Bi-directional Slab Roller Construction Plans
Why bi-directional you ask?
It is incredibly fast to roll out slabs when you can crank the feed handle left, lower the top roll 1/8" with a single turn of the top adjustment and then crank the feed handle right, all without repositioning the clay or having to stop and add shim boards. My philosophy on studio equipment is to build things that work as well as or better than the best commercially available equipment. Before I built this, I looked at what was available and identified the features I would want to make my slab roller more efficient. Over the years, the added features have saved me lots of time that would have been wasted with other designs.
I have had many requests for the plans to this slab roller. Rather than respond to each separately, I have chosen to post photos with a written description here on my web site. I believe this machine can be built simply by seeing the photos and reading the descriptions. The rolls for this slab roller are made with ordinary schedule 40 black iron pipe for ease of machining. Since I wanted both bi-directional action and infinite height adjustment, I designed these features into the machine from the start. Below is a photo of the entire slab roller with stand.
The main board is 24" x 36" x 3/4" thick high density floor underlayment (a type of particle board). It is very rigid and smooth. The stand is constructed to standard 37" counter height of light weight materials to make moving the machine easier.
Infinite adjustment is achieved by means of a sliding block constrained by vertical pieces of 1" x 1/4" flatbar which fits into grooves on both sides of the sliding block made of a piece of 1" x 2" x 4" flatbar. A 1" hole is drilled centered 1" from one end. A 1" OD x 3/4" ID bronze bushing is press fit into the hole after the vertical hole used for adjusting elevation is drilled and tapped 1/2" x 13 TPI . Below you can also see a photo of the 4 28 tooth 12 pitch steel gears that transmit the handle's rotation to the top roller and synchronize the two rollers perfectly. Notice a pair of much smaller gears slightly to the left of the larger gears but still inside the connecting bars. Those gears are welded to the bars to make the linkage stay rigid under the force of the turning gears. They make this transmission bi-directional and keep the linkage functional throughout its entire travel range.
This view shows the vertical adjusting handle. Notice the nut and bronze thrust washer on the underside of the cross piece. I used a small spring tension pin to secure the nut to the threaded 1/2" x 13 threads per inch threaded rod. By counting the turns of the handle from the fully raised position and recording the turn count in the lowering direction, it is possible to repeat any desired thickness again and again.
In the photo below, you can see how the two shafts were synchronized to assure absolutely level slabs every time.
In this view, you can see the bottom block which is identical to the top block except is is only 1" thick x 2"x 2". The assembly method is primarily welding but notice the bottom is bolted to allow disassembly for servicing of the components if parts ever wear out or break.
Below you see how the bottom roller is positioned to perfectly support the carry board as it passes through. Notice the angle iron guides that keep the board both centered to the rollers and level end to end. This is critical because even a small misalignment will result in tapered slabs as the board begins to drop due to its overhung weight.