsion factor is to the smallest radius.
Help me understand. The anvil measures 3/8" along all 4 sides. This undercut is obviously smaller but I don't have anything to get in there to measure. Thanks for the reply by the way!Hard to tell but I bet the undercut is 3/8 diameter. If so, there is no reduction in strength as the torsion factor is to the smallest radius.
a weak point to save the handle from bending? seems crazy idea
Could be I guess. It wouldn't make sense to be a weak point to protect the innards as everything is replaced in a rebuild kit. My question is because I thought I'd seen these before with the anvil profiled like a normal ratchet, and I wondered why it changed (if it did). My memory could be wrong.a weak point to save the handle from bending? seems crazy idea
WWheeler
Well-known member
Perhaps in testing with a 'big F'in pipe on it' level of torque setting the pawl/gear/ratchet body was sustaining damage which was found to be more expensive to fix than the drive tang or would cause the ratchet to fail suddenly risking user injury or cause damage more so than if the drive tang were designed to fail by twisting under a lower torque ( that was still far and above what anyone would be able to put on it without putting a 'big F'in pipe on it').
Seems like a good idea to me.
That is a 3/8" anvil with 1/4" guts model ratchet, so they probably reduced the 3/8" square drive at the base to make the square drive the weakest link in the ratchet mechanism, just like it is for their regular sized 1/4" drive and 3/8" drive ratchets. That way, all current Snap-on ratchet designs fail at the square drive before anywhere else. Yes, almost everything is changed out in a rebuild kit, but an anvil twist failure is more of a slow controlled failure and can often be felt by the person cranking on the ratchet before it snaps because you will feel the square drive yield a little bit before snapping if it is heat treated properly. An internal gear failure is often sudden, thus more likely to injure a person when it happens and give no warning.
Internal ratchet failures could also potentially damage a chromed surface inside the ratchet depending on how the mechanism fails. The underside of the coverplate could also become damaged from time to time. Damage to a chromed surface inside the ratchet would be unfixable and coverplates are still available individually as far as I know, but they aren't included in the standard rebuild kits.
It's also a good visual reminder that the Snap-on nano style ratchets need to be held to 1/4" drive torque standards even though they are 3/8" drive.
My 2 cents.
That is a 3/8" anvil with 1/4" guts model ratchet, so they probably reduced the 3/8" square drive at the base to make the square drive the weakest link in the ratchet mechanism, just like it is for their regular sized 1/4" drive and 3/8" drive ratchets. That way, all current Snap-on ratchet designs fail at the square drive before anywhere else. Yes, almost everything is changed out in a rebuild kit, but an anvil twist failure is more of a slow controlled failure and can often be felt by the person cranking on the ratchet before it snaps because you will feel the square drive yield a little bit before snapping if it is heat treated properly. An internal gear failure is often sudden, thus more likely to injure a person when it happens and give no warning.
Internal ratchet failures could also potentially damage a chromed surface inside the ratchet depending on how the mechanism fails. The underside of the coverplate could also become damaged from time to time. Damage to a chromed surface inside the ratchet would be unfixable and coverplates are still available individually as far as I know, but they aren't included in the standard rebuild kits.
It's also a good visual reminder that the Snap-on nano style ratchets need to be held to 1/4" drive torque standards even though they are 3/8" drive.
My 2 cents.
Last edited:
neophyte
Well-known member
The 90 degree corners on the square drive would be subject to mire torsion then the rest of the steel from which the part is made.
Over time, this could cause stress fracturing at the corners.
Milling the round groove might eliminate the extra corner stresses.
There may also be a differentially tempered zone below the square section, allowing the anvil to absorb the extra torsion, similar to screwdriver bits made for impact use.
This is just a guess at a possible reason.
The idea that that the groove may be there to prevent mire significant damage yo other oarts also seems plausible.
Over time, this could cause stress fracturing at the corners.
Milling the round groove might eliminate the extra corner stresses.
There may also be a differentially tempered zone below the square section, allowing the anvil to absorb the extra torsion, similar to screwdriver bits made for impact use.
This is just a guess at a possible reason.
