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Showing results for tags 'thickness sander'.
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The final major part of the assembly is the table. The piece of ¾” Melamine is from the scrap box at the local Vocational School and the piano hinges are pieces left from a project made for my brother in law. The top is reinforced with a frame of ¾” plywood on three sides and a 1” piece of oak on the hinge side. (top and bottom w hinge) The hinge is then screwed to a mounting/adjusting bracket that fits between the two sides of the frame. A slotted hole in each side of the bracket allows for vertical adjustments to assure the table is parallel to the drum. Although not shown, the backs of the slotted piece are covered with PSA sand paper to help prevent slipping during adjustment. The bolts are tightened securely once the table/drum alignment is achieved. (table mount, bracket top, mounting bolt) The opposite end of the table (front of the sander) in screwed to the top of the lift mechanism with countersunk screws Had to buy 2 carriage bolts and nuts.
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Time to mount the drum and motor to the frame. The choice of 2 x 6 sides was made to hopefully eliminate any flexing when work pieces were in contact with the sanding surface. However, that lead to difficulty in figuring out how to be able to mount the drum bearings to the sides. Long carriage bolts can be expensive! The sides are counter bored about 3” and then drilled to match the bolt diameter. An area around the mounting surface was mortised for an aluminum plate. The pillow block bearings will set on the plate, not the wooden surface. Again, my hope is to improve stability. (counter bore and carriage bolts) I was afraid that the soft pine might crush enough to allow the bolts to spin during tightening. Once everything was dry fitted, the bolt heads were Gorilla Glued to help prevent them from spinning. (gorilla Glue) Finally, the aluminum plates are placed in position- ready for the drum to be bolted down. (alumin plates) The motor is mounted to a piece of 3/4 “ plywood. The plywood is fastened to the frame using small “barn style” hinges at one end of the plywood. The weight of the motor creates the tension on the belt/pulley system. I routed slots for the motor mounting bolts in order to be able to adjust the motor side to side to align the belt/pulley. (motor mount 1,2,3)
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Now that the drum runs true and the table lift works, it was time to start building the frame. My intention was to use mortise and tenon joinery but my choice of material was 2 x 6 for the top and bottom of the sides. This was larger than my mortiser could handle. I know, I could have chopped them out by hand. I opted for half lap joints. The overall width of the frame is 23” and the table height is about 31”. The length, at the bottom, is about 36”. The table is 16” x 24”. The frame is made of pine 2 x 4 and 2 x 6. All the joints are glued and screwed. The table is a piece of ¾” Melamine with ¾” plywood support and a 1” oak piece for the pivot hinge. These photos are from the dry fit. I’m gonna need to get some more clamps! (View 1,2,3,4) To increase the structural integrity, I added two 2 x 4 cross members at the bottom of the front and back of the frame. You will be able to see them in a later section.
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After building the drum, a test was in order. After all, if this part didn’t run true there was no sense in moving forward. Using a piece of Corian, the motor and drum were clamped down in position. The motor is a 120v 1/3 HP motor salvaged out of our old furnace. The belt is the one from my table saw- a link belt replaced it. (fire in the hole and Test 2) With some anxiousness, power was applied. Holy Cow, It Worked!! The pulley ratio is about 1:1.5- the drum being larger- so the speed of the drum is slightly more than 1000 RPMs. I hear everyone talking about the “Nickel Test” so what the heck- (Nickel Test)
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Most of the photos used for this part of the blog were taken “along the way.” As with everything made in my shop, there are always changes, modifications and “S**t! I should have….”. The first thing was when Mimi passed by and said, “it’s nice but where are you going to put it”? Anyone who has been in the shop knows you need a road map and a course in choreography to get around all of the stuff crammed in there. OK, we are gonna need some wheels to move this thing out of the way. (wheel axle, wheel mounted,complete wheel assembly, assembly front-rear) Only two wheels were needed, as the unit is not very heavy. Mounting them was simply a lag bolt and washer. A 16d nail through a hole in each one provides the locking mechanism to keep the wheels down when moving the unit. The wheels came from a salvaged skateboard. They were originally destined to become a lathe steady rest. (Note to self- find another skateboard for the steady rest.) (wheel up,down) Another change was the addition of a “handle” to the adjustment wheel. It is more of a visual indicator and lever than a handle. Turning the large knob, against the spring pressure, is a little difficult. The handle/lever adds a little more surface to grip and provides a better indication of how much the knob is turned. (hand wheel) The final modification is the paper end hold-downs. The original ones were small blocks of maple. A screw pulled the blocks into recesses cut in the wooden end caps of the drum. They work fine but the wood blocks seems to cut into the paper, almost tearing it. My thought is to replace the wood with another material. Something firm enough to hold the paper but yet soft enough to expand, from screw pressure, into the recess. Like one of those thermos stoppers with the lever. The material shown is a firm foam rubber block cut from a toy golf ball- still open for ideas here. (improved paper holder) Didn’t have to buy anything!! Love it!
