Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Cabinets-Speakers => Topic started by: bluesbear on January 09, 2012, 04:19:33 pm
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Well, once again I screwed up! The last cabinet I made came out perfect. This time, I used the same wood and the table saw hasn't been touched... but the box joints didn't work. :cussing:
I give up! I'll just pay to have dovetails cut. I hate that but it's cheaper than wasting every other board I buy.
In the meantime, I have to get new wood. I've been using clear white pine cause it's cheap and available. It's harder than southern yellow pine, which is what I'd prefer. Trouble is, I can't find that in Cincinnati in 12" widths. 10" is just a bit narrow for the chassis I had made. From now on, I'll get the chassis made 1/2" narrower but I have a couple more of the old ones to use first. Does anyone know what kind of wood I could get that would have approximately the same hardness and characteristics as yellow pine? Looks aren't important as I cover them but I want clear. I don't want knots that can vibrate loose.
Thanks!
Dave
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If your going to cover it maybe you could make a face frame to make up the difference in width and glue it to the main box, front or back. :think1: If you run the grain the other way from the box it'll be a -- little -- stronger/more stable?
There's poplar, mills well, takes glue/finish well, but I think it's maybe a little softer than pine, and I don't know if you can get in 12" width's? I have no idea how it would sound.
I thought there is a southern yellow pine that's much harder than white pine?
You could try maple, but it's harder than pine and more $$. I had a friend years ago that made a speaker cab. out of cherry and put bees wax on it for a finish. He loved it. Both mill well and glue up well, but you wouldn't want to cover them?
FWIW, the last time I saw a "real" lumber yard out here (Chgo. area) was a long time ago. :w2: There might be a few left down in the city, I don't know.
15 years ago there was 1 old yard left by my parents house that had a very nice housed/covered yard, stocked well with clear pin, oak, maple, cherry, along with rough stock, etc. I don't even know if it's still there or what they still stock.
They had a few bins stacked full of 1"x 12" @ 10', 12', 14' clear pin (some very small tight knots), 2 rows wide, 3' to 4' tall in each length. :icon_biggrin: But I fear those days are gone. :w2:
Most places now that I have seen, big box stores, have gone to glue-ups of pine strips, or glue-ups of finger jointed pine. Also some with a core made of MDF or particle board with a wood veneer ply bonded to it. Even plastic/vinyl.
I did find some very nice pine 7 ply, 1/2"x4'x8', ext. glue, with no voids at Menards, for $30 a sheet? I made a nice work bench out of some and it came out great IMO. I'm very tempted to make a speaker cab. out of some and see how it sounds.
Edit..... It's 3/4" not 1/2".
One more thing I'd like to try, (since we're running out of options with solid wood) is to try using 3/8" or 1/4" no void plywood. Using cleats in the corners with a good carpenters glue, it should be strong enough and still resonate? Worth a try.
I wish you well on your build blue bear.
Brad :icon_biggrin:
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You're right; contrary to what I've been told, eastern white pine is softer than yellow pine. After reading your post, I did what I should have done. I researched it. It seems white pine is a better choice than yellow. It's at any Lowe's and it's relatively cheap.
As far as construction, I've never had a problem with box joints... at least not in the strength, only in the cutting of them. Well, dovetails are stronger and I know a bass player who's a retired carpenter. My only problem is that I'm cheap. I hate to pay for work I should be able to do myself. Well, I'm too cheap to pay even more for my own mistakes. I'm just so stubborn that it took me a long while to admit defeat.
Thanks,
Dave
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I use an inexpensive half blind dovetail jig for my cabinets. Pretty easy to use & I even have a photo tutorial that I'd be willing to email you if you're at all interested. If so, just leave me a PM with an email address.
This is the jig that I use:
http://www.thewoodshop.20m.com/pc4112_p.htm (http://www.thewoodshop.20m.com/pc4112_p.htm)
Popular is a good wood to use since it is light weight and resonant. White pine without knots is good. One of the best sounding cabs I've made was an 11-ply plywood one. I thought it sounded great. It may have been birch plywood?
