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#33953 - 08/30/16 01:24 PM Hammer Beam - Tulip Poplar
Arne Offline
Member

Registered: 08/30/16
Posts: 2
All:

I am working on designing and building a hammer truss timber frame for housing tractors on my family's farm in PA.

We are in the process of clearing 6 acres of partial pasture/woodland to plant a 6 acre orchard. There are a number of tulip poplars that will be cut down.

Is tulip poplar suitable for a timber frame? I have found a number of conflicting sources on the internet.

Please see the images attached.

If you have interest in analyzing the structure/joints please PM me and I will send you the sketchup file.

Thank you very much.

Best,

Arne


Attachments
Interior.JPG (67 downloads)
Frame.JPG (62 downloads)
Side.JPG (60 downloads)


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#33954 - 08/30/16 05:13 PM Re: Hammer Beam - Tulip Poplar [Re: Arne]
Roger Nair Offline
Member

Registered: 10/20/99
Posts: 437
Loc: Bakerton, WV, USA
Green tulip poplar will check and twist reliably and it's placid grain can react in ways you will not predict. There is a tendency towards spiral grain. I have used tp but prefer it for secondary wood free of heart but sawing straight lumber can be a challenge in longer lengths.

Anchor seal the end grain and oil the rest to keep the drying rate slow.

I generally dislike the hammer beam configuration and would disqualify tp as major framing timbers in a hammer beam frame. Your hammer beam drawing gives the impression of an English hammer beam without some of the essential elements. I believe you'll get a better frame if you use a king or queen post truss design. On other condition is to not trust tension joints such as the principal rafter foot without additional relish.

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#33955 - 08/30/16 06:13 PM Re: Hammer Beam - Tulip Poplar [Re: Arne]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 469
Loc: Vermont
Hi Arne,

I think I would have to validate this post into two distinct topics.

First would be Tulip Poplar (TP is actually a Magnolia) is one of my favorite wood species to timber frame with...

I love the color, the size it can attain, (especially without knots!!!) its general strength (comparably slightly stronger than White Pine) so all in all a great wood for many timber framing projects.

The caveat...!!!...I don't always recommend this species to those that have little to no experience in selecting wood for a structural timber frame project. (Not sure if you do or don't?) Further, just getting one of these big (or small!!) trees down in a green off the stump state...can be a challenge without shocking, shattering and/or damaging the strength of the log bolt. Past this are all the issue with proper milling (as Roger suggested) each bolt into the proper Cant for the applied timber within a frame.

All these challenges are manageable (if not easy for the most part) yet this ease comes from years of selecting timber from stands, proper rigging and logging methods appropriate for the species, germaine milling methods for the species, and then further considerations as well.

Second is a Hammer Beam frame...

I love Hammer Beams, yet as I state for most posters and people who contact me and want to DIY a timber frame...I strongly suggest that the frame design go for PE approval before proceeding any where near a completed project. A HB frame is full of wonderful challenges even for an experience Timberwright...let alone a DIYer (but I own that is just my view.)

Again I don't know your experience, nor the quality of your trees. I would suggest (if new to this) to consider much and remember that just copying or getting a HB CAD model is not going to make it a safe frame to build. I will also share (and this isn't to discourage but a suggested warning) that there are more Sketchup Frames I see that may look O.K. yet this does not mean they are...real timber frames...only virtual. Experience makes them this and I have most of my frame PE examined at minimum...

Good luck...Hope this wasn't to discouraging, and you are successful with your project!!

Regards,

j
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#33959 - 08/31/16 06:47 AM Re: Hammer Beam - Tulip Poplar [Re: Arne]
TIMBEAL Online   content
Member

Registered: 12/10/07
Posts: 1871
Loc: Maine
Jay, didn't Ted Benson build a Hammer Beam framed shop to soon find it was spreading and then to arrest the problem put in cable ties? Hammer beams are fine in stone buttressed walls. They are not a truss. Great advice to have a PE review such plans. A king will be much more forgiving, and get to the root of the problem.

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#33960 - 08/31/16 08:44 AM Re: Hammer Beam - Tulip Poplar [Re: Arne]
Arne Offline
Member

Registered: 08/30/16
Posts: 2
Jay & Roger:

Thank you very much for your responses.

I have done two very small frames in the past, please see the attached images. I tend to agree with you on avoiding the hammer beam frame for this structure. I will put together a revised Sketchup model and post it for review.

Hammer Beam
On an aside, the truss design came from A Timber Framer's Workshop by Chappell. I created the Sketchup model with specific joints - not visible in the screen shots. I have attached two images with detail. I believe the modified English tying joint is insufficient in its current form.


