BUILDING A ROUND TABLE
A Serious Page
Steve Leigh don't build contraptions
I use the best grade, straightest lumber available. I suggest that you buy the very best grade in all materials, since this should be a "one time" project. I use dry, straight lumber, and plywood graded "excellent" on both sides. It was a little more expensive, but very easy to mark, cut, glue and paint. I suggest you buy 10 pounds of each length drywall screw, and not even worry about running out. Also, buy a dozen extra phillips head screwdriver bits for your Makita. Find the best grade wood glue - something that really bonds and welds wood. If you have access to a table saw or radial arm saw, you'll get much better results than with a circular saw. If you're a genuine perfectionist, you can countersink the screw heads, and putty over the tops before sanding and painting. And - if you're good with a router, USE it! Even though it adds a lot of time and some mess, a little sanding will help to get the tables neater and maybe make things fit nicer in the long run. Use a belt sander or an orbital if possible. A drill press is also a necessity. For the steel, it's a good idea to use a countersink, and chamfer all holes. You'll note that almost all bolts and hardware are at least 3/8" thread, 9/16" bolt heads. Some of the more stressed connections call for 1/2" thread, 5/8" bolt head. You may think this is "overkill", but 5000 dogs down the road, you'll be glad you used heavy materials. I've tried to design these tables in such a way that we never have to worry about powerful dogs - these tables will hold together for years. Only the Astroturf should need replacement after time.
All wood surfaces should be waterproofed before painting with exterior grade paint. All steel surfaces should be sanded, steel wool, primed before coating with rust proof paint or powder coating.
Take your time, and build them right - the FIRST time. I was a fool - I built them wrong - three times. (I'm not even counting the very first one. That table only lasted about two weeks, (thanks mainly to rain), so I've really been through five round tables.) I wasted plenty of time and blew a lot of money before my tables were really right. That's why I had to get to the fourth generation. They'll last a long, long time, and serve you well in the future.
As you read through this page, note that there are UPDATES. After building and using the tables, a lot of changes have been made in design and features. These updates are quite important.
Incidentally, this page originally was huge. It contained the full set of plans for the square, long, and round tables. I edited it down, just to discuss the round table. Some of the updates may repeat or seem a little out of sequence - sorry about that.
On my first and second round tables, I used four legs on the lower frame, two on the upper frame (total 6). The updates will explain that only four legs were necessary.
PORTABLE ROUND TABLE
6' - 6 1/2' diameter (your choice, I've had two of each, the 6' moves a little easier, but I like the 6 1/2' better)
18" high, plus top thickness: 19 1/2" actual height
BASIC MATERIAL LIST:
top - 4' x 8' x 3/4" plywood (4 sheets needed)
frame - 2" x 6" x 8' (four pieces needed)
legs - 4" x 4" (1 piece, 8' long)
drywall screws - 1 1/4" and 3 1/2"
center post - 3 1/2" O.D. heavy wall (1/4") steel pipe, 60" long
post mount plate - 1/4" plate steel, 10" x 10", 3 1/2" hole in center, four mount holes (machine shop details below)
spinner or rotator - 3 1/2" I.D. heavy wall (1/4") steel pipe, 12" long
roller bearings - approximately 1 1/2" diameter x 1/2" bore (use bushings if necessary)
bearing mounting screws - 1/2" stainless pan head x 1 1/2" long
plate mounting screws - 1/2" stainless flat head x 3 1/2" long
Cut wood pieces to correct size. We will build the table frame in two pieces - the "lower" frame and the "upper" frame. The lower frame has four legs, the upper frame has two. [UPDATE: The lower frame only requires two legs, not four, but I recommend using the two "spacer blocks" as shown in the pictures. These are just short pieces of 4" x 4".]
Frame and legs:
Cut four legs, 4" x 4" x 18". Cut four frame members, 2" x 6" x 72". Mark down 3 1/2" from top of the frame members, then mark a 45 degree angle at the ends of the frame members. Cut as shown in the pictures below. You should now have four pieces of 2" x 6", exactly the same. Mark two frame members "upper", the other two "lower".
Mark the centerline of all four frame members (36"), and from this mark, mark 1 3/4" out from the center in both directions. This will leave a 3 1/2" center area for the post.
Mark 1 1/2" notch areas outside of the center area. Using a radial arm or table saw, notch (dado) 2 3/4" deep x 1 1/2" wide - down from the TOP of two frame members, and up from the BOTTOM of two frame members in these 1 1/2" notch areas. The pictures below will clarify the notches and positioning.
