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Seam scraping

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  • Member since
    October 2021
  • From: Michigan, USA
Posted by J.A. Modelworks on Saturday, November 13, 2021 8:58 PM

Funtec out of Japan makes a tungsten carbide scraper bit that mounts in a regular pin vise handle. It works good for getting rid of mold seams on plastic, resin, and cleaning up putty. Its solid and doesn't chatter on the surface like a regular hobby knife blade. Gouging isn't an issue since it doesnt have a knifes edge, unless you exert to much pressure. 

  • Member since
    June 2021
Posted by rocketman2000 on Saturday, November 13, 2021 9:53 AM

MJY65

On one of the Flory videos, he showed a set of scrapers with various curves and angles that can be used to scrape seams along curved surfaces without leaving flat spots.  I believe they were made my U-Star.   I haven't been able to find them at any of the usual US suppliers and not sure I want to order from eBay.  Seems just as likely I'll get a flattened beer can from China instead of the real thing.  Nice idea, though.

 

I think if you really get into scraping, a set like that would be of some benefit, like in scraping the inside of a curved surface.  But for flat surfaces or outside of curved surfaces a good rigid knife blade works fine- no need for fancy stuff.  While a #11 blade does work if you are careful, it tends to bend a bit too easily and can chatter.  I really recommend a stiffer blade.

Don Stauffer in Minnesota

  • Member since
    February 2021
Posted by MJY65 on Saturday, November 13, 2021 6:02 AM

On one of the Flory videos, he showed a set of scrapers with various curves and angles that can be used to scrape seams along curved surfaces without leaving flat spots.  I believe they were made my U-Star.   I haven't been able to find them at any of the usual US suppliers and not sure I want to order from eBay.  Seems just as likely I'll get a flattened beer can from China instead of the real thing.  Nice idea, though.

  • Member since
    June 2021
Posted by rocketman2000 on Friday, November 12, 2021 7:46 AM

Chemteacher
I’ll use the scrapping technique on small stuff like fuel tanks and ordinance and if there is a big mismatch in fuselage halves. However, I’m always worried I’ll take too much off on large assemblies.
 

Its a matter of learning the right downward pressure.  The lighter the pressure, the less you take off, like filing or sanding.  Like any technique, practice helps to gain experience.  You'll get the feel pretty quickly.

 

Don Stauffer in Minnesota

  • Member since
    June 2017
Posted by Chemteacher on Thursday, November 11, 2021 9:27 PM
I’ll use the scrapping technique on small stuff like fuel tanks and ordinance and if there is a big mismatch in fuselage halves. However, I’m always worried I’ll take too much off on large assemblies.

On the bench: Revell-USS Arizona; Airfix P-51D in 1/72

  • Member since
    April 2020
Posted by Eaglecash867 on Thursday, November 11, 2021 11:48 AM

I use essentially the same technique as PJ.  I used to use the #11 blade, but found that its just an extra step that can potentially damage things, so I just use my Micromesh sticks to sand and polish the bead of melted plastic away.

"You can have my illegal fireworks when you pry them from my cold, dead fingers...which are...over there somewhere."

  • Member since
    September 2006
  • From: Bethlehem PA
Posted by the Baron on Thursday, November 11, 2021 8:36 AM

plasticjunkie

I never scrape and seldom use putty. I use Plast I Weld solvent glue to melt the plastic along the join creating a ridge that is easily sanded smooth when cured overnight. I use multiple grit grades of sanding sticks to sand and polish the join. Even 0000 steel wool will do a great job at polishing out scratches on plastic. 

That's pretty much the same thing, though, PJ. The technique is really based on squeezing out that bead along the seam, and then removing it, when the glue has cured and the plastic is hard again.  Whether we use a blade of some kind to remove the bead, or abrade it away, are just different flavors.  I generally use a Nr 11 blade to remove the weld bead, then smooth it out with sandpaper, or a Flex-i-File, especially on fuselages and leading edges of wings.

The bigger the government, the smaller the citizen.

 

 

  • Member since
    November 2008
  • From: Central Florida
Posted by plasticjunkie on Wednesday, November 10, 2021 11:30 PM

I never scrape and seldom use putty. I use Plast I Weld solvent glue to melt the plastic along the join creating a ridge that is easily sanded smooth when cured overnight. I use multiple grit grades of sanding sticks to sand and polish the join. Even 0000 steel wool will do a great job at polishing out scratches on plastic.

 GIFMaker.org_jy_Ayj_O

 

 

Too many models to build, not enough time in a lifetime!!

  • Member since
    July 2003
  • From: Building models on my kitchen counter top~somewhere in North Carolina
Posted by disastermaster on Wednesday, November 10, 2021 8:47 PM

The homogeneous material really seams to be the best way when possible.

                      Sometimes I just can't help myself.....