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It was finally time to add the sand paper to the drum. Having decided on a Velcro (hook and loop) system, it was off to Super Grit http://www.supergrit.com/ . Their store is only a half an hour drive from here. The hook portion required 5 feet of material. This PSA stuff is 4” wide and is $2/foot. Also bought 3 different grits of the 3” wide loop paper. Their minimum purchase is 3 yards but at between $1.50 to $2.00 a yard it is reasonable. It took about 73” to wrap the drum but I think I can get it down to 72” and be able to get 2 applications from 4 yards. The first step was to clean the PVC drum; started with mineral spirits then denatured alcohol. Next, carefully wrap the hook material, press it down, and allow it to “rest” overnight to get maximum adhesion. (Velcro front, Velcro rear1) The above pictures also show the cross members added to the bottom of the frame for stability; also, another view of the table’s rear support/adjustment bracket as well as the screws holding the table front to the height adjustment. Next, wrap the paper- this is 40 grit. Anchor BOTH ends. We have dust! (dust) All day, I had been working from the rear of the sander. When it came time for the live fire test, I had anchored what I thought to be the leading edge of the paper- Wrong! As soon as the drum got some speed, the paper lifted and re-wrapped backwards around the drum. Fortunately, it did not tear but it did knock off some of the grit. Note to self- anchor both ends. (mistake) Had to buy the hook and loop system.
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After researching many sander designs and knowing my tendency to over engineer everything, there was only one choice for the table adjusting/lifting mechanism. The source of the lift came from this site and I give the author full credit- http://home.mchsi.com/~woodywrkng/DrumSander.html. The only change/addition I made was to add springs the help eliminate any “backlash” in the movement. The author of the site felt this mechanism gave more support over the full width of the table. The arm pieces were made from ¾” x 1” oak, the top/bottom and front/rear pieces were thicker and wider to add support. All the pieces were cut and drilled prior to assembly. Assembly was with ¼” lag bolts and washers. The adjustment rod is a piece of 5/16” steel all-thread. A T-nut is used, on the rear of the back piece, into which the rod threads (pieces 1 and 2) (arm assembly) (pieces assembled) (springs and adj) Originally, the plan was to use a small star knob. However, it was difficult to determine how much adjustment was achieved from a slight rotation. The oversized knob makes it easier to see even the slightest advance. As it turns out, a full turn raises the table very close to 1/16”. (Oversized Knob)
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When making my rolling pins, I use the thickness planer to bring the thin strips down to 1/8” thick. Unfortunately, if the grain in the wood is not uniform- or there are knots- the strips shatter. This wastes a lot of wood and doesn’t do the planer any good either. It seemed to me a thickness sander would be perfect for this process. Well, Craig’s List wasn’t producing any results and I couldn’t afford a new one. Time to take action! Starting with what seemed to me to be the most critical/difficult part; I began researching construction methods and gathering parts for the drum. The choices were narrowed down to three. One- buy the kit, two- solid wood cylinder or 3- PVC/wood combination. #1 was quickly eliminated- I’m cheap! #2- maybe, but then I found a hunk of 3” PVC in my stash of plumbing left overs. #3 it is- I’m cheap! Next, the pillow block bearings- had to buy these- $20 each. The 5/8” shaft was from the scrap bin at the local Vocational School. Glued up some oak scraps and began turning the end cap, pulley end and center supports. (EndBlock) The process is the same for the end block, pulley block and center supports. The center supports were sliced from a single turning. Turn a blank to a slightly larger diameter than the PVC. Turn a tenon on one end to permit the use of a chuck. (Turned round w/ tenon) Remount the blank with the tenon in a chuck. (Remount) Drill the blank to fit the center axle. (drill for shaft) Remove the drill bit/Jacobs chuck and remount the live center. Advance the live center into the axle hole. Check to make sure the blank spins true. The first end cap turned out to be slightly misaligned. I didn’t see it until testing the drum and motor combination. Fortunately, it wasn’t too difficult to disassemble the drum and make a new end cap. Place a piece of cut off PVC over the Live Center. This will be used to test for the correct diameter as the blank is turned. (Remount Live Center) Turn the blank to the inside diameter of the PVC, testing for a snug fit. I left about 1 ½ “ long shoulder- turned to the PVC’s outside diameter- on the End Cap piece. (test for fit) The center supports are snug fit piece that was sliced in half. The pulley end is turned in the same fashion as the end cap. The only real difference is that the “shoulder” is longer to accommodate the integral pulley. In addition, the tenon, used by the chuck, is left in place to allow a spring pin to capture the axle. (all pieces 1 and 2 and pulley) The PVC is cut to length and the wooden pieces fitted into place. Mark the locations of the center supports and the end pieces. These will have screws to capture the PVC to the wood, later. (PVC installed) Drill and countersink the PVC for screws. I wasn’t sure how these would affect the balance so I evenly spaced the screw lengthwise and at 90 degrees around the circumference. Also, not being a plumber, I did not realize that 3” PVC is not solid (at least what I had). Mine was a foam core type. It seems to be working OK, however. Just had to be careful not to press hard on the countersink! (PVC screws) Once the PVC is secured and everything is positioned, drill a hole in the pulley end tenon to accept a spring pin. This hole is drilled completely through the axle and tenon. I wanted to be certain that if something broke the spring pin could be driven back out. (Spring pin) So far, I had to buy the pillow block bearings and the spring pin.