The idea that that the groove may be there to prevent mire significant damage yo other oarts also seems plausible.
No, the anvil could extend fully to the gear without the taper and still fit. The cutout curves back to the diameter of the anvil at a point that sticks out of the ratchet a good millimeter, so there's no obstruction as the gear turns. If that made sense.Maybe gear needs to be smaller to fit the compact body so they needed to taper the anvil out to hit 3/8? Just a guess.
That makes a lot of sense to me at least. Thanks!Seems like a good idea to me.
That is a 3/8" anvil with 1/4" guts model ratchet, so they probably reduced the 3/8" square drive at the base to make the square drive the weakest link in the ratchet mechanism, just like it is for their regular sized 1/4" drive and 3/8" drive ratchets. That way, all current Snap-on ratchet designs fail at the square drive before anywhere else. Yes, almost everything is changed out in a rebuild kit, but an anvil twist failure is more of a slow controlled failure and can often be felt by the person cranking on the ratchet before it snaps because you will feel the square drive yield a little bit before snapping if it is heat treated properly. An internal gear failure is often sudden, thus more likely to injure a person when it happens and give no warning.
Internal ratchet failures could also potentially damage a chromed surface inside the ratchet depending on how the mechanism fails. The underside of the coverplate could also become damaged from time to time. Damage to a chromed surface inside the ratchet would be unfixable and coverplates are still available individually as far as I know, but they aren't included in the standard rebuild kits.
It's also a good visual reminder that the Snap-on nano style ratchets need to be held to 1/4" drive torque standards even though they are 3/8" drive.
My 2 cents.
Thanks for addressing the milled corners. I noticed them but didn't pay much attention. They do seem like stress relief cuts.The 90 degree corners on the square drive would be subject to mire torsion then the rest of the steel from which the part is made.
Over time, this could cause stress fracturing at the corners.
Milling the round groove might eliminate the extra corner stresses.
There may also be a differentially tempered zone below the square section, allowing the anvil to absorb the extra torsion, similar to screwdriver bits made for impact use.
This is just a guess at a possible reason.
The idea that that the groove may be there to prevent mire corners. damage yo other oarts also seems plausible.
2ndGearRubber
Well-known member
The undercut on the 3/8 in 1/4 bodies is a new safety addition. Apparently the 1/4 body itself can fracture and break before the anvil shears in some applications.
The older units of 3/8 in 1/4 body did not have this. They added this maybe 6 months ago?
The older units of 3/8 in 1/4 body did not have this. They added this maybe 6 months ago?
Great analysis - makes total sense.Seems like a good idea to me.
That is a 3/8" anvil with 1/4" guts model ratchet, so they probably reduced the 3/8" square drive at the base to make the square drive the weakest link in the ratchet mechanism, just like it is for their regular sized 1/4" drive and 3/8" drive ratchets. That way, all current Snap-on ratchet designs fail at the square drive before anywhere else. Yes, almost everything is changed out in a rebuild kit, but an anvil twist failure is more of a slow controlled failure and can often be felt by the person cranking on the ratchet before it snaps because you will feel the square drive yield a little bit before snapping if it is heat treated properly. An internal gear failure is often sudden, thus more likely to injure a person when it happens and give no warning.
Internal ratchet failures could also potentially damage a chromed surface inside the ratchet depending on how the mechanism fails. The underside of the coverplate could also become damaged from time to time. Damage to a chromed surface inside the ratchet would be unfixable and coverplates are still available individually as far as I know, but they aren't included in the standard rebuild kits.
It's also a good visual reminder that the Snap-on nano style ratchets need to be held to 1/4" drive torque standards even though they are 3/8" drive.
My 2 cents.
ronkz650
Well-known member
They claim the ratchet will do 90ft/lb, so a 6" handle length can take 360lb of pressure which is utterly impossible. I guess the design is plenty strong with the reduced diameter is all that matters.
2ndGearRubber
Well-known member
The issue was head failure. The head could split around the gears. Causing FOD concerns plus an erratic failure mode. My understanding was this was not the typicaly failure mode, but they were concerned enough.