With respect, Tubenit
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I bought my dovetail jig from Rockler for less than $100. That and a mid priced router (right around $100), plus an hour or so of finicky set up time, and your set. If you buy a dedicated router for just that task, you won't have to reset it every time, saving quite a bit of time. If you are trying to make a living at this stuff, there is no good reason not to just spend a few bucks to be set up to do it quickly and easily.
Gabriel
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Tubenet, I have the same jig, but a little bit older model. Different style locking, levers instead of a T-knobs. I never got around to buying the other templets they offer, but I still would like to.
I use the finger/box joint template. It works great, as long as I use a scrap of backing wood behind the piece I'm cutting to stop tear out on the back side where the router bit exits. I also like to use a 2 flute solid carbide up-cut bit with a 1/2" shank.
I have used Watco Danish oil in dark walnut for a finish a few times and they came out nice. Never got around to putting a harder top coat on.
Brad :icon_biggrin:
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As a cabinetmaker I agree with the above who recommended poplar. Cheap, clear, glues well and can be had in wide widths. Stay away from the yellow pines with the exeption of long leaf heart pine. If you know someone with a jointer and thickness planner I'd make up the width in narrower pieces with each board flipped heart side/ sap side as it with cup a little less if you do. Another and better option joint wise is to hand cut the dovetails by hand. Unless you're in a production situation they are not hard to do and all you need are a couple of sharp chisels and a decent dovetail or japanese saw.There are tons of tutorials online and you may even live near an urban center that has wood classes. I taught myself 30 years ago from a James Krevnof book. My first project was a tool box that's still in daily service .
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I have done dovetail on bubinga, saple, mahogany, maple and poplar--but never pine. I like the grain and always thought it was too plain jane. Supposed to sound great though. Of the dozen or so made, mahogany/saple or poplar always sounded the best to me. I do feel your pain BB because it is usually 6 months between cabinet making campaigns and the relearning curve is steep for a simpleton like me. Regards
dennis
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I've given up! I have only 2 options... and neither includes box joints! Either my retired carpenter friend can do dovetails for me or he can show me how to do it myself. It just depends on how much $$$ he wants to do it compared to how much $$$ I need to spend to get what I need. We'll see...
As for the wood, to finish the last 3 chassis I have on hand, I'll need 12" boards. I'll probably have to use white pine as my Lowes doesn't have 12" clear poplar in longer lengths. From now on, I'll get my chassis made 1/2" smaller and 10" boards will work. That'll give me more options. I didn't think about that when I had that batch of chassis made. Then I'll compare white pine versus poplar. Looks doesn't matter to me as I always cover them in blue tolex anyway and I want them to all look similar... for brand recognition.
Thanks!
Dave
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Another and better option joint wise is to hand cut the dovetails by hand.
There are many types of woodworkers in the world, but they can be divided into two groups - those who make a living, and those who cut their dovetails by hand. (It could also be called those who make a living, and those who take Fine Woodworking seriously, but that's neither here nor there.)
Get a cheap dovetail jig - it will take you no more than a handful of cabinets before it pays for itself, given the time savings involved. Particularly if you leave the router for it set up all the time.
Gabriel
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G. Hoffman, I agree.That's why my next sentence began"Unless you're in a production situation". I mentioned hand cut not realizing he apparently is in production. I still think hand cutting joints is the way to go for non-pro's, and even pro's will improve their game by being skilled in hand tools.I've seen many customers of mine the past 30 years with a garage full of stationary power tools they haven't a clue how to use that could have spent the money from one tool to get what they wanted done with a lot less risk to their health.Last guy I saw like that was using his crosscut miter and using his fence as a stop, wanted to know why the board smashed threw the wall behind him!
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as for cab construction, I prefer doweling.
build with simple boxjoints, then lay a line out half the thickness of your material and drill your holes, add glue and hammer the dowels in.
