Thursday, April 03, 2008

RIP Mr Router


Last night I got home from work and went down to the matchbox I laughingly call a workshop to continue attempting to fabricate a new top for the jewelry case of extreme time wastage. I made the thing a couple of years ago for a friend who sells (amongst many other works of art) inexpensive jewelry to the Renaissance Fayre crowd, but storage in a cold, damp garage had resulted in the top cracking and its return for repair last year around this time. What with one thing and another I let time get away from me and so if I was going to return it to the owner this weekend (at I-Con 27) I would have to get my finger out and finish the work needed.

I had cut the sections of maple that would make up the top, but had found a one-half of one degree error in Mr Chopsaw's protractor had introduced a requirement for a session with the newly arrived in theatre Mr Oscillating Spindle And Belt Sander, a tool of some spiffiness I bought recently1 and nearly killed myself getting the wardrobe-sized thing past the eagle-eyed Mrs Stevie without comment or regard for the fact that it is apparently manufactured from depleted uranium.

I am a slave to my art3.

I had already decided on a simplified approach to this vexing "readjustment" of the geometry of the wooden wedges that the top is made of. I would glue up two lots of three to make two halves of the top, then sand the edges of the two unglued faces to make them flat so they'd mate with the other half with no gaps. Technically this would be called the "naff" solution, producing as it does a slightly asymmetric hexagon, but there are two factors to consider before insisting I go the fine woodworker route and sand each and every wedge to perfect 30 degree angles from the 30.5 degrees they seem to be right now. Firstly, the difference in geometry between the sanded and unsanded parts will be unnoticeable with the human eye and B) I could give a rat's bottom what anyone else thinks. If you want absolute perfect geometry, go out and make your own Hexagonal Rotating Tower of Jewelry Displayment and Handyman Annoyance. Maybe then you'll be too busy to nag me with pettyfogging nitpicks about "half a degree here" and "Two Pi Cos Theta there". All this fuss over three degrees of error over twelve cuts made on a saw designed for cutting house timbers with! Get a life for Azathoth's sake!

Where was I? Oh right.

I had decided, as I was saying before I was interrupted, that I would make the pieces into two larger pieces by gluing them up before I attempted the sanding task. Now I had already come up with a way of stopping the new top from cracking, which involved using home-made metal plates screwed across the joints to hold them in place. I would have used my biscuit joiner, but the pieces are so small and stupidly shaped that I can't clamp them down in a way that doesn't get in the way of some or other part of the biscuit joiner and prevent it working properly. This obstacle was pondered over for a very long time before I reluctantly decided not to use the biscuit joiner. The point of doing these stupid projects is to deploy as many tools as is humanly possible, after all. Pulling a tool off the duty roster is a serious business requiring Herculean effort to come up with some alternate plan, one that saves the tool's place in the Scheme Of Things. Sadly, Mr Biscuit Joiner was benched.

The new plan involved making metal plates that could be screwed over the underside of the join to strengthen it. This plan had already suffered one setback when the chuck on my drill press decided to kill itself and it took a week to get a new one. Last night I gained definitive proof that this bloody job is cursed and is attracting the most malignant anti-handyman demons it has been my misfortune to encounter in a long time.

I did some messing about with the pieces while Mr Brain milled the problem and figured out some last-minute gotcha-removal operations. If I was going to machine the half-tops I would have to recess the plates so they wouldn't foul the sander's table. This would require a session with Mr Router, currently mounted in my router table as a light-duty shaping machine, and already equipped with the bit I needed for the task at hand.

I was forced to fart about with the fence4 on the table for more time than I cared to spend before I concluded that it would have to come off and be replaced with a piece of wood clamped to the table. It would not retract the distances from the bit I needed, and the cutout in the fence meant I did not have perfect control of the small wooden parts as they were moving over the fast-spinning, razor-sharp bit. There was a quarter hour more farting about trying to figure a way to get the clamps to work on the table without sliding off the various castings on the underside. Then there was the business of finding an appropriate piece of wood for the makeshift fence. It was all very tedious, but eventually I got it all sorted out and with a sigh of pleasure I donned the ear-protectors and began work machining the wooden pieces.

