Bests & Worsts Reviews from Amazon

**** Update June 2019 **** See ‘IMPROVEMENTS’ section at bottom **** **** Lots of new pictures added too, all having a yellow band at bottom. Original pictures have no band. **** I have bought a number of retracting casters over the years and none has satisfied me until now. I believe the best ones out there now are this Powertec model and a very similar product made by Rockler. Since I needed three sets of casters for different power tools, I decided to buy both a Powertec and a Rockler caster set and compare them to find out which one is the best. Being a mechanical engineer, this seemed like a fun little test. I would then buy two additional sets of the winner and return the set that came in second place. Read on if you want to know the winner… (Spoiler alert: it’s the Powertec) Please reference all the pictures. First, let me define the part names that I will compare. There are three main steel sections which can be seen in the picture titled ‘Part Names’; with the three labels “Mounting Bracket”, “Pivot Arm”, and “Tilting Plate”. The other parts of the caster sets that I will not discuss are the actual casters themselves and the ¼” and 5/16” nuts and bolts. These parts are identical on both sets. I mean identical. Pivot Arm One picture shows both sets’ pivot arms when looking from the top. The Powertec arm has small ridges on top, perhaps to increase traction with the sole of your shoe? I do not see this as a significant advantage. The real significant difference can be seen in the picture with the caption of “Pivot Arm Comparison” showing side views of the two pivot arms. Notice that the Powertec has a much more rounded surface where it contacts the tilting plate, making it easier to slide and decreasing the wear on both this part and the tilting plate. This is where all the action happens when you are raising and lowering the casters so I think that the Powertec is designed better, will last longer, and will take less foot pressure to raise and lower power tools and benches. Tilting Plate Look at the picture with the caption “Tilting Plate Comparison”. Note that the Powertec plate is slightly flared at the top of the picture whereas the Rockler plate is straight. This will add some rigidity making the Powertec plate a little stronger on one end. However, in looking at where the bending stresses are the greatest (red dashed lines in the picture) you can see that the Powertec’s flared section offers no real benefit. The only real effective difference is that the Powertec is about 1/16” of an inch wider at this high stress point. Slight nod to the Powertec here. Now look at the picture with the caption “Tilting Plate not Horizontal”. I am holding the Powertec’s parts in place when the caster would be in the fully lowered and locked position, i.e., when you would be rolling your equipment. Note that the tilting plate is tilted down 6.4 degrees from horizontal which can be seen clearly in the picture. In a system like this when significant weight is placed on the caster, up to 100 pounds per caster, then this angle will decrease under load. Since I have not yet installed these casters on any of my tools, I do not know what the angle will be under such load. The 6.4 degrees will decrease but will likely not go to zero, potentially making the casters uneven. The Rockler also tilts down 1.8 degrees, much less than the Powertec. My guess is that the Rockler’s tilting plate will be more horizontal under load than the Powertec, although this is really conjecture on my part. I will not know more until they are installed. Mounting Bracket One minor issue is that the Rockler mounting plate has two sides and a center section that should be bent 90 degrees from each other. Unfortunately the sides have been bent slightly more than 90 degrees. See the picture with the caption “Rockler Mounting bracket sides not square with center section”. This is primarily a cosmetic issue, but speaks somewhat to the care taken in manufacturing. The Powertec sides are exactly at 90 degrees. Material Thickness The pivot arm, tilting plate, and mounting bracket on the Powertec are fabricated from steel that is 1/8” thick, or .125”. The Rockler’s components are all a little thinner at .120” thick. This is not noticeable to the naked eye but will make the Rockler’s load bearing capacity a little less than the Powertec. Mounting Screws The Rockler has slightly beefier wood screws supplied to attach the mounting bracket to a wooden frame member of a workbench or similar hardware. Advantage Rockler. Since I usually supply my own mounting hardware, this is a not a significant factor for me. Conclusion I give the nod to the Powetec for the two big reasons of: 1. The more rounded surface on the bottom of the Powertec’s pivot arm 2. The slightly thicker metal used throughout the Powertec’s components I like both caster sets and either would likely meet my needs. But I am guessing that the Powertec probably has about a 10% greater load bearing capacity so I see that as a tie buster. **** IMPROVEMENTS (Updated Jun 2019) **** I finally installed these Powertec casters on a variety of my power tools and decided to make some significant improvements to an already good design. Please read about the changes I made and the corresponding new pictures, all having a yellow band on the bottom to identify as new and updated pictures. Bolts I did not like that the bolts used as pivot points had threaded sections that touched the mounting holes in the tilting plate and pivot arm. So I replaced these bolts with ones that had a longer solid shaft that reached all pivoting areas. See the picture with the word ‘Bolts’ in the yellow band at the bottom of the picture. My new bolts with the longer non-threaded shafts are below the original bolts. Mounting Holes in the Mounting Bracket I replaced the single mounting screw hole at the bottom of the mounting bracket with two screw holes near the outside edges of the bracket to prevent bending of the bracket under heavy load. See the picture with the words ‘Added Screw Holes’. The holes I added have red arrows pointing to them. Flexing Between Caster and Tilting Plate The casters have a small mounting surface when bolted to the tilting plate. This caused the caster body to tilt relative to the tilting plate when under load. It didn’t matter how tight you tightened the mounting nut. This was a bad design. So I added a thick heavy duty washer to prevent any flexing. See the pictures ‘No Washer Installed’ and ‘With Washer Installed’. This improved the stiffness of the caster assembly greatly. The grade 8 washer I used is has a .812” ID and slightly over .2” thickness. You can find them at McMaster.com, part number 98025A036. Raise Wheels Off of Floor I prefer to sweep the floor around the caster without the caster wheel touching the ground so I added a spring to the caster assembly that raises the wheel off the floor when the caster is not engaged. See the pictures ‘Spring’, ‘Spring installed” and ‘Wheels Suspended Above Floor’. I purchased the extension spring from Lowes and shortened it to meet my needs. The spring is 11/32” in diameter, 2-3/8” long before I shortened it, and has a wire diameter of .035”. I really like this new feature and it is easy to do. Tilting Plate Not Horizontal I mentioned this problem in my comparison of the two casters in my original discussion. It turned out to be a very noticeable problem with the Powertec casters I bought, causing the casters to not track smoothly. I fixed the problem by putting in a wedge between the caster’s mounting bracket and the vertical surface of the tool that I mounted the caster on to. This wedge can be seen in the picture ‘Fixing Tilt’. The biggest challenge with this fix is to determine the correct angle that the tilting plate deviates from horizontal when the caster has weight on it. This is tricky as there is no way to mount a level on this small tilting plate so I improvised by gluing two small pieces of wood together to extend the surface of the tilting plate to a point where I could measure it for level. See the wood pieces in the picture ‘Tilt Measuring Tools’. You can see how I measure the tilt using this wooden piece in the picture ‘Measuring Tilt’. I measured the tilt on all four tilting plates, averaged the angle, and made the wedge to counter that angle. This process requires attention to detail but, once implemented, makes my casters glide easily and I can change my tools’ direction of travel effortlessly since all tilting plates are horizontal. As an aside, the Rockler casters that I compared to the Powertec casters had less tilt (1.8 degrees vs. 6.4 degrees) so they would work much better out of the box, without adding wedges, than the Powertec. Tilting Casters on Steroids I installed a set of these casters to my heavy table saw but I wanted the caster assembly to have a much increased weight bearing capacity. The weak points in the design of these caster assemblies are in the tilting plate (metal is relatively thin at about 1/8”) and the caster wheels themselves which are perhaps medium duty at best. So I first manufactured new tilting plates. See the picture ‘Stronger Tilting Plate (Top)’. This plate is thicker at 3/16” and slightly wider where the bending stresses are greater. I also replaced the original casters with heavy duty casters seen in the picture ‘Stronger Caster (on right)’ with each having a 250 pound capacity. McMaster part number 9795T41.The only challenging part of fabricating the new stronger tilting plate was to locate and weld the tube to the plate at the proper height so that the tilting plate, when engaged in the horizontal locked position, would be perfectly horizontal. This takes some trial and error but, if done right, prevents the need for making wedges as I had to do for the stock tilting plates. All in all, these upgrades turned my casters into truly useful tools to easily move my tools around. I encourage you to buy any of these types of casters, whether it be Powertec or other similar brands, and make the upgrades that I outlined above. You won’t be disappointed.