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Derrick build

Started by SWIdaho, June 23, 2008, 11:14:58 AM

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SWIdaho

Hello all. I've a project going (way above my skill set) and I wondered if any one here would like to point and ask questions? It's a stretch to call this a timber frame, but it's a little different than carpentry and it does involve logs a bit.

I'm building a balance beam hoist. Where I live it's called a hay derrick or a Mormon derrick. It is similar in design to a post mill trestle. This is a scale model 40 ft boom, 25 ft mast and 16 ft square base.


Here's where I am now. The tension cables keep all the wood joinery in compression so I don't have to pin the corners.
 

Here's the next step. This is the cross tie layout that centers the mast base tenon. Load weight actually travels through the brace poles to ground.


And after that,


It's the 'after that' that has me conflicted. The brace poles need to be just the right length and have perfect tenon and mortise shoulder angles for proper weight transfer. I'm debating two possible methods. 1. Make the base of the brace pole adjustable, which changes the shoulder angle as adjustments are made or, 2. Stand the pole and template the perfect length and shoulder angle for the brace poles. Either one will be a PIA.

Questions or comments welcome?

Later SWIdaho



logwalker

Great project. Is the boom meant to swivel after picking the load? Joe
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

Thehardway

Neat! do you have a detail drawing of the post top swivel connection?  I am assuming it is steel.  How is it put together to prevent the beam from rolling from side to side under load?

If i were trying to get all the braces and post length to match I would do the post/bace joinery and get the angles all right first leaving all of them a little long on the base end.  I would then  nail some 2X material in place to keep the braces and post at the proper angle at about midspan.  Once this is done a plumb and level  or laser line can be used to strike a line for cutting the bottoms even.

Another approach would be to use splines to join the braces to the post.  There are a couple advantages to this in my opinion.  1, simplifies joinery, 2 increases strength of post by removing less wood, 3 insures brace load is equalized at the post.
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Jim_Rogers

As I see it you have three joints you need to solve.
One is the lean pole/brace to the mast.
The second one is the lean pole/brace to the short diagonal.
The third is the lean pole/brace to the double long diagonal.

Lets start with number one.
The lean pole to the mast.

If the mast is square then you have four sides to make flush cut to. But you don't want to take away a lot of wood out of the mast, as it can weaken it right there.

Each lean pole/brace just need to prevent the mast from leaning out over it.

A simple stop on the end of the lean pole/brace should do this and not reduce the mast by every much.
Like this:



Here I have created a mast as an 8x8 and the braces are the same size.
I have cut a simple stop joint into the mast by 1" on each side so that the mast is now a 6x6 and braced on all for sides. May work, it really needs to be checked by an engineer.
You may need a through bolt to hold this all together.

Also, here is an idea about the brace to short diagonal:



Here I have added a black line to represent a bolt that could go through the joint to hold it together.
I've see such things used on bridge work and other large buildings that need the extra strength to hold things together.

On the third joint you could do the same type of stop joint but also add a tenon down between the two long diagonals and put the through bolt through the tenon or place a stop block between the two long diagonals for the tenon to press again.

What you have to watch out for is the shearing off of the diagonals across the grain. If the brace joint could be moved back from the end of the diagonals or the diagonals made longer it would be stronger....

Just some of my ideas.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

SWIdaho

Hi Joe, Thehardway, Thanks for looking in.

Yes Joe, A team of horses was hooked to the hoist line. The load was lifted and rotated over the stack and then dumped by a trip basket device, like a 'jackson fork'. The boom anchor cable is a static line the same length as the mast height, so the boom returns to horizontal and swings towards the words 'stack continues'.




This is the cable route. When the load is first lifted most of the energy goes into lifting and very little goes into rotation. When the load stop hits the tip pulley the  cable freezes in all pulleys except the boom butt pulley, and the load continues up and rotates over the stack.



Thehardway thanks so much for the ideas they are much better than mine. Would you mind dropping by one day for a week?









 

This adjuster just seems 'to much'. I've been debating this amongst myself for a long time.  I have scaffolding and I can stand the mast and like you say measure first hand to get the length. How about this? When I measure the length of the brace poles the mast tenon should not be fully seated into the cross tie mortise. When it's all together the load weight will pass down the brace poles to ground instead of going down the mast to ground.

