Pages, some stolen, some original

▼

Wednesday, July 29, 2020

3D Table Saw Repair

My old friend James reports on his table saw repair:

Craftsman Job Site Table Saw
So I bought this Craftsman table saw (photo 1) many years ago when I lived in Santa Cruz California. It has served me well, especially since I have always had a small two-car garage with no place to leave a saw set up. So this folding rolling saw works great. When I moved to Washington it continued to work extremely well. But about six month ago, just before we move to Phoenix, the extension table lock stopped working. I would extend the side table and then operate the lock lever, but the extension was not locked. So I've had to resort to various clamps to keep the extension from moving when I'm using the fence on the extension.

Fast forward to the lockdown, and I'm sick of dealing with this bug, so I decide to spend some of my ample spare time to investigate. With Agnes's help, I got the saw onto the operating table. But I don't mean her physical help. She's the genius who realized that my folding work table could be configured as a ramp, with one set of legs folded. Brilliant! One ratchet strap served as a winch and the saw was soon on its back on the table.

Since I am pretty blind, I have to resort to lots of lamps and flashlights and I wear a heavy-duty stereo magnifier headpiece. After a small amount of disassembly (one bolt and a few plastic pieces), I locate the problem: two missing plastic pieces called bushings that go on the ends of the steel locking pins to protect the aluminum slides while exerting an ungodly pressure on them to hold them in place. The only reason I found this problem was that there was a fragment of the previous bushing still in the slide.

So I consult the Goo-Gul and find many companies that sell Craftsman parts. And if you are patient enough to peer at their fuzzy parts diagrams, you can eventually locate this part, along with the inevitable label "part unavailable".

3D Printed Bushing
What to do? Actually, I had already asked Agnes to warm up her 3D printer and I gave her an estimate of the required dimensions. So she whipped up a replacement (photo 2) that worked perfectly in the front lock but was too thick for the back lock. So, she is, as we speak, making a pair of bushing that are only 70-thou thick, instead of 90-thou. It takes about a half-hour to print them, so it's time to eat some pizza. Besides, the garage is too frigging hot to work in right now anyway.

at

2 comments:

  1. xoxoxoBruceJuly 29, 2020 at 9:32:00 PM PDT

    I wonder if the two were different thicknesses, like 90ish in the front and 70ish in the rear?

    ReplyDelete
  2. AnonymousJuly 30, 2020 at 6:29:00 PM PDT

    So here's the rest of the story: After dinner, I went out to the garage and installed the new 70-thou bushings. The front lock still works perfectly, but the back one was still too tight. And it's a fairly light cam follower, so I didn't want to force it. Fortunately, the rear lock rod is adjustable, like a car's steering rods. After a few minutes with a couple of metric open-end wrenches and the back lock was also working perfectly. So, tomorrow, the saw goes back on duty. For now, it can roast in the garage while we go for a swim. And tomorrow I can also retire the bungee I had been using to hold the extension closed when moving the saw.

    BTW, another possible issue is the material used for the bushings. The new 3D-printed items are made with Polylactic acid (PLA) and they are as hard as a rock. So the lock rod adjustment is quite critical. But I examined the carcass fragment of the old bushing and it seems to be made of some kind of flexible squishy plastic resembling gummy candy. That's probably why it worked with insufficient clearance, until it was crushed into oblivion.

    Your pal James.

    ReplyDelete