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I may be in production... but it's small production. I have the time to do the cabnets myself but not if I keep wasting wood. Of course, that can be sorted. I have another issue, though, and that's room. I have a not very large shop that has an 8' x 6' L shaped bench, a drill press, 2 table saws (one for box joints and one for cutting), a thickness planer, an edger/planer, the freezer and the furnace. I've already given my chop saw to my son and I can't set up the planers because of room. I can get the wood cut at Lowes for $.25 a cut. That adds about $2 per amp for the price of the wood. If I can get the cabinet assembly done somewhere else, I can actually have enough room in my shop to work without rearranging everything every time I go in! Just putting the saws and planers in storage would give me tons of room. I'm also checking with a local metal shop about getting chassis made with all holes already cut. Then I can spend my time making amps instead of getting ready to. That being said, a router and dovetail jig doesn't take up much room. If the price of finishing the cabinets is too high, I'll go that route... AFTER my friend shows me how.
Thanks, this thread has really helped sort out what I need to do.
Dave
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G. Hoffman, I agree.That's why my next sentence began"Unless you're in a production situation". I mentioned hand cut not realizing he apparently is in production. I still think hand cutting joints is the way to go for non-pro's, and even pro's will improve their game by being skilled in hand tools.I've seen many customers of mine the past 30 years with a garage full of stationary power tools they haven't a clue how to use that could have spent the money from one tool to get what they wanted done with a lot less risk to their health.Last guy I saw like that was using his crosscut miter and using his fence as a stop, wanted to know why the board smashed threw the wall behind him!
It does sometimes feel like you should be required to pass a test before you can buy some of these things, doesn't it? I've got nothing against had tools skills - it is part of the trade, and there are many things you can do faster and better with a good sharp chisel, but I get somewhat frustrated when people who don't have a clue ask why we have so many machines to make "hand made" guitars, and the various wood working magazines don't much help!
Gabriel
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I get somewhat frustrated when people who don't have a clue ask why we have so many machines to make "hand made" guitars, and the various wood working magazines don't much help!
I have a small CNC machine, and I've had people tell me the things I make on it aren't really hand made.
To me a tool is a tool, different set of skills are required, but they are tools.
Carl Sagan is quoted as saying " To make an apple pie from scratch, you need to first create the universe"
Some where we all buy our base components.
BB, take advantage of your best skills and talents, and capitalize on someone else's best skills and talents where needed. This will allow you to build the high quality amp you really want to build .
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My carpenter friend says, "Don't be an idiot!" He makes his bass cabinets with double rabbet, glued and screwed joins. He says they are stronger. I know they're easier; I've used this join before. Basically, he says that Leo wasn't a carpenter and "screw anyone that doesn't like it." I think he's right. I sure simplifies everything. No learning curve and I only need one of the table saws.
Lots to think about but, after 62 years, I've learned that simpler is usually better.
Dave
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There is an old notion that dovetail joints are the strongest form of box construction.
This is true if you are only using a brad or two and no glue to hold the joint together.
any joint where you can create enough surface area for the glue to hold will be stronger than the wood itself.
besides, the baffle and back make up such a rigid cross brace as to not put much stress the corner joints at all., these are cabs, not drawers.
Basically, he says that Leo wasn't a carpenter
Leo may not have been a carpenter, but I bet he consulted with a few before building his cabs.
the box joinery he used may well be for other reasons than strength. box joints would allow very precise alignment of the panels and perhaps a bit a bit of stability as its assembled and sent down the line to be clamped in a squaring jig, who knows. Leo was know more for building things practically and inexpensively, not for durability.
Guitarist and musicians in general are not big into change, that is to say musicians have lots of respect for traditions, history and lore. so to many, if a cab was built with box joints in the "golden years" it was because it was somehow better and the best cabs built should be built the same way.
as your carpenter friend may say musicians aren't carpenters :icon_biggrin:
in the end, without dissembling your cab, who will know what type of joinery you used.
You'll actually be using what Leo would have most likely done if he were in your shoes, the most practical, least expensive means to join two pieces of wood.
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any joint where you can create enough surface area for the glue to hold will be stronger than the wood itself.
besides, the baffle and back make up such a rigid cross brace as to not put much stress the corner joints at all., these are cabs, not drawers.
in the end, without dissembling your cab, who will know what type of joinery you used.