Guys need to consider, these head kits are also being used to make Franken-ratchets in any 1/4 ratchet snap on sells. Add a 12" handle and quick shock loading, and lots of force can be produced.
Guys need to consider, these head kits are also being used to make Franken-ratchets in any 1/4 ratchet snap on sells. Add a 12" handle and quick shock loading, and lots of force can be produced.
Shoreline_
Well-known member
Mine does not have that. Date code also 2022. But it's not a flex head.
FSUwelder1212
Well-known member
- Joined
- Jul 9, 2013
- Messages
- 149
Interesting, I would be willing to bet they are doing this to curb warranty costs, if the anvil shears a rebuild kit is alot cheaper than a whole new ratchet if you bend the body. This is a new addition, my older FC72 doesnt have it, and I just recently swapped a FC72 rebuild kit that didnt have it into a THLF72. it could also be a safety thing as you have people like me frankensteining these kits into ratchets snap-on never intended.
VolvoRyan
Well-known member
Seems a smart thing to do for the 3/8" in the 1/4" thing.
I recently messed up something in one of my compact ratchets. It's easy to get into tugging on these like it's a proper 3/8" ratchet when it's really a "convenience".
-Ryan
I recently messed up something in one of my compact ratchets. It's easy to get into tugging on these like it's a proper 3/8" ratchet when it's really a "convenience".
-Ryan
purplezr2
Well-known member
This, I broke the body on mine. I was being dumb, had a 17mm socket in a tight spot I was using it for. Exceed the capacity of the ratchet.....The undercut on the 3/8 in 1/4 bodies is a new safety addition. Apparently the 1/4 body itself can fracture and break before the anvil shears in some applications.
The older units of 3/8 in 1/4 body did not have this. They added this maybe 6 months ago?
Whew! At least my memory was correct. Thanks for this info.The undercut on the 3/8 in 1/4 bodies is a new safety addition. Apparently the 1/4 body itself can fracture and break before the anvil shears in some applications.
The older units of 3/8 in 1/4 body did not have this. They added this maybe 6 months ago?
It's too precise to be an error. 2ndGearRubber and Tools4Me seem to have the answer, but thanks for the reply.Has you asked Snap On or your dealer about it? Could it be something that got passed QC. I've never seen an undercut anvil.
The issue was head failure. The head could split around the gears. Causing FOD concerns plus an erratic failure mode. My understanding was this was not the typicaly failure mode, but they were concerned enough.
Guys need to consider, these head kits are also being used to make Franken-ratchets in any 1/4 ratchet snap on sells. Add a 12" handle and quick shock loading, and lots of force can be produced.
This is obviously the answer. They purposely reduced the strength of the anvil, so that it would fail instead of the entire head or ratchet. SO wants the warranty failure to be an inexpensive rebuilt kit and not an entire $100+ ratchet. And they're right to do this.
I found it interesting in one of Clientgraphics’ videos that the Snap On he tested sheared the anvil off before the ratchet handle bent. While some of the others reached higher torque before they failed, either the handle bent or the flex joint snapped and the the ratchets were useless afterwards.This is obviously the answer. They purposely reduced the strength of the anvil, so that it would fail instead of the entire head or ratchet. SO wants the warranty failure to be an inexpensive rebuilt kit and not an entire $100+ ratchet. And they're right to do this.
I found it interesting in one of Clientgraphics’ videos that the Snap On he tested sheared the anvil off before the ratchet handle bent. While some of the others reached higher torque before they failed, either the handle bent or the flex joint snapped and the the ratchets were useless afterwards.
If you watch the Project Farm destruction videos, the failure mode of the better, non-flex head ratchets is almost always the anvil. This is why breaker bars have mostly become useless today- they have the same anvil, and will fail at about the same torque as a ratchet with an anvil of the same size, material, and hardness.
What SO obviously did with this is to undercut the anvil to reduce the polar second moment of inertia, J, (the torsional strength area value) of a 3/8 anvil so that it approximately equals that of a 1/4 anvil. I don't need to talk to someone at SO to confirm this, this is obviously the intent.