Monday, November 19, 2007

A Sanding We Did Go

I didn't get to spend any time in the shop on Saturday. My daughter had asked me several times to go with her to her gymnastics class and watch her practice. Last week I promised her I'd take her this past weekend, and that's how I started my day. After that, the family went to the phone store & we bought new cell phones. They had a deal, buy one phone & get 3 free, so we ended up getting the kids phones of their own, too.

The deal basically was buy one fairly expensive phone, then you could get three free by choosing from two more basic models. Because my wife's number is the primary number on the account, and because of some weird quirk in Verizon's system (or maybe it was because the salesman couldn't figure out how to do it), my wife's number had to go on my phone & my number had to go on her phone.

So when we got back from church on Sunday, I tried to swap the phone numbers on Verizon's web site. This didn't work, so I went back to the store and I told them the web site wouldn't let me do the swap. I was told it would cost $20 a phone to do the swap, but I could do it on their web site for free. At that point, I figured I'd go back home & try again, after asking which of the 5 different numbers on the label in the phone was the right number to enter.

Well, it didn't work, so then I called customer service. After dealing with some more phone company strangeness, the customer service rep finally got the numbers on the phones switched & we were happy. But by now, it was just too late and I didn't have the energy to do anything.

I wasn't too worried about not spending any time on the cabinet this weekend, though, because I have this whole week off. I won't do anything on Wednesday & Thursday, but today I spent sanding everything in preparation for the glue-up.

The first order of business was to remove the pencil marks from everything and hand sand the plywood parts. I figured I'd remove the pencil marks from each part as I went, then do the sanding.

To get rid of the pencil marks, I used a trick I had learned on WoodNet a few years ago. I took a paper towel & wet part of it with denatured alcohol. I then started rubbing along one of the pencil marks and watched as the line faded. This has had varying degrees of success for me in the past, depending upon how hard I was pressing the pencil to the wood to make the mark. The lighter you press, the easier the pencil marks come up, and vice-versa.

This worked very well for me on all of the plywood parts, and not so well on the solid wood parts. I guess I pressed down harder while making those marks than I thought. The alcohol did remove some of the pencil marks, just not all of it. The remainder would come off while sanding without any trouble.

This is what the same board looked like after I finished wiping it. As you can see, I was able to remove all of the mark in this case.

One of the things I learned on WoodNet was that rubbing a board with alcohol, like mineral spirits, gives you a preview of what the piece is going to look like if you apply a clear finish. At one point, while I was wetting a paper towel, I accidentally spilled some alcohol on the board. Since the alcohol was now contaminaed with wood dust, I decided just to spread it around & see what that board would look like.

The picture at the right shows you that board after I was done. I had been thinking about putting a clear water based wipe-on poly on to the inside surfaces of the cabinet, and now that I see how this board is going to look, I just might do that. I will have to speak to the customer (hey, Mary!) and see what she thinks.

After removing the pencil marks on the first board, I started hand sanding with 180 grit paper on a sanding block. This was going along fine, when I noticed a ding on the show face near the bottom. This ding was high enough on the panel to show, so I knew I had to do something about it.

The ding can be seen in the picture at right. It's hard to see in the picture, but it's in the red circle. It's not very big, but there's really no reason to leave a blemish like this in the panel when there's an easy way to get rid of it. And it doesn't require that I sand away the veneer, either.

There was a time something like this would have really stumped me, but I had a trick up my sleeve that made fixing this problem a piece of cake. I decided to use an old trick I learned from a friend of mine whose father is (now) a retired general contractor.

I took a shop towel & soaked it in water, then wrung it out so it wouldn't drip as I carried it through the house into the garage. I layed the cloth on top of the panel, as shown at right.

Next, I took a clothes iron we have but never use & plugged it in. I set it to the hottest setting it has, Linen, and waited for it to get up to temperature. Once it was hot enough, I started to iron out the ding. This sounds counter intuitive, but it really does work. Here's how.

As shown at right, I basically ironed the paper towel. (I'm wearing latex gloves, in case you're wondering why my hand looks odd). The heat from the iron made the water in the towel boil & turn to steam. The steam penetrated the crushed wood fibers in the top of the veneer. The wood cells in the veneer absorbed the water & expanded.

The net effect is the wood in the ding expanded and raised itself back even with the wood around it, more or less. This also raised grain of the wood that was under towel, so I had to sand that area again.

