Best way to join chops with wedges

[Framar]

I started ordering chops with wedges when I could not find any bright putties for the corners on certain frames, or for frames with round edges which do not fit in my Stanley.

Problem is - the glue I normally use, Maxim, is sets up in one minute (can no longer find the five minute stuff) and that is not enough time to do all four corners at once. I find that no matter who I order these from, they need a lot of finessing and juggling.

I switched to Frank's - but it seems to be too runny for wood.

Then I tried Weld Bond - which is OK but doesn't seem very grippy.

Last couple of frames I had so much trouble with I ended up using and sinking brads.

So, if you have ever used these things (the ones that look like little bow ties or the ones that look like Tie Fighters), what is your method of approach? Do you make two L shapes and then join them (as one would with a Stanley)? Or do you do all four corners at once?

What glue do you use?

This is driving me nuts. I have been joining frames with a vise for almost 50 years (Kramer joined frames with a furniture vise - the Stanley seems like a Godsend after that!) and I feel like an idiot.

 

[Larry Peterson]

I've had good luck with this stuff: Amazon product

 

[wpfay]

You don't need to join the frames all at once. Glue up one corner at a time and insert the "keys". Make sure you are working on a very smooth but relatively hard flat surface, especially with the Hoffmann dovetail keys since adjustment after they are fully inserted is almost impossible. I have little experience with the "H" shaped keys, and that what I have wasn't nearly as good as the Hoffmann system.

I talked with Len Lastuck about the Maxim glues and the demand for the slower set time product simply didn't justify the cost of the batch size that had to be made.

if the glue you are using sat in your shop the whole time you were not allowed access, you may need to replace whatever glue you have remaining. I use either Titebond or Corner Weld since the slow setting Maxim stopped being made.

 

[Framar]

I will rummage around in my vast glue collection and see if I have any Titebond. Any glues left at my shop during the shutdown never got below fifty degrees. I figure if the Frank's is still working OK, everything else is too.

I guess I just have to be more patient in joining these things.

Thanks!

 

[Larry Peterson]

I will rummage around in my vast glue collection and see if I have any Titebond. Any glues left at my shop during the shutdown never got below fifty degrees. I figure if the Frank's is still working OK, everything else is too.

I guess I just have to be more patient in joining these things.

Thanks!

I have used many of the Titebond glues for general woodworking. What drew me to the one I recommended, the Moulding and Trim Titebond is that is is supposed to be better on end grain.

 

[David Waldmann]

Firstly, as gently implied by Wally, they are not "wedges", they are "keys". Yes, I tend to be a bit more blunt...

By the way, while I understand why they're called wedges by some (OK - many), and see a scientific principle that applies, the Manufacturer takes exception to their being called that, so I acquiesce.

Secondly, you only need to glue one corner at a time for the first two joints, then two corners to finish. One minute is waaay more than you need for that. There should be no need for "finessing and juggling" - maybe you need different suppliers...

Lastly, also as pointed out by Wally, the surface you join on should be as hard, smooth and flat as possible. This will ensure that the faces are flush. If the surface is hard, smooth and flat there is near zero chance of marring the finish. If it's not hard, there is no way to ensure the faces stay aligned. Of course, if it's not smooth, that texture could transfer to the finish. And if it's not flat, you will have a hard time getting all four pieces properly aligned.

We recommend phenolic sheet as an ideal joining surface. At least 1/2" thick paper or canvas with the least expensive phenolic will work great. No need for high heat, electric resistive or other fancy properties.

Oh, by the way, we sell pre-cut phenolic sheet, or can custom cut to order...

 

[Framar]

Sorry for calling them wedges - all of the companies I order from call them that. And in the art world, keys are little triangles of wood which are hammered into a stretcher to drive the corners further apart and thusly cause a canvas to tighten. So I could never ever refer to those little plastic bow ties as keys. What we have here is an overlap of wood worlds and wood words.

I have a nice flat hard workbench - a sheet with a formica-like surface.

