Sliding dovetails with the MFT and OF1400??
- Thread starter Jesse Cloud
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Dan,
I really want to help you avoid work for as long as possible. I can see in the second pic (from underneath the table) that the setup leaves room to cut a tenon with the router flat on the mfs rail and the bit projecting below the mfs rails and against the workpiece. The first pic puzzles me a little, though. Isnt there a problem with support for the base of the router as you cut down what appears to be 3/4" stock? Also, in that first pic, what does the mfs gain you as opposed to simply clamping the workpiece vertically on the edge of the table?
Thanks
Dave
I really want to help you avoid work for as long as possible. I can see in the second pic (from underneath the table) that the setup leaves room to cut a tenon with the router flat on the mfs rail and the bit projecting below the mfs rails and against the workpiece. The first pic puzzles me a little, though. Isnt there a problem with support for the base of the router as you cut down what appears to be 3/4" stock? Also, in that first pic, what does the mfs gain you as opposed to simply clamping the workpiece vertically on the edge of the table?
Thanks
Dave
Dave Rudy said:
I appreciate your dedication to my attempts at anti-productity.
As long as the router's riding on the MFS, it's supported. This is kind of a dummy set-up, that was just the first piece of small stock I pulled out of the closet, if I were trying to cut a real tenon I'd put a spacer in between that stock and the table (so that I wouldn't hit the rail with the router bit), and adjust the MFS so that it made a rectangle that pulled the appropriate amount of stock off all sides of the stock.
It supports the router, and gives me an edge on all 4 sides to work against (I'd need 4 sides for a tenon, but only 2 for a sliding dovetail). For a sliding dovetail setup I'd set the length far longer than the piece needs to be, set the width to the desired tail width plus the copy ring diameter plus the narrow diameter of the dovetail bit, clamp the stock centered in the resulting rectangle, and set the bit depth to have wherever I measured the narrow diameter at exactly the top of the stock.
Run the router around the rectangle, being careful that it doesn't kick in to the stock, and there's your sliding tail.
Since in that setup centering on the length doesn't matter, just the width, if you use a common spacer then you can clamp the MFS to the table and just change out the pieces in which you want to cut the tails, only worrying about height and angle alignment for them. For that I'd probably take two pieces of 1/4" ply, one smaller than the rectangle, one larger. Glue the smaller one to the larger one, put this on top of the MFS face down, and push the stock up hard against it before clamping so that the top of the stock is parallel to the top of the MFS, but recessed 1/4" to allow for room for the copy ring or guide bushing. Instant height and angle adjustment.
(and if that's not clear, then maybe I need to scrounge an excuse to cut a sliding dovetail so I can take pictures all the way through)
Thanks Dan. This is really helpful. Of course, routing the dovetail with pics all the way through would really put it over the top, but no pressure. I think I understand what you are describing. I just took the earlier pic too literally. The effect is very similar to Pat Warner's tenonmaking jig (shown below on its side), but the next question is how to make the mfs jig adjustable so that we can "sneak up" on the final tenon width? With Warner's jig, you use an edge guide on the router to micro-adjust the depth (or width) of cut, cut one side of the tenon or dovetail and then flip the workpiece and re-clamp to cut the other, parallel side. If you're a FW subscriber, there is a movie showing it athttp://www.taunton.com/finewoodwork...ques/SkillsAndTechniquesArticle.aspx?id=5276. It seems like the mfs will do the job just as well, but how to micro-adjust the fit? More on the jig and additional pics athttp://patwarner.com/tenonmaker.html
Dave
Dave
Yeah, a lot like the Pat Warner jig you show the picture of. I'm not sure what he's using for a fence or a guide, I'm using the copy ring on the bottom of the router.
Adjustability is tough because the MFS is fixed by one of its arms, so while it's easy to adjust the MFS, it'd be hard to adjust both sides of it evenly. But that's what we've got calipers for, get close and sneak up on it with a sanding block.
My sweety is sick right now and last night used phrases like "you're not going to use power tools, are you?", but I've got an adjustable chair frame (we want to be able to quickly prototype seat and back angle and height with a number of different seat and back shapes) in my future, if I can get my taxes under control this weekend I'll try to sneak in some of these techniques and make sure they work as well as I'm claiming...