I have more photos but can't get them into this post. Thanks all, Idaho

SWIdaho

Hello Jim Thanks for the drawings. Confirms the fate of the brace-base adjustment. Cool pic's. The mast is round and I thought I would have to use a mortise and tenon joint. I'll get more shots of the mast and the hinge/swivel for Thehardway. Thanks, Ida

Here's where I am now. Top left is the Boom and mast.




These are the cross ties, single in the forground, double in the back.




This is the double cross tie tenon and shoulder that goes into the corner mortises.





SWIdaho

Couple more pic's. Jim, I had thought of using a mortise and tenon at all the cross tie/brace, joints and have the pickle fork on the ends of the cross tie squeeze together and pinch the tenon when the tenon shoulders are jamed into the corners by the tension cable.

First is hinge/spindle with rain protection made from an old propane tank.




 

Second pic, the little key clamp goes on the spindle on top of the mast.





This is the mast pole with spindle and key clamp and it's groove




Corner detail with all-thread rod and swivel. That will change. Bye bye swivel and the cable will be hooked to the end of the bolt. Hummm how? Later, Ida






Jim_Rogers

Here is an exploded view of the lean pole/brace to long diagonal as I thought it might be constructed:



Again it would probably need a through bolt....

As far as measuring things, you can make the mast and two opposite braces with the laying flat on one side. Then use that measurement to make the other two braces.
The mast should set on all braces and the long diagonals all the same to make all the weight go to all points not just down the lean pole/braces.
The lean pole/braces should be for bracing only not for carrying the load.....

Just my ideas....

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Thehardway

Ida,

Great pics.  I'd love to "drop by" for a week but unfortunately Idaho is not on my way to anywhere at this point.   :-\   Is this a restoration or salvage project?  Did you fab and weld all those band clamps.  I see how the mast top swivel works now and it is pretty cool.

What are you planning to lift with this when it is completed?

I can think of about 50 uses for a handy little machine like this and I haven't even got started.

Jim's drawings with the stop joints are exactly what I was thinking although I thought staggering them might be an improvement so that so much wood was not removed creating a stress point at the top of the braces.  Then using a through bolt or spline rather than peg to lock them in place and also allow for easy take down and storage?  Jim has much more experience with lifting apparatus than I though so if he thinks offsetting braces is not neccessary I would defer to his recommendation and use his simple but beautiful drawing.

I am currently working on a derrick design and thinking of using a hydrostatic transmission/axle out of a  heavy duty garden tractor for the winch powered by a belt and a small electric motor to run the pump.  I will probably do most of it with welded steel rather than wood but the principle will be the same.  There are a couple nice things about a hydro tranny.  It give me raising, braking and lowering forces without having to use a clutch or engage/disengage any pawls.  It should be much more precise and much safer than windlass type designs.
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

SWIdaho

Hello Jim, Thehardway,

Jim your drawing program is much better that my graffite etch-a-sketch. That's the joint I had thought might work. Will the tenon hold the away-from-center thrust of the brace pole? That reminds me, I thought that the brace poles would carry most of the weight because the double cross tie can flex down under load but the brace poles can't so they would end up carrying most of the load as the cross tie sags over time. No? And your on the ground layout is perfect. I have to lay down beside a board to determine which side is up so ground layout is my favorite.

Thehardway, this is mostly a fun project. My uncle had one of these and I always marveled at how they worked. There are several near here but most are in sad shape. Ones that are kept standing are to weak to use.

I'm building this one to carry at least 1250 lbs. Thats the tip-over-weight for a machine of this weight, height and base size. I'm going to set the boom at a 30 degree or so, angle up, and use the shadow as a sundial. I'll leave the hoist line nearly touching the ground so the grandkids can swing on it.

A hydo tranny would be a great hoist motor. Up, down, stop all in one. Show pic's.

Here's todays progress. First is the tension cable mounting bracket.




This is the bracket clamp connection. I'[m trying to spread the tension cable force out and keep the ends of the logs from splitting.




This is the new and inproved cable to all-threrad rod connection on the top and the old bad crazy-persons-dream swivel lash-up below.