But I may just have to resign myself to going back to the Stanley and my diminishing supply of #19 and #18 brads.

Again - thanks!

 

[wpfay]

The tensioning triangles on stretchers are technically wedges since they are pushing two legs of the stretcher apart. The keys on a Hoffmann dovetail join pull the joint together.

Mar, here's where you can replenish your supply of wire brads, though I don't think you should give up on the dovetail option completely.

United Mfrs Supplies - Framing supplies for all your frame and frame supply needs.

 

[Framar]

Thanks, Wally. I have not bought anything from United in years - still waiting on a few backorders from ten years ago . . . LOL

 

[David Waldmann]

The tensioning triangles on stretchers are technically wedges since they are pushing two legs of the stretcher apart. The keys on a Hoffmann dovetail join pull the joint together.

Yes. But.

Wedges typically work by forcing things apart. The Hoffmann keys use the exact same principle, but in reverse. Each half of the key IS a wedge, and moves the piece of wood it's attached to in the direction that you would expect a wedge to do so - AWAY from the wide end of the wedge. As it happens, the wide end of the wedge is further away from the joint than the narrow edge, which has the effect of pulling the joint together.

Again, I fully believe and embrace the idea that the keys are acting as wedges, but in deference to the manufacturer, who I highly respect, I do not call them that any more.

 

[wpfay]

OK, technically correct. It is using an inclined plane to force something in a particular direction, only, in this case, 4 directions at once. I agree with the name of "Key", and the route being a "Keyway". It is more specific than "Wedge".
Not Kwite what to call the Bainbridge joining system, though. They do not "force" anything, but are passive joiners.

 

[alacrity8]

I wouldn't hold United's past mistakes against the current company that holds the name, as they are not the same thing.
Not is not to say that I order from them either.

 

[Echobelly]

I use the "thumbnail master Joiner" for most of our frames. The plastic wedges are H shaped. I glue the frame up in a vice first and after it's set, I squirt glue in the void and insert the wedges. Never had a problem.

 

[Framar]

I glue the frame up in a vice first and after it's set, I squirt glue in the void and insert the wedges. Never had a problem.

Well, I'll be dipped.

That is the best idea I have heard in really long time! I think my problem was trying to do this from the back.

THANK YOU!!!

 

[David Waldmann]

I use the "thumbnail master Joiner" for most of our frames. The plastic wedges are H shaped. I glue the frame up in a vice first and after it's set, I squirt glue in the void and insert the wedges. Never had a problem.

FYI, that does nothing. I challenge you do do (even non-scientific) testing of the strength with and without the glue "squirted in".

Adding the thumbnails after the joint has been glued and set DOES add something - it will probably keep the frame from completely falling apart if the glue joint fails.

The thumbnail system compared to the Hoffmann system is Chevy to Mercedes. Yes, they both will (generally) get you from A to B. Thats about it. Note - your feet will also get you from A to B...

 

[Framar]

OK, I am officially confused.

Could one of you wood wizards please explain to me what exactly are the differences between "thumbnails", "wedges/keys" (those plastic bow ties and Tie Fighters) and the Hoffman system? When I order joins from either LJ or my local supplier they use those little metal V-shaped gizmos.

I have joined frames for fifty years using glue and brads and a 16 oz. Craftsman claw hammer. In hardwood I predrill the holes with brad with the head cut off. I do this in my one and only Stanley miter vise. Sometimes when my chops have been badly cut by certain suppliers, I end up gluing and clamping them for a few minutes before inserting the inserting the brads. I have heard tell of framers who join their frames with four vises - letting the glue set for 24 hours before underpinning the frames. No one had ever brought back a frame with opened corners - not in all these years. So why wouldn't following the same path, only using the plastic gizmos instead of brads, be as sturdy?

I ain't Norm Abrams or Bob Vila - I am not making "earthquake proof" frames. (We always used to laugh at those guys with their glue and biscuits and power-driven brads.)

