I am soooo disappointed!

[Burkhardt]

So, this post is not about getting advice. I know what my stupid mistake is.

But here are a few pictures of an almost nice project and how I screwed it up. Any consolation is welcome :o

The task was to take up Bob Eustaches' idea of making "invisible" wood hinges (http://www.talkshopbot.com/forum/showpost.php?p=170223&postcount=21) with glued-in dowels, but machining the whole hinge out of solid wood. The outcome would be a kind of pill box from Myrtlewood with several compartments. To make it pretty, the lid was to be adorned with a Cherry inlay.

So, this is the blank for the lid with inlay. Not perfect with a few chipped out inlay spots but acceptable.
https://lh4.googleusercontent.com/-awsZQ4FTsQA/VD3uyZi2gbI/AAAAAAAAFXI/98IKmlBVMZg/w640-h853-no/DSC02787.JPG

Unfortunately I forgot to take pictures of the bottom and top with the hinges before assembly but this is the drill jig that I made to get the holes aligned.
https://lh6.googleusercontent.com/-NKdiPTC-8zM/VD3u0uLMBHI/AAAAAAAAFXQ/vkfK7qveswE/w1260-h853-no/DSC02793.JPG

This is the bottom of the pill box with the drill jig and drill still in place. For the photo I removed the clamps that held the jig in place.
https://lh6.googleusercontent.com/-OmKklFhyYfI/VD3u2pQChUI/AAAAAAAAFXY/uecF_m4qg94/w588-h853-no/DSC02795.JPG

More pictures of my sad story to come......

[Burkhardt]

After drilling the bottom and the top I jammed an 1/8" brass rod through the holes. That was the beginning of trouble. Since the drill bit was also 1/8" there was a lot of friction but I got it in, after all. I should have better used a 3mm rod to give it some clearance.
https://lh5.googleusercontent.com/-EtF_l7czHoc/VD3u43hgxxI/AAAAAAAAFXg/gPV9yQKky6s/w1121-h853-no/DSC02797.JPG

But, the box even opened, albeit with some resistance. Inside is not sanded and finished yet.
https://lh5.googleusercontent.com/-sd7fTtY68Mo/VD3u7qXCe_I/AAAAAAAAFXo/ZwV_xMKGQGk/w930-h853-no/DSC02798.JPG

Finally I had the dumb idea to hold the brass rod in place with a droplet of CA glue on the outside. But when I put the glue bottle tip to the rod it gushed out a good squirt and glued part of the top hinge to the bottom. At the next opening attempt it broke the hinge. C-R-A-P.
https://lh5.googleusercontent.com/-J-V5pQqYEjQ/VD3u9z4ZI7I/AAAAAAAAFXw/XVZ1-l80hMM/w1351-h853-no/DSC02799.JPG

Oh well. I think I have some of that pretty Myrtlewood left and will try again. Live and Learn. I will also change the grain direction to the long dimension to reduce the warp after machining.
https://lh4.googleusercontent.com/-zevts43pteY/VD3u_wcab-I/AAAAAAAAFX4/2KFIHgSv3Yk/w1137-h853-no/DSC02800.JPG

[elcar903]

looks very nice

you should be able to glue the joint back together just glue and clamp it for 24 hours.

I have had to fix several projects that way :)

I use titebond 3 wood glue

[Bob Eustace]

What a bummer Gert - my crappy instructions! You have imitated the Incra Hinge Crafter perfectly. The pics here of the almost invisible hinge are of my initial tests, so the timber is crazy thick. The hinge is a piece of 1/4 dowel with a 1/16 drilled hole each end. Five pieces seem to work well. I think you mentioned you didn't have a lathe?? You need a jig to drill the hole central - that's the aluminium bit in the pics. You do need another jig to ensure that the dowels are cut off square. The dowel does need to be round or you get binding. This hinge is truly amazing and if the dowel/lid/back are the same species you just wont see it from the back with the lid closed. With the lid open it looks really good. Works best with a recessed lid like on the Paradise Box.

