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MachinistBlog.com

Plans, projects and how-to's for home machinists

Heart Valves, Digital Levels and Happy Holidays.

My new workbench uses metal shelving units and laminated countertops. I used deckboards to help support the countertops and boards that sit between them and the basement walls. The boards create some more overhang at the front (toe kick) and bridge a gap I had to leave in the back because of a drainage channel along the walls. I tried leveling the countertops with wood shims but it didn't go well. So I removed one of the countertops and started leveling the boards with paper from old catalogs and magazines (that blue stuff is masking tape). I finally realized my Harbor Freight digital level wasn't accurate. Read the article to find out why you shouldn't buy one.

My new workbench uses shelving units and laminated countertops. I used deckboards to help support the countertops and some boards between them and the basement walls. The boards create some more overhang at the front (toe kick) and bridge a gap I had to leave in the back because of a perimeter drainage channel. I tried leveling the countertops with wood shims but it didn't go well. So I removed one of the countertops and started leveling the boards with paper from old catalogs and magazines (that blue stuff is masking tape). I finally realized my Harbor Freight digital level wasn't accurate. Read the article to find out why you shouldn't buy one.

The worry level is pretty high at my house right now because my 30-year old stepdaughter is getting a heart valve replaced tomorrow.  We knew she had a “minor” and somewhat common mitral valve defect but she didn’t have any problems with it until just a couple of weeks ago.  We hope it goes well because we have two young grandchildren who need a healthy mom.

I have no room in my workshop

There’s also another reason why I haven’t gotten much work done in my workshop or added much to MachinistBlog or MachinistVideos lately.  We’re having some major remodeling done and our contractor has finally finished taking over my garage workshop with his tools and materials.  As a result I haven’t had room out there for awhile to work on my CNC router.  So I’ve been concentrating on getting my new “winter” workshop in our basement finished.

I have only one major task left before I can start using it.  That’s to install a couple of 10-foot long laminated countertops that are mitered to join in a corner.  My contractor said that to get a good joint the two pieces have to be perfectly level and I’ve been having a lot of problems getting them that way.

The countertops are on heavy-duty shelving units that can also be assembled as workbenches.  There’s a small variation in their height and they’re sitting on a basement floor that’s not very level.  To make a long story short I have to do a lot of leveling over a 20-foot distance and I wasted hours of work before I realized my digital level wasn’t accurate any more.  I bought it at Harbor Freight because it was inexpensive, it had much greater resolution than a standard construction level and it had a built-in laser that I thought might be useful.

DO NOT BUY Harbor Freight’s Digital Level Model 93884

I checked and it was very accurate when it was new.  But it’s out of warranty now and it can’t be easily recalibrated like many other digital levels.  You can typically place them on a fairly level surface, press the recalibrate button, turn the level exactly 180 degrees on the same spot and press the button again.  They can then determine true level.  The Harbor Freight digital level can’t do that and it has to be recalibrated by a “qualified technician.”  I wasted another couple of hours unsuccessful searching the net and trying button combinations to see if I could find a way to calibrate it myself.  So do not buy the Harbor Freight 24-inch digital level model 93884!

Oops

I then switched to using my 8-inch Starrett machinist level on top of a much longer construction level.  It’s extremely accurate and so sensitive you can easily see the difference in height caused by a very thin piece of paper.  They cost about $120, so I was heartbroken when I managed to drop it a few inches and ruin it by cracking its vial.

iPod Touch to the Rescue?

So now my plan is to use my iPod Touch.  It has a couple of digital level apps on it that are very fast and sensitive.  But it’s not long enough and the back of its case is a little rounded.  So I’m going to attach it to my construction level with double-sided tape and if necessary, bed the edges in Play-Doh if it needs more support.  Then I’m going to calibrate it for true level using the method I described earlier.  I’ll probably use the Clinometer that comes with AppBox Pro, a $1.99 collection of useful apps that I like because it includes the best tip calculator I’ve ever found.

I just have to find (make?) some time to finish the job.  If you’re a regular reader you probably know that I’ve been unusually busy with my job, family and yard work.  Things have finally begun slowing down and I’m getting caught up.  But to be honest I’m tired and a little burnt-out.  I’ve also got a bunch of relatives and good friends who are going to be in town visiting next week.  So I may take some time to relax and goof-off if things go well with my daughter.

Happy Holidays

I want to wish you all Happy Holidays, Merry Christmas, Happy Hanukkah,  Joyous Kwanzaa, Happy Festivus and a Happy New Year. (Yes, I do try to be PC – Polite and Considerate to all).

