Thursday, April 28, 2011

Adventures in Machine Land (III)

The fun, thrills and spills, continues with my various machine diversions and challenges.

First off was my truck, which suddenly died on the highway, then started again just as the tow truck was on its way, then died another few miles down the highway, necessitating a reacquaintance with the tow truck driver. I had it towed to my house, and left out in the street at front.

The following morning, I felt the familiar fog that seems to come over me whenever I have to work on a vehicle. For some reason, I enter an Alzheimer's like state, where I seem to know nothing, remember nothing, and am easily flummoxed by challenges. I don't know what it is about vehicles that brings this out, but I have to fight against the inertia and insecurity, the "I'm not going to be able to figure this out" mental soundtrack. This, even though I rebuilt my truck from the ground up and know every single nook, cranny, and idiosyncrasy. Go figure.

I sought refuge in my Toyota factory manual, where I looked through the sections dealing with diagnosing non-starting issues. For my truck's condition, which was "Engine turns over but does not start", all indicators pointed to a fuel-system related problem. The few electrical causes listed I could already rule out. So, that morning, I ripped out the entire fuel system from fuel tank to injector pump, cleaning and checking, hoping to find the smoking gun of debris which was clogging the system. However, nothing turned up, though I did get to ingest a small quantity of diesel fuel. Yum!. It was fine - the fuel system, not the taste of the fuel itself. I can't say I recommend it actually. With each check and re-starting attempt, my battery grew weaker and weaker until it simply wouldn't turn over the engine at all.

I felt that the manual had in fact not been much help, as it led me down a path which did not serve to rectify the problem in the slightest. That's the trap of manuals sometimes, if you rely upon them too much.

I was growing frustrated by this point. I had some tea and phoned a friend more experienced with diesel engines than I, and after some discussion, we both agreed that the problem had to lie somewhere in the electrical system. I then spent another hour or so in a fruitless attempt to track down the problem, to no avail. I was pretty sure though that it involved an engine shut-down module, the only piece of electronics on my truck. It's a little gray box which functions as a device to read the oil pressure - if the pressure suddenly drops off to zero (at it would if you ran the crankcase into a rock, smashing it open and all the oil suddenly gushed out), the box sends a signal which shuts the engine off immediately to prevent damage.

That module had four lights on it but none of them were coming on. Still, I couldn't quite figure it out, and couldn't test anything too well as the battery was too dead to turn the engine over. Not a jolly good time at all. And lying under a truck and getting crud in your eyes loses its appeal soon enough.

I basically gave up at that point, and called a local diesel shop - a specialist converter of diesels to run on waste veggie oil actually - and eventually made contact with the proprietor. He was taking the day off, but said he would try to swing by and take a look.

An hour later he said he had some time and was coming by. Great!

I was down at the truck waiting for him and having a last stare at the engine bay, checking wiring connections to the engine for old times' sake, as it were, and then noticed something funny about a little green wire connected to the negative terminal on the battery. Upon closer inspection I discovered that the wire had broken off internally, and was pretty much hanging by a thread. Enough of a thread that if the battery or wire was bumped in the right direction, the connection would be working, and if bumped in the other direction, the connection would be cut off. I then realized that that particular green wire was the ground wire for that module I just mentioned earlier. A-ha! While I had wired that gizmo in myself, it was three years ago and I had forgotten what that green wire was for.

As soon as I saw the broken wire I realized that it was at least 99% likely that it was the problem in regards to the engine non-starting. The diesel mechanic showed up a few minutes later, I told him I thought I had the problem solved, and, "by the way, do you happen to have some wire and crimps kicking around?" He helped me out with those bits, no charge, and we talked about the WVO scene for cars and trucks, and a few minutes later I had the wire repaired and with a boost from my new mechanic friend, the truck fired right up. Problem solved, whew!

I wish I could say I arrived at the solution by rational deduction, but in fact I had reached a point where I had had enough, and it was really a matter of luck to have spotted that faulty wire. Still, sometimes ya gotta take your victories where you can get 'em.

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Back to those devilish machines in my shop. While waiting for Tim, the machinist just around the corner from the shop, to re-do those double adjuster rods for me, I realized I could take a couple of the adjusters off of the infeed table and instead use them on the outfeed. With all four corners fitted with rods, I could then place the outfeed table in place. The outfeed table is the one which provides the reference surface for the joint. The infeed table aligns the wood for delivery to the cutterhead.

