Judging Broach Marks

[Michael W.]

Re: Judging Broach Marks

My company uses broaching machines to cut inverted 'fir tree' shaped slots in the periphery of turbine disks. The corresponding turbine blades have a mirror-image base machined into them and the assembly is held together with rivets or plates prior to balancing.

The broaching blade is approx 30 feet long and cuts one slot per pass. As any sort of surface defect would be considerd a potential stress riser, there no residual broaching marks would be allowed. The blade gets changed out after each disk for a fresh one and the old is routed to the tool and die room for freshening up.

This info may be valuable in understanding whether fresh broach blades caused the marks on the engines or old dull ones.

[Jack H.]

Re: Judging Broach Marks

Gotcha, Boss! What keyed me is the ladder diagram for the thread. That shows whose particular post you clicked on to enter your message. From that it appeared you were commenting directly on what I'd written in the thread sequence...

That was why I asked what I did/said that was wrong. Now, I understand... You were simply commenting on the thread in general and not picking a particular line item in the thread to reply to. THANKS for the clarification!

[Timothy B.]

Re: Judging Broach Marks

If I understand this correctly the spare engine I store for my 63 is correct cast and dated three days from the original in the car. The engine has clearly visable broach marks but incorrect stampings on the pad because it's from Impala SS.

The original in the car has a more rusted or darker pad without clear broach marks but original stampings. I don't know if the block has ever been decked, I just can't tell.

If the spare passes cast number, date and then broach inspection but not stampings, then the block would score just 12 points less than the original if the broach is not visable on the original and deduction is taken? I am glad I kept that block!!

[Michael M.]

Re: Judging Broach Marks

Joe, I'm curious why the stamp pad appears to be chipped or broken a little after the rebuild versus before.

[Jack H.]

Re: Judging Broach Marks

"If the spare passes cast number, date and then broach inspection but not stampings, then the block would score just 12 points less than the original if the broach is not visable on the original and deduction is taken? I am glad I kept that block!!"

Well, in the text of the first part of the rule describing the cylinder case casting, you'll see the term 'correctly configured' in addition to cast date and cast number. If your set aside spare is a Tonawanda vs Saginaw casting, you'll lose ALL of the originality points as Corvette SB engines were cast in Saginaw and assembled at the Flint engine plant...

But, assuming the passenger car block you have IS a Saginaw/Flint product with the balance of the information you state, you'd expect it to lose 50 points on the judging field because the engine ID and VIN derivative emboss lines don't agree with Corvette norms...

[Michael W.]

Re: Judging Broach Marks

If the spare passes cast number, date and then broach inspection but not stampings, then the block would score just 12 points less than the original if the broach is not visable on the original and deduction is taken? I am glad I kept that block!!

Yes that's correct.

One engine would lose 50 points for incorrect engine suffix code (25 points) and VIN derivative (another 25 points)

The other would lose 38 points for a NTFP pad surface.

Difference= 12 points

[Timothy B.]

Re: Judging Broach Marks

Thanks for the response , what is a good strong cleaner for my original stamp pad?? I want to spend a little time cleaning it to check for these broach marks.

The spare is a Flint block standard bore, never taken apart from a Impala 300 HP car.

In my opinion, it's not worth the expense and worry trying to restamp when you can come this close with another block.

[Jack H.]

Re: Judging Broach Marks

"Thanks for the response , what is a good strong cleaner for my original stamp pad?? I want to spend a little time cleaning it to check for these broach marks."

If you're trying to get rid of oil/grease/dirt, something like Simple Green works well. But, be GENTLE using a toothbrush or equivalent non-abrassive...

"In my opinion, it's not worth the expense and worry trying to restamp when you can come this close with another block."

That's EXACTLY the intent of the current NCRS scoring policy that assigns specific deduction points to the various areas of the engine block! Why move heaven and earth with decking, re-broaching and re-stamping costs, when the deduction(s) for a replacement block that's OBVIOUSLY not the original motor is rather minor?

[Kenneth B.]

Re: Judging Broach Marks

"Thanks for the response , what is a good strong cleaner for my original stamp pad?? I want to spend a little time cleaning it to check for these broach marks."

If you're trying to get rid of oil/grease/dirt, something like Simple Green works well. But, be GENTLE using a toothbrush or equivalent non-abrassive...

"In my opinion, it's not worth the expense and worry trying to restamp when you can come this close with another block."

