Wednesday, September 29, 2010

Wednesday, September 22, 2010

Tuesday, September 21, 2010

Tech Tip Tuesday

My students always seem to panic when they start working with epoxy because they're concerned that they're not going to have enough time to work with it and that it's going to cure before they're done.


Working with epoxy has nothing on steaming wood.

Steaming takes place fairly quickly - after you get the part out of the steam box you have a limited amount of time before the wood starts cooling to the point where it will not bend well anymore. Typically, something like 30 seconds to a minute depending on the type and thickness of wood that you're working with.

So, before you even begin, I recommend that you have your stock wet or pre-soaked, all of your clamps ready, your fixtures ready, any backing straps (either plastic or metal straps used to keep the grain from "running". You should be able to lay your hands on everything you need almost without thinking about it. Plan to have extra hands if you can and absolutely no interruptions. Think through what you're going to do and how you're going to do it before you start.

Put your stock in the steam box and wait the prescribed amount of time - about 15 minutes of steaming time per quarter inch of stock thickness. If it is a thick piece of stock, you may want to swab it with hot water during the steaming process to keep it from drying out and becoming brittle.

When the stock is ready, put your gloves on pull the stock out and start bending! Support the bend with your gloved hands or your strap to help it bend - almost like you're trying to stretch the wood around the bend and clamp or tack in place as is appropriate.


That wasn't so hard, was it? Now all you need to do is to let the parts cool and dry on your form until you're ready to use them!

Here are some pieces that I steamed this evening for the kayak's coaming and storage hatch rim and cover. The pictures aren't pretty, but you get the idea:

The inner rim of the gear hatch is two layers of 1/8" cherry and has been glued around the plywood hatch form after the earlier steaming session. I steamed another thinner layer of scrap - about 1/16" thick as a spacer and taped that around the inner rim as a spacer (so the cover will go on easily) and steamed and bent another two layers for the hatch cover. As I've said before, the goal is a hatch that looks a bit like a Shaker oval box cover.

The coaming is 5 layers of wide (1-1/4") cherry that are 1/8" thick. Two or more layers of narrower (1/2" wide) cherry will be used to form the cockpit rim after the wider portion of the rim has been glued up.

Both the coming and inner rim will have a series of holes drilled through them after finishing to allow them to be sewn into the skin. Obviously more to come, here.

Saturday, September 18, 2010

Thursday, September 16, 2010

Confession is Good for the Soul


Here goes nothing.

I've had lots on my mind of late. I think it is starting to show in spots.

I've been working on things for my canoe building class and the school in general. I've got things going on at home and would be lying if I said that there wasn't a lot going on at work, too. For whatever reason, I decided that I'd fire up the steam generator and bend some of my cherry I've cut for the coamings on the kayak.

Recalling the canoe building class with Jerry Stelmok up at the WoodenBoat School, I remembered that dry wood - like the mahogany that we used for gunwales, needs to be soaked before steaming to avoid simply tempering the wood and ending up with hot, brittle wood.

For this eventuality, I made some soak chambers from a 2" piece of ABS pipe with threaded caps on the ends. The "steam box" was another piece of 2" ABS pipe.

Before I left for work this morning I had a moment that Click and Clack of NPR's Car Talk would have described as "unguided by the thought process". I wanted to prepare the wood for steaming this evening by soaking it first. So, I took some pieces of cherry I'd cut for the purpose and put them in the tube, filled the tube with water and plugged the end. Simple, right?

Well, I came home form work this evening and had dinner. After dinner, I set up the "steam box" and the steam generator to bend the wood. I then went to the soak tank to extract a few pieces of the wood to steam.

I repeat - I then went to the soak tank to extract a few pieces of the wood to steam.

Nothing was moving out of the tank.

Mental note - don't put too much wood in the soak tube - when wet, it EXPANDS.

A lot.

The pieces of wood were not that tight in the tube, but when I filled it with water, they expanded so much that I couldn't pull them out of the tube.

I did finally smarten up a bit - I used the soak tank as the steam box and when the wood was heated, it shrank allowing me to pull the wood from the tube. The hot wood bent like a noodle.

Wednesday, September 15, 2010

Tuesday, September 14, 2010

Tech Tip Tuesday

Well, yesterday's post was indeed apropos.

