Tag Archive | plastic
April 11, 2012  

The Slippery Truth

When you are working in your shop it is important to have control of your work. Work surfaces, especially tables, should support your lumber and provide as little resistance as possible. This makes your job safer, more accurate, causes less fatigue, and just makes it more enjoyable. It is not instinctual to make your work area slick. But, in the right place, slick is exactly what you need.

For making surfaces slick there are two excellent options–one temporary and one permanent. The temporary solution is to apply something to the surface, like wax. There are also sprays available made with different compounds, but I recommend good old Johnson’s Paste Wax.

You can use wax for all of your tools with metal or wood parts. I use it on all of my fixtures and jigs where I want less friction, especially my crosscut sled. You should wax every stationary power tool table in your shop. The obvious ones are the table saw, jointer, router table and planer. I also use it on my hand power tools, including the jig saw and router. If you want the wood to glide along nicely, wax it.

No need for wax here. The planer board has taller sides and an UHMW surface to keep the boards going through smoothly and without end snipe.

The planer board has a piece of plywood mounted to the bottom to hook the bed of the planer. This is all that holds the board in place and makes for easy removal when you need the extra width.

The outfeed side of the planer board can be longer than the factory table for more support. This board is 48" long, but could be longer if you have the space.

The permanent solution is to use UHMW (Ultra-high molecular weight) plastic. I have found this most useful on the planer. As a matter of fact, setting up a table board with a sheet of UHMW was one of the first things I did once I got my new planer up and running. I used a sheet of 3/8″ thick UHMW plastic on top of a box made from 3/4″ plywood that is easily removed from my planer. The only adjustment to the planer was to move the bed rollers all of the way down and out of the picture. I was happy to do this because I think bed rollers are a terrible solution to the problem of boards getting stuck in the planer.  No matter how they are adjusted they make the ends of the boards snipe every time. In contrast, boards never, never, never get stuck on the UHMW and having a flat bed with no bed rollers eliminates the snipe. Lumber just goes in one end and out the other with no dip on the ends.

The UHMW is available in sheets and adhesive-backed strips. The strips can be applied to fences and jigs where friction can be a problem. The strips and smaller pieces are available at Woodcraft or Rockler and the larger pieces I purchase from Regal plastics here in St. Louis. They aren’t cheap (a 36″ x 48″ pieces cost about $50), but well worth it.

Before you start your next project, wax your work surface or add a piece of UHMW plastic. You will wonder why you hadn’t done it sooner.

September 30, 2011  

Utility Knives And Plastic Don’t Mix

A utility knife is one of the few tools that is always in my tool belt and is on my top-ten list of often-used tools. They have many applications, but cutting plastic not one of them. As a matter of fact, utility knives should just stay away from plastic all together.
Utility knives dig into plastic and don’t ride consistently. They will cut smoothly, then just as quickly, dig in and get stuck. Or, they might just completely release and hop around uncontrollably. And, plastic has no grain direction, so there is nothing to direct the knife and an errant cut could go anywhere.
The worst cut I have ever had came from using a utility knife to cut plastic when I was in college. I had a project laminated and was trimming it to size with a utility knife while using a metal ruler as a straight edge. The plastic was thick and I was pushing down hard. Before I knew it, the knife slipped and I cut a corner of my fingertip almost completely off. The only thing that stopped it was my fingernail, which did not cut through.
Also, while I was in college a classmate was doing the reverse. He was using a plastic triangle as a striaght edge and the knife hooked into the plastic and jumped over his outlayed thumb. He was a big guy and it made a big mess. He went to the ER and they sewed it back together again.
If I ever cut plastic with a utility knife I am extremely careful, and I make sure to keep my fingers bent so the knife doesn’t just ride over them if I do slip. Hopefully, the handle will hit a knuckle before any real damage occurs.
Very recently, I was working with a friend who was cutting plastic wire ties off of some new lighting fixtures we were installing. I wanted to say something about plastic and utility knives, but I didn’t. I thought he was smart enough already and didn’t need my two cents. After a couple of minutes, I heard the yelp that I was expecting. I knew what he did – he cut himself with the knife. But what really makes the story worth telling, is that while we were looking for a bandage he said, “That was the third time I cut myself this morning.”

Remember: Utility knives and plastic don’t mix.