I think by Friday or Saturday I'll be able to install the double cross tie. Later Ida.

SWIdaho

Made much better progress than I expected. The double cross tie is in. I made a rookie mistake, swapped ends with the cross tie and the angles wouldn't fit. So I hacked and sawed on the ends until it was almost to short. Dumb Ass! Character gaps is what I call them.




Here are closeup shots of the corners. Not very good work. I pulled the frame a 1/2 inch out of square to get them to fit better but the double cross tie still has about 3/8 inch float end to end. Maybe I can use that mistake to put a metal foot on the end of the double cross tie to act as a stop for the brace pole.



That's a 2 inch space for the brace pole tenon.





In the first pic the two single cross ties need to be trimmed and joined to the double cross tie. What kind of joint should I use?  I think it has to be a drop-in joint. Maybe with angled faces that wedge it in position. Is there some way to get part of the single cross tie under the shadow of the mast pole so the mast will hold the cross tie in position?
Later Ida.

Thehardway

Ida,

IMHO the single crosstie should be one continuous piece rather than 2 pieces.  As such it would allow you to do a half lap at each double x-tie (as shown in your mast base layout 1 drawing) and still allow for a stub tenon into the single x-tie.  I believe the 2 piece x-tie will make your base want to buckle up or down and go out of square.  Cables will provide some help but don't think it is near as good as if you could find a piece long enough for a continuous one.  This is a tricky one because the x-tie can be in either tension or compression based on the dynamic movement of the load. as it swivels.  The xties do not share the load equally.  If you don't have a single peice long enough you may want to consider a scarf joint with some steel fish plates and bolts.  If the base is not flat and rigid the load will want to swing erratically and can cause serious damage or injury. don't forget that the idea behind the wide base is not just stability but to distribute the weight over a larger footprint.

One thing that was always interesting to me is the variation and ingenuity in these home brew machines.  They are a true testimony to "form follows function".  A wedge here and a plate there do nothing for beauty or show but can mean the world between success and failure.

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

SWIdaho

Thanks Thehardway. I do have a pole long enough but it is only 8 inches in the center. I could only get a 6x6 or 5 1/2 x 5 1/2 to make a half lap and a mortise hole. Plus I'm afraid that kind of joinery is to far above my skill level. The mortise shoulders for the brace poles and the mast base would all be on the same plane and the half lap would have to be placed perfectly, no sloppy joints. The pic shows the long pole, (1st butt on the left) and the base of the mast, on the right. That tenon will have to get smaller but how small can I go?




I think I'll have to use a steel saddle clamp of some kind and a wedge joint where the cross ties join. Have the clamp force the pole into the wedge joint to keep every thing in compression as much as possible. That's the next best thing to two solid cross ties.
This is corner detail of the single cross tie. String lines, line up with the cables.



This shows the center mast mount. It needs to go down another 3/4 inch to plane with the ends of the cross ties.




How do I make a wedge joint between the double cross tie and the single cross ties? A less than 90 degree angle on the side of the double cross tie and a greater then 90 degree angle on the end of the single cross tie, right? How do I get the tenon to slip into the corner mortise and then engage the angle joint and end up the right length. Maybe a solid member isn't so hard after all.

Do I have to account for how far the tenon on the cross tie has to go into its mortise at the skid log/stretcher corner, to determine the angle of the joint? Got any drawings Jim?

I'm still unsure about how much weight the brace poles are supposed to carry. Are the brace poles just to brace the mast and let the cross ties carry the weight to the frame,  or are they meant to transfer the weight from the mast to the frame and to ground?

Later Ida-know?

deeker

WOW!!!!!!!!!!!   8) 8)
I need one at my sawmill.
To those who fight for it, life has a flavor the protected will never know.  On an empty C-ration box.  Khe-Sahn 1968

Jim_Rogers

About joints.
First of all my model in my drawing program was based on pictures of your model and drawing shown in your first post, in this thread.
There you show the long double diagonal above the skid logs and stretcher assembly.
Having these above this assembly means you don't need any joints. Just secure it to the base assembly. You now seem to be modifying your base design to try and make everything on the same level.
If you try to suspend the diagonal assembly between the skid log and stretcher assembly then you have to solve the joint being able to support the load as well. That is if you intend to fully load this derrick.