[scottp55]

OH! Gert! Looked Soooo close:(
Wonder why so many things screw up at the very last second? Like putting a USB in when it's dark is supposed to be a 50/50 chance----NOT!!
Keep trying-- MUCH better look:)

[myxpykalix]

Oh man......you really screwed that one up!:eek:I would offer words of consolation but this is more fun:D
Actually that is alot of nice work and a shame you had a problem:(

[POPS 64]

Very nice work , hate to see someone else has my luck ! Great idea . Jeff :D

[tlempicke]

I know a lot of your guys know this but for those of you that dont here it is.

A screw or bolt is undersize. Usually about .003. That way it will go into the named hole. A 1/2 inch bolt will measure out .497 or thereabouts.

To accommodate this you have letter drills and number drills. One will provide a hole just over the nominal size and one will provide a hole just under. Sitting here at the computer I can't remember just which is which.

A drill will never drill the exact size it is sharpened to. It will always drill oversize and out of round just because of the geometry of it. The only way to get an exact size and a round hole is to drill undersize and use a reamer for the final pass.

In your case you had a rod of .125. You should have drilled the hole with a .128 bit. These are cheap and available because the 1/8 inch rivet used in aircraft work requires them. I used to buy them by the dozen and pitch them when they were dull rather than try to sharpen them.

On the wall of my shop is a large poster with all of the numerical, number, and letter drills in order. They used to give these away but now they sell them for about three bucks. Try WT Tool on the web.

[Burkhardt]

.....A drill will never drill the exact size it is sharpened to. It will always drill oversize and out of round just because of the geometry of it. ..........In your case you had a rod of .125. You should have drilled the hole with a .128 bit. These are cheap and available because the 1/8 inch rivet used in aircraft work requires them. ...........

Yes, that would have been a good idea but I just used what I had at hand. For that technique, I needed a drill that is at least 8" long. While you can get such a long drill in 1/8 everywhere I did not see slightly bigger ones. Next step up was 3/16 and no smaller ones at all.

Lessons learned for the next attempt:
- change wood grain parallel to the hinge (avoid hinge warping)
- change individual hinge barrel length from 1/2" to 1"
- try inserting a piece of vertically oriented wood into each barrel to strengthen
- change pin wire diameter to 0.08"
- make own long drill 0.094" from drill rod.
- probably change to maple for the body. That myrtle tends to splinter.
- stay away from the CA glue bottle

[Burkhardt]

What a bummer Gert - my crappy instructions! .......

Oh no, perfect instructions. I just chose not to follow and instead of making the hinge barrels separately from a dowel and glueing just to cut them from the same solid board in one process. Technically this should be the same except for the need of a very long drill with jig to keep it properly in line. But hey, it was a first try. Should have practiced with scrap wood.

[Brady Watson]

Slick hinges, boys! Thanks for posting.

-B

[Bob Eustace]

The almost invisible hinge also needs perfectly square ends on each end of the dowel. A simple sled is all that is needed (made on a Shopbot of course)! I use this thing for heaps of other jobs (like small 1" feet and toy cars sand trucks) and its so much safer than the cut piece flying off into outer space!:eek:

[barrowj]

Hi Bob,

I am always on the lookout for items like your sled, any chance you still have the cut file for it and would be willing to share. I think we need a place to share these type of production aids. I will start posting any that I make for the group to use if they want or even comments on improvements. If we already have a place for that I would really like to find it...

[shilala]

I have the Incra, and when I drill I run that bit in and out and in and out until it's not touching anything. It gives just enough slop to get the brass in.
If the brass rod is the least bit tight, I chuck it up in a cordless drill, hit it with some sandpaper (400 or 800 or whatever is laying around) and then shine it with a scotch-brite pad.
It takes very little work to change the diameter of the rod that tiny little bit if I need it.
Running the rod in the drill also shows me if the rod is true. Sometimes there'll be a little whoop or hogleg that's a problem and I can straighten it out or grab another rod.
I buy them in lots on ebay for next to nothing, so I don't mind chucking one. Not at hardware store prices.

