I am making a set of drawers with half blind dovetails using my Rockler Dovetail jig. This jig is incredibly difficult to set up to get perfect dovetails. OTOH I don't make a ton of drawers so maybe I should just suck it up. I would value the opinions of members of this group as always.
That's probably because most of those jigs are in fact very difficult to setup. The key problem is the height of the bit. Or the offset from side to side. The offset from side to side is easy to work with. Just make the sides a little larger and plane or saw down accurately after they are joined. Put a knife mark from the front to the sides and cut to that mark.
I handcut dovetails rather than deal with it. But if I had production work to do I would not hesitate to spend the time setting up a jig. Half blinds are much harder both with a jig and by hand than through cut DTs.
I often have to make a "ton of drawers", have both the Leigh DR4 and the Akeda 16DC, and both are equally finicky, although the Akeda a bit less so than the Leigh.
I have learned to deal with the fact that router based dovetail jigs are problematic at best, but for productions runs, they are absolutely necessary for a small shop.
Way back in 1980 I bought a Craftsman DT jig. It really worked quite well and IIRC had darn few instructions but I do recall it mentioning to start on scraps and start with a particular bit depth and adjust from that point. IIRC I paid about $40 for the jig.
The point here is that Blind dovetails are incredibly simple. BUT you have to have every thing set up precisely and the bit cutting depth of both sides of the mating pieces is the same.
Be certain that you are using a good quality and exact size guide bushing that the jig calls for. If you can center the base/bushing to the bit, do that before making any cuts. This can save you a lot of heart ache.
If not remember to never clock or turn the router during the cutting operation. If the bit is not perfectly centered in the guide bushing and you even slightly rotate the router during the cutting operation some of the pins and tails will be a bit larger and or smaller than others. When you are rotating the router and the bit is not centered in the guide bushing you are cutting off center and rotating the router will change the cutting location even more.
Typically you mount a vertical board in the front of the jig a bit lower than the top of the pin board. You set the end of the pin board up against the back side of that vertical board and then lower the template down on to the top pin board.
The template must set flat on top of the pin board, no exceptions. This mandates that the board also be flat.
Next, the vertical tail board must be flushed up to the bottom of the template. Be careful not to push up too much and bow the template. Remember the template must sit flat on top of the pin board.
Once you have this all correctly in place you begin your trial cuts.
Make your cuts and remove the boards.
Is the fit too tight? Raise the bit a touch, cut shallower. Is the fit too lose? Lower the bit a touch, cut deeper. Does one end fit differently than the other end of the joint? Your wood and jig set up is wrong.
Get new scraps and test again. DO NOT reuse the same ends that were previously cut.
Each DT bit tends to have it's own sweet spot as to how deep it should be used at. When you are finished with the operation you can either leave that bit in the router, ;~) or measure the height setting before removing that bit so that the trial by error fit will be less trouble the next time.
And because of all the things that have to be just right I have really started to like using box joints over the DT's. Especially with the Incra iBox box joint jig on the TS, joints are a breeze compared to the DT jig.
Most people don't have a dedicated router to leave a DT bit in. Unless you are a production shop. I do leave a 1/8 inch round over in one of my routers.
But like Leon said you should mark it. The best way is to rout a new board as a depth gauge, just put it in the jig. Then mark this board as the gospel.
But you still need to work out the offsets. Still don't know which issue is your problem, the router bit heights or offset..
Everything you say matches my experience with the Rockler Dovetail jig. The problem is that making adjustments can be a total pain in the rear. For example, there is a fence that determines how far your router will go in to the grooves or sockets on the board that is lying flat. Each end of the fence has to be tightened down separately with a screw and handle and it is a BEAR to get the fence to be exactly parallel to the template. I need many measurements with a digital caliper to get it exact.
I guess the message for me is "suck it up. The setup process is a pain in the butt"
I have made a depth gauge just as you mentioned above so that getting the router bit to the right depth is fairly easy. It is the adjustments to the jig which are really time consuming and frustrating. I just put up a reply to Leon to give you one example.
I think I see the jig on Rockler's web site. That jig with the fence introduces yet another adjustment. If the base on your router is not round and or centered too, clocking it will cause you to cut too deep or shallow too. Typically the bottoms of the fingers on the template dictate the depth of cut front to back, that is.
You are right. There are other weak spots too that I won't go into. If I was doing a lot of drawers I would probably shop around for a better jig but not in my case I think.