You'll actually be using what Leo would have most likely done if he were in your shoes, the most practical, least expensive means to join two pieces of wood.
I agree with Ray.
Ray, I think you hit the nail on the head. Oh wait "NO NAILS". :laugh:
Brad :icon_biggrin:
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My carpenter friend says, "Don't be an idiot!" He makes his bass cabinets with double rabbet, glued and screwed joins. He says they are stronger.
Your old carpenter friend is lazy. His joint may be strong enough, but it ain't stronger.
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The more the surface area for the glue, the more strength the joint will have.
Brad
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The more the surface area for the glue, the more strength the joint will have.
Brad
yes, BUT!, once the joint is stronger than the wood then the wood gives before the joint. Todays glues are AMAZING compared with anything commonly used even 20 yrs ago.
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If you're committed to nothing more complex than the double rabbet, how about the joint in the attached picture. I don't know what that joint called, so I had to draw it. With a dado stacked to half the width of the board, it's just about as simple as the double rabbet and provides more surface area for the glue. I've done a couple quick head cabs with that, and they're plenty solid.
I've been doing cabs with a box joint jig I built a few years ago. This past weekend I borrowed a friends half-blind dovetail jig and put together a quick 20" x 16" x 9" speaker cab out of a 6' 1x10" pine board I had in the shop. It was super simple and came out great. The thing is, after gluing it up, I forgot to check it for square as I was clamping it. When I came back to check it, it was dead nuts square. I think the dovetails probably help getting perfectly 90-degree corners.
I play with a 300+ pound bass player who sits on his Eden cab for the better part of our three hour rehearsals. I don't know if it was designed for that, but you never know what your cab might be subjected to! :laugh:
-John
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yes, BUT!, once the joint is stronger than the wood then the wood gives before the joint.
Yes I believe that's true. I guess the question is, how much is enough before it's over kill? :dontknow:
The joint that Boots posted is yet another very good one to use. Not only does it increase surface area for the glue, it also has a shoulder that helps fight any sway in the joint.
The thing is, after gluing it up, I forgot to check it for square as I was clamping it. When I came back to check it, it was dead nuts square. I think the dovetails probably help getting perfectly 90-degree corners.
Another good point to consider.
Today's glues are AMAZING compared with anything commonly used even 20 yrs ago.
Yes, we now have a wide variety of different types of glues that are available to use that are amazing.
OTOH, there's still a lot of things that are still around, that were made out of wood a LONG time ago and were glued up with animal hide glue.
Brad :think1:
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Just to step in with a bit of practical contrariness - while it is, in some ways, true to say that a good glue joint is stronger than the wood itself, it is in no way complete. Different glues are stronger in different ways. Most glues have good strength in a expansion strength (i.e., if you try to pull them straight apart, they won't budge) but they tend to have really poor sheer strength (they don't hold up so well if you try to slip them side to side, and it is frequently relatively easy to peal them apart), and they have horrible shock strength (hit them hard enough, and they break - we remove bridges on guitars by hitting the glue joint with a chisel, which gives MUCH cleaner results than any other method, but please don't try it at home!!!!) Most glues also have very poor resistance to atmospheric changes (moisture and heat can make them let go).
Also, in most of these categories, the oldest glue - hot hide glue - has the best performance. The only area where it DOESN'T is open time. Because it is worked hot, and it cools quickly, you just don't have much time to get things clamped up. Also, it requires some specialized equipment (not much, mind you, but a bit). So hide glue is a hassle, but for most things it works better. The marketing for the modern high tech glues is great, but for most things I really do prefer hide glue if I can clamp it quickly enough (or, as with veneer or Tolex, if I can reheat it with pressure in a manner which will work).
I also would want to avoid screws you can't re-tighten in any cabinet, because an amp is always going to rattle more than I would be comfortable with. Give me a good glue joint, and I'll be a happy man. On my cabinets, I usually use machine cut dovetails, though on one I did use a box corner bit I have, but that was even more hassle than the dovetails, since I already have the dovetail jig setup, and the corner bit needs to be in the router table, which sees a lot of other uses. I also once used biscuits, but I'm just not fond of biscuits for some reason. I can't exactly tell you why, but they never feel as strong as a proper joint.