As part of the kayak build, it is necessary to bend some wood for coamings, hatch covers and rims. I've spoken about bending wood before - and canoe ribs specifically - but I'll recap quickly here. You can cut pieces of wood so that they are curved after cutting - often done with crooks or knees so that the grain direction follows the intended curve to yield a strong part. You can laminate thin layers of wood around a curved form like we do with our stems, or you can heat the wood by boiling it or steaming it to soften it for bending.

In my case, I'm bending long strips about an inch wide at their widest and about 8 feet long. The stock cannot tolerate the tight bend that I'm contemplating for any of the parts. I tried one method that I've seen used successfully - taking a damp T-shirt and steam iron to heat the strips (because they are s thin) and bending them around the forms. This didn't work too badly, but my scrap rate was a bit high for comfort. (The rims are going to be cherry!) I decided that I'd better bite the bullet and just steam them.

Alas - no good way to create steam. Time to make one.

I like the brute force behind a propane fired steam generator (think large kettle on big propane burner with 100 gallon propane tank and regulator), but don't want the expense or safety issues associated with a set-up like they have at WoodenBoat. I decided that an electric steam generator would work best for me. I'd seen some that I liked. Here's my first cut:

First, before thinking of undertaking this type of project, be sure to know and understand what you're doing - it can be dangerous if you are not careful. Live steam, electricity, flammables and other hot parts can hurt your badly or even kill you if not treated with respect. Details are important - like choosing the correct wire gage for the cable, proper grounding, avoiding electric shock and not creating a sealed area where dangerous amounts of pressure can build up. Think before doing.

I've shown part of the steam generator before, but let me describe it a bit. What we have is a frame to support the apparatus and on the left is a bucket which gets filled with water. (both for feeding water and counter-balance - note that the feed on the pipe is higher than the bucket's bottom) on the bottom of the bucket is nipple which lets the water feed into the high-temperature black heater hose, through a ball valve, and into the "T" on the pipe assembly to the right. Located in the pipe at the bottom is a 1500 watt electric hot water heater element. I was very careful to ground the pipe with the cable and to cover the connections with a silicone cover to isolate them from water and to prevent electrocuting the operator. I also located the element at the bottom to avoid boiling it dry - I've seen similar steam generators with elements in the "T" and fed from the bottom. The water is boiled in the tube and expands as steam exiting at the top brass fitting and into another piece of heater hose which is held in the steam box with a rag.

Because of the length, this presented some issues. I picked up some ABS pipe to use as both a soak tank (wet wood steams better...) and another piece for the steam box.

It's all R&D.

Lessons learned? Yup. Bigger diameter pipe would have been better. First, it would have created a larger surface area making more steam. Second, the expanding steam wouldn't push the hot water up the relatively narrow column; I'd started with some shorter pipe, but the expanding steam pushed hot water up and out of the top of the device - like Old Faithful! That's one of the reasons that this is such a tall device - this one is about 3-1/2" tall. I'd also make a more robust custom cap for the bottom to protect the electrical elements.

"If they don't find you handsome, they should at least find you handy."

- Red Green

Monday, September 13, 2010

It's all R&D...

If we knew what it was we were doing, it would not be called research, would it?

-Albert Einstein

Thursday, September 9, 2010

Priorities, Priorities

Well, it has been time to get back to work on the skin-on-frame kayaks. While DW would probably question my choice of priorities in working on the boats when I could be doing other things, I've started picking away at the boats again.

When at the WoodenBoat Show this past June, the folks from Chesapeake Light Craft had some nice foot-braces for a very good price. After three attempts at home-made foot braces, I wasn't fully pleased with the results and the plastic ones looked to be a good solution as I had already spent more time than the effort was worth. I did utilize the dovetailed cherry stock from a previous effort to support the foot braces in the frame as shown below.

I've also been working at the deck rigging. It is polyester webbing with brass grommets and screws with Fastex hardware. The shorter pieces shown at the bottm will be used to attach the elastic cord in front of the paddler. Another set that are similar, but with "D"-rings will be sued to hold the seat-back. The longer pieces will be to hold the deck hatch in place.

I've got a bit more to do on the steam box assembly so we can bend the coamings and the hatch frame and cover frame, but that should be my weekend task.

It's on my priority list!

Wednesday, September 8, 2010

Tuesday, September 7, 2010

Tech Tip Tuesday

In my line of work, one often comes upon some unusual engineering wildlife. I think you'd better check out the post quickly as I'm not sure how long the link to the first image will be working:


The Alumabeaver (Castor Aluminus) is a diurnal mammal; the third largest rodent in the world. The Alumabeaver is characterized by its large flat tail, webbed paws, soft silver fur and tungsten carbide teeth.