Drill 1/2" hole in exact center of 3 1/2" area of -LOWER- (notch up) frame members. Later, this hole will be used to pass a bolt through the frame and the post. [UPDATE: Ignore this - the bolt is completely unnecessary.]
Using a square, glue and screw the legs and frame members together, one set with the notches UP, the other set with the notches DOWN. The legs fit just behind the 45 degree cuts for a slight inset. Be sure you use a square to get the legs perfect. Five screws (3 1/2") on each side of each leg is recommended. [UPDATE: On my most recent tables, I used seven 3 1/2" screws on each side of each leg. I made a simple template out of cardboard with the seven holes in it, and used it to mark each location for drilling and countersinking the screw heads. After the screws were set, I used filler putty over the heads, and sanded. The screw holes are completely invisible after painting.]
The 2" x 6" frame members will now fit together at right angles with the notches interlocking.
click picture for fullsize view
The easiest way to mark the round tabletop is to use something like an aluminum strip, longer than 40". Drill 2 holes, about 1/8", at 39" separation. (This will give you a 6 1/2' tabletop. 36" will give you a 6' tabletop.) Lay the plywood on sawhorses, and use a finishing nail to tack the aluminum strip to the very edge of the plywood at 40" from one end. This is your pivot point. Stick a pencil through the other hole, swing the strip, marking a semicircle on the plywood. Use a saber saw to cut this radius. Repeat this for the other three pieces of the tabletop. You'll have a lot of scrap plywood. (This assumes you're building a tabletop with two layers of plywood - I highly recommend this. My very first round table was single layer: it was wrecked within two weeks.)
Lay two halves of the tabletop together on a flat surface, forming a circle. Use a lot of glue, then lay the other two halves on top, making sure that the seams are 90 degrees from each other. Thus, each "top" piece will overlay both "bottom" pieces - this will add considerable strength and rigidity. Measure out a "screw pattern" and use plenty (I used over 100) of 1 1/4" drywall screws, making these four pieces of plywood into one super strong, rigid assembly. The tabletop is now 1 1/2" thick, and weighs quite a bit, (an estimate is 200+ pounds), but it can be rolled around on its edge fairly easily, as long as there are two or more people. (I really don't recommend you take a chance with just one person moving the tabletop - it's just too heavy and bulky.)
After the glue dries, mark the exact center of the tabletop, and mark a 3 3/4" circle. Cut out this circle with a saber saw. Later, Astroturf will be stapled to the tabletop, and the excess at the center will be stapled inside this hole, causing a very tight fit with the steel post.
If you choose to secure the tabletop to the frame with bolts, yet maintain portability, place the finished top on the assembled frame, exactly centered, and locate 4 places where bolts can pass between frame members behind the legs. Drill for 1/2" T-Nuts, and mount T-Nuts on the upper surface of tabletop. Test fit 7 1/2" x 1/2" thread (5/8" bolt head) bolts up through steel retainer plates, into the T-Nuts, then cut/grind the bolts to exact length, so the bolts do not protrude above the tabletop. [UPDATE: Please ignore this. I tried it and didn't like it at all. Keep reading, and you'll see this method is foolish.]
There are alternate possibilities for locating the tabletop to the base frame, while retaining complete portability. For example, short (approximately 6"-8") blocks of 2" x 4" can be glued and screwed to the bottom of tabletop, fitting between the 2" x 6" frame members just behind the legs when the top is in the correct position. No bolts or hardware are required for this method. This is the method I plan to use on my next table. [UPDATE: YES!! THIS IS IT! I finally used some logic!] Hopefully, the frame members will be built accurately enough that the locator blocks will fit the frame in any of the 4 positions. An important consideration at this point is to know *exactly* where the 1/2" bolt hole will be for bolting the post to the lower frame. See "STEEL" below. [UPDATE: As mentioned above, the use of a cross bolt is entirely unnecessary.]
As it turns out, those locator blocks do not fit in all 4 positions, but they do fit in two. I've built several more tables, and none accept the blocks in all four positions. Maybe I'll figure that out someday. Obviously, I'm measuring something incorrectly somewhere. Something is out of square. Duh. (I better go find some more logic - quick!)
Machine shop work is required. You should expect to spend some pretty serious money for the steel parts.
Fabricate a 10" x 10" x 1/4" square steel mount plate with a 3 1/2" hole in center, 1/2" mounting holes 1" x 1" inset from all corners.
Through drill & tap 1/2" holes at 17", 19", 21" and 23" down from top of the post. These holes will be used later to mount roller bearings for the spinner at four selectable heights. Mark the post at 44" down from the top. This is the location for the top of the square steel mount plate. Ask your machinist to scribe reference marks on the post AND the plate BEFORE welding! Bevel all edges, and round all corners slightly. Weld the mount plate perfectly square with the post at 44" from the top.
