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Forum topic by dakremer posted 01-31-2011 07:39 AM 1379 views 0 times favorited 21 replies Add to Favorites Watch
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dakremer

2583 posts in 2559 days


01-31-2011 07:39 AM

Topic tags/keywords: holstery chiropractic table

Hey everyone. For those that dont know, I am going for my doctorate in chiropractic (unfortunately that means hardly any time for woodworking…except at night in my dreams). Chiropractic adjusting tables are not cheap, and tons of students are looking to buy them. So I figured maybe this would be my chance to build something and maybe sell it for some income. My design is below. It is foldable in the middle for easy storage/transport. The legs fold up, and when they are down, sit at a 65 degree angle. My question is this. How do I do the dowel part (where it rotates)? This joint needs to be strong, yet it also needs to be able to act as the hinge. I hopefully plan to make/sell a few of these, so dont want anything fancy/over complicated/expensive. I’m just not sure of the best way to do this. Also, do you think when the legs are in the down position, I need to incorporate some sort of brace running from leg to leg, so it doesnt fold back up into itself!? Let me know what you think. Anything I can improve upon? All comments and critiques and suggestions are welcome! Thanks a lot guys!!

-- Hey you dang woodchucks, quit chucking my wood!!!!


21 replies so far

View JuniorJoiner's profile

JuniorJoiner

463 posts in 2908 days


#1 posted 01-31-2011 07:56 AM

i would be concerned about the patients weight plus adjustment pressure being supported by the screws holding those hinges. bad news if you drop a patient on the floor.
the dowel part is simple, drill a mating hole into the side frame members. directly mark the second hole off the first, drill them on a drill press, and when it is assembled, peg it in place.
best of luck

-- Junior -Quality is never an accident-it is the reward for the effort involved.

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dakremer

2583 posts in 2559 days


#2 posted 01-31-2011 08:03 AM

JuniorJoiner…..I was thinking the same thing. I was thinking about adding a brace going up from the bottom of each leg to the center….that way when it is set up, the weight is being supported.

-- Hey you dang woodchucks, quit chucking my wood!!!!

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Loren

8315 posts in 3116 days


#3 posted 01-31-2011 08:08 AM

I wouldn’t be inclined to trust a 1” hardwood rod to hold up in this
application. If you must use this sort of design feature, I recommend
you go to steel pipe.

Even with a steel rod, the end grain on the end of your leg joint
may bust out as well. Not a robust design in solid wood as the hole
is too big and too close to the end of the board. Something with
a bolt and bushing would be more reliable. Cruise the hardware
catalogs like Lee Valley for hinge ideas.

A hollow pipe in the middle, the leg part counterbored a bit to
accept the ends, with a 1/2” threaded rod run through the whole
thing and big fender washers and lock nuts on the outside would
do the trick. Those right angle ground joints will fail you over time
from racking I bet unless the c-shaped frame is supported below
the pipe by a stretcher.

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dakremer

2583 posts in 2559 days


#4 posted 01-31-2011 08:17 AM

I was thinking that those stop blocks for the legs would take most of the pressure/weight off of the leg joint (dowel). Maybe I’m wrong.

-- Hey you dang woodchucks, quit chucking my wood!!!!

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Loren

8315 posts in 3116 days


#5 posted 01-31-2011 08:23 AM

My workbench has 10” wide stretchers which are held in place only
by long 1/4” threaded rods set in grooves at top and bottom. Holes
are bored through each leg and the whole shebang holds tight like
you would not believe. I can tighten it up any time if it ever starts
to get sloppy but it never has. A totally inappropriate substitute for
wood-to-wood joinery in fine furniture but for a workbench it rules.

Something similar would be good for your pivot joint. Tough and easy
to put together.

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dakremer

2583 posts in 2559 days


#6 posted 01-31-2011 08:27 AM

I wish I could see a pic of what you mean, Loren. I definitely want this thing strong. Obviously dont want it falling apart, especially if i’m going to be selling them, and someone could get hurt. Here is a new pic with some added supports for the legs to help with the racking….

-- Hey you dang woodchucks, quit chucking my wood!!!!

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dakremer

2583 posts in 2559 days


#7 posted 01-31-2011 08:45 AM

I was thinking maybe something like this for the middle, to support the weight of the patient and adjustment…... Not sure if I like this though – looks kind of awkward. (but it has to fit inside when folded up…...)

-- Hey you dang woodchucks, quit chucking my wood!!!!