All went well for three of the six pieces.

As I was machining the fourth piece, there came a loud5 "Chunk" noise and the router began spitting sparks up through the table while making a sound reminiscent of the great Shop Vac Rebuild Test Run Fiasco6.

I made a loud sound of my own and quickly turned off the router. I took off my ear protectors and examined the tool, whereupon I discovered the most perfidious skullduggery perpetrated on me by Mr Brain: I had forgotten to use a table insert.

The table insert is a little plastic disc with a hole sized for the bit you are using in the middle. It goes in the much larger hole the bit pokes through in the table itself, and is designed to prevent crap dropping through the table onto the router body, which is handily equipped with vents so that in the event stuff does fall through that is heavier than sawdust, it can enter the mechanism of the router itself. Had this in fact happened, or was what I had witnessed a piece of metal, maybe a screw from the table itself, bouncing around in the cavity under the table where the bit was spinning? I didn't know

I did a quick visual check of the environment, and discovered nothing fouling the bit or the spindle. The router didn't seem particularly dusty or covered in wood chips either. I checked the spindle lock, used for when you need to tighten the collet nut that holds the bit and don't want the spindle to turn, hadn't engaged itself. It hadn't. I turned the spindle by hand. It moved freely with no squeaks, creaks or pieces falling out of the router. Having satisfied myself that the problem was probably transient I quickly turned the router on then off again. I was rewarded with a sound similar to that made when a garbage disposal has a spoon in it.

I dismounted the router from the table and turned it right-side up. A piece of metal fell out of it.

Had I stupidly allowed a piece of metal to sit on the router table and swept it into the router during the machining operation? It wasn't beyond belief that that had happened, but I had vacuumed the table top just before starting work. There was nothing for it. I grabbed Mr #2 Phillips Head Screwdriver and dismantled the router.

Once I had the case in half the damage was obvious, as was the source of that metal piece. I found six of its brothers inside the case. They turned out to be what was left of the dozen or so blades that had been sheered off the fan mounted on the armature spindle of the motor7. At least one of them had taken a voyage of discovery through the rotating part of the armature and gouged out cool little fillets from the soft iron core too. That was the indication that the whole assembly was unserviceable, since the motor has to be finely balanced and it was now missing some iron on one side.

In point of fact, I was amazed the whole thing hadn't exploded. Most people respect the whirling blades on a power tool and believe that the danger in using them lies there. Most don't consider that a high-speed tool represents a reservoir of dangerous kinetic energy (the sort you get from how heavy and how fast something is moving) too.

The router motor has a no-load rotational rate that is measured at around 18000 rpm. That translates to 300 full turns every second. I don't know about you but I cannot imagine anything moving that fast. My brain simply won't model it, and puts it in the "too fast to imagine" box. Now, to that 300 RPS, add in the knowledge that the moving element isn't just the spindle and the bit, which have a relatively small diameter and mass and hence a low moment of inertia8 but also the much more massive and larger-in-diameter soft iron laminated armature core and the copper windings it supports. Copper and iron are used because they are abundant and have properties that lend themselves to electric motor construction. The iron is easy to work and has certain useful magnetic properties, the copper is ductile9 and conducts electricity (and heat) very easily.

Copper and Iron have another property in common, one that often does not occur to people but in this case is rather important: They are heavy. Things that are made of them that are spun up to high speeds store huge amounts of energy, which can be thought of in this case as the "desire" by the materials to break into pieces and fly out in a radial fragmentation mine of death. Obviously the motors are engineered to withstand the forces they are put under, but on this evening almost half of the cooling fan of this motor had disintegrated and fallen into the whirling parts. How none of them were propelled through the case and into my soft tissues is a cause of wonderment and a testament to the design of the thing. How the motor didn't sieze up and attempt to tear itself apart in the manner of an improvised claymore mine of handyman destruction is also a matter of some amazement to me. The robust design of the router notwithstanding, the router table is due for redesign or replacement as a result of this, since I may not be so lucky next time. I want something between Mr Crotch and any red-hot fragments of catastrophically failing router when the modern designs prove less than those of twenty years ago.