Gabriel
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"Your old carpenter friend is lazy. His joint may be strong enough, but it ain't stronger."
Actually, he has a complete dovetail setup, router, table, and what looks like about a million bits. It's set up and always ready to go. He doesn't use them on his bass cabinets because he honestly feels his way is plenty strong. Keep in mind, the very first cabinet I ever built was rabbeted. I don't know how many jobs it's been hauled to over the years but I'd bet it's over 500 between my son and myself, and it's NOT been pampered. It's still solid. I coutersunk the screws and filled the holes with plastic wood so they really can't loosen. The only reason I ever wanted fingerjoints or dovetails is, as stingray_65 says, that old " If Leo did it, it must be best" thing when actually it's more like "If Leo did it, it was probably the cheapest and easiest way to get it done". That's not a put down; everything he did was that way... but it worked, and worked well.
I'd prefer boxjoints but I just can't make it work consistently.
The whole thing is a major irritation for me. Amp building is fun and easy. Getting chassis and cabinets together is neither!
Dave
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> double rabbet, glued and screwed joins
This joint?
(https://encrypted-tbn3.google.com/images?q=tbn:ANd9GcRshGN8r6aECOgT4KpiQmgxVy22_e6nkqm1X7tChEaHyXacQqZD-w7E1ZFStw)
Looks like all end-grain to me.
I don't like gluing end-grain, though I admit some new-goos do better.
Dovetails are all side-grain glue, and also the wedge reduces some stress on the glue. OTOH it is easy to cut dovetails so badly the glue won't join.
I like 2"x2" even 2x3 cleats inside. Heavy, brutal, ugly. Also, with boards, resists shrink/swell and the boards will crack (but never come apart).
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> double rabbet, glued and screwed joins
This joint?
(https://encrypted-tbn3.google.com/images?q=tbn:ANd9GcRshGN8r6aECOgT4KpiQmgxVy22_e6nkqm1X7tChEaHyXacQqZD-w7E1ZFStw)
Looks like all end-grain to me.
I don't like gluing end-grain, though I admit some new-goos do better.
Dovetails are all side-grain glue, and also the wedge reduces some stress on the glue. OTOH it is easy to cut dovetails so badly the glue won't join.
I like 2"x2" even 2x3 cleats inside. Heavy, brutal, ugly. Also, with boards, resists shrink/swell and the boards will crack (but never come apart).
You're right about the end grain, but if you are screwing it as well, it is probably OK.
And while it does take a while to get a dovetail jig setup, if you leave it setup it will work fine every time. Well, assuming you use the same sized wood - if you are using plywood, that's easy. Even without that, I can usually get it right with just 2-3 test pieces.
Gabriel
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PRR, that's the one except I'd put the board on the left on the top. Since I do combos, that'd put the weight stress on the sides instead of on only the half lap. I flipped your pic to show what I mean. I had a bit of a brain flash this afternoon. I'll do the rabbeted joint but with glued in wooden pegs. That oughta hold it. There's plenty of furniture and barns hundreds of years old that show how strong and durable it can be. Also, no screws to work loose. The best part is that I've done rabbet joints before. I can do it and I have the equipment. That'll fix everything! Now I just need to find someone to supply chassis with at least the PT opening cut. Maybe even the tube socket holes. That would sure make amp building quicker and more enjoyable!
Thanks for all the ideas. It made me think... and led to the solution that works for me.
Dave
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Well, it's back to dovetails! I mentioned to a friend about my jig problem and he showed me his. It's a General Tools 861 EZ Pro ll. He called it, "stupid simple." It's amazing! It's easy to set up. No measurements, just use the alignment attachment and tool and it turns out perfect every time. Plus, I have the added advantage of a good friend to show me the ropes. I ordered one yesterday. It's only $80!
I'll report on the results when it comes.
Again, thanks!
Dave
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Dave, I'm looking forward to your impressions of the EZ Pro jig. I've got a bit of a homemade jiggy-thingy (because I too like to do things on the cheap) I use with my router table, which works great, but it's really slow-going.