Turn the spinner in a lathe, face the top and bottom square, and bevel the edges. Fabricate 3" x 3" "D" ring with 3/8" solid round steel rod. Weld the flat part of the "D" to the spinner, centered in the 12". (see illustration picture above) My current table has two "D" rings welded to the spinner on opposite sides, and, as shown, a "skirt" prevents the chain from touching the roller bearings.
1/2" T-Nuts are used on the bottom of the tabletop. I use 1/2" (thread) pan head cap screws for the mount plate. (They require an Allen wrench.) These screws have no sharp edges, thus the dog's paws cannot be scratched or cut. If you can find these, they're worth the price and trouble. 2 1/2" or 3" x 1/2" heat treated (black) panhead cap screws is what you ask for. If you can find them in stainless, all the better.
After all details have been performed, the tabletop can be coated with Thompson's Water Seal, or something similar, and allowed to dry well for a day or two. I suggest two coats of a good exterior grade paint, as well. The tabletop is then covered in Astroturf. I use the rubber backed Astroturf. Lay out the carpet, and, using an electric or pneumatic (compressed air) carpet staple gun, (3/16" x 1/2" long staples), tack it down all around the center hole. Then stretch the carpet tight to the outer edge of the tabletop and tack. You'll want to wear gloves while stretching, as this is very rough on the hands. Two people help - one stretches while the other staples. A local carpet man told me the tighter the stretch, the longer the carpet lasts. Who knows? Mine's pretty tight. Cut the center post hole in an "X" - the excess will be stapled inside the post hole, and will provide a tighter fit when the post is installed. I also stapled under the edge of the tabletop, so the carpet actually wraps around. I'm considering adding an "edge" of aluminum, plastic, or something to my next table, so it can be rolled from place to place, even on concrete and rough gravel, without tearing up the Astroturf.
After the carpet is installed, cleaning up and opening the post mount bolt holes is very easy: just use a soldering pencil. The heat melts the Astroturf, and makes holes and any ragged and trimmed edges very neat.
Roller bearings can be purchased at most any automotive store, but I've had trouble finding bearings with 1/2" center bores. If you also have difficulty, just buy some press in bushings (bronze, I believe) to reduce the center bore to 1/2". Most any size roller will do - I used 1 3/8" O.D. with the reducing bushings. I also use stainless button head screws to bolt the roller bearings to the post. You'll probably discover that the rollers won't roll, so you'll need to find some thin spacer washers (1/2" hole) to "stand" the center of the rollers away from the post and the bolt heads slightly. This happened to me, and spacer washers are the solution.
You'll notice that there are four height adjustments for the roller bearings. Many dogs like to work on their hind legs, and occasionally the spinner jumps around a little. Lowering the spinner (thus the angle of the chain) can help with this sometimes, if you have acrobatic dogs. Also, if you're concerned with the spinner actually flying off the top of the post, just drill and tap a 1/4" hole anywhere around the top of the post, and put a 1/4" bolt in. (This happened only once here, and it scared the shit out of me! The dog was on me in a flash, dragging the chain and spinner behind him. Thirty minutes later, that post was drilled, tapped, and had a bolt in it! I was still bleeding 4 days later.) This will definitely hold the spinner from coming off the post. Another possibility would be to drill and tap four different holes, about 1/2" above the top of the spinner, to limit the vertical travel of the spinner at each of the four possible heights. A little more work, but you might like it better.
Regardless of the above - my last round table did not have any bolt hole to stop the spinner from coming off the post. The only reason for this is that I removed and replaced the spinner so often, I just couldn't be bothered removing an extra bolt before I removed the spinner. Pure laziness.
I just completed two new round tables, and there are several interesting updates. The four top pieces (two thicknesses of 3/4" plywood) were cut to a perfect circle using a router after the tabletop was assembled, but before the post hole was cut out. I found an old sheet of 3/16" plastic, about 4' long, 12" wide, and adapted it to the router base. I measured very carefully, then I drilled a center pivot hole, attached the plastic to the exact center of the tabletop, and the router cut an exact 6 1/2 foot circle. I had already cut the tabletop with a saber saw, but the edge wasn't perfect. The router required three passes (due to the 1 1/2" thickness) and it is as perfect as I can ever ask for. The same basic technique could be used with a saber saw, also. The requirement is fairly simple: a piece of material (plastic, metal, possibly even thin wood) which will pivot from the exact center of the tabletop, and keep the cutter (router or jigsaw blade) at the exact distance you have set up.