[Bob Eustace]

This is a superb example of how good the hidden hinge looks on a very high end box by Rob Cosman. You just cant see it! The lid is on the left and is 5/16" thick.

[Burkhardt]

This is a superb example of how good the hidden hinge looks on a very high end box by Rob Cosman. You just cant see it! The lid is on the left and is 5/16" thick.

Ha! That looks really great! Something to strive for.....

I still have my sights set on machining it out of one piece. The first attempt was actually not that bad until I screwed up with the CA glue.

Obviously, when using a ball end, the hinge barrels can not be square and all edges must be beveled at least with the ball end radius. But I designed the 3d-model with a CAD system that allows me to do that in a fashion that there is constant clearance between all surfaces of the hinge. For now I am planning to use 0.01" clearance. If I can machine that precise enough (will use 1/4" bit instead of the 1/8" bit next time) the hinge should be almost as invisible as with the glued-in dowels, I hope. I also bought a few 1" abrasive buffing wheel brushes for gentler sanding of the hinge inside corners. I will post if I am successful. Oh well, maybe I will even post again, if I am not.

[Burkhardt]

....I still have my sights set on machining it out of one piece.........

Oh well, I give up on the one-piece design. I have been playing a bit more with the CAD and I get everything to fit without voids and machinable with a ballnose bit. But there is an unavoidable interference of the top and bottom part bevels when opened fully.

So, I will try to stay closer to the proven invisible hinge concept. To simplify the fabricating of the dowels I made them on the CNC with the additional advantage of integrating alignment tabs to help with the assembly. These tabs will be machined off after glueing (if I don't screw it up again....).

End grain strip of maple. The area where the dowel ends is recessed 0.004" to give the hinges a tiny bit of play.
https://lh6.googleusercontent.com/-syHstVWg0b8/VENAS6Et_PI/AAAAAAAAFYI/-7kT3xUkpoc/w924-h853-no/DSC02801.JPG

Dowels with assembly tabs drilled and machined free 7/8" deep
https://lh4.googleusercontent.com/-Cnd-4itR94k/VENAU8A6_RI/AAAAAAAAFYQ/LlgCN_UQB7k/w1052-h853-no/DSC02803.JPG

https://lh3.googleusercontent.com/-Wk8NvsOHuQ8/VENAXWjkBCI/AAAAAAAAFYY/7OKAMYhePBk/w1312-h853-no/DSC02804.JPG

Lined up on the stainless steel hinge pin (0.08") and temporary brass rods.
The dowels are not totally symmetrical. One half has 0.004" larger radius where they are to be glued.
https://lh4.googleusercontent.com/-qwW9rb2yQ0U/VENAZrgF7cI/AAAAAAAAFYg/MsXcGiBdPEA/w789-h853-no/DSC02805.JPG

So far so good. I will try to cut the box body tomorrow and glue it in. I just wonder what will now go wrong.

[Bob Eustace]

Gert I'd kill to have your ability to think outside the square like you seem to do weekly coming up with such original stuff! A MASSIVE advantage you have over the Buddy and Desktop brigades is you can clamp vertically. On the invisible hinges its a real bummer having to do them on the router table. I have "dug" a well in the table down to the power stick but it is horribly limiting particularly when I see what you and Brian get up too!

[Burkhardt]

Bob, that is probably a professional affliction. I have been the R&D manager for my company for 15 years and they paid me to come up with new stuff. For the last couple of years I am responsible for Operations and need another outlet for ideas :rolleyes:

Actually, my machine does not allow vertical clamping. But I do have full 8" clearance under the gantry as well as 8" z-stroke. That allows for some pretty tall parts and long bits or, like in this case, the use of a sturdy machinist vise to clamp smaller part solidly.

[scottp55]

Lookin' Good G. !:)

[Burkhardt]

Modest progress on the box body. But at least I got the new lid inlay cut. I used a home-made fractal design to avoid the pesky copyright uncertainty and to find out how detailed such an inlay can be made.