As I mentioned as a follow up to Swingman, Incra makes the iBox jig. Well thought out and works on a TS or router table. Less complicated to set up and box joints are not terrible to look at. ;~)
Welcome to the "pain-in-the-ass" club. I think I currently own "about"
3 dovetail jigs.
I bought a PC "el-cheapo" about 15 years ago.... poor - fair results. I bought a PC Omnijig about 10 years ago. Same as above. My wife bought me a PC 4210 jig about 5 years ago... more of the same.
That subject has been beat to death here for years with varying results.
My current plan is to spend a month or two and learn how to make a "perfect" locking rabbet and sell all those dovetail jigs at a flea market.
Except for the most treasured projects (those I consider may gain heirloom status in my immediate family some day), I have taken to using locking rabbet joints for drawers when 'eating my own dog food', as well as for those projects where the client doesn't want to spring for dovetail joints.
I make them on the table saw, and (like any other project), as long as your stock is consistently flat and square, they are quite useable joints that can be made and assembled very quickly.
AAMOF, I went to the trouble of making a short SketchUp video and put it on youtube, more to refresh my own memory on the steps as I get older than for any other reason.
------------------------------------------------- Saw your other post.
I built some drawers using the Jet jig and had to be very careful to maintain registration since the guide bushing was not concentric with cutter.
Still had other problems which I was able to resolve to produce acceptable results.
As I remember, glad I don't have to making a living producing dovetails.
Clearly the source of errors consists of router end play of the router shaft, variation of stock thickness, the profile of the cutter which affects depth of cut and the concentric registration between bit and guide bushing.
While your plate doesn't solve all the sources of error, seems like it should make life a lot easier, if you insure concentric registration between bit and bushing.
Easy enough there are many centering bits on the market. Do not buy the woodline centering, it's useless. The pc collar that came with it did not fit any of my routers it was way undersized. And it requires you to use 1/4" collet. Others use 1/2 and 1/4 flip style shafts.
I remember my delight when I saw the drawers in the formal dining room's bu ffet. I expected... well... I don't know what I expected but I didn't expe ct to see the drawers rabbeted together. I have been using that joint for years, but was a little embarrassed by it since it seems everyone "knocks o ut" their full and half blind dovetails perfectly in unlimited numbers on a n as needed basis. I was pleased as punch to see a professional of your cal iber use that joint.
I started using that when we were building cabinets on the job back in the
70s as that was the way I was shown/trained. We had a table saw on the job that did everything we needed if we were working out of town, if not, the guy I worked for had a wood shop in the back of his warehouse where we woul d build.
Rabbets were easy on the tablesaw. And at that time half lap doors were th e rage as folks wanted that smooth look, so no panel type doors. For a fan cy job, we would put beading in a frame pattern inside the perimeter of the door face, painstakingly cut on a monstrous hand powered miter saw.
I tried out a giant 24" Rockwell jig that a cabinet shop had and loved it. I waited a couple years after I opened my biz and bought the 12" and never could get the half blind joints to be completely repeatable without a lot of fuss. No doubt 1/4 shank steel bits, and smaller routers had something to do with it. So, after watching a guy at a woodworking show (remember th ose?) make rabbet joints with his router, a light bulb went on and I starte d doing that again. This time I made the joints with a router, not a table saw.
So drawers became a no brainer. I used a router bit to groove the drawer f ace, sides and back for its plywood bottom, a router bit to cut a rabbet in to the rear of the drawer to inset the back, and a the router again to cut he locking rabbet on the face. Now the table saw could stay back at the sh op! I took the properly width dimensioned wood/plywood with me to the job and I could set up on site and work there. If it was one of my jobs as a G C, then this was outstanding as I could work on site and keep an eye on the job at the same time.
I even used that joint in a sets of super heavy duty drawers that were goin g to be carrying about 50+ pounds of stuff in them at all times. Think of pan drawers carrying the cast iron dutch oven, Pyrex, cast iron skillets, e tc., or all the hammers and crap in a garage shop. The pounds add up fast.
And to add to add 500% strength to that joint is easy. 30 mintue epoxy and few 18 ga. brads and it is unbreakable. Literally. For the record I have never seen one of my locking rabbets fail when it was just glued with white glue (go back to the 70s when we used Elmer's White grade g lue!)or any kind of yellow glue with no mechanical fasteners. The oldest o ne in use is that I know of is about 37 years old!
I like a good dovetail myself and appreciate what goes into them whether th ey are hand cut or machined. But since I don't do any of it for fun anymor e I go for speed, dash and accuracy.
Karl - looked for the video and couldn't find it. Could you post a link?
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