Shop Light Upgrade & T12 Phase Out

I have about a dozen 4-foot fluorescent shop lights in my basement and garage.  They’re all hanging from chains and plugged into ceiling-mounted electrical outlets that are controlled by wall-mounted switches.  They frequently have to be replaced because the cheap magnetic T12 ballasts in them go bad.  On my last trip to buy a replacement I learned something I didn’t know and you may not either.  T12 ballasts and some fluorescent bulbs are being phased out in the U.S. next year (2012) because of higher energy efficiency standards, although some exceptions are being made for residential use.

I don’t know if the residential exceptions will allow you to continue buying cheap ($10) shop light fixtures.   I won’t be sorry to see them go because I’m tired of replacing them every 2 to 4 years.   I’d already seen the video above and had decided that I was going to start repairing my shop lights with T8 electronic ballasts.  So I came home from Home Depot with an $18 replacement ballast, a box of ten 32 watt T8 “daylight” bulbs and a new $30 T8 shop light fixture in case my repair failed.

Repair and upgrade was not that difficult

It wasn’t hard to repair my old shop light by replacing its T12 ballast.  But I’m not going to describe how to do it because if you don’t do it right you can turn your shop light into an electrical or fire hazard.  If you want to learn how then do a search for “T12 to T8 conversion” (without the quotes) and you’ll find many helpful web pages and videos.  But I will give you this advice:

  • Make certain you use the proper size wire nuts so there’s no chance your new connections will come apart.  Vibrations and temperature changes can cause poor connections to become loose.
  • Your new ballast will have to be attached and grounded to your light fixture using sheet metal or self-tapping screws.  Make certain they won’t come loose and you scrape the paint off the ballast underneath your screws so they will make a good electrical connection.
  • Make certain your power cord’s ground wire is also properly attached to the fixture.
  • And make certain you unplug your light before you start working on it 🙂

T8  Advantages

  • A 32 watt T8 bulb is slightly brighter than a 40 watt T12 bulb of the same kind.  I’ve begun buying “”Daylight” bulbs because they are much brighter than “standard” fluorescent bulbs and they also seem to make colors appear more accurate.  And because they use less power T8 bulbs also produce less heat.  Which can be an advantage in air conditioned environments.
  • Florescent bulbs dim over time and a T8 bulb won’t lose as much of its brightness as a T12 bulb will.    A T12 bulb will lose about 20% of its initial brightness and a T8 will only lose about 10%.
  • T12 lamps can flicker, hum and sometimes create a stroboscopic effect because they operate at low frequencies (120 or 100 Hz).  T8 lamps won’t because their electronic ballasts operate at much higher frequencies (20,000 Hz).
  • T8 ballasts can work at much lower temperatures than most T12 ballasts.

T8 Disadvantages

The only disadvantage I’ve seen so far is cost.  I don’t remember there being much of a difference (if any) in cost between T12 and T8 bulbs.  But T8 light fixtures seem to cost at least twice as much as T12 fixtures.  [Might still be true at Home Depot but Lowes sells a really nice T8 shop light for $15.]  I’m also concerned about how long their ballasts will last.

A “fortuitous” keyboard and mouse podium for my CNC mill

This is the “fortuitous” keyboard and mouse podium I made for my CNC mini-mill.  The previous owner kept the keyboard and monitor on top of the cabinet and used a “thumb” mouse that dangled down on a cord.  They obviously weren’t easy to use and I wanted some kind of table or stand to put them on.  But I didn’t want to invest a lot of time or money in one because it was probably going to be temporary, until I could build a new workbench for the mill and an enclosure that can handle coolant.

I considered making one from wood but I’m glad I built one using a spare tire and some pipe fittings instead.  It may seem a little “red neck,” but it is very strong, very stable and easy to move.  It was also quick and easy to build.  A wooden stand would have probably been wobbly on my somewhat uneven concrete floor.  I would have also built it too low, and I would’ve had to use it that way or cobble together some kind of riser.  By using pipe, I simply had to replace one section with a longer one to increase its height to where I wanted it.

If you’re wondering, the top is made from part of an old desk and it’s offset a couple of inches from the center toward the edge of the tire.  For strength I supported it with two pipe flanges in a “Y” configuration.

The definition of fortuitous is “happening by a lucky chance,” which describes this podium.  I stopped to look at pipe fittings at Lowe’s and found they had flanges on clearance for 99 cents.  If they hadn’t been I probably would have switched to wood construction, because I needed three of them and there’s no way I would have paid the normal price of $12 each.  I did have to buy some reducing bushings for them, but in all, I only spent about $30 or so for the pipe parts.