I have always understood that the nails hold the wood in place until the glue sets up. As the years have gone by the glues have become stronger and faster. Kramer used to buy cheap white glue in 5 gallon buckets and it was used for everything from dustcovers to double mats, needlework (God forbid!) to frames.

The picture framing industry sure could use a proper glossary.

 

[neilframer]

Hi, Mar!
The metal V-shaped gizmos are v-nails and we have 2 v-nailers that we use every day.
There are a number of frames that we just join right in the v-nailer with glue.
We use Corner Weld glue.
You have to look at the moulding profile and decide the size of the v-nail, how many positions on each corner to v-nail and if you need to stack the v-nails.

I also use Stanley vises for some profiles to join and then I quickly v-nail after joining with glue in vises.
There are some profiles where I feel that I get a better join in a vise before I V-nail.
It doesn't have to sit in the vise very long before v-nailing, maybe 10 minutes and I don't just stand and watch the glue dry, there are plenty of other things to do while the frame joins in the vises.

We have 10 Stanley vises, some of them are my own personal vises that I bought in the early 80's when I also drilled and nailed the corners back then.

When I use vises, I usually join the halves for a bit, then I join the third corner and let it sit for a few minutes before I join the fourth corner because sometimes if you have some warpage and you try to join the 4th corner right after the 3rd, the 3rd will move before the glue has set.

Thumbnails are plastic keys put into the corners after machining the corners to accept them.
I don't like the thumbnails because you have to remove wood from the corners for them possibly weakening the corner and they are made of plastic and can break.

I haven't use the Hoffman system and I believe that it is kind of like the Thumbnail system only with wooden corner keys instead of plastic ones.
I have methods that I use for moulding with slant backs and rounded backs but that might require it's own thread.

As always, a good join with good glue will give you a strong corner.
When you get a well glued corner, you almost can't even beat it apart with a hammer even without v-nails or keys or finishing nails.
The rest is there to just reinforce the corner and prevent the frame from just falling apart if it's dropped or highly stressed.

 

[David Waldmann]

Thumbnails are "H" shaped in cross section. The Hoffmann system uses bow tie shaped ones. I'm not aware of any other system that's similar but there could be.

Both are plastic*, although from what I understand, the Hoffmann ones are much more durable. They also are offered in 4 different cross section dimensions, from eensy-weensy to ginormous.

*Hoffmann does sell key stock made of wood, however, it's suggested to only be used decoratively, as the grain runs longitudinally and provides very little strength across the joint.

 

[David Waldmann]

Thumbnail insert:



Hoffmann Key:

 

[Mike Labbe]

Tagging @Markus Hueber from Hoffman USA.

Hoffmann is also a sponsor of this forum!

 

[framah]

"I have always understood that the nails hold the wood in place until the glue sets up. "

Mar... nails are for holding the frame together long enough to get it back to a framer once it has fallen off the wall.
With only glue holding the joint together, when it falls and hits the floor the whole frame can come apart and break the glass, etc.

If you put a frame in a vise and glue it, nailing it right then stands the chance of weakening the glue joint by jarring it/ slightly pushing it apart.
Glue it, let it set there for 10 minutes or so and THEN drill and nail or V nail it.

Also, i have had damaged frames come in with the plastic insert snapped in half right at the joint line. V nails and brads at least hold the joint together.

 

[wpfay]

While I agree that nails serve more of a safety net role in the life cycle of the frame, both the V-Nail and the Hoffmann dovetail key, in most instances, and when used correctly, replace the need for using a vise or clamping the frame while the glue dries.
There are the odd variants because of profile shape that are better clamped until the glue is set then V-nailed, but that doesn't work at all with the Hoffmann system. If the keyways are not perfectly aligned the pre-glued corner will be broken open when inserting the keys. Maybe Marcus will explain the tolerances in the basic Hoffmann system with his colorful German idioms.

 

[CHolt]

Very little experience with Hoffman or Thumbnail, but some. I have always wondered if PVA glue would really permanently bond to the plastic keys.