Tim loaned me a precision machinist's level, which is much more accurate than a conventional carpenter's level. With that tool, I was able to set up the chassis of the Oliver properly - or so I thought. I used the level on each end of the chassis, directly above the support pedestals on each end of the machine:


I used a pallet jack to tilt the machine up and then I could adjust the shims I had on the floor underneath each pedestal, then down again, repeating until I had the surface leveled on each end of the machine:


Once the machine base was level, I could place, with some help, the outfeed table on the four double-wedged support points, using wood as temporary support:


Once I had the table attached again to the wedge pairs, i removed the wood and brought the table down to level with the cutterhead. Then I borrowed the 6' straightedge from upstairs to use as a means of leveling the table to the cutterhead. I placed the level on the table, and right away noticed light in the middle. No way that those fanatics who re-ground my table could have goofed up that badly, so I immediately took a closer look at the straightedge:


That's a thick steel bar, formerly a knife used in a paper mill, and I hope it is clear enough from the picture for the reader to see that it is bowed about 1/2" over its length. I've no idea what could have caused that bow, however it renders the bar useless as a straightedge. I was a little chagrined to realize I had set up the jointer previously based upon that very same straightedge....

Well, on to plan 'B'.

Plan 'B' involved using the machinist's level to set up the table. I figured I would get it pretty close, and really it is the jointing of two boards and fitting them edge to edge which will truly tell you if the table alignment is correct. So I proceeded along, and in no time had the outfeed table adjusted level on both ends and length-wise. Then I placed the level on the cutterhead, and discovered it was not level.

But...but! The cutterhead had to be level as it is held in a cast iron carriage bolted to the main 'bridge', or chassis of the machine, and I had just gone to great lengths to level the chassis out. I took the level and checked the bridge on both sides of the cutterhead assembly. I discovered that the chassis was not level there - which meant that the chassis is in fact slightly twisted in the middle. Nothing I can do about that, short of removing the bridge, which must weigh close to 1000 pounds, and get it re-ground, along with the associated table carriages. Not this time my friends.

I thought about it some more, and realized that I could work around the problem. I got some brass shim stock, removed the drive belts to the cutterhead, unbolted the cutterhead, and then shimmed it with the brass until it was level. I reasoned that once the lower table wedges were adjusted to give a level table, the table moves up and down independently of the relative position of the bridge. The table moves relative to the wedges, so it should be fine.

I could proceed no further in the rebuild though without those three adjuster rods. There still was the outstanding issue of the one adjuster, mentioned in the previous post, which wasn't aligned properly. I had obtained a left hand thread 1/2" UNC tap to clean the thread out on the sliding wedge's hole, but it made no difference to the alignment. The rod still did not match up to the other hole on the chassis' tab.

I was puzzling over this some more and decided to see how well aligned a transfer punch would be if slid through the threaded holes at once. I was surprised to find that it slid through both holes quite nicely. So the holes themselves were well enough aligned - the problem must lay in the threads.

As a bit of a last-ditch try, I tried using the LH thread tap again, this time bearing downward firmly so as to see if I could make a slight clearance to the thread. I was pleased to feel the tap scraping out some gunge and cleaning a little bit of metal out of the hole:


When I re-tried the rod, it now aligned properly, to my considerable relief. Yay! Tomorrow I should have the 3 missing rods back and can get the jointer back together.

Then there's the drill press. I got a package in the mail today containing two of these:


Feast your eyes my friends on NOS Norma-Hoffmann bearings for the quill!! These pups are at least 40 years old, and it was almost a remake of The Hunt for Red October to obtain them.

I mentioned how these bearings are an odd hybrid of metric and imperial measurements - now you can see the equally odd configuration of the bearings:


I dropped in to the machine shop a few days back to see the bearings from the quill, which had at last been removed. It turned out that the bottom bearing, nearest the drill chuck, was 0.625" bore, instead of the 0.6355" bore of the Norma bearing on top. Now, the spindle slides into the quill from the bottom, and thus the lower bearing is a 'gatekeeper' of sorts. In order for the spindle to get by, the bearing surfaces on the spindle needed to fit into its smaller bore. So, can you guess what the genius (excuse the sarcasm) who last repaired this assembly did? That's right, he had the bearing points on the spindle, top and bottom, turned down to fit a 0.625" bore. Now, if he had also replaced the upper bearing with one having a 0.625" bore, all would have been fine, but instead, inexplicably, they left the Norma XH-179 in place, which has a bore some 0.0105" larger than the thinned-down spindle. In machinery land, that's pretty much a crevasse. An appropriate slide-fit clearance between the inner race of the bearing and the spindle would be on the order of half a thousandth of an inch or so. The gap in this case is some 200 times larger, and probably is the largest contributor to the spindle vibration I had with the machine. I just can't believe that the previous person to do the repair hadn't realized that 'little issue' with the bearing clearance, going to the trouble of re-machining the spindle for the lower replacement bearing, and not taking the step of spending another $10 to swap out the upper bearing. Jeez. Still, I enjoy the reverse detective work to determine what caused what and why.