Adjustability is tough because the MFS is fixed by one of its arms, so while it's easy to adjust the MFS, it'd be hard to adjust both sides of it evenly. But that's what we've got calipers for, get close and sneak up on it with a sanding block.
My sweety is sick right now and last night used phrases like "you're not going to use power tools, are you?", but I've got an adjustable chair frame (we want to be able to quickly prototype seat and back angle and height with a number of different seat and back shapes) in my future, if I can get my taxes under control this weekend I'll try to sneak in some of these techniques and make sure they work as well as I'm claiming...
Dave Rudy said:
Dave,
Is there a reason you couldn't use a fence with the MFS instead of the bushing? Or even in conjunction with the bushing for that matter. By having a bushing in you can assure yourself you won't damage the MFS but you can still sneak up on the size with the fence.
greg mann said:
Greg,
I was wondering that too. If so, that solves the "micro-adjust" part of the problem. I think we're at the point where some experimentation is needed. I'm talking about this instead of doing it because I need to carve out enough time to finish my large MFT before I can even start playing with the MFS.
But to keep the thought process going, there is one more issue -- the workpiece needs to be at exactly 90 degrees to the base of the router (or top of the MFS). How can we move the workpiece in and out of the "jig" assembly quickly with repeatable positioning at perpendicular? (This of course is one of the delightful aspects of the Leigh FMT (which I just sold to get the Domino)).
Thanks
Dave
John Stevens
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Dave Rudy said:
Actually, you may want to make a fence that is capable of being placed at angles other than 90 degrees. My old jig (and the two prototypes that preceded it) was able to do that by means of an adjustable fence.
Dave Rudy said:
There are a couple of ways of clamping the workpiece if you're not restricting yourself to clamping it to the side-rails of the MFT. My old jig used a combination of Festool clamps and extruded profiles. The two prototypes of the final jig used bolts mounted in the clamping faces with star nuts to tighten a clamping bar, and that was a pretty fast and secure way to clamp.
Sorry to mention my jig again, in light of the fact that I didn't think it was worth bringing the pics and text about the jig from the old site to this one. It's just that I regard the sliding dovetail as a relatively weak joint that is time-consuming to make in comparison to other methods of joinery that are sufficiently strong, so I ended up not using the jig for sliding dovetails. Its other uses were for splines, M&T joints and floating M&T joints, but the Domino makes it obsolete for those uses. If anyone's interested, I can dig out some pics of the fences and clamping systems and post them here when I get back home next Thurs.
Regards,
John
Michael Kellough
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Good points John.
On my MFTs the frame is not exactly 90 degrees to the table surface. I have used plastic shim stock from McMaster.com to correct it (the frame splays out a bit) but you could also construct a perpendicular fence that attaches to the bottom of the MFS. This may make it easier to adjust the position of the board relative to the aperture. Doing so makes the MFS rig similar to the Pat Warner jig.
The picture above of the Pat Warner jig shows a large "versatile" aperture (unless I misunderstand it) which requires some kind of fence on top to constrain the router travel. This type of jig would be much more efficient if the aperture was the specific size for the guide bushing (or router base). Maybe the best option is to use the MFS to make a plate with the specific aperture for the tenon required, although this is contrary to Ned's appreciation for the MFS being a multitude of sizes of jigs in one compact form.
Combining both the above paragraphs, you could make the aperture (or MFS configuration) deliberately slightly oversize and use plastic shim stock (with double stick adhesive) to close in on the final size for the perfect tenon.
On my MFTs the frame is not exactly 90 degrees to the table surface. I have used plastic shim stock from McMaster.com to correct it (the frame splays out a bit) but you could also construct a perpendicular fence that attaches to the bottom of the MFS. This may make it easier to adjust the position of the board relative to the aperture. Doing so makes the MFS rig similar to the Pat Warner jig.
The picture above of the Pat Warner jig shows a large "versatile" aperture (unless I misunderstand it) which requires some kind of fence on top to constrain the router travel. This type of jig would be much more efficient if the aperture was the specific size for the guide bushing (or router base). Maybe the best option is to use the MFS to make a plate with the specific aperture for the tenon required, although this is contrary to Ned's appreciation for the MFS being a multitude of sizes of jigs in one compact form.