The new piece of cherry was less brittle but I believe what made a major difference was to soak the inlay blank surface with ample thin CA glue (and a whiff of accelerator spray after that). It reduces the tendency to fuzz and stabilized the tiny protruding slivers somewhat. I also used the even sharper 1/8" version of the Kyocera 30-degree bit. Total machine time for both pieces was about 55 minutes.

https://lh6.googleusercontent.com/-LOzNg4oN810/VERBcykYg9I/AAAAAAAAFY4/73BMsZY0Br0/w1242-h853-no/DSC02810.JPG

https://lh3.googleusercontent.com/-62NAs7B8-IA/VERBfQwTj7I/AAAAAAAAFZA/ISFjLE45Uuc/w751-h853-no/DSC02811.JPG

[shilala]

That's gonna look great. Can't wait to see it!!!

[scottp55]

G. , While playing with buttons, I wound up with some lacquer that had been thinned about 80%(Yeah, what do I know), and to use it up- I coated the button blanks after surfacing and had way less fuzz and tearout.
So when I started Vinlays and Paul Z thought a thin CA coat before second pass(he recommends Always doing a second pass)(I just duplicate toolpath and do full depth and double or triple X,Y,Z MS) would stiffen wood. I TRIED and didn't like results, BUT next time tried the thinned lacquer-- Worked Great! Penetrates DEEP/Flashes in 10-15 minutes and doesn't appear to affect CA bond when gluing and stops CA penetration(darkening). A good swipe with solvent alcohol(been working oily woods anyway) and a 320G "scuff" on the flat works. Nice thing is it's so thin it doesn't "pool" in the bottom of the cuts noticably. Seems to stiffen fibers a LOT, and then a bamboo "Shish-Kebab" stick knocks everything loose without scratching anything like a dental pic sometimes does.
Just saying:)

[scottp55]

Oh. Just used unstirred Deft Brushing Lacquer poured off the top(no retardants) first time.
Last batch was Watco Clear Lacquer.
Heck of a lot cheaper than CA:)

[Burkhardt]

That's gonna look great. Can't wait to see it!!!

Here it is. Looks quite nice, and very meaningful to learn the limits of the technique. But these fractal patterns are actually not that good for inlays because by definition they lead to unlimited level of detail that can not be machined and gets washed out. It also looks kind of busy to me. But hey, I am not going to sell it.

https://lh6.googleusercontent.com/-8HUsBv2hC_g/VEcex6XyaZI/AAAAAAAAFZs/KJnvQiMGfVg/w1159-h853-no/DSC02813.JPG

[myxpykalix]

Actually G, i accomplishes it's purpose, at least in this photo. When i look at it starting at the top it looks to me as if the top is rounded and further away from the camera, as you scroll down the center is closest and as you go to the bottom the wood curves away from the camera and you are looking at the underside of a rounded object.

So the illusion works.....:eek::D

[scottp55]

G., Came out way better than I thought it might!! BUT VERY useful for finding limits and improving technique! Any way to set on your Fractal program a limit for size, or would you have to group and "sweep" away the too small ones like I do for "noise" in imported bitmaps like the tree I just did(interesting that some "noise" I didn't zoom in enough to see still inlaid and looks like fly specks:) .
Think maybe denser wood or different speeds and you would have "Gotten" it!
Reminds me of some Escher's I tried way back in the beginning with the same problem with the "Infinity Fade" :)
Did you try the Vac Bag with "pressure plates?" (think I might know what you're talking about now". Epoxy? (would Vacuum Bagging need to be epoxy?).
Great Work!:)

[Burkhardt]

I did one first try with epoxy and that does work quite well but I found that I used a 30 degree bit while the path was calculated for a 60 degree bit. So that was not a good fit and I machined it off and started over. But for this (correctly machined) result I ran out of epoxy and tried the Titebond again. This time I diluted it with a good sip of water so that it becomes really liquid and can be brushed on thinly. Also that allows wiping excess glue from the surface and bigger pockets with a shop towel.

It would be nice to have an easy way of eliminating too small detail automatically. But I am only aware of the bitmap vectorization detail settings and the bezier curve conversion. Both don't do enough for that purpose (or may I am not using it right). Maybe I need to "despeckle" the image first in a photo editor before vectorization.