Cutting momentum
Posted: 17 November 2007 03:52 AM   [ Ignore ]  
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What is the best way to cut momentum for a quilt? I have read about using a soldering iron for nylon, is that best, or should I just use scissors?

Thank you,
-Rick

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Posted: 17 November 2007 04:03 AM   [ Ignore ]   [ # 1 ]  
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a rotary cutter and a self healing mat work great

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Posted: 17 November 2007 10:12 PM   [ Ignore ]   [ # 2 ]  
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Thank you for the response.

In case anyone else doesn’t know, a rotary cutter is not a dremel. After I bought the mat, I kept thinking there was something wrong with what I was about to do. Stopped in a store and picked up an Olfa.

Can I cut the fabric and not hem it immediately? Will it start to come apart?

Thanks again,
-Rick

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Posted: 18 November 2007 12:36 AM   [ Ignore ]   [ # 3 ]  
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In case anyone else doesn’t know, a rotary cutter is not a dremel.

visualize a pizza cutter.

Can I cut the fabric and not hem it immediately? Will it start to come apart?

That depends:
* on the fabric
* how much handling it’ll need when you sew it
* kind of seam.

The typical thing is to lightly melt the edge with a candle or (better) an alcohol lamp.  But don’t bother if it’s going to be in a french seam or otherwise enclosed (as with an overcast stitch or binding tape of some kind). 

Momentum is the least fraying light wt. breathable nylon fabric I’ve used.  I can’t think of a close second.

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Posted: 18 November 2007 01:03 PM   [ Ignore ]   [ # 4 ]  
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Rotary cutting beta:

Large mats are more useful than small mats since you can cut more of the pattern in one go.  Rhino brand mats from cutting-mats.com (no affiliation) are an excellent value and offer sizes as large as 6’ by 12’.  Large mats can be stored under area rugs when not in use for folks in apartments or the otherwise space constrained.

Stack cutting saves lots of time for items with some kind of symmetry such as shell-insulation-liner items.  Use pattern weights to keep stack and pattern from shifting during cutting. 

Buy extra cutting wheels and change your wheel often.  The sharp edge of the cutting wheel will dull quickly.  Dings in the blade from hitting debris or pins will cause a few threads every revolution to not be cut which is an annoyance. Bulk wheels available at reasonable prices from southstarsupply.com (no affiliation).

The diameter of the cutting wheel influences how well it will cut tight radii.  Smaller wheels cut curvy patterns better than larger wheels and vice-versa.

Alcohol lamps burn with lower temperature flames than paraffin candles so they are less likely to over sear light fabrics.  Find wick alcohol lamps from places that sell science stuff (old school chem lab kit eq’t such as sciplus.com (no affiliation)), or house kitsch places in the tea light aisle.

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Posted: 22 August 2011 12:10 PM   [ Ignore ]   [ # 5 ]  
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AYCE - 18 November 2007 01:03 PM

Alcohol lamps burn with lower temperature flames than paraffin candles so they are less likely to over sear light fabrics.  Find wick alcohol lamps from places that sell science stuff (old school chem lab kit eq’t such as sciplus.com (no affiliation)), or house kitsch places in the tea light aisle.

Regarding alcohol lamps, exactly what kind of alcohol should be used?

I found one yesterday but the store I bought it at had no idea what kind of alchol to use, or where to get it. I bought some “completely denatured ethyl alcohol” at a local drug store but wanted to make sure that is the right stuff before I try it.

I also see that REI sells it as a stove fuel so is that a better option?

http://www.rei.com/product/614112/crown-alcohol-quart

Also, which is preferable for sealing the edges of fabrics like Momentum: alcohol lamps or a hot knife?

Thanks!

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Posted: 22 August 2011 12:18 PM   [ Ignore ]   [ # 6 ]  
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I find hot knives to be more trouble than they’re worth. 

Denatured alcohol is what you want.  You can get a quart of it cheaply at a hardware store in the paint aisle.  This is the same fuel used in alcohol stoves.

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Posted: 22 August 2011 12:41 PM   [ Ignore ]   [ # 7 ]  
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Great, thank you!

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Posted: 24 August 2011 01:46 AM   [ Ignore ]   [ # 8 ]  
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Now that I have one, any suggestions as to the best way to use the alcohol stove? Is there a basic technique for sealing the edges?

