radrobgray Posted February 1, 2007 Report Share Posted February 1, 2007 ive been trying to joint my 1/4 top for 2 days and im still getting gaps. ive tryed the different ways i found in search but to no avail, gaps. my question is it even possable to get it perfect? mines pretty close but there is a small gap that i can see when i hold the peices together up to the light. i checked the gap with a feeler guage and is about .002" or less is some spots. i know thats not a lot, but i just dont want to get a fat noticeable glue line. thanks rob Quote Link to comment Share on other sites More sharing options...
fryovanni Posted February 1, 2007 Report Share Posted February 1, 2007 ive been trying to joint my 1/4 top for 2 days and im still getting gaps. ive tryed the different ways i found in search but to no avail, gaps. my question is it even possable to get it perfect? mines pretty close but there is a small gap that i can see when i hold the peices together up to the light. i checked the gap with a feeler guage and is about .002" or less is some spots. i know thats not a lot, but i just dont want to get a fat noticeable glue line. thanks rob Rob, Here is a pic of how I make my final adjustments(I use my jointer first which gets it darn close then this for final). You can probably see I have a 1/16" piece of wood below the set. This prevents a ridge from forming close to the table when you sand. Also I only sand in one direction using even steady full passes. The plane is a natural because the sole and edge are flat and square, but a square sanding block works equally well. Good luck with it mister. It is great to see you are really holding very high standards for your joints(great work). Peace,Rich Quote Link to comment Share on other sites More sharing options...
Mickguard Posted February 1, 2007 Report Share Posted February 1, 2007 Well, since it's bookmatched, this might not work for you, but what I've found is that by sliding the pieces against each other, you'll find the place where they 'fit'. But then again, I take stuff down the hill to joint them on my friend's big ol' table thingamarig...it's very precise, and I haven't had to do any adjusting afterward to get a pretty near invisible glue line. Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted February 1, 2007 Report Share Posted February 1, 2007 With proper clamps (parallel) and clamping pressure, 0.002" will close shut and you won't see it. Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 1, 2007 Report Share Posted February 1, 2007 i disagree...you want to have absolutly zero gap anywhere before glueing....clamping just puts it under stress. Quote Link to comment Share on other sites More sharing options...
cherokee6 Posted February 1, 2007 Report Share Posted February 1, 2007 If you have a router table with a split fence, you can mount a straight cutter onto the router and use a shim in the outfeed part of the fence. The shim or shims if, you need more than one, are usually very thin plastic. A piece of formica can be used, for example. You can probably get a scrap from your neighborhood home building supply or cabinet/ counter builder. The bit should just "peek" past the infeed/first half of the fence. Use your calipers to help with the measurement because you only want to take minute amounts off at a time. Run each piece of wood thru it and check for fit. Run the wood pieces so that they are consistant in how they will fit, ie; run them so the faces are both face down so if the cutter is minutely out of plum the resulting cuts will make the tops join in in a slight "tent" fashion which can be glued down to hide any imperfections (could be the other way around so check on scrap first). Google "using a router as a jointer" or some variation and some sites will come up that have pics and better description. Good luck with your project! Quote Link to comment Share on other sites More sharing options...
Southpa Posted February 1, 2007 Report Share Posted February 1, 2007 There are gaps and then there are other problems. You can still get a noticeable glue line even if you don't see daylight shining though. Make sure the mating top corners of each piece are cut at a true 90 deg. angle. Its very easy to accidentally round off one of these corners resulting in a surface gap. It could be a tight fit underneath but once its glued and clamped you could still see glue at the surface line. Quote Link to comment Share on other sites More sharing options...
postal Posted February 2, 2007 Report Share Posted February 2, 2007 I think Southpa is close, regarding surface gap, but 90 deg is not critical. In Fryovanni's pic, the 2 pieces are laid together with the edge to be joined matching--- in a "closed book".. If this was joined at 87 degrees to the top surface.... both sides of the book would be off angle identically and still fit perfectly tight as long as the jointed edge is perfeclty flat along it's length. It is therefore critical that you work both peices together as Fry shows. I would be dissatisfied with .002 gap, but roughing up the edge with 80 grit *may* help hide the line. I hear many people use this method, I do not. I go straight from power jointer to glue, but jointer setup and its use is very important.... and yes, I clamp the pieces together in a closed book, and pass both through the jointer together. Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted February 2, 2007 Report Share Posted February 2, 2007 i disagree...you want to have absolutly zero gap anywhere before glueing....clamping just puts it under stress. Bah humbug! Measure the compression on your top the next time you clamp up....two thou is 1/5th of your high-E string, its 50 microns...it's a hair man! Literally. human hair diameter Now, Rob G may not have measured the gap accurately. However...if you think your jointing is flat and straight at better than 50 microns across 20", you're fooling yourself. For the record, you can find a glue line on very light-colored woods no matter how tight your joint is and how white your glue is, if you look hard enough. Quote Link to comment Share on other sites More sharing options...
postal Posted February 2, 2007 Report Share Posted February 2, 2007 I *think* he measured it wrong. I think if you can see light it would be off by more, and that is bad. Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 2, 2007 Report Share Posted February 2, 2007 like postal said...if he can see it,it aint .002 you want it perfect...perfect means no light...nothing less and i HAVE done the clamping thing in the past...it don't work,man...if it's under pressure it creeps right back into a visible gap...sometimes a few days after you clamp it....sometimes longer.now you can scoff if you wish...but all it does is make you sound like a "good enough,screw it" guy Quote Link to comment Share on other sites More sharing options...