A friend was visiting my workshop at about the same time.  I mentioned I was looking for a free tire rim and was going to put a want ad on Craigslist.  A couple of days later he dropped off a spare tire and rim from a Triumph TR-6.  A few days later I accidentally stumbled across a nice Microsoft wireless keyboard and mouse on sale at Walmart.com.  I got them for $19, which including tax and shipping.   But my luck didn’t end there.  A week or two later I found a bigger and better LCD monitor at a garage sale for $10 that fit an articulating wall mount I found at another garage sale for $5!

I’ve discovered that I could use another small table on the right side of the mill for my tooling and parts.  So the new bench I’m going to build for the mill is probably going to be “U” shaped.

Making Particle Board Workbench Tops

This article describes how I make workbench tops using particle board.  I’ve been using this method for about 20 years with good results.  Although the next time I build a similar bench I may use a laminate counter top for two reasons, which I’ll explain later.

I don’t like benches that move, shake or vibrate.  I think the heavier the frame and top are the more stable a workbench will be and the better it will dampen vibrations.  Particle board is very heavy which is why I like to use it.  To make it even heavier and stiffer I glue two 3/4-inch layers together.  Particle board is also very dense, unlike plywood and MDF,  which means it won’t dent very easily or much if you hit it with a hammer or drop something heavy on it.  It’s also inexpensive and it won’t warp.

I’ve tried using plywood but it dented and splintered easily.  Wood planks will do the same.  Plus planks can warp and it’s not easy to build a smooth seamless work surface out of them.

Construction

I built the L-shaped bench shown in the picture a couple of years ago.  The frame was built with 2x6s instead of 2x4s to make it strong enough so I could eliminate all but two legs and keep the space under the bench unobstructed for storage.  The legs are at the ends and are made from pressure treated 4x4s.  I began construction by screwing the back rails to the wall studs.  I made certain they were level and used screws that could support a lot of weight.  Then the front rails, side rails, legs and cross braces were added.  I used metal joist hangers, angle brackets and deck hardware to fasten them all together.  They added to the cost but I think they made the bench much stronger and quicker to build.

You might want to bring some help with you when buy the particle board because 4×8- foot sheets are heavy.  I got Home Depot to rip them in half lengthwise.  It saved me a lot of work and made the boards easier to handle to bring home.  If you have them do it make certain they measure correctly.  The first sheet they cut was off by 3/4-inch and I wouldn’t accept it.  They very graciously cut another.

This L-shaped bench top was harder and more complicated to make than a simple rectangular one.  I began by fitting the lower-layer pieces against the walls.  Then I cut and glued just one of the top pieces so it overlapped the seam in the bottom layer. When the glue was dry I fitted and glued the remaining piece, making certain that it butted very tightly against the other one.  I also made certain it was well clamped and weighted down while the glue dried.  I ended up with a very tight seam that only needed a little bit of wood putty to make it disappear completely.  It’s still invisible two years later.

I used the “original” Gorilla Glue to glue the particle boards together.  There might be cheaper alternatives but I wasn’t going to take any chances on the seam between the two layers coming apart.  This kind of Gorilla Glue is water activated and you’ll need to use a spray bottle or wet rag to slightly dampen the surfaces just before you apply it.  I used a plastic spreader to spread it out evenly.  Then I used lots of clamps along the edges to make certain I got a good bond with no gaps.  I also stacked as many heavy objects as I could on the rest of the bench to weigh it down.

It’s not likely that you are going to get both layers of particle board cut and lined up so the edges are perfectly even.  So after all the glue was dry I used a router with a flush cut bit to make them even.  This may require positioning your router on both sides of the bench top.  I couldn’t do that because there wasn’t room to flip my L-shaped top upside down, and the support frame prevented me from holding the router upside down against the edge.  So I had to plan ahead and make certain that the top layer extended beyond the bottom one a little bit so the router bit could trim it flush.

I then used the router with a 1/2-inch round-over bit to round the edges of the workbench.  It’s a little bit more work, but I think it makes the bench top look more finished and professional looking and it makes the edges more comfortable to lean against.  Rounded edges also won’t dent or splinter like sharp ones will if they get bumped with something heavy or sharp.  They’re not hard to make but I recommend practicing on scrap first. Continue reading Making Particle Board Workbench Tops

Random Quote

Women and cats will do as they please, and men and dogs should relax and get used to the idea.

— Robert A. Heinlein