glue lines

[Reb]

Hi

I have some plastic that 2 halves were glued. Afetr turning the pen I can see the lines. I tried CA and sanding but didn't work. Any Ideas?
Thanks
Randy

 

[leehljp]

Glue lines are something that I rarely see anyone talk about here as most people just accept them as part of the segmenting experience. But there are some fine craftsmen here do know how get around the glue line through technique and experience. To fine woodworkers in flat work, glue lines usually are a disdain. PERFECT match in fitting is a must. "Good enough" and "eyeballing it" (without considerable experience) doesn't cut it.

Two ways to get around noticeable glue lines without _perfect_ joints: accent the glue line by adding an aluminum, brass or other thin laminate/segment at the joint. Or make the halves to be so contrasting that the glue lines are not noticeable.

How did you cut the sections that were glued? It will be most noticeable on bandsaw kerfs. A circular saw kerf (table saw) can also leave blade marks, but a TS is easier to tune saw marks out than a BS, IMO.

Another way is to sand the pieces flat. I wouldn't settle for anything less than 400 in sand paper but the sand paper would have to be on a FLAT base, such as tempered plate glass, to guarantee that the half to be joined was perfectly flat. Otherwise, a glue line will be inevitable.

AS far as the already made and turned blank, I can't think of anything outside of a pen mill or laser cutter to make a kerf and fill it with contrasting color.

 

[Texatdurango]

Hi Randy, I think everyone fights the glue lines, me, I just work my designs to hide the glue! Instead of mating two contrasting colors together, I work in a black or other dark veneer as part of the design as Hank suggested. Once finished, I doubt anyone looking at the pen can tell where the glue stops and the dark veneer starts.

Just something to think about.

Here is what I'm talking about....note the black veneer strips.

Here is how the pen looks and I think the veneer adds to the look.

 

[redfishsc]

Without a ton of experience in gluing plastics, I can't say a whole lot about that.

However, I have noticed that CA glues show a LOT more glue line in wood than standard yellow wood glues. I can't say why for sure, but I suspect that the yellow glue tends to cure up closer to the color of the wood.
I laminate wood together quite a bit at work (cabinetry), and usually get those super-tight glue joints that Lee was talking about. I use plenty of glue, very strong I-beam clamps, and leave clamps on for at least a couple hours. I have seen biscuit joints in wood have uncured glue in them for a couple days after removing from the clamps--- I had to cut out a square part of a large wooden countertop for a cooktop range to be installed, and the biscuits still had wet glue on some parts.


I would suspect that a thin viscosity CA would have less of a visible glue line than the thicker stuff.

 

[rherrell]

Get yourself a marble floor tile at Lowes and glue some 220, 400 and 600 wet/dry sandpaper on it. Sand (dry) the pieces with long strokes and keep them flat. The better the fit the smaller the glue line.

 

[monkeynutz]

I upgraded my diamond hones, and as a result ended up with two old 6x3 diamond-on-metal hones, one coarse and one medium (like the ones they sell at Woodcraft), which I now dedicate to joinery. I flatten small pieces on these. You don't want to use 'em for tool honing any more after this, as they will pick up material deposits. I can keep them somewhat clean by going over them with an art-gum eraser every so often, or you could also use one of those rubber cleaning sticks you tune up your belt-sander belts with.

 

[Reb]

Thanks guys for all the help.

Randy