postal Posted February 2, 2007 Report Share Posted February 2, 2007 What you're referring to Wes, is the "TLAR" method..... "That Looks About Right!" It certainly has it's place, but this isnt one of them! Quote Link to comment Share on other sites More sharing options...
fryovanni Posted February 2, 2007 Report Share Posted February 2, 2007 i disagree...you want to have absolutly zero gap anywhere before glueing....clamping just puts it under stress. Bah humbug! Measure the compression on your top the next time you clamp up....two thou is 1/5th of your high-E string, its 50 microns...it's a hair man! Literally. human hair diameter Now, Rob G may not have measured the gap accurately. However...if you think your jointing is flat and straight at better than 50 microns across 20", you're fooling yourself. For the record, you can find a glue line on very light-colored woods no matter how tight your joint is and how white your glue is, if you look hard enough. Erik is making a good point here. There are levels of accuracy that make sense for metal work, but are over the top in wood work. My test for joints is generally only a visual one. I do look at joints with a light source behind them, but I know you have to be aware you can fool yourself if the joint is not square so I also lay the joint on a flat surface and look close at both sides. beveling a joint is not a real good method if you need a structural joint, and if you sand a beveled joint you will start to see more glue the deeper you sand. I don't really get technical with trueing my joints. Like I said I run them over my jointer, and then maybe one or two passes as in the picture just to be sure I don't have any skips from the jointer. As far as being able to see my glue joints. Yes, I can find them even on my spruce soundboards. I do have to get very close though, and I generally have to look for a clue in the grain and try to follow a line across the board(it is very easy to lose though). Peace,Rich Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 2, 2007 Report Share Posted February 2, 2007 As far as being able to see my glue joints. Yes, I can find them even on my spruce soundboards. I do have to get very close though, and I generally have to look for a clue in the grain and try to follow a line across the board(it is very easy to lose though). but fry...that IS perfect.you can always find the joint....and depending on the wood,some are harder to see than others... maple for example...the joint is always visible...it's the glueline that can't be seen...now alder is different...the texture of the interlocking grain is such that the wholejoint dissapears if you have 2 pieces with grain running perfectly straight... but as was said...if you can see light,a clamp will not suffice...as i said,i clamped a body join in alder to invisibility...you could just barely see light before i did...and now 2 years later(i had it in a closet for a while)you can clearly seea glueline where the middle spread back apart metalwork is the opposite...any decent fit can be welded and ground into invisibility...the tolerances in woodworking are much tighter... Quote Link to comment Share on other sites More sharing options...
Southpa Posted February 2, 2007 Report Share Posted February 2, 2007 (edited) You will always see the center joint in a patterned bookmatch. Heres a pic of one I did recently out of wrn. maple burl. The center line is obvious regardless of how tight you make the joint and from whatever angle its looked at. I still haven't figured out what sort of shape I'm going to turn this into. I prepped the joint halves using my sanding table and fence method. Edited February 2, 2007 by Southpa Quote Link to comment Share on other sites More sharing options...
fryovanni Posted February 2, 2007 Report Share Posted February 2, 2007 Wes, metalwork is the opposite...any decent fit can be welded and ground into invisibility...the tolerances in woodworking are much tighter I was talking about machine fit parts(say motor parts, bearings, straight edges and such). Wood expands and contracts with moisture. It is a material that just can't hold an edge like other materials. I am by no means calling sloppy tolerances acceptable though. Quote Link to comment Share on other sites More sharing options...
radrobgray Posted February 2, 2007 Author Report Share Posted February 2, 2007 i disagree...you want to have absolutly zero gap anywhere before glueing....clamping just puts it under stress. Bah humbug! Measure the compression on your top the next time you clamp up....two thou is 1/5th of your high-E string, its 50 microns...it's a hair man! Literally. human hair diameter Now, Rob G may not have measured the gap accurately. However...if you think your jointing is flat and straight at better than 50 microns across 20", you're fooling yourself. For the record, you can find a glue line on very light-colored woods no matter how tight your joint is and how white your glue is, if you look hard enough. I *think* he measured it wrong. I think if you can see light it would be off by more, and that is bad. like postal said...if he can see it,it aint .002 you want it perfect...perfect means no light...nothing less id have to disagree. you can see a .002". if you can see a human hair you could see light thru that gap. i may have mesured it wrong but i guess that doesnt matter. all that matters to me is that i get it jointed properly. also i understand there will always be a glue line, i was just trying to minimize the chance of having one bigger than i could help. anyways i fixed it by starting with southpa's method and then finishing with fryovanni's. thanks to all who have commented, rob Quote Link to comment Share on other sites More sharing options...
westhemann Posted February 2, 2007 Report Share Posted February 2, 2007 Wes, metalwork is the opposite...any decent fit can be welded and ground into invisibility...the tolerances in woodworking are much tighter I was talking about machine fit parts(say motor parts, bearings, straight edges and such). Wood expands and contracts with moisture. It is a material that just can't hold an edge like other materials. I am by no means calling sloppy tolerances acceptable though. okay...gotcha Quote Link to comment Share on other sites More sharing options...
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