My initial trial attempts were a bit ineffective. The flame is about 1-2” high, making it hard to accurately sear the edges without overdoing it and burning the fabric… Should the fabric edge actually touch the flame, or just be near it? How long should it be in contact with the flame?

Also, the sealed edges seem a bit rough. Should I smooth off the edges somehow?

And if you use French or flat-felled seams, do you still have to sear the edges?

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Posted: 24 August 2011 01:11 PM   [ Ignore ]   [ # 9 ]  
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Try lowering the wick to reduce the flame size.  Move the fabric quickly @ 12” at a time.  It takes practice, esp with lightweight fabric, but soon you’ll be able to do it quickly and effectively.  I pass the fabric through quickly down by the wick head.  The faster you move, the less heat per unit area the fabric absorbs and the less it sears.  The cleaner the cut (ie: the less the fabric is already frayed), the less likely it is for you to oversear/melt.

If you’re going to be finishing the seams as you mention, you don’t need to sear and should avoid it if you can.  But note that french seams are trimmed prior to finishing so that rough edge is removed.  The seam is finished immediately after trimming, so there is little time for the item to fray.

If you don’t sear, you need to be careful with the pieces to keep fraying to a minimum until the seam is finished.

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Posted: 24 August 2011 01:29 PM   [ Ignore ]   [ # 10 ]  
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AYCE - 24 August 2011 01:11 PM

Move the fabric quickly @ 12” at a time.

To get an idea of the speed, how many seconds should it take to pass 12 inches of fabric through the flame?

AYCE - 24 August 2011 01:11 PM

down by the wick head

Yes, I forgot that the flame is hottest at the top…

AYCE - 24 August 2011 01:11 PM

The cleaner the cut (ie: the less the fabric is already frayed), the less likely it is for you to oversear/melt.

Do rotary cutters work better than scissors in this respect?

AYCE - 24 August 2011 01:11 PM

The seam is finished immediately after trimming, so there is little time for the item to fray.

So as long as the seams are enclosed (ie, French, felled, etc), it is OK not to sear? It won’t eventually unravel inside the enclosed part?

And do pinking shears work well for nylon?

And what does a good job of searing look like? Some of my attempts ended up with puckered edges…

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Posted: 24 August 2011 01:38 PM   [ Ignore ]   [ # 11 ]  
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It will vary depending on the weight of the fabric.  For M90 it’s going to be about one second per 12”.

A good job of searing is the minimal amount of melting that prevents fraying.  If you’re making one of the apparel kits, the sear is just to prevent fraying until you finish the seam.  You don’t need much.

Keep it simple; practice makes perfect.  You’ll get the hang of it.  You should have plenty of cut-offs and time to get it right.

Rotary cutters are preferred but not required for apparel.  I don’t use pinking shears (or a pinking disk in my rotary cutter) much, but they will reduce fraying somewhat on unfinished simple seams/ swatches or if you’re going to try and not sear prior to finishing a seam like a felled seam on something prone to fray.

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Posted: 24 August 2011 04:19 PM   [ Ignore ]   [ # 12 ]  
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Great! That makes it a lot more clear.

Thank you.

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Posted: 06 September 2011 01:52 PM   [ Ignore ]   [ # 13 ]  
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AYCE - 24 August 2011 01:38 PM

...If you’re making one of the apparel kits, the sear is just to prevent fraying until you finish the seam.

... I don’t use pinking shears (or a pinking disk in my rotary cutter) much, but they will reduce fraying somewhat on unfinished simple seams/ swatches or if you’re going to try and not sear prior to finishing a seam like a felled seam on something prone to fray.

 

After trying the searing method, I find it works OK but it does sometimes end up burning into the edge a little too much, making it a little difficult to line up the edges of the fabrics.

Am I understanding correctly that you really only need to prevent unraveling until you finish the seam?

If so, would pinking shears do the job for all of the seams of the insulated apparel kits? Or would they eventually start to unravel inside the jacket?

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Posted: 06 September 2011 02:44 PM   [ Ignore ]   [ # 14 ]  
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Correct: the seams need to be either a finished seam (like a french seam) or seared/overcast.  Pinking alone is insufficient for simple seams.

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Posted: 06 September 2011 04:19 PM   [ Ignore ]   [ # 15 ]  
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Darn! ;)

Oh well, at least some of the seams can be left un-seared, if you know in advance which ones will be finished as part of the construction.

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