somegeek

My Feedback: (2)

I'm working to smooth out the sheeting on the fuselage of my Sure Shark and having issues sanding down the aliphatic seam between sheets of balsa on top. I got the upper sheeting glued in place yesterday morning and sanded down/puttied last night with Bondo glazing putty. Sanded stuff smooth today, but having trouble getting the aliphatic glue seam down to the same level as the balsa next to it using a sanding block and 220 grit. I've not doped the wood yet so I am wondering if this will make things difficult to get level?

I have an order of dope coming in from VHS next week.

Appreciate any input.

somegeek

combatpigg

My Feedback: (3)

SG, you might have to treat the wood to bring it up to the same toughness as the glue joint. The 2 part sanding primers by K&B or Klasskote work pretty well. Water based glue like Titebond should be sandable, but real soft balsa on either side will melt away faster than the glue seam.

somegeek

My Feedback: (2)

Thanks, CP.

I'm using Titebond II and I used a pretty lightweight sheet of balsa for these pieces on top so they're pretty soft. Will wait until I get some dope on it then before I move forward with any more sanding.

combatpigg

My Feedback: (3)

Dope should strengthen and toughen the wood pretty good. The masters of lightweight finishing techniques are the C/L stunt gurus like Windy Urtnowski and Phil Granderson, Bob Hunt. Any chance you get to read any of their articles is time well spent. I'm anxious to try out carbon veil and dope [over balsa sheet] on a 1/2 plane now.

dennis

My Feedback: (90)

Do not use white glue or Alphetic resin,epoxy, or any'hard' glues. Simply put, trying to sand the stuff will cause you to make caves in the sheeting.
Use acetate glues as Ambroid,Duco, Sig, Etc, Oh and don't use CA's either. It's like sanding rock when you use that stuff.
You should make sure that your wdges are trued, not bowed, Tape the seams together, open them and glue them, seal and dry, then sand smooth.
Remember if you have any holes including pin holes and you dope the wood that you run the risk of getting dope on the foam with an instant melt.
Really not a difficult process, goes fairly fast once you have done it a time or two.
Dennis

addendum, The use of foam wings was an RC thing. Believe that the first were done by Ed Izzo back in the 60's. Controlline has upped the ante by people such as Bob Hunt with his lost foam technique wings and also the developement of coring out the wings to get rid of excessive weight.

boberos

Make sure edge fit of sheet is excellent.
Tape as Dennis noted above.
Use a damp rag to remove all visible aliphatic glue before drying. Then you won't have to sand the seam much.

BMatthews

I'd suggest doping with well thinned dope so it can penetrate as much as possible. Then sand using a block wraped in 150'ish grit FRESH paper. The fresh grit cuts far, far better than an older well used sheet. Use light pressure and fine control to avoid cutting into any more wood. With a light touch and fresh paper that raised seam will just go away.

Rick W

My Feedback: (20)

Hello all,

I had the same problem on a scale project I was working on. While watching late night TV I caught a woodworking show where the host was scraping a glue joint with a cabinet scraper. Being one to try new things I ran to the local woodworking store and picked up a set for around $20.00. This was 4 piece set.

They worked great. Took the seam down without touching the surrounding balsa. Since then I have found a dozen uses for them. Give it a try..

Rick

MJD

My Feedback: (1)

I wonder if running a strip of masking tape down either side of the seam, then hitting it with the sanding block might give a headstart on the glue joint.

When I end up with grumbly little sanding jobs like these, I usually make up a small sanding block or two, say 1-1/2"x3" or thereabouts, with maybe 120 grit contact cemented to one side and 220 grit to the other. I find I can exercise a little more "finesse" (that's a relative term here.. ) with the small blocks and detail a fiddly job better.

MJD

combatpigg

My Feedback: (3)

Problem is masking tape is pretty thick. I've used clear packing tape and scraped the joint with a single edged razor. The suggestion to use Sigment sounds good. It's been years since I inhaled that stuff.

