Help with Leigh Dovetail jig

[Randy Rizzo]

Was doing some one pass blind DT's the other night. I'd get 2 or 3 corners just right and then the 4th would be a total disaster, see photo. I used a marker to color the end of the joint for clarity. I cannot figure out what I'm doing wrong. The stock is planed 1 3/4" wide and 1/2" thick. It is straight and square. I did a 5 sided cut on my SCMS to recheck that and it was under 1/64". When I'm inserting the stock into the jig I'm making sure it's flush against the stops, the drawer front butted firmly against the side and the side is pushed up tight against the fingers. Any help form users of this jig would be greatly appreciated. It's making me nuts. And frustrating to boot.

[Ron Bontz]

Are you using the D4 or D4r. My D4 has gotten the legs out of wack before. Also is it only the 4th corner?

[Chip Lindley]

Try adjusting clamping pressure of the Leigh's hold-down bar more. A strip of sandpaper glued to the underneath side of the bar is a good investment. Stock has a tendency to be pulled in the direction that the bit cuts--more so when the bit gets a bit dull.

I have never had this particular problem with my Leigh D4R. Dovetails in 3/4" stock turned out perfect the very first time. But, a lesser Sears dovetail jig gave me fits years ago until I glued the sandpaper to the clamping bar.

[Alan Schaffter]

Since you say only some of the joints are as shown while the others are fine, then the boards are moving and NOT staying tight against the stops when you cut the improperly aligned ones.

[Randy Rizzo]

I'm using the Super jig, don't remember the exact model designation. It's not always the 4th corner, but I'll usually get 3 out of the 4 cut correctly. Movement of the stock is something I didn't consider, I thought I had the clamps fairly tight to begin with. The sandpaper under the clamping bars sounds like it might be a solution. I'll give it a try. Thanks all for the responses.

[Alan Schaffter]

Instead of the boards moving, it could also be your clamping technique- you place the board against the stop, but when you go to tighten them, you are allowing them to move slightly (1/16") before they are firmly clamped. Check that the stock is against the stops after tightening.

[Paul Murphy]

One possibility not mentioned is router guide bushing possibly not centered. The joints not meeting at the side could happen if you rotate the router relative to the passes made on properly mated joints.

[Dave Stuve]

I'm not sure exactly how one-pass works, but is it possible that you're getting the boards mixed up? If you route them together and then flip one around and try and match it to another board it might give you that offset. Check your labeling carefully.... I zoomed in on your photo and it seems like the offset is suspiciously close to the size difference in the pins. Just a wild guess...

[Randy Rizzo]

One possibility not mentioned is router guide bushing possibly not centered. The joints not meeting at the side could happen if you rotate the router relative to the passes made on properly mated joints.

I always position the router in the same relationship to the jig and I've checked to make sure the bushing hasn't rotated, I'm using the Leigh supplied bushing that allows the dovetail joint to be adjusted for tightness, but in the case of one pass blind DT's it's set at 0 offset or the same as using a standard 7/16 bushing.

[Randy Rizzo]

Instead of the boards moving, it could also be your clamping technique- you place the board against the stop, but when you go to tighten them, you are allowing them to move slightly (1/16") before they are firmly clamped. Check that the stock is against the stops after tightening.

Been doing that, after clamping I recheck the setup. I'm going to do some test joints later this week with sandpaper under the clamping bars. I'll report back after the test to see if I get better results.

[Randy Rizzo]

185848

Well I spent most of the day screwing around with the Leigh Super 12. I milled up some stock this morning. And I spent more time and closer scrutiny examining how the stock was loaded. I noted as the top piece (Drawer front) was held against the lateral stop when it contacted the side instead of being flush it had a slight angle to it. (Fig 1 of the attachment, exaggerated) Just using sight and feel seating the front firmly against the side (fig 2) resulted in correctly aligned joints. Holding the drawer front against the lateral stop produced consistent offsets. Going by sight and feel I was able to get better results but I was never sure how they would turn out. I had contacted Leigh tech support as well last night and they've been very responsive. They provided a measurement for the offset, should be .445. When I checked my jig with the stock against the lateral stops it was .51, which produced the offset in the joint. I went back and checked the original alignment of the lateral stops and they were OK. Then I made up a gauge out of 1/4" ply that I could stick in the jig to get the required offset and I was able to produce repetitive correctly aligned joints until I got tired of doing it. The only thing is the top piece of stock cannot be held against the stop or misaligned joints will occur. BTW I did add sandpaper to the underside of the clamping bars and that really makes for a rock solid bite on the stock. Thanks for all the suggestions. I've forwarded all this to Leigh. Last email, they were going to spot check in house material to see if they have a problem. I'll post a follow up with their result. At least it wasn't pilot error!

