Author Topic: How much weight can the DF700 connectors hold?  (Read 2375 times)

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Offline aaduranh

  • Posts: 21
How much weight can the DF700 connectors hold?
« on: August 24, 2019, 03:51 PM »
Hi,

I need to attach heavy legs to a table top.  Each leg is 28" x 28 3/4, 3" 1/8 thick. It is in hard maple. Each leg is around 80 pounds. The top is 72" x 36" 1" 1/4 thick in maple too.
If i use around 6 DF700 connectors in each leg, would the connectors be strong enough to hold the legs to that top?

Thanks
Alex
« Last Edit: August 24, 2019, 04:37 PM by aaduranh »

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #1 on: August 24, 2019, 04:26 PM »
I can't answer the question directly, but....

When I first got the 700 kit we did a few test mock ups, we could not pull the expanding piece out of the mock up after removeing the center post, we had to cut the wood away from it so we could reuse the insert (I'm to cheep to waste the pieces).

If you're wondering if 6 of the connectors in the leg will hold it to the top it when the table is lifted----my guess is yes they will.

Tom

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #2 on: August 24, 2019, 04:29 PM »
I would have done the same thing:)

Let's hope someone put the df700 connectors to the extreme.

Offline mwolczko

  • Posts: 26
Re: How much weight can the DF700 connectors hold?
« Reply #3 on: August 24, 2019, 04:31 PM »
A while ago I looked but could not find any published specs on the strength of the connectors.  If anyone has a source I’d love to see it too.
In any case I went ahead and built an outdoor sofa using connectors and it feels solid to me (and has stayed solid for the ~2years it has been used).

For your table, are the connectors carrying the weight of the top, or is that being transferred directly to the material of the legs?  If they’re not carrying the weight, but being used to prevent racking, then I would think they will suffice. For my sofa I recessed the seat members into the armrests so that the connectors were not carrying the weight, just providing tension.

Also, be sure to consider any cross-grain wood movement that may occur.

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #4 on: August 24, 2019, 04:37 PM »
The top would be seating on the end grain of the leg.

Let's say i would have to move table. The connectors would have to carry the weight of the legs attached to the top.

I know some people do beds with the connectors. They have to take the weight of two people. I imagine they are good enough. Does it make sense?

Offline mwolczko

  • Posts: 26
Re: How much weight can the DF700 connectors hold?
« Reply #5 on: August 24, 2019, 05:18 PM »
Should work fine — I would guess the pulling force needed to remove one of these connectors is measured in hundreds of pounds.

Online Cheese

  • Posts: 6466
Re: How much weight can the DF700 connectors hold?
« Reply #6 on: August 24, 2019, 05:20 PM »
They always use wood Dominos along with the removable ones. Here's a photo from the printed Festool connector catalog. Read the TIP in the lower RH corner of the page. 

If you're going with 6 for each leg I'd probably do 4 wood versions and 2 removable versions.

Let us know how that works. [smile]


Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #7 on: August 24, 2019, 05:44 PM »
They always use wood Dominos along with the removable ones. Here's a photo from the printed Festool connector catalog. Read the TIP in the lower RH corner of the page. 

If you're going with 6 for each leg I'd probably do 4 wood versions and 2 removable versions.

Let us know how that works. [smile]

(Attachment Link)

Their examples are in shear, the question posed here is for pullout.

I do agree, six is probaly over kill, I'd start with 2 connectors, one on each "inside face", 2 normal Dominos on the "visible faces".

Tom

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #8 on: August 24, 2019, 05:48 PM »
I need to attach those legs to the table top. This not exactly my table. My table is in maple.

I am sorry i should have started with the picture ;D

« Last Edit: August 24, 2019, 05:51 PM by aaduranh »

Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #9 on: August 24, 2019, 05:51 PM »
I need to attach those legs to the table top. This not exactly my table. My table is in maple.

Are the legs solid or hollow?

Tom

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #10 on: August 24, 2019, 05:52 PM »
super solid hard maple!

Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #11 on: August 24, 2019, 06:27 PM »
super solid hard maple!

Each leg weighs ~65-1/2 pounds (using the dimensions you posted).

I'd put 2 connectors on the long sides of each leg (4 per leg), about 3" in for the sides. Centered I'd place 2 Dominos, these will aid in alignment.

