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Can't cut BMF nice and even?


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#1 Johnt671

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Posted 16 March 2013 - 12:44 PM

 Anyone one have any suggestions on trimming BMF to follow the trim lines?  I can do a pretty nice job around the windows but not on the body trim.  I go nice and slow but the blade seems to have a mind of its own.  Maybe helping to cause this problem is the fact that I'm holding the model in my hand when I trim it?  How do you folks do such a nice job on it?  Thanks.



#2 GeeBee

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Posted 16 March 2013 - 12:46 PM

I simply burning the BMF down into what ever I want to trim upto, and use a brand new #11 blade, and don't put any pressue on the blade, let the blade do the work, it you put pressue on the knife, it will wonder off line, apart from that, I don't do anything special.



#3 Art Anderson

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Posted 16 March 2013 - 01:42 PM

I simply burning the BMF down into what ever I want to trim upto, and use a brand new #11 blade, and don't put any pressue on the blade, let the blade do the work, it you put pressue on the knife, it will wonder off line, apart from that, I don't do anything special.

Practice holding your #11 Xacto blade at a very shallow angle to the surface of the body shell.  That will let the blade follow the edge of the chrome spears.  It does take some practice, and a bit of patience, but it does work (been foiling model cars for a good 40 years now.

 

Art



#4 Cato

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Posted 16 March 2013 - 01:50 PM

I run a pointed toothpick along all edges to burnish tightly first. Then, remove the blade from a scalpel (or select a brand new one) and hold only the blade with thumb and index finger. Try to prop the model with heavy paper weights and cushion with towels-so you're not holding it..



#5 Yahshu

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Posted 16 March 2013 - 02:36 PM

You could try laying tape down 1st along the trim line then the BMF, burnish the BMF down, then cut using the tape & trim line as your guide as you now have a "valley" in which the blade can travel. Don't forget to always use a brand new blade.



#6 Chillyb1

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Posted 16 March 2013 - 03:19 PM

A couple of thing in addition to the above. I use a magnifying glass on a stand so I can see what I'm doing. I use a guitar pick to burnish the BMF: this tool is firm, smooth, and slightly rounded so it is perfect for the job. Try running a black Sharpie marker along the edge of the blade, the better to tell the difference between the foil and the blade. And I found this handy little blade holder that really makes following the proper cut line easy:

fiskars-detail-knife.jpg



#7 Gluhead

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Posted 16 March 2013 - 03:29 PM

Burnish it well. I like a toothpick, so I can either use the super-pointy end or quickly cut the shape I need into the other end.

 

Ditch the handle for your blade. Really. It does more harm than good in this situation. Make sure it's a brand new blade and that the very tip has not broken off. Do yourself a favor and pick up a pack of Excel #11 blades. They blow any version of Xacto brand away.

 

No line to follow, to speak of? Or a really bad angle of approach? Take a ruler and give yourself one nice good straight edge when you trim your foil off the backing, and carefully line it up with the offending trim.

 

:)



#8 MrObsessive

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Posted 16 March 2013 - 03:41 PM

The above tips are very good, and I'd like to add another...............try "establishing" your cuts before you do any priming or painting. In other words, if you're doing a BMF intensive kit such as AMT's '58 Chevy (or Revell's '59) you might want to use your Exacto blade to make a slight "trough" in the trim. That way when you go and do your final BMF trimming after painting, your knife will have something of a track to slice through, than fresh untouched paint and plastic.

 

You might want to practice this on a junk body, but it's what helped me years ago when doing the trim on the '58 Chevy I did. That model was no joke when it came to BMF! :o



#9 modelercarl

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Posted 17 March 2013 - 02:35 AM

Chillyb1...Where did you get that blade holder?  It uses the standard #11 blade?



#10 James2

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Posted 17 March 2013 - 03:30 AM

I have found good lighting to be my best tool. Using the shadow or in some cases the reflection of light, I can see the desired cut line clearer. It is best to use a "NEW" blade and keep it at a low angle.

I also will use the blade without a handle some times, seems to help with tight detail. I would suggest practice on a junker to find the way that best suits you. 



#11 my80malibu

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Posted 17 March 2013 - 03:57 AM

Chillyb1...Where did you get that blade holder?  It uses the standard #11 blade?

Fiskers makes a handle like that you can find in the stationary section at Walmart

#12 modelercarl

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Posted 17 March 2013 - 04:28 AM

Fiskers makes a handle like that you can find in the stationary section at Walmart

Thanks for the info!



#13 Guest_G Holding_*

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Posted 17 March 2013 - 05:09 AM

Thanks for the info!

Is this it ?

 

swivel%20knife.jpg



#14 Joker

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Posted 17 March 2013 - 05:40 AM

My tip for BMF ..picked it up from Marcos Cruz..(thanks for the tip Cruz)

 

before you use primer/paint..

 

scribe the trim deeper, so the trim edge won't get buried under primer/paint.



#15 Blown03SVT

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Posted 17 March 2013 - 05:50 AM

You could try laying tape down 1st along the trim line then the BMF, burnish the BMF down, then cut using the tape & trim line as your guide as you now have a "valley" in which the blade can travel. Don't forget to always use a brand new blade.

That's what I do.... I use a machinist rule and cut strips of tape and lay them closely to the burnish edge at the cut line. The weight of the blade rides in the groove. Leaves the foil edge razor sharp and straight and when you pull the tape it pull the cut away foil. Similar in theory to what pinstriper's would use as a guide



#16 Johnt671

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Posted 17 March 2013 - 06:27 AM

 Thanks everyone.  Good tips here.  I'll give them a try.  Even though I've only done a couple of cars, this stuff just make a model look great.  I consider it a must do now.



#17 Cool Hand

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Posted 17 March 2013 - 07:00 AM

My tip for BMF ..picked it up from Marcos Cruz..(thanks for the tip Cruz)

 

before you use primer/paint..

 

scribe the trim deeper, so the trim edge won't get buried under primer/paint.

 

X2

 

I used this technique on my last 5 or so builds,makes things so much easier. 



#18 Captain Obvious

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Posted 17 March 2013 - 04:34 PM

I'm fascinated by that blade holder!  Gonna have to grab one of those and give it a shot.  Worst case, I keep the receipt and return it if I don't like it.  ;)



#19 Tom Geiger

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Posted 17 March 2013 - 05:40 PM

.  Maybe helping to cause this problem is the fact that I'm holding the model in my hand when I trim it?

 

Yea, don't do that.  You want the model body to be stable.  I like to take something soft, like a wadded up t-shirt, and place that on your table.  The model can indent into it changing the shape to it's contours without scratching the body.  As you follow the trim line, you want your hand to be resting on something.  One pin striper once taught me to use a bean bag, or a large bag of M&Ms as a hand rest.  And when doing a long side trim, I may hold the knife stable and gently move the model forward.  



#20 my80malibu

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Posted 17 March 2013 - 06:37 PM

Is this it ?

 

swivel%20knife.jpg

The one I have holds a #11 blade exclusively, However that one looks like it would do the job just fine.