[Ron Bontz]

Thanks for posting. Interesting.

[Randy Rizzo]

After a week or so emailing back and forth, Leigh tech support they came up with a suggestion was I may have over torqued the nut holding the lateral side stop. The stop is plastic with two little nubs to hold it in proper alignment in an aluminum channel. I checked mine and the nubs appeared to be slightly deformed. When I reported this to Leigh they offered to send new ones gratis. After installing the new stops and only using moderate torque I was able to get better results, but still slightly mis-aligned corners by just trying to hold the stock against the stop. The foolproof method was using my shop made gauge to check the offset dimension and making adjustments then locking down the stock. Perfect corners every time. BTW they did do a spot check on in house inventory and reported no problems. So it's either this particular jig or operator error. But as least I'm to the point to where I can get joints in plane

[Alan Schaffter]

One question- how did the board get askew in fig. 1 above? On that jig aren't you supposed to ensure the end of the drawer front (or back) is tight up against both the drawer side and the lateral stop before you clamp it? If you do that it will never be cocked. Also, are you using a spacer board under the fingers on the right side of the jig or being real careful to get even clamping pressure across the drawer front?

[Randy Rizzo]

One question- how did the board get askew in fig. 1 above? On that jig aren't you supposed to ensure the end of the drawer front (or back) is tight up against both the drawer side and the lateral stop before you clamp it? If you do that it will never be cocked. Also, are you using a spacer board under the fingers on the right side of the jig or being real careful to get even clamping pressure across the drawer front?

I am using a spacer on the right under the clamping bar/fingers. When inserting the drawer front (top board) it's supposed to be held against the top lateral stop. In doing so instead of butting up against the vertical board it is cocked or askew as in fig1. Not anywhere near to the degree shown, but it is not making full contact across the face of the vertical board, it's open on the left end. Butting the drawer front tightly to the side (vertical board) means it's no longer in full contact with the top lateral side stop, but that's what it takes. The replacement stops that Leigh sent reduced the angular displacement so I probably did have the bolts cranked down too tight, but it did not correct the problem entirely.

[Alan Schaffter]

I am using a spacer on the right under the clamping bar/fingers. When inserting the drawer front (top board) it's supposed to be held against the top lateral stop. In doing so instead of butting up against the vertical board it is cocked or askew as in fig1. Not anywhere near to the degree shown, but it is not making full contact across the face of the vertical board, it's open on the left end. Butting the drawer front tightly to the side (vertical board) means it's no longer in full contact with the top lateral side stop, but that's what it takes. The replacement stops that Leigh sent reduced the angular displacement so I probably did have the bolts cranked down too tight, but it did not correct the problem entirely.

Hmmmm, I don't understand how and why you have skew and why the end of the drawer front can't be both tightly butted against the drawer side (vertical board) at the same time its edge is tight against the drawer front lateral stop? Geometrically it is impossible.

It is hard to tell from looking at the photos of the Super Jig on the Leigh website, but it looks like the drawer front lateral stop is located well back from the front of the jig under the clamp bar and may only be a half inch to an inch wide at most, so positioning the drawer front against it first, which sounds like what you are doing, is just asking for trouble and can easily result in the drawer front being skewed!

With both my old Sears fixed finger jig and my Leigh D4, I set and check the front and side lateral stops first. Then I temporarily clamp the drawer side to the front of the jig so the end is slightly above the deck of the jig. I insert the drawer front under the fingers, slide it forward against the (vertical) drawer side. While holding it butted tightly against the drawer side, I slide it sideways until the edge contacts the lateral stop and lock it down. Then I unclamp and reposition the drawer side so its end is flush with the top surface of the drawer front and its edge is against the lateral stop.

Since the drawer front lateral stop is not wide and does not extend front to back, it should be considered a point reference, but should always make a right triangle with the front apron of the jig. Essentially you should have three points of a right triangle - each edge of the drawer front and the drawer front lateral stop (see my sketch). Check to see that the end of the drawer front lateral stop is parallel to the side of this triangle.

If you insert the drawer front against the back face of the drawer side and the end of the drawer front lateral stop is not parallel to the edge of the drawer front, then you have a problem with the stop.

If you mount your boards the way I suggest and still have skew, then you have:


Operator error- (1) either your boards are not cut as square as you think, or (2) you are letting them move before or during clamping.