If this is only going to be used as a museum piece and not ever be totally loaded to original design loads that one thing. If you want it to be able to load it to original design values then you may need to step back a bit and look at everything again.
I haven't run any numbers on the point load of the mast to the double diagonals at all to see if they are truly the correct size first of all. They maybe just too small to begin with.
Loads are usually figured to be supported without the add of braces. Braces are just for making things stiff and thereby strong.
Usually supports are designed without consideration of the braces as load bearing at all.

As to the specific joint you'll need to use, or how to figure it's length, it can be done on paper in a cross section type of view, if the drawing is done correctly with accurate measurements of existing assemblies. Then cutting the joints and leaving lots of extra wood to be slowly removed as trial fits are preformed, so that the joint or joints are custom fit.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

SWIdaho

You are right Jim, the model and the drawings show every thing on top of the sub frame and now it looks like I'm changing in mid stream. Sorry. This is a 'project piece' just to look at and let my grand kids swing on. As you say nothing has been enginered. But I would like to be reasnoably sure that it won't collapse during construction. 

Thanks for the info on how braces are added after the support structure is designed to carry all the expected load. That's why they are called brace poles and not load poles I guess.

The double cross tie will be equal to two 6" by 6" pine beams 22' 10" long sitting on 2" thick tenons on the ends. 6x6 inches is how much meat is left in each cross tie (after the mast mortise is cut) at the center where the mast sits. That is a long span to set the mast pole on. I think an enginering plan would want more meat there like full span timber both ways.

Thanks for all the pic's and suggestions, I appreciate the help. Later Ida


SWIdaho

I have one of the short cross ties nearly complete. I'll try to get the second done tomorrow. The first pic shows the first cut, safely long. The second pic is two cuts and about ten shaves later. The angle is 70/110. Later,  Ida








Don P

I haven't been following real close (connection is too slow to keep up) but I think those brace poles are taking a good part of the load as the loaded boom moves around  ???

SWIdaho

Hello Don thanks for stopping in. I think you are right, considering the way I have built the cross ties. They will flex down and the brace/lean poles will take more load. That will be OK for a mostly show piece. I think Jim is correct, a working machine should be designed for the cross ties to carry the load and the braces add extra support.

I got the idea from the derricks I've seen. The cross tie's on most just didn't seem big enough.

So good news and bad news. Good; The cross ties went together much easier than I ever thought. I used chalk on one surface to mark the other. Next I'll make a saddle clamp that pulls down on the single cross tie and up on the double cross tie.








What size should the tenon be on the base of the mast. Is a 4"x4" big enough. the mast is 11 inches so a quarter of that is about 3x3 inches. Jim are you still watching?

Bad news; one of our heffers has pink eye. Vet trip thursday morning. Her right eye is weeping and looks like cloudy white is strarting in one corner. Number 13. Later Ida.




Jim_Rogers

QuoteJim are you still watching?
Yes.......

Quote
What size should the tenon be on the base of the mast. Is a 4"x4" big enough? the mast is 11 inches so a quarter of that is about 3x3 inches.

Tough to call, I'd say the bigger the better but you don't want to remove much stock from your long diagonals.....

To bad about the cow....
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

SWIdaho

Hello everyone. After two prototypes I finally got the saddle clamp done. It won't increase verticle strength of the joint, but will add to lateral stability and make sure the joint stays tight. After a short 'punch list' to tiddy up the frame I'll move it to its final resting place. Then I can set up for brace poles.

The pics' show the saddle clamp top and bottom. That's the hammer I dropped on my foot. Not bad; but I dropped it at the bottom of a long arching swing that started well over my head, glanced off the offending member (the clamp) and well I nearly had sphincter-by-pass. Still hobbling.

Thanks to the site admin. for the photo upload stuff. Short learning curve and great results, Thanks. Later Ida.






SWIdaho

 Hello again, I got the mast up and the boom is done. Next is; buy hoist cable and hire a crane to set the boom.

The base is 16 ft square, the mast is 22 ft tall, and the boom, in the back ground, is 40 ft long. Later, Ida.




beenthere

Lookin good.

No tall, strong trees around to hook a pulley (or block and tackle) in for hoisting the boom up?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

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