View Dez's profile

Dez

1162 posts in 3545 days


#8 posted 01-31-2011 09:14 AM

Have you looked at the commercially made portable tables?
The ones I have seen are very light weight – approx. 1” legs and if I remember correctly, have cables as reinforcement. Some I have seen also use a plywood brace.

Remember you have to be able to carry this thing around and not need your own services later!

Here are a few examples.
One
Two
Three
Four

One of my BILs is a massage therapist / Reiki-Light therapist
Hope that helps!

-- Folly ever comes cloaked in opportunity!

View Gregn's profile

Gregn

1642 posts in 2451 days


#9 posted 01-31-2011 09:37 AM

Instead of the center leg support to support the hinged joint. My thought would be to drill 3- 3/8” holes and use 3/8” eye bolts and washers and wing nuts to fasten the joint and relieve pressure on the hinges yet making it a solid joint. The eye bolts could be attached to a small cable or chain to avoid loss of bolts when folded up. In effect you are bolting the joint together and yet can unbolt it to fold up for portability. Just a thought!

-- I don't make mistakes, I have great learning lessons, Greg

View tdv's profile

tdv

1139 posts in 2538 days


#10 posted 01-31-2011 11:26 AM

I think using butt hinges is a bit risky the pressure on them would probably split the wod along the screw line & then you & the patient may wind up in a compromising position fold up tables have a flat radius hinge that screws onto the outside face this gives sheer strength & to lock the legs in place when open the best arrangement I have seen is a simple block & 3” wide x 1/4” thick blade of hardwood/birch ply which locates into a shallow pocket in the top crossraill, as you stand the leg into the upright the blade works like a spring & snaps into the pocket locking it in place & preventing the legs folding up,to fold it you simply turn the table on it’s side & pull back on the tensioned strip of wood lifting it clear of the pocket & fold the leg assembly. Any luck with the fan inlays yet?

-- God created wood that we may create. Trevor East Yorkshire UK

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TMcG

191 posts in 2468 days


#11 posted 01-31-2011 02:00 PM

I think if you made each section have 2 sets of legs that fold out, ie fold in for store and move, then the force/weight is being directed down on a vertical support rather than the angled support as shown.

Should be able to bear more weight and solves the “support in the middle” question.

-- http://wood.mcgivern.org

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AaronK

1441 posts in 2932 days


#12 posted 01-31-2011 02:35 PM

in light of some of these comments, it might be better to use multiple laminated pieces of good quality plywood (like batlic birch) for parts like the legs that are going to be stressed in multiple dimensions.

View Ken90712's profile

Ken90712

16957 posts in 2657 days


#13 posted 01-31-2011 03:19 PM

I think you’re on the right track for this idea. One of my close friends is a back cracker in Long Beach California. He adj’s over 400 patients/weekly. I made him solid oak bases raising all his tables off the ground an additional 5 inches. After all day of bending over exerting force for adjustments it relieved him form bending over so much. (He’s only 32, so pretty young) Sorry rambling, my point is to consider the height carefully. I agree with others as well, incorporating some metal into this is a great idea for strength. Nothing against heavy people at all, but when I made platforms for his massage tables, (6 of them), he mentioned he adjusts people weighing over 300 pounds. So I built them like a tank. Look fwd to seeing what you come up with.

-- Ken, "Everyday above ground is a good day!"

View Bob42's profile

Bob42

456 posts in 3258 days


#14 posted 01-31-2011 03:52 PM

All good points but remember the downward pressure when making an adjustment. Plus the wait of the person all going onto that leg joint. Keep in mind the liability if your selling them. I am thinking the some sort of light weight bracing between the legs to take some of the pressure off the legs. They will want to spread apart when the downward pressure is applied.
Just my 2 cents.

ps: I love those woodchucks

-- Bob K. East Northport, NY

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dbray45

3187 posts in 2244 days


#15 posted 01-31-2011 04:45 PM

You may not like this but this will probably come under the durable medical equipment category. In the USA, this falls under the FDA and potentially other agencies and must be approved and certified prior to being sold. This is why the cost is so high. These tables are usually made of hard maple and can take a static load of somewhere around 500 lbs. If a table breaks and is certified, the Dr. may be held harmless, if not, the Dr. is done – their insurance will be so high that they will not continue to practice. This is why a patient is wieghed at physical therapy places etc…, so they can be “placed” on an appropiate table.

-- David in Damascus, MD

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