 

[David Waldmann]

I have always wondered if PVA glue would really permanently bond to the plastic keys.

I've never wondered that. In fact, I have always assumed it would be similar to using grease instead of glue.

Not sure what the Thumbnail people say/said, but in a properly rolled Hoffmann joint, there should be no glue touching plastic. Glue goes on the wood:wood surfaces, the key pulls it together.

 

[CHolt]

I've never wondered that. In fact, I have always assumed it would be similar to using grease instead of glue.

Not sure what the Thumbnail people say/said, but in a properly rolled Hoffmann joint, there should be no glue touching plastic. Glue goes on the wood:wood surfaces, the key pulls it together.

I didn't think of it before but now I remember taking some keyed frames apart by driving a #2 or #3 screw into the bottom of the key to pry it out of the keyway.

 

[Prospero]

The big problem with plastic wedges is that while they do hold very tight, they do reduce the glue area.
Quite significantly on narrow mouldings. The main strength of the join is in the glue. No matter how strong
you think the glue is, it is limited to the area of the face that is in contact with. If the wedges were wood, then
the area would be increased, like a biscuit join - but as already mentioned, wooden wedges are intended for cosmetic
reasons only. Where the slot is visible they can be capped with a thing slice of wedge, rather like the wooden
'Dutchman' used to fill a knothole or defect. I would contend that on a tall, narrow moulding a pair of conventional
nails inserted crosswise near the top would produce a stronger join. Go back 40 years and all frames were joined like this.
Someone ought to do a few tests.

 

[David Waldmann]

The big problem with plastic wedges is that while they do hold very tight, they do reduce the glue area.
Quite significantly on narrow mouldings. The main strength of the join is in the glue. No matter how strong
you think the glue is, it is limited to the area of the face that is in contact with...

...I would contend that on a tall, narrow moulding a pair of conventional
nails inserted crosswise near the top would produce a stronger join. Go back 40 years and all frames were joined like this.
Someone ought to do a few tests.

Strong, stronger, strongest. How strong does it need to be?

 

[framah]

Strongest possible, I would think.

 

[David Waldmann]

Strongest possible, I would think.

Well then maybe one should consider skipping wood altogether and go with welded titanium?

Seriously, if X is strong enough, why go to the expense and effort of 10X? 100X? 1000X?

BTW I'm not saying that a v-nailed and cross pinned joint is 10x stronger than a Hoffmann, but for those that claim it's any stronger - does it matter?

 

[framah]

Ooohhhh.. welded titanium!! That sounds sooooo much stronger than plain old wood.

 

[CHolt]

Those keyed systems are not intended to make a superior joint. The benefit of routed keys is in workshop overhead, as there is supposedly no need for an underpinner or a craftsperson who can operate and maintain one, nor corner vises for that matter. Let the end user be the judge.

 

[Prospero]

However strong the glue bond is, it is proportional to the glue contact area. If you rout away a portion
(say 30% of the face) then the joint strength is reduced by that amount.

Maybe not a problem with a 2" wide, 10x8" frame, but a 36x24" 1" wide frame.......

 

[wpfay]

There are much stronger ways to join frames that haven't been discussed, but they are usually reserved for closed corner frames. Any joining that has added linear grain surface to the glue face is going to be stronger than end grain joinery.
Peter's suggestion of a plate biscuit makes a far stronger joint than anything else discussed, but the application is somewhat limited in pre-finished mouldings because of size issues.
Museums and galleries that use contemporary stem profiles almost always insist on splined miters because they are less likely to come undone from the normal handling and transport in museum settings.
The miter joint is arguably one of the weakest joints in woodworking second only to a butt joint. Any of the traditional furniture joints are better though they are far from expedient, especially in pre-finished mouldings.

Peter, the keyway cut in the miter for a W-0 Hoffmann key results in a loss of less than 2mm X the length of the key. Properly sized, the key provides uniform pressure to the entire joint during the drying/curing process, and like brads, serve as a moderate failsafe should the glue fail.