I'll take these new Normas to the machine shop tomorrow and hopefully they can re-do the spindle (which needs to be built back up to dimension at the bearing locations) and get it back together with the quill by week's end. It feels good to be on the homeward trek with these two machine rebuild projects. I might have to start cutting some wood again soon. Imagine that!

Thanks for coming by the Carpentry Way Today, soon to be renamed The Wannabe Machinist's Haunt.

4 comments:

  1. Looks like you are getting there with the 166. Don't worry too much about the cutterhead not being level. It doesn't need to be as you will set the tables to the cylinder and then the knives to the tables.

    The most important thing is that the base is not twisted. Any twist in the base will cause the tables to follow the twist as they are adjusted. With the tables zeroed to each other they might be correct, but as soon as you drop the infeed to cutting depth any twist will impact the new position of the table. Also, make sure that you are checking for level directly on top of the base way.

    The wedge adjusting screws were cut in the early days from square stock with middle section left square to take a wrench. The later vintages had a hole cross drilled in that spot. I suspect it was easier to make them that way. It is also much harder to strip a hole than it is the square with a wrench. Which style did yours have originally? Mine has the holes, and I find that it is really easy to make adjustments using a short allen wrench through the hole. You might consider having that feature added, or doing it your self.

    Keep in mind that the tables are very flexible, they are also very adjustable. If the base is not twisted you will be able to get everything just right using the wedges, and your efforts will be worth it.

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  2. Thanks for the comment Will on the 166. Sounds like you are familiar with the machine.

    I am not convinced however, by the explanation:

    "Any twist in the base will cause the tables to follow the twist as they are adjusted."

    Here's my take: since the tables essentially rest upon four points (wedges) each, if there is twist (and there is) then one could see that one of the wedges would be lower/higher relative the others. If you simply pulled the table down to that wedge height, then the table would be twisted, sure enough, and when you raised and lowered the table, it would remain twisted. However, if one draws the wedge forward/back to compensate for the low/high spot formed by the twist in the chassis, then the table would be back to riding upon four level points. It would simply be the case that one of the support wedges would be further out/in than the other ones.

    This is how it seems to me, and I'm totally open to being wrong about it. What I'm going to do to test this idea is raise and lower the outfeed table, as I have it set right now for level, with the precision level on it to see if it changes level, to see if it "follows the twist" as you put it. I'll post up results of this test in the next post. I hope you're wrong!

    The original adjuster rods on mine had the cross-holes, but the machinist chose to make the replacements with wrench flats. I think that so long as they turn easily, and the wrench flats are sized well, the potential to round over the flats is minimal. My old ones, with the holes, were rather badly mangled at those holes, the openings stretched and distorted. So that system has its drawbacks as well. The real issue is whether the wedge blocks and threaded connections are rusted up or frozen for some reason, no?

    ~Chris

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  3. Many years since I last adjusted the Porter, but I seem to recall that what I did was take a long straightedge and lay it along the length of both tables so that the length was entirely flat across both of them at the same time, and also just hitting the cutterhead, positioning the straightedge parallel to the tables and also across them diagonally. Then, also having the tables be level along the length. The base being level wasn't a concern, but relying on each adjusting block to get the positioning required.

    Easy enough to hand plane a decent enough wood straight edge, and hard to find a metal one over that length that isn't somewhat corrupted.

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  4. Dennis,

    thanks as always for your comment. I would have made more use of that metal straightedge if it had been straight. I found that I was able to obtain good results using the machinist's level alone, followed by some test cuts on a couple of pieces of wood.

    The Porter, like the Northfield, has the tripod base and uses large wedge-beds for supporting the tables - I dare say it is a better design than the Oliver in terms of eliminating problems stemming from the base, but harder to deal with in certain respects if the castings have moved over the years. If the wedge beds have worn sufficiently, then the only recourse would be grinding the entire chassis, it would appear.

    I'm beginning to think that iron castings aren't quite as stable as they are made out to be, as both the Oliver and the Felder I used to own years back had warped castings. A lot of machines I have looked at have less than flat castings.

    ~Chris

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