The picture at the right shows the panel after I finished sanding it. The ding has pretty much disappeared at this point.

As I went through the panels, I found a few more dings in various places, about 4 in all. I also found a couple of them on a couple of the solid wood pieces, and I treated them the same way.

I'd like to note that I only sanded the plywood parts on one side, the show side. I'll sand the other sides after I've finished the glue-ups, but not until I'm ready to apply finish. It is my intention to put one or two coats of whatever my top coat will be on the exterior, not visible surfaces. I'm not 100% sure of this though, and I may just leave them unfinished entirely. All of the panels will be held in place by glue, plus they're made of plywood, so there shouldn't be any movement to be concerned about.

When I finished with the plywood, and after a lunch break, I took out my PC 7334 random orbit sander (ROS) and put a 100 grit disk on to it. I then connected it to my shop vac & started going to town. The idea was to keep the ROS moving and flatten the ridges left by the planer, and to remove any remaining burn marks.

It took a while to finish sanding all of the solid wood parts with the 100 grit paper. When I was done with the 100 grit, I put a 150 grit disk on the ROS & started all over again. This went faster, since I had smoothed everything out with the 100 grit & I was just removing the 100 grit scratches. Once I finished sanding with 150 grit, I put the ROS away & pulled out the 180 grit on my sanding block & hand sanded every part.

By this point, the kids had been home from school for a while & dinner time was approaching. I had been putting all of the parts in the family room after I finished them so they could start warming up. The temperatures have been in the 40s during the day, and that's just too cold to get a good glue bond. Bringing the parts in and allowing them to warm up ensures a good glue bond. I had brought the glue into the family room a few days ago, so the glue is already at the right temperature.

Tomorrow morning, I'll do one dry fit just to make sure everything fits together right, and I'll fix up anything that needs fixing. Then I'll glue both carcases up. After that, I'll probably either cut the blanks for the adjustable shelves, or I'll just get started working on the arch in the bottom most molding.

5 comments:

Steve W. Carter said...

Tony -- thanks for all the pointers! You've given me an idea. A week or so ago I was in the process of repairing a chair. I used my new Jet Clamps to pull a joint back into place and glued it. The glue job worked perfectly. Unfortunately the clamps on a curved surface weren't such a good idea. I now have a couple of dents in the chair from the clamps. Do you think the iron trick will work on them. Needless to say the chair has a finish on it so I wonder if the steam and H2O will create more problems than they resolve.

Tony V said...

Steve:

The iron trick will work, provided the dents aren't too deep. Finish does not stop wood from absorbing or losing water, it just slows the rate at which water transfers.

There are other things to worry about, though. If the chair was finished with shellac, this trick will probably turn the shellac white. This is easy to fix, though -- just apply more shellac. I'm not sure what water will do to lacquer, but lacquer's as easy to fix as shellac. If the finish is poly, there shouldn't be any issues.

In the future, if you ever have to repair a chair again, you should either place cardboard or pieces of scrap wood between the jaw clamps & the legs, or get yourself a band clamp and use that. Either way, you won't damage the wood with the clamp.

Tony

Steve W. Carter said...

Tony -- If nothing else I learned that the clamps definitely need padding when they are used on anything other than a flat surface! I can't believe that I didn't realize that before I damaged the chair. I was a victim of tunnel vision here and was only thinking about the glue job. I'm not sure what finish was used on the chair. My Mom purchased it sometime in the late 60's from Ethan Allan. As luck would have it most of the finish in the area I damaged has worn off during the many years of use and needs to be worked on anyway. It seems the first step is to try to remove the dents and then restore the finish. Thanks for your help!

Ace HoleInOne said...

Tony:

I've had good luck removing stubborn pencil lead lines on wood using a standard pencil erasure (the little brick shaped kind). Just buy a package of them. They really do last awhile. I haven’t had any finishing problems using them.

Great blog, excellent info on the steam iron for dents.

-Ace-

Tony V said...

Thanks, Ace. I do appreciate the compliments.

The pencil lines didn't survive a meeting with a 100 grit pad on my ROS. They pretty much just disappeared after a couple of passes.

Now that the glue-up is done, I've got to sand with the ROS some more to even out the face frame joints. It shouldn't take much sanding, but it's necessary.

Happy Thanksgiving!

Tony