Craig
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Considering the amps being made are custom amps, why not custom joints
Because hand cut dovetails are a waste of time, are very hard to do well, and have not structural benefit over machine cut dovetails. There fine for a person who wants to have fun with woodworking, but if you are trying to make a living they are impossible to justify.
Gabriel
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My son and I made our first cabinet with the EZ Pro ll Tuesday. We did 3 test cuts first... just to figure it out. Then we made the cabinet. It worked great. Once figured out, it was easy. Obviously, it isn't 100% perfect but it's close enough for tolex and it'll get better the more we use it. All it took was a router and table. It can be done with just a router and a clamp but this seems easier. What I like about it is when you assemble and glue it, clamps are totally unnecessary. It taps together tight as a drum with a rubber mallet and the joints are pulled to a perfect 90 degrees. I tried my corner clamps but the joints were exactly right without them.
Best $80 I've spent in a long time!
Thanks for all the help and advice. It's great to have people to bounce this stuff off of... just to get it straight in your head.
Dave
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What I like about it is when you assemble and glue it, clamps are totally unnecessary. It taps together tight as a drum with a rubber mallet and the joints are pulled to a perfect 90 degrees. I tried my corner clamps but the joints were exactly right without them.
Well, you can usually get away with that, but it really is best to clamp them up. four bar clamps pulling everything together. Use cauls to protect the wood. Use wax paper to keep the cauls from sticking to the cabinet.
Gabriel
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Believe me, clamps are redundant. It takes a rubber mallot to assemble and the wood would break before it flexes. Here's the pics I forgot to post last time.
Dave
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Believe me, clamps are redundant. It takes a rubber mallot to assemble and the wood would break before it flexes. Here's the pics I forgot to post last time.
Dave
Nope, they aren't. Believe me, I know how tight they fit. You still want to clamp it.
Gabriel
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Nope, they aren't. Believe me, I know how tight they fit. You still want to clamp it.
Gabriel knows what he is talking about. I always clamp my half blind dovetails.
Your job turned out very nice. Congrats!
With respect, Tubenit
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On my PA and bass cabs I've been using Pocket Screw joinery. Very Fast, Very strong.
http://www.kregtool.com/Kreg-Jigreg-Jr-Prodview.html (http://www.kregtool.com/Kreg-Jigreg-Jr-Prodview.html)
I haven't used them on my guitar cabs yet, because most paying guitar customers are married to convention.... i.e. Finger Joints.
j.
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I have tried box joint and my jig is a pain. I don't know if I can justify the PC dovetail jig. Question for bigsbybender, I have a kreg jig but wondered if the screw length would cause a problem when routing the edge?
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I have tried box joint and my jig is a pain. I don't know if I can justify the PC dovetail jig. Question for bigsbybender, I have a kreg jig but wondered if the screw length would cause a problem when routing the edge?
It depends on how much you want to round over the edges. For an 1/8" round over? Probably not. For a 1" round over? Probably. For something in between, you'll likely have to experiment. On the other hand, if you've got a powerful enough router, and you are covering the cabinet, it might not matter. It's not exactly GOOD for your router bits, but if you don't need them for high production you would likely be OK. The bits will wear out pretty fast, though.
Gabriel
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I use tongue-and-groove, but seem to be the only one. It does provide side-grain surface area. I have also used dowels to re-enforce the tongue-and-groove joints. It's pretty easy for people like me with limited woodworking ability. The interlocking aspect is more appealing to me than the double rabbet, which I would feel compelled to cleat.
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I have tried box joint and my jig is a pain. I don't know if I can justify the PC dovetail jig. Question for bigsbybender, I have a kreg jig but wondered if the screw length would cause a problem when routing the edge?
I have to cut back on the roundover somewhat to avoid hitting a screw. I've actually been using DA (Dual Action or Random Orbit) sanders to do the roundovers which allows me to try different amounts of roundover until the cab looks good.... it also is faster for me to do rather than worry about router setup. It also means I can hit a screw without damaging anything. I still use the router with box jointed guitar cabs (usually copying Leo).
j.