Combining both the above paragraphs, you could make the aperture (or MFS configuration) deliberately slightly oversize and use plastic shim stock (with double stick adhesive) to close in on the final size for the perfect tenon.
Thanks for the contributions, John and Michael. The Warner jig (and Greg's idea for the MFS) uses an edge guide on the router which allows horizontal position in relation to the workpiece (i.e. lateral depth of cut) to be micro-adjusted. In this configuration, the MFS rails would be further apart and the setting on the edge guide would move the router bit closer or further from the workpiece.
Dave
Dave
John Stevens
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Had some time to kill before hitting the road, so I'm trying to post some pics. I don't have software to resize, so I can only post the ones that are 175kb or smaller in size. Not many good choices, but here goes:
1. Clamping system using festool extrusions and clamps. Could have used the rapid-action clamps instead. Shown clamping a "traditional" tenon at 90 degrees. The pic only shows one clamp, but you must use two in order to keep the workpiece from moving when cutting the joint.
2. Fence system--two little buttons that can be slid along the extrusion to form lots of angles. Shown here being set to clamp at 45 degrees.
3. A sliding dovetail cut with this jig.
Unfortunately, I can't post a pic of the prototype jig with the pivoting fence and star-nut clamping system because the file is too big. But I hope these pics are helpful.
Regards,
John
1. Clamping system using festool extrusions and clamps. Could have used the rapid-action clamps instead. Shown clamping a "traditional" tenon at 90 degrees. The pic only shows one clamp, but you must use two in order to keep the workpiece from moving when cutting the joint.
2. Fence system--two little buttons that can be slid along the extrusion to form lots of angles. Shown here being set to clamp at 45 degrees.
3. A sliding dovetail cut with this jig.
Unfortunately, I can't post a pic of the prototype jig with the pivoting fence and star-nut clamping system because the file is too big. But I hope these pics are helpful.
Regards,
John
Dave Rudy said:
Dave - sorry about the delay in responding. Dan's using the same concept, and I can't really improve on his pics. But now I'm back in range of communications, I'm following the discussion with interest. The flaw with the setup I used, and which Dan posted, is in getting accurate, repeatable, incremental adjustments. I'd like to find a solution to this, because it's otherwise a quick and easy way of routing tenons. I have to make a couple of windows over Easter, so it will be an opportunity to tinker with tenon technique.
Matt
John Stevens
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Dave Rudy said:
Hi, Dave. Sorry for the delayed reply, but I just got back in town. I hope these pics answer your questions. The first two are from the same jig pictured above. The fence is set with a square, and the "face" is fixed at 90 degrees to the top with corner braces. The corner braces are cut at exactly 90 degrees on the MFT, with the fence set on the MFT using the method Rick Christopherson teaches here:
http://home.att.net/~waterfront-woods/Articles/Double-Error-Squaring.html
The second two pics show a different fence and clamping system from a prototype of the other jig. The fence pivots. The clamps are just oak sticks backed with a high-friction polymer material (carpet underlayment from Home Depot, but the high friction tape from Lee Valley would work as well).
The last pic is of my late dog playing in the bushes. Sorry, it's appropos of nothing, but it was on the same CD as the jig pics, so I couldn't help myself.
Jesse Cloud
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Great thread.
I built the jig from Jerry Work's MFS manual and it works great.
This forum really adds a lot of value to the tools. I just got my domino and I'll bet in a few weeks there will be dozens of creative new uses for it on this board. I can hardly wait!
I built the jig from Jerry Work's MFS manual and it works great.
This forum really adds a lot of value to the tools. I just got my domino and I'll bet in a few weeks there will be dozens of creative new uses for it on this board. I can hardly wait!
John,
Thanks for taking the time to post those pics. Excellent work, as always!! It is amazingly helpful when creative people are willing to share their ideas and help solve common problems.
Sorry about your dog. I know how attached I am to my four-legged friend. I know that one of us will be in for something of a rough time when the other one departs.
Dave
Thanks for taking the time to post those pics. Excellent work, as always!! It is amazingly helpful when creative people are willing to share their ideas and help solve common problems.
Sorry about your dog. I know how attached I am to my four-legged friend. I know that one of us will be in for something of a rough time when the other one departs.
Dave
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