For those in the know, what percent of blanks are culled by the blank maker due to straightness? It probably varies with maker, but given that no blank is perfectly straight, how much deviation do they let out the door?

I have noticed that Point Blank states on their website they cull, and I would assume some, if not most, of these culls are due to straightness

When you get a new blank, do you check it for straightness, what method do you use, and what do you feel is acceptable?

I have no idea as to the first part of your post. Based on condition of a couple of blanks that I have received, I would feel safe in saying that they don't check every blank for quality issues. And if they do, their quality standards certainly aren't what mine are.

With that said, I have 3 builds that I will doing this winter off season, which for me will bring my total number of builds up to 21 rods total. Of those blanks, 25% of them have been arrow straight, with another 25% having only very slight bends. Other than 2 blanks that I sent back because of straightness issues or other blemishes in the blank, the remaining blanks had curves that I wouldn't consider slight, but I found them acceptable.

I base whether or not I find a curve in a blank as acceptable, by my judgement of whether or not the weight of the guides will make the blank appear straight. once the rod is built.

I will not accept a blank that has a curve in two different directions.

Oh, and I check a blank for straightness by sighting down it against a light back ground



Edited 1 time(s). Last edit at 01/08/2022 06:50AM by David Baylor.

This has been copied/pasted from an unknown author. I can't speak to its accuracy, but its safe to assume there's considerable rejections.

Here's how the math works from a real factory that produces both blanks and rods for sale. They build 1000 blanks. Fifty random blanks are put aside for testing. If less than 5 of the 50 fail, the others are cleared for the next step. If a 10% of the 50 don't pass, 50 more are randomly pulled and tested. If the second group also has 10% failure, a third group of 50 is tested. If that group also has 10% or more failure, the entire run is scrapped. Assume the 50 pass and we now have 950 ready for either custom rod builders or production rods. All 950 go through an inspection process. Typically about 20% are thrown out for crooked tips or other major cosmetic blemishes.

So now you have about 760 blanks that are ready. Those blanks are divided into 2 groups, one for production rods and one for custom builders. The custom builders only get the straightest blanks with the best finish. About 200 or so are put aside for custom builders and the other 560 go to the finished rod production line. The 200 are then looked at under special lighting and on a rack to insure they are the straightest and cleanest blanks. This usually weeds out another 50 or so blanks. So in the end, you start with 1000 blanks, about 150 are judged to be good enough for custom builders. About 700 are used for finished rods.

I'm guessing that means there is more money in mediocre production tolerances and throwing out lots of culls, rather than having more precision manufacturing. The cull rate above seems astronomical. Is it really that hard to consistently make straight, clean blanks?

The material is rolled onto the mandrel under considerable pressure, the tip is very fine and isn't the same diameter as the butt so it has to be rolled in a sweeping motion correctly so there is the same amount of turns at the tip and the butt simutaneously, there is probably more than one layer of material in the blank, so it goes through that process more than once.

I have actually built some blanks on a factory floor during a special "Build-Your-Own-Blank" promotion. The biggest issue is how the graphite cloth is "tacked" to the mandrel. If it is tacked on perfectly along the same axis of the mandrel, the blank comes out straight. As noted in a previous post, the tip of the mandrel is very thin, so it is very difficult to tack the cloth on perfectly every time. This process is typically done by hand, and in a production enironment, it must be done very quickly. This leads to the "culls" as noted in prior posts.

Another possible source of curvature is the way the cloth is cut - a poor design will have unequal overwraps on one or more axis' of the blank, or sometimes an overwrap that spirals around the mandrel. This leads to the multiple curves noted above. This issue would normally be identified early in the process and rectified in the cutting specs, but that may not be the case for the least expensive blanks as they do not devote the time and energy to these blanks as they would need to reassess their cost factors if they did.

In my experience, the straightest blanks are typically the multi-piece blanks, as the cloth is tacked onto multiple mandrels in shorter sections. Working with a shorter piece of impregnated graphite lends itself to more accuracy in getting the cloth tacked straight on the mandrel, and hence, a straighter section of blank. One example I can cite is the American Tackle Matrix line of 4-piece fly rod blanks. I have NEVER had one of these blanks that was not die straight! It could happen, but has not done so yet in my experience.



Edited 1 time(s). Last edit at 01/10/2022 06:15PM by Richard Bowers.

Above is a very good explanation of why most multi-piece blanks do not have curvature issues.

The most expensive bass blank I ever bought (just recently) has to be in the top 3 most crooked I ever bought. It's a 7-6 MLXF 1 pc. Does that make it bad? If I was picking top end blanks to send out to customers, I would likely have culled it. Had I seen 100 of them I might think differently. It could be few of them are very straight. It's a long lightweight blank. My thoughts were: It's a top notch company, if they think it's good It should be good!

We're talking about blanks being culled because of how straight they aren't, but what of blanks that are culled, if any, because they don't match the manufacturers published dimensions? I wonder if part of the the process described above, is checking the dimensions of a certain number of blanks as well.

I recently received a blank that has a tip that is a full 1/64 larger than its' published dimension, and a .028" larger butt than its' published dimensions. I haven't done CCS tests on it yet, but it feels like it will have the power I expected it to have when I ordered it. Although I will say that it doesn't have quite as light of a tip as I was hoping for. And whether it is a good practice or not, I was basing that hope on the listed tip dimension The blank is listed as being a fast action, and in flexing it, it is certainly a fast action, but it doesn't appear to be as fast as I was hoping it was.

Anyhow ...... do you think they even consider variations in published blank dimensions versus what the blanks actually measure?

To me a blank with a listed tip of 4.5 64ths shouldn't have a tip that measure 5.5 64ths. Or maybe I just didn't get the blank I ordered. Wouldn't be the first time I've had that suspicion.

Now that David mentioned tip size, the blank I mentioned above was listed as a 4 tip and I could (easily!!!) have gotten by with a 3.5. The blank also weighed less than specked. I don't care about all that as long as it's a good blank. Lotta surprises in one package for me however.

I have experienced this as well, from a leading blank manufacturer that will remain unnamed. frustrating when you Pre-order the tip based on what is specified on the website. Seems like QC is lacking

Another thing I was surprised about with the blank I mentioned above. It weighs .28 oz less than its' published specs. I wouldn't be surprised by that normally, but the tip and butt dimensions were larger than those published for the blank. With the dimensions being larger, I would have expected the weight to be slightly higher than the published weight.

And I did the same as Roger above. I ordered a tip top based on the published dimensions, but because you never know, I ordered one a size larger. That one didn't fit either. Luckily I happened to have an extra tip top that was the right tube and ring size.

Anyhow, not going to leave any sleep over it. Just wondering ....