I suggested inside only in a previous post due to the covers for the set screw access mortices, there are covers that are very close to maple color. You could fabricate your own plugs for the visible side.

Tom

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #12 on: August 24, 2019, 07:19 PM »
Thanks a lot for your help.

Just to make sure that I understood. you would install the connectors only in the inside of the leg, nothing on the outside?
Creating my own maple plugs is a great idea!

Thanks a lot

Offline tjbnwi

  • Posts: 6075
  • Cedar Tucky Indiana
Re: How much weight can the DF700 connectors hold?
« Reply #13 on: August 24, 2019, 07:20 PM »
Thanks a lot for your help.

Just to make sure that I understood. you would install the connectors only in the inside of the leg, nothing on the outside?
Creating my own maple plugs is a great idea!

Thanks a lot

For even load lift, install 2 inside, 2 outside.

Tom

Offline Jim_in_PA

  • Posts: 77
Re: How much weight can the DF700 connectors hold?
« Reply #14 on: August 25, 2019, 09:36 AM »
As in Cheese's reply in post #6, I used them for a Twin-XL over Queen heavy bunk bed setup recently and I have no concerns about strength. The connector plus two 14mm Dominos can support a whole bunch of weight and the design of the connector brings the joint in very tight. If the materials are cut true, that fully engaged surface to surface touch adds to the stability of the joint, too. Most of the weight of the joint is borne by the adjacent 14mm dominos...you don't often use "just" the connector in the joint.
----
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Offline tjbnwi

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Re: How much weight can the DF700 connectors hold?
« Reply #15 on: August 25, 2019, 09:50 AM »
Now I'm wordering if one on each end would suffice??? Regular Dominos on the long sides?????

The connectors are only there for when the table is lifted.....hummmm.

Tom

Online Cheese

  • Posts: 6466
Re: How much weight can the DF700 connectors hold?
« Reply #16 on: August 25, 2019, 09:59 AM »
Ya, my thought was that any lateral loading to the table and consequently through the legs, would be transferred to and carried by the wood Dominos, while the D14 removable Dominos would maintain the tightness of the joint and facilitate lifting the table and moving it.
« Last Edit: August 25, 2019, 10:01 AM by Cheese »

Offline Michael Kellough

  • Posts: 4222
Re: How much weight can the DF700 connectors hold?
« Reply #17 on: August 25, 2019, 10:18 AM »
Straight withdrawal resistance is not the concern. A couple fittings per leg are sufficient for that.

The powerful leverage the non-aproned legs possess is what you have to resist. What happens when someone leans into the end of the table or the movers set one end down too abruptly?

I’d use a minimum of four per leg but probably twice that, placed close to the long faces of the legs.

If the mechanical fittings weren’t available your best joining method would be wedged through tenons (3 or 4 per leg) the full thickness of the leg (3 or 4 inches?).

This merits full scale testing. The mechanical replacement should be equally strong but I don’t know how many fittings that would require.

Offline Birdhunter

  • Posts: 2688
  • Woodworker, Sportsman, Retired
Re: How much weight can the DF700 connectors hold?
« Reply #18 on: August 25, 2019, 10:59 AM »
I’d worry a lot more about the table racking and snapping off the legs.
Birdhunter

Offline Bob D.

  • Posts: 1293
Re: How much weight can the DF700 connectors hold?
« Reply #19 on: August 25, 2019, 11:23 AM »
I’d worry a lot more about the table racking and snapping off the legs.

A single stretcher up high, maybe 5 or 6 inches tall, and down the center of the table
would mitigate that concern, and not detract from the look of the table, at least for me.
-----
It's a table saw, do you know where your fingers are?

Offline Michael Kellough

  • Posts: 4222
Re: How much weight can the DF700 connectors hold?
« Reply #20 on: August 25, 2019, 12:15 PM »
I’d worry a lot more about the table racking and snapping off the legs.

A single stretcher up high, maybe 5 or 6 inches tall, and down the center of the table
would mitigate that concern, and not detract from the look of the table, at least for me.

That works for me too.

Offline Svar

  • Posts: 1839
Re: How much weight can the DF700 connectors hold?
« Reply #21 on: August 25, 2019, 12:19 PM »
I’d worry a lot more about the table racking and snapping off the legs.
Exactly.
I'd put two dominos for registration and 4 or 6 connectors per leg.
Non glued wooden dominos are useless to prevent racking, which is the main issue for a table.