If you really don't have skew but truly have an offset, then you have:

Operator error- (1) the lateral stops were not not properly set initially, (2) are not properly locked and have slipped or are slipping, (3) you are not using the snap-in accessory drawer side lateral stop, or (4) the widths of both boards are not identical, or (5) the boards are not snug against the stops.

Jig problem- the drawer front and/or drawer side lateral stop(s) is (are) the wrong length

I can't imagine any other causes.

188600

[Randy Rizzo]

Hmmmm, I don't understand how and why you have skew and why the end of the drawer front can't be both tightly butted against the drawer side (vertical board) at the same time its edge is tight against the drawer front lateral stop? Geometrically it is impossible.

It is hard to tell from looking at the photos of the Super Jig on the Leigh website, but it looks like the drawer front lateral stop is located well back from the front of the jig under the clamp bar and may only be a half inch to an inch wide at most, so positioning the drawer front against it first, which sounds like what you are doing, is just asking for trouble and can easily result in the drawer front being skewed!

With both my old Sears fixed finger jig and my Leigh D4, I set and check the front and side lateral stops first. Then I temporarily clamp the drawer side to the front of the jig so the end is slightly above the deck of the jig. I insert the drawer front under the fingers, slide it forward against the (vertical) drawer side. While holding it butted tightly against the drawer side, I slide it sideways until the edge contacts the lateral stop and lock it down. Then I unclamp and reposition the drawer side so its end is flush with the top surface of the drawer front and its edge is against the lateral stop.

Since the drawer front lateral stop is not wide and does not extend front to back, it should be considered a point reference, but should always make a right triangle with the front apron of the jig. Essentially you should have three points of a right triangle - each edge of the drawer front and the drawer front lateral stop (see my sketch). Check to see that the end of the drawer front lateral stop is parallel to the side of this triangle.

If you insert the drawer front against the back face of the drawer side and the end of the drawer front lateral stop is not parallel to the edge of the drawer front, then you have a problem with the stop.

If you mount your boards the way I suggest and still have skew, then you have:


Operator error- (1) either your boards are not cut as square as you think, or (2) you are letting them move before or during clamping.

If you really don't have skew but truly have an offset, then you have:

Operator error- (1) the lateral stops were not not properly set initially, (2) are not properly locked and have slipped or are slipping, (3) you are not using the snap-in accessory drawer side lateral stop, or (4) the widths of both boards are not identical, or (5) the boards are not snug against the stops.

Jig problem- the drawer front and/or drawer side lateral stop(s) is (are) the wrong length

I can't imagine any other causes.

188600

my comments in red

Hmmmm, I don't understand how and why you have skew and why the end of the drawer front can't be both tightly butted against the drawer side (vertical board) at the same time its edge is tight against the drawer front lateral stop? Geometrically it is impossible. And this is where the problem is, holding the drawer front firmly against the lateral stop the front does not fully contact the vertical board, it’s open at the left end.

It is hard to tell from looking at the photos of the Super Jig on the Leigh website, but it looks like the drawer front lateral stop is located well back from the front of the jig under the clamp bar and may only be a half inch to an inch wide at most, (it’s actually closer to 1 ½”, but still not much of a reference) so positioning the drawer front against it first, which sounds like what you are doing, is just asking for trouble and can easily result in the drawer front being skewed!

With both my old Sears fixed finger jig and my Leigh D4, I set and check the front and side lateral stops first. Then I temporarily clamp the drawer side to the front of the jig so the end is slightly above the deck of the jig. I insert the drawer front under the fingers, slide it forward against the (vertical) drawer side. While holding it butted tightly against the drawer side, I slide it sideways until the edge contacts the lateral stop and lock it down. Then I unclamp and reposition the drawer side so its end is flush with the top surface of the drawer front and its edge is against the lateral stop. This is pretty much what I’ve been doing and now I’m getting consistent corners that are in plane

Since the drawer front lateral stop is not wide and does not extend front to back, it should be considered a point reference, but should always make a right triangle with the front apron of the jig. Essentially you should have three points of a right triangle - each edge of the drawer front and the drawer front lateral stop (see my sketch). Check to see that the end of the drawer front lateral stop is parallel to the side of this triangle. Right, or it should be 90 degrees to the vertical clamping surface. I’ve got a friend with a metal milling machine, we’re going to make up a longer stop to replace the plastic one. From what I’ve seen the D4/D4R have machined aluminum stops that are significantly longer. But for the time being what I’m doing works. I just need to check the offset on every joint to make sure it’s correct

If you insert the drawer front against the back face of the drawer side and the end of the drawer front lateral stop is not parallel to the edge of the drawer front, then you have a problem with the stop. I believe that’s it, I’ll let you know how our Rube Goldberg fix works