MJD

My Feedback: (1)

True, but with a little pressure on the blade these materials are all so soft I would think the blade will get down in there, wouldn't it? I sand leading and trailing edges flush using a sacrificial strip of masking tape. I try to peel it off while it has just enough strength left to allow you to peel it off without too much cursing.

Yeah, I realized after I mentioned the tape idea that the only place that would be any use was on outside curvature down to nearly flat but possibly not dead flat - not thinking of all the angles today I guess. Hmm, if you could reach it from underneath and push a bit to flex the sheeting up 10-20 thou at the seam, then sand.. hmm. Might work in the odd case.

Is this a flat surface, as in no curvature in any axis? Because if the sanding block is long enough to always span at least two glue joints and better yet three, you should be fine - at least that's how I do it, but I always use cross-grain sheeting in 2" or 3" widths, so a 12" block works perfectly to level the surface. Is this cross-grain sheeting, or a longitudinal seam or what?

MJD

OzMo

My Feedback: (3)

Its very curvy. EEERRR UMMM just make it a striped shark LOL
I often scrape the seems after gluing but before drying then sand again after drying. Very light pressure on curvy surfaces. a good layer of filler first helps too. I like Elmer's Non shrinking Spackle

combatpigg

My Feedback: (3)

As modelers we sweat small stuff too much and never get anything done. The thing to do is spend some time at an "air museum" and look at the sloppy fit and finish on those planes up close.....then go home and start slamming planes together [>:]!!

somegeek

My Feedback: (2)

If I didn't obsess over the details, I'd produce planes much quicker. Damn details...

Thanks for all the suggestions! My dope shipment gets here late this week so I'll get cracking then.

KidEpoxy

wait, let me see if I understand this...
You guys sand your planes?[&:]

Measure, cut, fit, curse, measure measure, cut, fit, glue, cover, fuel, fly !!
When I lawn dart I can say "At least I didnt spend a lot of time sanding this" as I fill the bag with bits.

Yuu

I like the idea of the 'cabnet scraper' mentioned before. Put the scraper in the vise, long edge horizontal, and "draw file" the edge [pull a flat file across the edge to get a perfectly flat, straight edge]. Then get a good American drill bit with hard steel, and hold it at a 45 degree angle to the vertical surface and 90 degrees to the top straight edge, and press and pull that drill bit toward you. This peels over the tiny corner of the edge, and forms a tiny 'j' hook on the edge. Only do that once for each side. Take the scraper out of the vise and gently lay the 'j' on your thumb nail and pull toward the end of your thumb. You will see a flat, scraped sruface appear on the thumb nail. Good. Now head toward that glue joint. Another thing I liked in these answers was to use Ambroid glue. The rubber plane modelers use that stuff to install the nose plug, because if the angle of the down thrust or side thrust is 'off' a little, you can soften the glue joint with acetone, and re-position the angle, wipe off and let it dry again. That means you could disolve a little of the 'glue hump' off the joint before you start sanding.

MJD

My Feedback: (1)

Some of the wood glues when cured behave a little bit thermoplasticky, I wonder if a hot iron might squash those humps or do something else useful.

MJD

Jim Thomerson

To follow up on MJD's comment. When sanding alphatic clues, take it easy. If you sand hard enough to generate friction heat, you can soften the glue to the point that it won't sand.

Yuu

So heating the glue with sand paper would be easier to heat it with an iron and scrape it off with a knife.....?

somegeek

My Feedback: (2)

I ended up shaving off the seams of glue.

Something I need to pay attention to going forward while building.

Tee Bee

At first I thought this thread might become something useful to me when I get around to building my Sure Shark. Now, I realize that it's much too hard and I'm not worthy.

somegeek

My Feedback: (2)

Naw... it's just that I am still a noob. I need to learn to control my glue.

tweedy

My Feedback: (1)

Ditto Dennis next time use Ambroid,Duco, Sigment. on any exposed joints and throw away the CA