That's EXACTLY the intent of the current NCRS scoring policy that assigns specific deduction points to the various areas of the engine block! Why move heaven and earth with decking, re-broaching and re-stamping costs, when the deduction(s) for a replacement block that's OBVIOUSLY not the original motor is rather minor?

This all go's back to my original post & premise. If the stamping looks factory why deduct any points for the pad condition when the consensus is that it could look like anything from the factory except that it's not the Cooke cutter look alike. I am sure more restamps fit the norm than most factory machined ones. This is what is happining & this was my point. People will do anything to get the 99.9% top flight originalty be damed. It's not NCRS's fault only our desire to to reach the unreachable but I guess that is what made America great.
KEN

[Terry M.]

Re: Judging Broach Marks

I do not recommend this, but I pass on this story for what it is worth. This is one of those "don't do this at home, kids" stories.

I was Team Leader at a regional that will remain nameless. The mechanical (engine) judges had taken a 38-point deduction on a Corvette for lack of broach marks, and since this is a full deduction for that line item the TL initials are required. I looked, could see not broach marks -- even under high-powered magnification -- and as gently as I could I told the owner that I was supporting the judge's assessment.

The owner asked if he could apply something to bring out the marks. I cautioned him about abrasives -- just like Jack said above -- but I agreed to let him try. He came back with a plastic squirt squeeze bottle -- like chemicals come in, and proceeded to flood the pad surface with some of this liquid.

After a brief time he poured water from a bottle on it, wiped it off and asked me to look. There were some very fine broach marks visible, and after asking the judges if they wanted to look we agreed to award him full credit for the machine marks.

I asked him what he had put on the pad. I was gob smacked when he said: "battery acid!"

I should tell you that at the time this owner’s name was on the second page of The Restorer Magazine – and no he was not a fellow Team Leader.

[Michael W.]

Re: Judging Broach Marks

Terry

This story should be made a standard part of judging schools in order to pass the message that not every engine had broach marks easily visible to the naked eye!

[Kenneth B.]

Re: Judging Broach Marks

That's EXACTLY the intent of the current NCRS scoring policy that assigns specific deduction points to the various areas of the engine block! Why move heaven and earth with decking, re-broaching and re-stamping costs, when the deduction(s) for a replacement block that's OBVIOUSLY not the original motor is rather minor?[/quote]

JACK
Point is who can say that it's not the original pad if dates,casting #'s look original. Who can play MR. OBIVIOUS when it comes to pad surfices. Terrys point was well taken. Point deduction to you might be minor but to others that spend upteen thousands for points it means a lot.
KEN

[Timothy B.]

Re: Judging Broach Marks

I am going to try to clean it a bit. I will be careful but it looks like some oxidation and a little rust.

[Kenneth B.]

Re: Judging Broach Marks

I am going to try to clean it a bit. I will be careful but it looks like some oxidation and a little rust.

We had a metal cleaner at work to clean our iron surface plated that was called Metalprep. It was a deleted hydrochloric acid. This goes back to Terrys post. Before you try to clean your pad get some form of rust remover & try it on something else first & flood it with water after it removes the rust. It will not disturber the parent metal.
KEN

[Jack H.]

Re: Judging Broach Marks

Well, Ken, here are my last comments in this thread. I think we've beaten the dead horsie WAY too long.

So, you're saying that when the guy shows up with an engine where he'd decked the lid with a mill and then polished out the swirl marks and hit the pad with a nasty rasp file to lay down HUGE/UGLY 'simulated' broach marks and then wacked the pad with 'K-Mart' stamping dies we ought to accept that without deduction(s) because there WAS some variance at the factory?

If your answer is no, then you get into the slipery slope question of how many angles can dance on the head of a pin. The issue becomes a judgment call/personal opinion as to exactly what constitutes acceptable Typical Factory Production variance for that particular engine...

Once ole Pandora is out of her box here, you wind up where we are today. Some calls are right, others are wrong...

On your prior comment of why anyone would want to 'prep' and re-stamp a pad when they can obtain a raw block from a passenger car/truck that's close enough to grant them the lion's share of judging credit, understand the world...

NCRS is not the only game in town regarding factory concours judging. There are some owners who want/expect to have their Corvette judged on multiple circuits (e.g. NCCB/Bloomington & ChevyVette Fest).

We have a rather liberal scoring system in our judging rules that attempts to take the 'heat' off the restorer and does NOT force him to the extremes of creating a 'restoration' engine. But, we're not the only guys who judge Corvettes and grant award recognition for restoration...

So, maybe your comments in this area should be addressed to the other judging organizations that view the world of Corvettedom more strictly than NCRS does.