 

[Markus Hueber]

Hello All,
Great conversation – allow me to respond to a few of the statements and questions:

• Prospero has a point that routing a keyway obviously removes wood and thus reduces the available surface area for a glue bond.
• 
  
• However – Hoffmann Dovetail Keys bring a number of advantages to the party:
• 1. They are “double-dovetail” shaped and thus create a force that pulls the miter faces tightly together (while at the same time aligning the parts). This is reason that most of the time a corner joint with Dovetail Keys should not need to be put in a vise, saving you time during assembly. That being said we recognize and understand that a vise or clamp is sometimes needed if the moulding is bowed, the miter is not cut perfectly, a dull saw blade was used, etc. In theory every joint will go together perfectly, in real life sometimes help is needed.
• 
  
• 2. The Keys have ridges in the sides which causes them to “bite” into the wood fibers, further increasing the “pulling together” force.
• 3. To keep the removal of potential gluing area to a minimum we offer a variety of Key sizes and lengths to select from based on the moulding being joined

To sum it up – YES routing a keyway reduces the surface area for glue but the Key adds strength to the joint and eliminates the need for alignment aids or clamps.

• To the questions of which glue to use, that is almost like the question of which engine oil to use in some motorcycle forums. Some seasoned forum members over there always run to get beer and chips whenever that question comes up, knowing darn well this will go one for a while
• In seriousness, my suggestion is to use a high-quality, professional grade product. Some glues are specifically formulated to be thicker to work better in a miter joint application, somebody mentioned the Titebond Trim and Moulding glue. I haven’t used that type myself but heard good things about it.
• While we as company do not recommend or endorse one specify brand or type, in my personal experience as a hobby-woodworker “monkeying around” in my home workshop I’ve had consistently good results with Titebond II or III. In fact, most of the sample frames and corner joints we show at trade shows and in our catalogs were made in my home-shop using that adhesive and these samples have taken some abuse during shipping to multiple shows.
• It is always advisable to make your own tests with different glues and then settle on one that works best for you.
• 
  
• Regarding on what to call these plastic fasteners – we have always referred to our fasteners as “Dovetail Keys” or “Hoffmann Keys”. There may be other plastic corner joining fasteners being referred to wedges, H-connectors, thumbnails, etc. and sometimes the resulting joints with these other methods maybe less than ideal which is why we prefer to stick with “Dovetail Keys”. That being said, we get calls every day from customers needing to “order some wedges”, or some “whatchamacallits” or some “bowtie doohickeys” – “you know, the plastic thingies you ‘all sell”… and in all cases were are gladly providing whatever specific fastener the customer is asking for.

I hope I was able to answer some questions, please feel free to contact either Gary or myself anytime if we can be further help.

Thank you for your business and Happy and Safe Holidays to all.

Markus
Hoffmann-USA.com

 

[Markus Hueber]

Here is a comparison of different Titebond wood glues presented by Marc Spagnuolo, aka The Wood Whisperer. It is geared toward woodworking but you might find some useful info in it.

 

[Prospero]

That's great info Markus.

Please be assured I was making a purely academic point - not Hoffman-knocking.

I tend to be an advocate of over-engineering. I do a lot of big, wide frames for a trade customer
and these frames tend to get loaded in and out of cars and generally have a hard life. So my usual
practice is to biscuit the corners, throw a strap clamp around, underpin the backs and then add a
3" 'L' plate to the back. This may seem a lot of faff, but I've done 100s and only one corner ever cracked.
This was after the frame was caught in a freak windstorm and went skittering 100yds across grass at an exhibition.
Even then it was only a hairline crack and I repaired it easily.

 

[Markus Hueber]

@Prospero - if your frame skittered 100 yds. and only had hairline crack - you are doing something right
(We usually stop testing at 75 yards )

 

[David Waldmann]

...This may seem a lot of faff,...

That it does, especially since we dispensed with faff in the Colony a good hundert year ago.