Offline Birdhunter

  • Posts: 2688
  • Woodworker, Sportsman, Retired
Re: How much weight can the DF700 connectors hold?
« Reply #22 on: August 25, 2019, 05:41 PM »
I’m very conservative when I build furniture that, if it fails, could hurt people. I’d use two stretchers for this design. I’d place them so people’s knees would not hit them, but far enough apart to provide stability.
Birdhunter

Offline aaduranh

  • Posts: 21
Re: How much weight can the DF700 connectors hold?
« Reply #23 on: August 26, 2019, 08:16 AM »
The customer of this table doesn't want to have anything but the legs under the top, even if you cannot see it.   [eek]

That's why i thought about the domino connectors. Tom had a great idea about making my own maple plugs.

Thanks
A


Offline Jim_in_PA

  • Posts: 77
Re: How much weight can the DF700 connectors hold?
« Reply #24 on: August 26, 2019, 09:23 AM »
Ya, my thought was that any lateral loading to the table and consequently through the legs, would be transferred to and carried by the wood Dominos, while the D14 removable Dominos would maintain the tightness of the joint and facilitate lifting the table and moving it.

Exactly.
----
ETS 150/3, Rotex 150, OF1010, OF1400, Trion PS 300, TDK-12, CT-22, MFT 1080, TS55, Domino XL DF 700, 8' track, (2) 55" tracks

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Offline Birdhunter

  • Posts: 2688
  • Woodworker, Sportsman, Retired
Re: How much weight can the DF700 connectors hold?
« Reply #25 on: August 26, 2019, 10:28 AM »
I just watched a video on making a huge conference room table from a large slab.

The builder routed a recess into the underside of the table and attached a steel  channels just short of the width of the table. The steel channel was attached using threaded inserts. The steel legs attached to the channel with short bolts. The structure looked bullet proof.

The steel channel probably would stop any cupping from the top. I seem to remember seeing more than two of these channels recessed into the table's underside.
Birdhunter

Offline ChuckM

  • Posts: 1230
Re: How much weight can the DF700 connectors hold?
« Reply #26 on: August 26, 2019, 12:19 PM »
Because of the massive weight, I would not feel comfortable with the two-leg design. In normal use, the table would be fine, but if racking happens (e.g. the table is pushed from one end in a moving attempt), the structure might not be sturdy enough.

I recommend that the customer be alerted of the safety caution in the absence of any stretchers. also consider orienting one of the dominoes along the grain direction of the top.

Offline Michael Kellough

  • Posts: 4222
Re: How much weight can the DF700 connectors hold?
« Reply #27 on: August 26, 2019, 12:58 PM »
Not an engineer but I don’t think the weight makes a difference. It’s the leverage of the legs that has the potential to rip out whatever kind of fasteners join the surface to the top ends of the legs.

I’d make a full scale model in construction grade softwood. Or, maybe just a full scale cross section like a 4x4 leg attached to the side of a 2x4. When an adequate fastening solution is found for the softwood it can safely be applied to the hardwood. I think the extra weight of the hardwood legs is accommodated by the flexibility of the tabletop.

Offline ChuckM

  • Posts: 1230
Re: How much weight can the DF700 connectors hold?
« Reply #28 on: August 26, 2019, 01:19 PM »
Not an engineer but I don’t think the weight makes a difference. It’s the leverage of the legs that has the potential to rip out whatever kind of fasteners join the surface to the top ends of the legs.

Snip

By weight, I was referring to the potential degree of damage or seriousness of injury if the table collapsed.

Offline Svar

  • Posts: 1839
Re: How much weight can the DF700 connectors hold?
« Reply #29 on: August 26, 2019, 02:10 PM »
Just put 6 connectors as in the picture. Each have at least several hundred pounds pullout strength, no different than a threaded insert or a screw. Alternative is a metal plate(s) wider than the leg screwed to the top of the leg to form flanges. Then recessed and bolted into the table top.
A table with this design (no stretcher) and weight is nothing unusual. I had similar one, just 4 threaded inserts per leg, that was all.


Offline Gregor

  • Posts: 1355
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).

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


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
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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

Online 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: 1355
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