Their habitat includes highly industrialized areas and they are particularly fond of machining and manufacturing facilities where their largest food source is to be found.
While seldom seen in the wild, these elusive creatures are often known to be in the presence of bad machinists and mechanical design engineers. Their presence can be noted by their tell-tale tooth marks found in aluminum along with chips and shavings. These tooth marks are often mistaken for those of the Bronze Muskrat (Ondatra Zibethicus Brundusinium) and strongly resemble very irregular marks made by end-mills, drill bits and files, but with unusual chatter and inconsistent lay marks. Their presence may also be given away by wet tracks of Tap Magic on floors in the region where shavings used to construct their lodges are found.

Alumabeaver Tracks

They tend to be solitary animals and their lodges (constructed mainly of shavings, cardboard and small diameter billets that have been gnawed off) are often found adjacent to work benches and built against the side of milling machines. They are not as industrious as their woodland cousins and often do not come out of their lodges unless bad manufacturing or shoddy design is to be found. Their diet consists typically of 6061-T6 and 7075 alloy billets but when food is scarce, they are known to consume 2024 angle.

Alumabeaver Skeleton

While their lustrous silver pelt and tungsten carbide teeth are both very desirable commodities, they are difficult to trap and attempts to do so near their lodges often result in severe cuts to those who try to capture them.

Monday, September 6, 2010

They're Baaaaaaccck!

We seem to have a seasonal problem with out local rodent population. The problem is that they like our house in all seasons.

A lot.

We've been hearing the pitter-patter of little feet above our heads when we're in bed for quite some time. Eventually, we heard them between the first and second floor making their ways between the joists. Mind you, these spaces are all but inaccessible, so it is nearly impossible to get at whatever is making the pitter-patter to trap them.

When we returned from our vacation, we discovered that our vermin (not the bilge rats) had moved into our basement to help themselves to the food that we have in our basement pantry space.

The major downside? - They've been eating our food.

The major upside? - They're in a space where I can trap them.

So yesterday, I put out some humane traps. Before 3 PM I had caught three of these little guys - juvenile White-Footed Mice:

(Note the sunflower seed for scale - they weren't much bigger than a quarter.)

When I catch mice, I get papa-rat-zi. DS and DD go running for their cameras so that they can gush ("Oh, it's SO cute. Daddy, can we keep it?") and proceed to try to take as many pictures as possible before I take it out of the house. ("But Daddy, I didn't get to say 'goodbye'!") Our rodents get sentenced to "transportation" - I either take them for a long ride and drop them in a wooded area or as I've been doing, take them for a really long walk to the wooded area behind our house. I've made the mistake in the past of not taking them far enough and finding them back in the house. (The same mouse came back. How can I tell? Here's a hint - he was called 'Stubby'.)

We also have voles outside of our house living in the gardens and under the splash-blocks. They are small brown animals that are very mouse-like with relatively small eyes. They have furry ears and remind me vaguely of Teddy bears. Unfortunately, they have been making grooves in the grass as escape tunnels from beneath the splash-blocks. Even worse, they girdled one of our ornamental trees in the front yard, killing it.

We had some help the other day from one of the neighbor's dogs who flushed one of the voles out from beneath our air conditioning compressor I managed to catch it in my hands and put it in the jar I had just used to take the third mouse out back. Here he is in confinement.

We knew about the voles as we have been working on a program of sheer terror for the voles - we go and lift the splash blocks on a daily basis - at least twice a day. When we started, I might see nearly a dozen and a half voles. Now I might see one or two - the rest have moved house.

Before I went to bed last night I checked the traps - the little guy on the left was in the trap. As the next-door neighbor children asked to see any mice we might catch, I put him in the jar for the evening. (Besides - I wasn't going walking in the woods in the dark at about 10 PM!) When DW went to the basement the next morning, the mouse on the right was in another trap. That's 5 mice in less than 24 hours! The mouse on the right was round at the middle - we figure she must have been expecting. Better out of the house than in!

Here's "mom" looking a bit nervous about what might happen next...

I was amazed when I released "mom" - she took off for the water that was nearby in the woods and proceeded to go for a swim! She swam strongly and confidently across this length of water before hauling herself out and wandering into the brush.

Thursday, September 2, 2010

Which one...

...would you rather see?


Wednesday, September 1, 2010