dispatches from TJICistan

I got a floor standing belt sander from my dad a few years back – he bought it at a garage sale (probably with an asking price of $30, and an actual sale price to him of $5 – that’s how he rolls) – and decided that he didn’t really need it. (…after dropping another $40 or so on sanding belts for it).

So, anyway, it’s been darkening my shop for a few years, and I decided to knock some rust off some Record handplanes I picked up a while back (bought at retail, and then never used – that is, all too often, how I roll. Harrumph.).

So, the belt sander with it’s 8″ wide and 24″ long platen is the perfect tool.

Plug it in, flip the switch. Nothing.

The switch has a child safety lock and the doohingus is missing.

Route around that, plug it in. Life!

Unplug, put a belt on, tighten the wheels … um… how do you tighten the wheels? (By “tighten the wheels”, I mean “the two rollers at either end of the belt are 1/2″ closer together, to give you some slack in the belt, when you put a belt on, and then they need to be moved 1/2″ further apart, to tension the sandpaper belt).

The roller is carried at each of its ends by a piston. The pistons slide in cylinders bored into the cast iron body, their shafts parallel to the long direction of the sandpaper belt. The pistons are maybe 6″ long, and 3/4″ in diameter.

How are the pistons forced along their paths, pushing the roller, tightening the belt?

Each piston has dedicated to it a small cam welded to a bolt. Turn the bolt, and the cam pushes against the other end of the piston. Once the piston is pushed out to tension the belt, there’s a bid meaty set screw bolt that can be tightened down.

The last 1/2″ of the the pistons that project out of the cast iron cylinders are all rusted up and caked with ancient sanding dust.

I lubricated them with WD-40, drove them out with a punch. They were rusted.

Also, they’re pinned to the roller’s axle with coiled / “scroll” pins.

More WD-40, more hammer and punch action.

Then chuck the pistons up into a metalworking lathe, and use some 200 grit sandpaper and WD-40 to clean up the surface (tried steel wool and 3M scrubby pads – no effect). The sandpaper does a good job, turning the pistons from dirt-colored to 99% silver … with rust “freckles” left over.

So I throw all the parts into the vibratory tumbler that I use to prep brass for reloading, along with some walnut media. A half hour later, things are looking quite nice!

While the parts were tumbling, I reflected that I needed more light at the Sherline, so I took a tripod-with-twin-halogens that I inherited from the Chimp, and which has been rattling around my garage with out purpose for a few years, and discarded the tripod, took the horizontal booms and the two halogens, flipped them upside down so they hung down from the shaft, then used aircraft hose clamps to secure the vertical shaft to some of the overhead garage infrastructure ( an angle iron bracket descending 8″ from the ceiling to support the garage door track). Bam! Tons of light over the Sherline. Nice!

With the belt sander parts cleaned up, it was back to the shop. Reinstalled everything.

Did I mention that one side of the belt sander had a cam to tighten the piston, but the other side did not?

I tried tensioning the defective side by using a lever arm against the roller, then tightening the set screw, but I couldn’t get the same tension as achieved with the cam. Result: fire up the motor, and the belt walks off.

I tried tensioning one side, tightening the set screw, then removing the cam and moving it to the other side to use it there … but because the cams have chirality, a cam that gets a bigger radius as you sweep around its circumference clockwise is not going to fit in the place of a cam that gets a bigger radius as you sweep around its circumference counter-clockwise.

So, take the good cam back out, trace it onto some mild steel I’ve got lying around, use the 4″ grinder with cut off wheel and rough out a new cam. Use a mill file to smooth the transitions and get a really nice came shape.

Grab some 3/8″ steel rod I keep on hand (Dang, I love a well-stocked shop!), use the grinder to cut facets on one end like a bolt head, then cut it off at the appropriate length. Now I’ve got a shaft.

Set both pieces up to be welded and – oh, oh ! make sure to remember to flip the cam UPSIDE DOWN before welding, because of the handed-ness !

…and it was at that point that I had turn off the welder, tighten down the valve on the Argon-CO2 mix, wash my hands, head out and get a burrito, and then head to Mass Ave to watch Jenny and the girl scouts march in the Patriots’ Day parade.

Also at the parade: make sure to clap loudly for the four GIs in the two humvees who were otherwise encountering deafening silence as they toured the enemy territory of the People’s Republic of Arlington.

(Oh, even with a loose belt, I did get some sanding done on the planes.

Cleaned up the #4 and #5. Took them apart, cleaned up the bodies, sharpened the blades, cleaned up the clamping area of the chip breaker, etc. I ended up planing the heck out of all four surfaces of a pine 2×4 scrap, and did a fair bit on the edges of a maple scrap. Got things adjusted just right, so that I was making translucent shavings that I could see shadows through.

Took the #7 apart, started to sand it, and realized that the loose belt and the long plane body were resulting in a chugging motion of the belt that threatened to put waves into the finish of the body. Stopped that post-haste!

Didn’t even get around to touching the #120.

I’ve got fairly strong plans to build a cabinet maker’s bench this summer and so some real planing, as part of real projects.

This entry was posted on Monday, April 20th, 2009 at 6:59 am and is filed under General, workshop. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.