If you mount your boards the way I suggest and still have skew, then you have:
• Operator error- (1) either your boards are not cut as square as you think, or (2) you are letting them move before or during clamping. Don’t think either is the problem. I’ve checked squared ends with a machinist’s square and re-check board alignment after clamping

If you really don't have skew but truly have an offset, then you have:
• Operator error- (1) the lateral stops were not not properly set initially, (2) are not properly locked and have slipped or are slipping, (3) you are not using the snap-in accessory drawer side lateral stop, or Am using the snap in accessory in the correct orientation, #1 up (4) the widths of both boards are not identical, or Always check width after preparing stock by setting boards on edges on cast iron saw table (5) the boards are not snug against the stops.
• Jig problem- the drawer front and/or drawer side lateral stop(s) is (are) the wrong length

I can't imagine any other causes.

[Tim Tritt]

I too have been fighting a Leigh Super 12 jig! I've spent a great deal of time attempting to produce consistent one-pass half blind dovetails for drawers I'm hoping to make. A few things I've found along the way are: The guide bushing included from Leigh seems a bit touchy to me. When routing I find the router held firmly still wants to rotate slightly as you advance your cut. I've tryed the Whiteside precision 7/16" guide bushing and it provides much better results ( as long as it doesn't vibrate loose! ). Another thing I've noticed, is that after I've clamped my boards in the jig and I've replaced the "finger board", depending on which side of the jig I tighten first the whole finger board will move as much as 1/16" of an inch! I've adopted the procedure to always tighten the right know first until the finger board is flush with the boards and then tighten the left knob. Another thing I've observed is that the finger board will actually easily bend without much effort. If your not careful, You can get some odd issues if that happens. Another item that isn't too big a deal but an issue none the less, is the silver finger nut fore/aft adjustment on the finger board. One more item that I've found to cause problems is the front lateral spacer to offset the side boards. In the beginning of their manual, they stress you need 6 side squared boards to set this. Be sure and check that it's still where you set it and is accurate. I finally switched the front right side later spacer with the left and for unknown reasons The alignment marks aren't "real" accurate and I've begun using my digital calipers to be sure it right.

Leigh tech support has been helpful, but I wasn't quite ready for the level of squareness required to make everything work. Indeed I do wonder how others are able to achieve their 2 thousands of an inch tolerance. So far the jig has allowed me to purchase a jointer, planer, new rip fence and dust collector. Had I known in the beginning these additions I likely wouldn't have purchased the jig.

Hope this may help in some small way.

[jonathan eagle]

I too have been fighting a Leigh Super 12 jig! I've spent a great deal of time attempting to produce consistent one-pass half blind dovetails for drawers I'm hoping to make. A few things I've found along the way are: The guide bushing included from Leigh seems a bit touchy to me. When routing I find the router held firmly still wants to rotate slightly as you advance your cut. I've tryed the Whiteside precision 7/16" guide bushing and it provides much better results ( as long as it doesn't vibrate loose! ). Another thing I've noticed, is that after I've clamped my boards in the jig and I've replaced the "finger board", depending on which side of the jig I tighten first the whole finger board will move as much as 1/16" of an inch! I've adopted the procedure to always tighten the right know first until the finger board is flush with the boards and then tighten the left knob. Another thing I've observed is that the finger board will actually easily bend without much effort. If your not careful, You can get some odd issues if that happens. Another item that isn't too big a deal but an issue none the less, is the silver finger nut fore/aft adjustment on the finger board. One more item that I've found to cause problems is the front lateral spacer to offset the side boards. In the beginning of their manual, they stress you need 6 side squared boards to set this. Be sure and check that it's still where you set it and is accurate. I finally switched the front right side later spacer with the left and for unknown reasons The alignment marks aren't "real" accurate and I've begun using my digital calipers to be sure it right.


Leigh tech support has been helpful, but I wasn't quite ready for the level of squareness required to make everything work. Indeed I do wonder how others are able to achieve their 2 thousands of an inch tolerance. So far the jig has allowed me to purchase a jointer, planer, new rip fence and dust collector. Had I known in the beginning these additions I likely wouldn't have purchased the jig.

Hope this may help in some small way.


I have the D4 jig. It has lots of issues in maintaining squareness as well. Some of this may apply. I found wrapping the clamp bar with rubber kept the wood from moving was required. also when using the router , make sure to keep the orientation contant when moving the router forward and back. This will correct for the position of the guide. Those guide based jigs want the router bit to be perfectly centered in the guide. Any slop will be transferred to your joint.
Jonathan

[DENNIS BURNS]

Looks like one is upside down to me