One of the initial problems I had was attaching the steel post to the tabletop while avoiding hardware that could injure the dog's feet. Buttonhead (or panhead) socket screws were a good answer, but flathead sockets are even better. Just countersink the mount plate, and use the flatheads.
I was unable to find 1/2" T-Nuts anymore, so I down sized to 3/8" - but I feel that the post will stay in place as tight as everything fits. I'm now using 3/8" T-Nuts on the bottom of all tabletops. I found 3/8" flathead socket screws in 2 1/2" stainless, and they were about $4.90 each. I also found stainless 1/2" x 1 1/4" buttonhead socket screws for the roller bearings. They were also about $4.90 each. And, I got lucky - I found sealed roller bearings with a 1/2" center bore and 1 3/8" outside diameter for about $8. each. The rollers were barely turning, so I completely removed the seals, cleaned out all the grease with gasoline and compressed air, and use silicone spray to lubricate the bearings instead. They spin much easier without any grease in there. Shim washers for the rollers are hard to find, so I'm still using regular flat washers, but they work just fine.
I added a plate (I call it a "skirt") at the bottom of the spinner. It's a circle, 6" in diameter, welded to the spinner. This plate completely prevents the chain from touching the rollers, so it can't get "hooked" on a roller bearing. We'll never have that problem again. I drilled and tapped the post at four different heights, allowing the spinner to be raised or lowered by simply moving the rollers to the desired height.
I decided to powder coat the steel. Plating (example: black chrome) seemed pretty expensive, and powder coating seems better than rust proof paint. I was quoted $40. for powder coating the post and the spinner, but - the steel had to be sandblasted before powder coating could be done. I ended up sandblasting all the steel for all the tables, and had it all done at one time. If you've never tried sandblasting, take my advice - pay somebody else to do it. It's enough to make you go blind.
The powder coat has been in place for over 6 months. It's definitely chipping a little, but not much more than paint, considering the same treatment. The chains can really fly around with some of the more active dogs, so this is a situation we have little control over.
I found some 1 1/2" wide strong vinyl called "rub rail", made for boats. It's used to keep boats from damage when they bash into each other. I will screw this to the outer edge of the tabletop. This will let me roll the top around with no damage to the Astroturf or the plywood. The rub rail I found has a slot in which you can press 1/2" rope or another piece of vinyl to cover the screws. It's about $2.50 per foot, and the table is about 22' in circumference. An alternative is to use aluminum - I believe it's called "threshold". This comes in different widths and lengths, too.
The two center legs have been removed:
As mentioned above, the center legs are not needed. The table stands better and without any wobble. As a side note, the down sized 3/8" T-Nuts are holding up perfectly. The table has had a lot of use, and they've never come loose. The powder coating is gradually chipping away, though, probably because I leave several other length chains on the spinner at all times.
2001 UPDATE: This is the final design. This table has now been in use for five full years, has been disassembled, moved around, and reassembled dozens of times, and it's (finally!) exactly right!
The Astroturf has been replaced twice, which is really a difficult project, but this is something that I feel can't be changed at all. I considered using a kind of "traction paint", with sand in it, in place of the Astroturf, but decided not to.
In addition to several hundred initial temperament tests, I estimate that approximately 1,000 different dogs have been on this specific table, and probably many, many more. Each dog has typically been worked through 200-2,000 separate bites and/or agitation (turn on-turn off) cycles. In other words, the actual number of mechanical, physical stress cycles on this table's construction has probably far exceeded 50,000 repetitions.
By my calculation, that's quite a bit of work done on the table. If something was going to fail, I sincerely believe it would have failed by now. I'm very pleased to state that the table seems just as strong right now as the day it was first used. Aside from the Astroturf, it just keeps going and going.
Having only 3 pieces plus the post makes moving it a pleasure. Only four bolts need to be removed and replaced. With two people and a short length of pipe, the table top can be rolled almost anywhere, even up and down stairs. It takes about three minutes to assemble or disassemble.
UNUSUAL UPDATE: This is written several years after I closed my dog training business. It's unlikely that I'll ever build another set of tables, but my mind never stops thinking of ways to improve on past mistakes.
If I were to build a new set of tables today, I would use a vertical milling machine for much of the work. The precision available from a vertical mill is absolutely unbelievable, compared to using any typical woodworking tools. "Precision" in this context is .001" - one one thousandth of an inch. This degree of precision is really not needed - in fact, just one coat of paint would throw the measurements out by several thousandths. Although I believe I could create the most perfect tables ever built, the construction accuracy wouldn't change even one exercise done on the tables.
And - in the long run - the correct exercises, consistency, and a true feel for reading the dogs is all that really counts.