How do you cut notches?

Posted by Kathleen Fasanella on Jun 25, 2008 at 11:33 am / Lean Manufacturing, Operations / Trackback

We’re having a bit of a debate in the forum on how you should cut notches. Obviously, we’re talking about multiple plies, not single or double layers.

The central question is, can -or should- you use your main cutting tool to cut notches? Those using a round knife have figured out this doesn’t work. Being round, the blade doesn’t cut far enough into the top or bottom layers and can nick too deeply into central layers. So, the question becomes, do you switch to a knife and use that for general cutting and notching, or do you buy a stand alone notching tool?


The contrary opinion is that it takes longer to switch tools but it’s not as though you can cut the notches with the knife as you’re cutting around the body of the pieces anyway. That’s done after. If anything, it seems more unwieldy to have to lug the knife around the table (or move the cut ply piles into it, possibly misaligning them) plus it has to be plugged in using power and the ratio of cuts to energy usage seems wasteful. The hand tool is easily scooted around, needs no power and you align the notcher into the plies without having to move bundles around. I think that there are no, if any, cost savings using the knife. If anything, I suspect using the knife would take longer. Besides, even if the knife did take less time, aren’t the quality gains worth it?

With a knife, it’s too easy to cut too far into the lay, they have to eyeball it and if they’re busy, that’s just too much potential for disaster. What if a given seam allowance is only 1/4″? Your cutter isn’t always going to know (or remember) which allowances are where -and for given sides for each piece? I’ve never had to give a cutter seam allowance information. As though they could remember what goes where on each piece (assuming they even know what each piece is; it’s not always obvious). As JC mentioned, you can buy blades for a variety of cutting depths (1/8″-1/4″) so it is impossible to cut too far into the lay. Additionally, cutting is a higher end skill. With the cloth notcher, anyone can do it freeing up your higher paid cutter to do other jobs. If it were me, I wouldn’t even hire a cutting service that notched with their knife. The very idea frightens me; lose an entire lot because one piece on one side was mis-notched? I’m not willing to take that risk. It didn’t even occur to me that a contract shop wouldn’t use a notcher. I’ll have to remember to add that to my list of criteria.

Edit 11/23/12
Vizu polls have closed down. Below is a screen capture of the poll results.

4 Responses to “How do you cut notches?”

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Mynrose
June 25th, 2008
6:14 PM

its a wise move to not risk cutting a whole pile just of one mistake, will cut out the loss, time, energy spent on them and one mistake and demolish all your hard work! >.its a wise move to not risk cutting a whole pile just of one mistake, will cut out the loss, time, energy spent on them and one mistake and demolish all your hard work! >.<

Vesta
June 26th, 2008
8:15 AM

I think notching with a knife is the norm in big cutting shops. I say this because I have never even SEEN a notcher, until the other day when I was perusing a sewing supply catalog (looking for something else). I have watched my cutter in CA, and my cutter here in Dallas, notch with a straight knife. So I assumed this was standard procedure. Then I ran into the aforementioned problems, because I’m using a rotary cutter.

I can totally see your argument, Kathleen. It just seems to be a minority view, in common usage. Having said that, I am all for dummy-proofing. So I’ll probably spring for the notcher.

Kathleen
June 26th, 2008
8:42 AM

I think that is WILD! LOL. I’ve seen exactly the opposite. Are you sure they don’t have notchers? They’re easy to miss being small items and usually stored under tables or on shelves. I did notice that Tom had them on my last trip to LA and he’s a small shop. That said, I shouldn’t be too surprised it’s a minority view. Best practices usually are :).

At this point I’m wondering if it has something to do with allowances. I’ve worked mostly in shops with very low tolerances requiring higher precision, iow, at most 3/8″ with 1/4″ seam allowances on outside edges. I wouldn’t be surprised to see notching with knives if products routinely took 1/2″ seam allowance (knits), the higher buffer can absorb a larger margin of error. The only operations I had known of that used 1/2″ were DEs (I’ve never worked in knits) and I categorized this as another practice which strayed from norms.

Come to think of it, I’m wondering how well a notcher *could* cut on knits. I’m thinking not as well; I could see the top layers being pushed (stretched) with the downward pressure of the blade. The blade would have to be very sharp. I’ll have to try a stack…

Renee
July 12th, 2009
7:56 AM

Kathleen, did you do this notcher/knife experiment cutting knits? I am buying a straight knife instead of round because I don’t think I can be precise enough otherwise, and while I knew of the existance of notchers I have never seen one in use either, and I’m talking huge sportswear knit factories. With my teeny tiny 1/4″ seam allowances you now have me worried about the notches, though. And my own dexterity…

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