On the kitchen counter top in North Carolina

  • Member since
    September 2006
  • From: Bethlehem PA
Posted by the Baron on Wednesday, November 10, 2021 9:35 AM

rocketman2000

At a club meeting last night, the topic was seam treatments.  I brought along a work in progress kit and demonstrated scraping as a technique to level and smooth seams after applying putty.  Scraping is a centuries old technique of smoothing a surface used by machinists and carpenters.  One draws a sharp edge along a surface with the blade almost perpendicular to the surface.  I had never heard of anyone else using the technique before, but half of the attendies last night do use the technique.  Yet no one seems to talk about it.  How many people in this forum use it? 

I use it, though it's not always possible, in every situation.  It's very useful building airplanes, for seams where fuselage halves meet, or tops and bottoms of wings.

I like the idea that the seam is filled with homogeneous material-the kit's own plastic.  So it should behave like the rest of the plastic.  That's why I like to use stretched sprue, too.  That doesn't mean I don't use putties, but I recognize that a putty might shrink as it cures, and will likely need sanding, thereby damaging the surrounding detail.

I'm surprised you haven't heard about it here in the forum, though, because I know it's been discussed.  Though it might not have its own thread, just mentions in build blogs or in threads about addressing seams.  i know I've suggested it when someone asks how to deal with seams.

The bigger the government, the smaller the citizen.

 

 

  • Member since
    July 2003
  • From: Building models on my kitchen counter top~somewhere in North Carolina
Posted by disastermaster on Tuesday, November 9, 2021 2:04 PM

Slower drying laquer thinner works well for this. When the squeezed ooze dries you have a prefilled seam ready to adz and smooth. No or hardly any filler at all.

On the kitchen counter top in North Carolina

  • Member since
    April 2003
  • From: USA
Posted by keavdog on Tuesday, November 9, 2021 12:11 PM

I do this as well.  Use a hot glue like weldon down the seam and sqeeze a bit.  The melted glue oozes out a bit.  After drying I use the back of an exacto to scrape.

Thanks,

John

  • Member since
    May 2020
  • From: North East of England
Posted by Hutch6390 on Tuesday, November 9, 2021 11:12 AM

I generally use the scraping technique if I have, say, a ridge of material to remove.  I use a curved blade & work carefully until I'm close enough to finsh with sanding sticks or pads.

Vell, Zaphod's just zis guy, you know?

   

TakkaTakkaTakkaTakkaTakkaTakka

 

  • Member since
    July 2008
  • From: Albany, NY
Posted by jeffpez on Tuesday, November 9, 2021 10:10 AM

I do it all the time - it's my preferred method.

  • Member since
    July 2021
Posted by Sgenest on Tuesday, November 9, 2021 10:05 AM
I’m new to modeling. I made an irreversible error on my current build, a 1/72 B17. The booboo caused some seam mismatch. I had never scraped before but it allowed me to wiggle out of the problem.
  • Member since
    April 2020
Posted by Eaglecash867 on Tuesday, November 9, 2021 9:11 AM

I used to use that technique, which I had always called "adzing", but I always felt it removed a little too much material.  I use Micromesh sanding sticks now for removing the bead of re-hardened melted plastic along a seam and rarely use putty.  The Micromesh sticks remove just the right amount of material and do minimal damage to surrounding detail.  Any tiny gaps that are left over get filled with tiny dabs of Gorilla super glue, scribbled over with an ultra-fine black Sharpie, and sanded again with the Micromesh sticks until all of the black Sharpie is gone.  If I ever use putty, its always Apoxie Clay, and that gets smoothed out with tools dampened in water before it cures...no sanding or scraping needed.

"You can have my illegal fireworks when you pry them from my cold, dead fingers...which are...over there somewhere."

  • Member since
    February 2021
Posted by MJY65 on Tuesday, November 9, 2021 9:09 AM

That's my preferred technique for getting it close.  I use either a straight or rounded blade depending on the contour of the area.  Follow up with 1500 grit sanding sponge to take off the scratch lines.  I find it much easier to limit damage to adjacent detail with scraping than gross sanding.

 

I should add that I generally use TET which tends to leave negative areas to fill with Mr Surfacer rather than positive extrusion on the seams.  If one uses slower setting cements and squeezes the heck out of the seam, you can make almost anything fill in without putty and deal with the flash later.  Of course, that comes at the expense of distortion, at times.

  • Member since
    June 2021
Seam scraping
Posted by rocketman2000 on Tuesday, November 9, 2021 8:46 AM

At a club meeting last night, the topic was seam treatments.  I brought along a work in progress kit and demonstrated scraping as a technique to level and smooth seams after applying putty.  Scraping is a centuries old technique of smoothing a surface used by machinists and carpenters.  One draws a sharp edge along a surface with the blade almost perpendicular to the surface.  I had never heard of anyone else using the technique before, but half of the attendies last night do use the technique.  Yet no one seems to talk about it.  How many people in this forum use it?

Don Stauffer in Minnesota

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