Heavy Duty Scarf Joint Design

Hi,

Can anyone point me towards a downloadable book or paper that illustrates various options and considerations for the design of a very heavy duty scarf joint. I would imagine that this might well be included within the pages of a bridge building manual or the like. I am looking for inspiration to help establish a good timber / bolted / banded design that is capable of medium to longer term adjustment.

Regards

Ken Hume

Here is one Ken.

http://www.tfhrc.gov/structur/pubs/04098/14.htm

Will T. should have some stuff. It will be interesting to see what you come up with for this scarf.

How long is the timber you are making, 68' was it?

Tim

Hi Tim,

This is a good document and just the very thing needed to kick start the brain into action to think about the issues that need to be addressed. The composite will be 84'.

Regards

Ken Hume

what does that mean? in what context will you be 'adjusting' it?

Hey All, here is a good one.

Strongest one I know of W/O bolts. All wood, opposing keys (in the 5" slot) to knock around down the road. Precision is beneficial on this one, otherwise you might get some splitting at the abutments (sp?).





my apologies for the sloppy ink, from awhile ago. Great Scarf Joint. A little labor intensive, but in the grand scheme of things....

Happy 4th!

Hi M & M.

The wood is bound to dry in service and so it would be important to be able to tighten up any metal bolts or hoops employed so that the joint can be kept tight in service.

Regards

Ken Hume

Ken,

I don't see the point in your new thread. You have asked a question about a reasonable issue, but have given no circumstances.

I am lost in this thread.

There are papers available -

Dr. Sangree having several, some which speak to specific scarf types.

http://cedb.asce.org/cgi/WWWdisplay.cgi?0609170


This I have yet to see but it may be what you are looking for -

http://www.highbeam.com/doc/1G1-91972717.html

Funny, but when I am in need of scarf to fit some funky loading issue, I always at least initially, look to the appendix in EHC for a list of potential choices.

Hi Will,

Thanks for those links - both of which seem to require registration and paying a fee. I agree that English Historic Carpentry is also my usual start point for selecting an all timber scarf joint as found mainly in buildings. Unfortunately this scarf joint is unsupported and will have to generate the same load, moment and shear carrying capacity as a continuous timber, hence the already recognised need for metal reinforcement. The marriage of differing materials is not uncommon in bridge, mill and ship building (rope / timber mast joints) and, thinking aloud, I seem to recall that the TFG Lexington Bellifortis trebuchet mast was banded to help hold it together. I shall need to retrieve TF No 44 to see what clues and / or design considerations are detailed within.

The manual reference provided by Tim is excellent and its worthy of note that the engineering for this document was done by Dr. B Brungraber.

Mo,

Thank you for your contributions. I did say at the outset that this was to be a heavy duty joint and would need a bolted / banded design.

Please don't punish yourself (or me) - all will be revealed in due course when I am a little more confident (or not !) about being able to produce a workable design solution.

Regards

Ken Hume

Hi,

I have now retrieved TF No 44 and Colonel Neel says "some main beams appear to be made up of several pieces scarfed and laminated, held together with Dutch pins and bound with rope coils, or with iron bands".
What are Dutch pins ?

Regards

Ken Hume

Light and Heavy Timber Framing Made Easy by Hodgson has some good heavy duty scarf joints illustrated.

The entire book, being now public domain , is available for download here (only to those in the US, I'm afraid.)
Light and Heavy Timber Framing Made Easy

Ken,

I will email you the section dealing with scarf joints, since those outside the US can't seem to access the google books version. (at least that was true a couple of years ago)

Hi Gabel,

This Goggle.pdf book, now received and reviewed, is an excellent book for heavy timber frame practioners and good reading for all. I have already picked up one tip that I had previously considered and dismissed re wedging and will now revisit. The book contains quite a few heavyweight metal reinforced scarf joint designs. This book contains just the right kind of "dope slap" material that I had in mind to help with making a fundamental design review.

I seem to recall that someone was requesting design information a little while back on hammer beam roofs and I note that this book contains quite a bit on this topic.

Books like this really need to be republished and maybe the Guild could examine this possibility now that the copyright has expired (first published 1909).

Regards

Ken Hume

That is a great book. I remember Gabel referencing it here before. I put it in my "google library" long ago. Google books is a treasure trove for old carpentry texts. A "library" almost unimaginable before.

But, it's also effectively killing the aims of those who wish to republish these texts. Why buy the book if you can view it and/or print out for free? (and just the sections you want.)

It seems there would essentially be no market in North America (or anywhere else google books is available) for these reprints.

Hi Don,

The point that you make is a blinding glimpse of the obvious.

However, I think that there still might well be a demand for an up to date paper version especially if the layout and quality of illustrations contained within an old book like this was updated and improved.

Have you made an index of the "out of copyright" carpentry books that you have managed to download for free ?

Regards

Ken Hume

Don – I have downloaded and read a couple dozen PDF copies of “public domain” books from Google Books, some on carpentry and timberframing, and quite a number of 19th century treatises on bridge building, some written by patent holders...

But, I guess I'm just old fashioned enough that I'd rather have a number of them as hardcopies. Physical books are just easier to read, and it is somehow far easier to find those passages I'd like to revisit.

Astragal Press would be the folks to look to or partner up with to work to see a long out of print trade related book republished, it is one of their specialties -

http://www.astragalpress.com/book_index.htm

I much prefer actual books to downloaded pdfs. I do all of my reading in bed, usually in the wee hours. I like the idea of bringing back some of the out of print stuff.

I, too, prefer a hardcopy, but I am not complaining considering that 10 years ago, I would never have heard of many of the books I now have as a pdf thanks to google.

In fact, with the L&HTFME book referenced above, I took the file to the local printers and had it printed and spiral bound for $30 or so. Well worth it.

Getting one of these old texts spiral bound for your own use is a great idea.

I'm with you guys. I like the feel of a book in my hands too. Sadly, convincing a publisher that a reprint would be marketable is a whole other endeavor.

Like Gabel said, a service like google books would have been hard to fathom 10 years ago. Imagine what the next 10 years holds. Paying for information (like a hardcopy book) is getting more and more old-fashioned. The public almost expects information to be freely accessible these days.

As a writer in the newspaper field, this is one facet they say is killing papers. Why stand in line and pay for a newspaper anymore? You and I may love the feel of the pages, but 20-year-olds don't line up to buy them. They're twittering.

Google is leading the way in this regard. email, picture services, libraries, news, television episodes, youtube, sketchup, etc, are all free. Your own website costs you all of $10/ year.

Ken,

I have a bunch of books saved in my google library. There's a search window to find what you need w/in your "collection." I can share my titles if you'd like. (A bit pressed for time at the moment).

Hey all, after checking out the link that Gabel posted, I checked amazon.com and they are selling a hardcover version that was published on 2008 for $37.

Colton