Author Topic: How much weight can the DF700 connectors hold?  (Read 2381 times)

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Offline Gregor

  • Posts: 1357
Re: How much weight can the DF700 connectors hold?
« Reply #30 on: August 26, 2019, 10:58 PM »
I recently had to replace the original screws (as someone misplaced them when disassembling for storage) and bolts of a table with 14mm connectors, used one per leg to connect it to the long aprons (the small side aprone were already glued to two legs each), no other fasteners. I was unable to pull the seam between the legs (~80cm) and the long apron (~1.5m) apart, even when applying force to the ends (of leg and apron) to get as much lever as I could.

From that experience: 6 connectors would IMHO be overkill, I would put normal dominos at the locations you have the mortices in the drawing, then add use 2 connectors  (centered in the material) at roughly 1/4 to 1/5 of the length from each end of the leg. That should be enough keep the seam together without any problems (and be less visible as their access mortices would be better hidden), and the nomal dominos by themselves should already give you enough stability against shear and racking (at least when the top is thick enough so you can put them in there some cm, but that should be no problem as you need enough thickness in the top to mount the anchors of the connectors anyway).

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Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #31 on: August 26, 2019, 11:22 PM »
My opinion;

The 14 mm x 140 Dominos will resist racking better than the connector.

Why;

Embedd 1-1/4" or so of the Domino in the top, this leaves about 4-1/4" into the leg. If you placed 3 on each long edge and 2 connectors on the ends, I cannot see this leg connection failing. 

For fun you could apply some numbers to the moment formula then guess what force it would take to have the 14mm Dominos fail

M=FxD

Tom

Offline Svar

  • Posts: 1839
Re: How much weight can the DF700 connectors hold?
« Reply #32 on: August 27, 2019, 12:04 AM »
The 14 mm x 140 Dominos will resist racking better than the connector.
No. Not without glue. Put together a piece of furniture with loose tenons without glue and see how it holds up to racking.

Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #33 on: August 27, 2019, 12:11 AM »
The 14 mm x 140 Dominos will resist racking better than the connector.
No. Not without glue. Put together a piece of furniture with loose tenons without glue and see how it holds up to racking.

I have, many times before the connectors came out.

The TV stand I've posted and 2 other piece of funiture I have are simply Dominos into the mortices. I'm to old and feeble to carry this stuff up 3 fights of stairs assembled.

Tom

Offline Cheese

  • Posts: 6466
Re: How much weight can the DF700 connectors hold?
« Reply #34 on: August 27, 2019, 12:39 AM »
No. Not without glue. Put together a piece of furniture with loose tenons without glue and see how it holds up to racking.

Not necessarily, we're not assembling furniture with just loose tenons...we're using loose tenons while being held tightly together with the joint clamping force of multiple D14 metal Dominos. No one has spoken up at this point to say whether this approach is realistic or folly. I assume the reason it was considered is because it's any easy fix...if it's a truly viable one.

Moreover, this brings up a more interesting situation that if this a commissioned product for a customer, then the conversation needs to be extended further and I think the solution could change drastically.

I assumed this was a home brew table for the family, so then it's in an environment that's friendly and any table/leg movement can be monitored on a continual daily basis. If the joint becomes wobbly or weak, it will be noticed in real time and the proper adjustments can be made by the original creator.

However, if this is a commissioned product, then once you unload/deliver/setup the table, any subtle movement over the next weeks/months will probably not be noticed by the owner until the movement becomes so great that it collapses or almost collapses on the floor.
And you certainly don't want to advise the client to be on the look out for any leg movement. That doesn't inspire any confidence in the client and probably eliminates any further commissions from him/her.

So if a full size test model of this table is not in the cards, and stretchers are also not in the cards, I'd then be a fan of inserting steel structural elements in the table & the legs to solve these issues...then again I'm a huge fan of metals. Metals are good...sometimes, even better than wood.  [smile]
« Last Edit: August 27, 2019, 09:44 AM by Cheese »

Offline Gregor

  • Posts: 1357
Re: How much weight can the DF700 connectors hold?
« Reply #35 on: August 27, 2019, 03:19 AM »
The 14 mm x 140 Dominos will resist racking better than the connector.
No. Not without glue. Put together a piece of furniture with loose tenons without glue and see how it holds up to racking.
That's where the connectors come in, since they pull the joint together the tenons can't pull out - and as long as they can't pull out it won't rack. Not at all.

In case you want to test that: get two longer pieces of (dimenional big enough so the connectors can be fittet) scrap and make a corner joint, as per manual with multiple dominos at the sides and one connector in the middle.
Then use this nice lever you just build and try to break it at the joint.

Offline JimD

  • Posts: 392
Re: How much weight can the DF700 connectors hold?
« Reply #36 on: September 12, 2019, 02:08 PM »
This is one of two you tubes I found on this:



In both cases, they simulated a apron joint and applied their weight to a single connector.  It held.  I'm not sure the leverage is the same as your legs but you aren't talking about one connector either.

Your leg attachment will be similar to a leg to apron attachment except you will not have any stabilizing effect of width of the apron if you assume the sliding of the table is along the length of the table.  Across the width it should be fine due to the length of the leg to top connection.  The thickness of the leg will help but doesn't seem equivalent to the normal apron width.  If it is, then 6 is overkill.  If the leg is thinner than an apron is wide, then you need more connectors.  But six seems like plenty.

Re: How much weight can the DF700 connectors hold?
« Reply #37 on: September 13, 2019, 12:59 PM »
I am not sure I have the photos readily available though I have used the 14mm connectors with the 14mm Domino tenons to build an indoor greenhouse with beams that were 115x115 mm if I remember correctly. Two 14mm tenons for strength, oriented perpedicular to the connector and then one connector per joint. The structure was all in all 6m by 3m and was supposed to be temporary, then dismounted and removed to a new location. It turned out to be very strong indeed. I need to look at the pictures as I seem to remember we were discussing adding a slight joint notch/recess to make it even stronger. 

If there is any interest I can try to dig up the assembly/joint pictures.
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Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #38 on: October 08, 2019, 10:45 PM »
I finished the table. Each leg was around 65-75 pounds. i installed 6 connectors. I think it would have been ok with only 3 or 4. It didn't wobble at all.  Once the legs were installed. i moved the table a lot. I didn't notice any difference with any other tenon and mortise or domino joints.

Please let me know if you have any questions