I still don't know what happened. My money would be on a chip of maple heavy enough not to be blown away by the fan dropping through one of the cooling louvers and snapping off one fan blade. That would be enough to cascade the damage in an eyeblink into the router-wrecking fiasco I saw last night. All I do know is that the router is completely written off. I'd rebuild it since I have a fondness for the tool surpassing all others, but the armature is no longer available. This is the first time I've been contemplating the purchase of a new tool with anything less than ecstatic delight.

I'll have to buy a new one, of course. The router has been such a massively useful tool, especially when mounted in the table, that I can't see myself getting by without one. Here is a short list of the most useful things that I've dome with it:

Shaping fancy edges on shelves. Lots and lots of shelves.

Fabricating a pirate treasure chest for Stevieling's fifth birthday. (New tool - box joint jig!)

Planing small stock.

Making new handles for a football table (New Tool - Router Crafter "lathe"!)

Making the numbers for our house so the Pizza and Chinese Food delivery guys can find us.

Putting hinges on new doors. (New Tool - Hinge Templates!)

Making ceiling roses. (New tool - Trammel point!)

Customising wall mouldings.

Getting rid of sharp edges on Stevieling's Tree House.

Making stairs for Pool Deck.

Reprofiling cedar decking.

Machining almost everything for the Stevieling’s American Girl Doll beds

List of things I hadn't got round to yet but fully planned to do:

Making bas-relief carvings (New tool - Pantograph)

SCA Wizard's Staff (Router Crafter again)

Two room-sized bookshelves

Custom bathroom wall and floor mouldings

Put simply, the router is probably the most massively useful power tool after the hand drill that a home handyman could own. This is why I've always recommended them as a good start to the toolkit, along with a router table.

RIP Mr Router. I'm sorry I allowed a moment of carelessness to destroy you. You will be sadly missed.

  1. Using the need to repair the jewelry display as a convenient and timely way to bring The Rule2 into play and obtain the elusive yet siren-like sanding machine for my very own
  2. No tool, No job
  3. The stealthy acquisition of tools, some of them useful
  4. To machine wood on a router table one needs a solid edge against which to press and steady the workpiece. This is called The Fence. It consists of a long piece of plastic (in this case) with a recess in the middle for the bit to occupy, some screws riding in slots with which to adjust the fence with respect to the bit and fasten it down with, a guard assembly of some kind to protect the operator's hands when the bit is spinning but the workpiece has yet to be fed into it, and a fixture for a vacuum cleaner to be attached for chip removal
  5. Bear in mind that I was wearing ear protection and the router was running. Any noise heard in these conditions would be, by anyone's definition, LOUD
  6. In which, during an attempt to salvage a ten dollar snow shovel I inadvertently wrote off a fifty dollar Shop-Vac. I drilled out a rivet on my drill press. The rivet fell into the motor of my Shop-Vac. I stripped out the motor and removed the rivet. Before replacing the motor I clamped it in the bench vise and test ran it to make sure all the parts were installed correctly. In the space of two seconds it ate the front ball-bearing race in a shower of sparks and, at the end, a rain of teenytiny ball bearings, all to the accompaniment of the screaming of tortured metal. After due consideration I concluded I had not, in fact, assembled the motor correctly. Unfortunately I was unable to learn which components were replaced out of position as most of them had either disintegrated or fused into shapless blobs of copper. It was all very annoying and I don't want to talk about it any more and anyway my new wet/dry vaccuum cleaner has no stupid vents on the top through which rivets could fall
  7. This is how power tools keep themselves cool when the electricity is trying hard to turn the motor into a red-hot ball of molten copper
  8. A way of measuring the amount of energy a spinning thing will store
  9. Chemist-speak for "bendy"

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