Tulip Poplar
I hire a guy to take down trees to avoid injury- $950 a day to take down ~60 trees is expensive on its own, but cheap if personally injury is taken into account. I would end up winging the dropping and milling of the Tulip Poplar given my lack of experience/control. My tree guy is dropping the trees this Friday, and I will have my woodmizer guy mill some poplar logs while he mills locust posts (see attached image of milled locust posts)


Best,

Arne


This is part of this project:Broadwater Cidery




Attachments
IMG00008-20100929-0737.jpg (79 downloads)
IMG00021-20101016-1416.jpg (75 downloads)
Modified English Tying Joint.JPG (59 downloads)
Detail.JPG (58 downloads)
20150404_134919.jpg (92 downloads)



Edited by Arne (08/31/16 08:45 AM)

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#33961 - 08/31/16 12:38 PM Re: Hammer Beam - Tulip Poplar [Re: TIMBEAL]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 469
Loc: Vermont
Hey Tim...

You're rattling my cobwebs..yet I believe you are correct on TB early attempt...

I can add that many HB often go down this path with related issues!!

Are there Hammer Beam trusses..yes...and they are wonderful in their aesthetic capture of a space whether large or small. They frame a vaulted ceilinged room elegantly. The only form I like better is a Cruck frame, which is the HB grandparent style.

Are most frames designed and built that are meant to be Hammer Beam truss actually a truss...NO!!!...not even close in my view. That is the challenge when I try to warn folks away from them. They are not for a novice Timberwright to design and build. Which is another issue I have with Sketchup, even though I love the program and use it professionally. Way too many (somehow???) think that because they find and/or copy a timber frame done in CAD it is safe or appropriate to build. Quite often it is not only aesthetically out of balance...it is in dire need of a PE's keen eye for loads and dynamic integrity. Ergo why we see the big freaking cable tieing many of the HB together, as this is the only way to make many of them work properly. In my view, that then makes them something else. A real HB does not need that cable, and those with them are faux Hammer Beams in my view, which seem to be more common these days...Many just...glued and screwed...to a ceiling after stick building a frame.

I also agree that a Queen, King, or related system would probably be more easily facilitated by anyone new to the craft.
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#33962 - 08/31/16 01:05 PM Re: Hammer Beam - Tulip Poplar [Re: Arne]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 469
Loc: Vermont
Hi Arne,

It is really difficult (over a forum conversation) to assess the merit of all the moving parts. Many assumptions have to be made about Logger, Sawyer, Design, and the person cutting the frame (no disrespect intended toward anyone.)

Just the logging and felling is fraught with very specific challenges to this craft. We either accept that the person doing the logging and felling has felled for timber frames before...or they have not. I can say that seldom do I see most (almost all actually) drop these trees properly for this species and intended outcome for the logs. They should either be lowered with rigging, climbed and rigged down, or dropped on very soft evened out pads...THEN...immediately assessed for Fall Shakes and Cracks...end sealed post haste...and move to milling location. Bark should be remove if at all possible in large sheets as a valued worth material in its own right for shingles siding. There is much to TP trees and their value and resource as a forest product, with a rich and wonderful tradtional history all in there own right!

IF...the above does not happen...then felling operation isn't much different than any other logger dropping trees. Which usually leaves the Bolts of questionable quality and worth, especially for this species and the intended outcome of the Cants to be made into a timber frame.

Steve's frames do (indeed) get replicated quite often. It still does not change that the frame really (and I can stress this enough) get examined by a PE with timber framing experience. Just the lengths of the tenons in some of the blown up views provided I can share would never muster approval before leaving my drafting board (aka computer these days) and my PE would think I was "pulling his leg" if I sent something with tenons that short and the loads an HB can be subjected to. I am also not seeing the triple post configuration as the most costly or elegant solution to strengthening these joint intersections. IF that type of bulky affect is pleasing to the client's aesthetic, then it may meet some of the load requirements, yet I doubt all of them. Even in a hardwood like TP (which is a soft variety hardwood) the tenons would all be exclusively oak, locust, clear maple (or related toughness) hardwood splines at most joint intersections, with through tenons everywhere else if part of the TP timber itself. That is just my style and demand for strength when designing and facilitating an HB style timber frame. Most likely however, I may well pass on the project if the client couldn't be talked into a Cruck Frame or related folk style. Otherwise they would have to pay to have the HB frame design PE approved before moving to jointing and assembly. I would also insiste (at minimum) of approving all log bolts dropped and would want to review felling procedures. I own that is just my take on this species and frame type.

Regards,

j



Edited by Jay White Cloud (08/31/16 01:08 PM)
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