Sunday, February 20, 2011

I got the bends

We Anoraks will sweat the smallest of details. For about a week now I've been pondering how to make the metal trim that fits around the pedestal. As previously reported, my workshop is set up for woodworking, not metal working. In terms of fashioning metals, I have limited experience (I once made a coat hook in Mr. Clack's metalworking class when I was 12...) and few of the right tools. I spent some time in the evenings last week figuring out how to go about it and running through some spare material to test my ideas.

My goal is to make the trim out of one piece of 2 inch aluminum bar, 1/8 inch thick with 2 X 90 degree bends and some fancy cut work. Since I could only find an eight foot length, I had some spare to waste in experiments. My aim here is to make 2 perfect 90 degree angles with no distortion to the bar. In other words, all sides have to be straight and flat after putting the bends in.

First test was to put a piece in the small bench vice I have, then bend it manually. The result wasn't that impressive:

The radius is too much and the side that wasn't in the vice has lost its straightness. To reduce the radius, I knew I'd need to remove some material. At this point, if he's reading this I'd advise my mate Nick (a master craftsman) to skip down to the end - he'll be horrified to see what I'm about to share with you...

My tool of choice to remove the material is a router with a carbide bit. The aluminum is a softer metal, the carbide should be able to cut through it ok. What I didn't want to do was make a deep cut in one go. To facilitate multiple shallow cuts, I built a simple jig. It's a bit of scrap wood where I've dadoed out a grove that is the exact width and depth of the aluminum bar, as shown here with the bar in place:

Running perpendicular to the wood, I've screwed in a couple of scrap bits of plastic, to act as a guide for the router:
Making a number of shallow cuts, I cut through about three quarters of the stock. When finished I simply bent the bar in 2 by hand. Result, a perfect 90 degree angle that lasted for all of 10 seconds. I flexed the thing back a little (since I'd gone further than 90 degrees) and it fell apart in my hands:

I'd cut too much out. A second attempt using a shallower cut (about half way down) and bending it in the vice resulted in a more sturdy, perfect 90 degree angle.

Saturday arrived and it was pouring down with rain. Great I thought, a full uninterrupted day in the workshop! "Not so fast" spoke the missus. It's time for that other great indoor sport that Americans enjoy at this time of year, yes you guessed it, prepare the tax return... Well if nothing else it gave me the incentive to get it done and out the way, since the next thing I was obsessing about was how to make the narrowed end of the trim.

The trim is a full 2 inches at the rear but at the front it goes down to 1 inch for about 7 inches in length. I want the thinner end to be as parallel as the thicker. My cutting tool options are limited. I opted for a jigsaw with a metal cutting blade. To stop the aluminum bar from flapping around, I screwed it down onto a scrap piece of 3/4 inch plywood. To make a parallel cut, I screwed in a fence guide for the jigsaw to push up against:

I then clamped the ensemble to the end of my workbench. Here's a shot with the jigsaw in action:

Result, a perfect straight line.

As for the angled cut, I just eyeballed it and cut it freehand:

Not bad eh? Repeated the operation on the other end. I purposely left the 2 ends a little longer than needed - I will cut them down later to get the exact dimension.

Back to the cabinet, I cut a dado all the way around the top to accommodate the metal trim. My goal is to have the trim run flush with the sides of the cabinet. Here's what it looks like:

A dry fit with the bar shows the challenge ahead - how to get the 2 X 90 degree bends in and still keep the whole thing flush to the sides:

I marked where the first bend was going in and made the cuts with the router:
Ok Nick, you can start reading again...

Now to make the first bend. I wrapped the jaws of the vice with thick pipe tape to prevent the surface of the aluminum bar from being marred. I then placed the bar in the vice vertically and clamped a piece of scrap to the end of the bar I will be bending. The pre-bend ensemble looks like this:

Here's what it looked like after pulling down on the wood/bar combo - not bad at all:
I put it back on the cabinet for another dry fit. Looking good. I made the mark for the second bend and started worrying. What if my mark is off by a fraction? Metal is a lot more unforgiving than wood. If I cuff up the second bend, it's back to the hardware store and start all over again on the fabrication. To hell with it - second bend went as smooth as the first.

Result? It fit perfectly! Oh you can believe there was some celebration tonight - rarlely does anything come together so well but my goodness it did. Next, I used a 220 grit fine sander to work out all of the saw cut marks and rounded off the cut edges. Screwed it in place and chopped off the over cuts. How does it look? Like this:
Ready for a little more filling, primer and paint. Now though, sleep. A sleep where I won't be waking up through the night panicking about those bends....

Monday, February 14, 2011

Back pedalling on the pedestal

This weekend I finally got to chat real time with a fellow sim builder (and blog follower), Gianluca. A great opportunity to compare notes (although I was doing most of the asking) and to swap ideas on design. Since his and my build are so similar in approach, we have a lot in common. In the conversation Gianluca offered up his opinion that I must be a perfectionist. I never thought so but then....

Spent any free time I had yesterday redoing the rails on the pedestal. I wasn't happy with the way the holes were lining up (see last post). Drilling bigger holes in the CPflight modules wouldn't have worked since the fake DZUS have very little wiggle room (almost none) in the face plates. My approach was to remove the rails and replace with fresh ones, mask off the units, place each on the rails in turn, drill through the face plates, tap and secure each one before moving onto the next. Given how fragile the paint is, I used a masking tape designed for such, so when you pull it off, it doesn't take the paint with it.
Then to the drill press where I very carefully drilled each hole, through the face plate of each unit. I drilled very slowly to minimize the swarf. Sometimes it can stuck on the drill bit and with it lashing around, it can strip off paint in an instant. Vigilance was key, as was the shop vac on standby to vacuum up any debris.

My plan was to shove the front units up against the MDF, get those seated then push the others up right behind. I quickly discovered though that the units still were not properly aligned! What is going on? Quick check with a set square revealed that the cabinet sides are not an accurate 90 degrees from the ends. Wouldn't normally be a big deal but with the tight tolerances of the metal work, you can see any misalignment. I wasn't about to rebuild the whole thing so I compromised with the next row of units. I set them at 90 degrees to the sides and left a small gap between them and the first row. I guess I'm not that much of a perfectionist..

Here's the finished result:

Good enough for me. Much better than it was. Although the sharp eyed of you will notice a little missing paint on the ADF. Even with masking tape for delicate jobs - beware.

I've received a couple of kind comments about the pedestal. I should acknowledge Rudy's design work, I took the idea and dimensions from here.

I should also acknowledge the comment from Rhydian about the qualities of MDF and that it can be dangerous to work with. According to this site the biggest threats are the formaldehyde leakage and the fine dust. I always wear a quality dust mask when working with the stuff and seal the finished article inside and out with primer as a minimum. Suggest you do likewise.

All for now. Will work on the metal trim and paint this week - honest I will.