Friday, April 29, 2011

Adventures in Machine Land (IV)

In yesterday's post I detailed some of the tricky aspects to setting up the Oliver 166 jointer, and mentioned my disappointment at discovering that the middle of the bridge had a twist in it though both ends were dead level. I didn't feel that was really going to be a problem, however a reader wrote in and advised,

"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."

I greatly appreciate readers taking the time to share their thoughts on the blog, and can see why such a situation as detailed in that comment might make a lot of sense - however, I replied that I thought they were incorrect in that assertion. I was definitely open-minded about the possibility mind you. I said I'd make a test to see if the assertion about the twist in the bridge would actually concretely affect the table when it was raised or lowered. I feel the test will confirm or reject the hypothesis, and obviously, it need hardly be said that having a chassis with no twist in it at all would be the most ideal situation. If the chassis/bridge does have a twist, however, is it game over?

As a starting set up, I leveled the table as best I could- the infeed table now, as I had obtained the adjuster screws in the morning from Tim and had set it up on the machine at long last.

The level is set at the end of the table, near the hand wheel:


And then the level is placed up at the cutter head end:


Next, the level is placed lengthwise in the middle of the table:


I take a step back to show the bigger picture, with the level left in the same spot:


You can see that I have the table raised a fair distance above the cutterhead, and that it is pretty darn level at both ends and down the length.

Now I'll wind the table way down, bringing it much lower than the cutter head, and I've set the level up at the table lip end near the cutterhead:


What does the level say?:


Next, with the table in the same lowered position, I'll place the level on the opposite end of the table near the hand wheel:


I step back to show the bigger picture once again, with the table lowered and the level on the end of the table:


So, as I suspected, a bit of twist in the chassis doesn't make any actual difference to the level-ness of the table when it is raised or lowered, as the wedge blocks on the sliding carriage below can be screwed in or out to compensate for a high or low spot at that location. Once those wedges are in their places, the tables travel up or down in height takes place entirely upon those blocks. So how could the chassis twist have any effect upon that?

The only way I can see chassis twist affecting anything is if the table were moved back on it's sliding chassis - then one could imagine the relative amount of twist at a given location could cause the sliding chassis to twist also with the weight of the table directly upon it. However the only time I would draw the chassis back is for purposes of working on the cutterhead, changing knives and so forth. Otherwise the sliding carriage stays in the same place all the time and the wedge blocks are adjusted to suit the situation.

Anyway, glad to have confirmed that hypothesis, at least to my own satisfaction at least. If any readers feel that my test was flawed in some way, or could be improved, please let me know.

Next on the slate was to relocate the power switch for the machine, which, for some reason, had been located right under the brake mechanism for the cutterhead. I located it a bit back from that, and shortened the length of BX cable which fed it from the junction box. The cast iron is quite easy to drill:


Then I used a Greenlee combination drill/tap to thread the hole:


That worked pretty well with the impact gun.

Some 1/4" cap screws secure the box in place:


Then it was time to connect the three wires:


And then the cover could be reinstalled:


The blanking plug had been knocked out of the wrong end of the box by the previous installer, which explains why the 'Allen-Bradley' plate is upside-down.

Once the wiring was done, I plugged the machine back in and it fired up just fine, so that's another minor 'mission accomplished'.

Then it was time to fuss the tables a bit more. I unearthed the dial indicator, and zeroed it to the table surface:


I checked few other spots on the same table for comparison's sake, and they were all 'dead nuts', so I then went to check the table in relation to the knife at T.D.C.:


I adjusted the outfeed to be 0.0015" below the knife, then slid the indicator to the other end of the knife to check that the table was parallel to the knife:


All was good. I set the outfeed table a hair below the knife's cutting arc to compensate for the slightly scalloped surface one gets from the cutting action.

Then I slid the dial indicator over to check the infeed table's height relative to the outfeed table, first at one end:


And then the other:


In between the above two photos I had to do a little bit of fine-tuning with the level. At one point I thought it would be interesting to compare the reading off the machinist's level with a quality carpenter's level, in this case a 48" Stabila:


It's funny to see the difference - the carpenter's level is looking like a crude tool all of a sudden. And of course it is perfectly fine for general carpentry work, but obviously inadequate for setting up a machine.

Next, the fence went on and I adjusted it to squareness with the table:


Checking at the middle and both ends of the fence, I had squareness in all three spots, a great improvement upon what I had previously. When I was a tender young lad, oh, 5 month's back, I had to spend several hours grinding about 1/16" of material off one corner of that fence, using a hand-held 4.5" angle grinder, just to make it serviceable. Glad those days are a distant memory.

With the table level and at exactly the same height, I could finish off the rebuild with the re-installation of the height indicator arm. For some reason, mine was about 3/4" short of the indicator gauge on the side of the table, so with some help from the jeweler upstairs, we grafted on some brass to make it longer:


You can see I've roughly lined out the trimming I need to do.

A while later, the pointer was re-done, all polished up and looking ready for bear:


It's almost too nice on the machine, however I do have some oxidation to look forward to of course.

Another view:


Well, all that remained was to actually cut some wood with the jointer - almost a novel concept after the machine has had such a lengthy period out of service. I ran a couple of pine pieces over the cutter, and was delighted with the results right away:


It felt right! I jointed that second piece, placed the two sticks edge to edge, found a slight hollow, and then made a final tweak to the beds, re-jointed, and in the end had the Oliver back where it needed to be.

Maybe I can do some woodworking again in the near future - imagine that! How does that work again?

Thanks for coming by the Carpentry Way Today. Comments always welcome.

8 comments:

  1. Hi Chris,

    Interesting account! I have a little jointer that is not working right and I have been dreading setting it up. I hope to have an easier time than you did!

    I was quite surprised to see the difference between the two levels. I have always thought that machinists levels are just nicer housings. What do you think is the difference? Does the machinist's vial have a coating or the liquid inside different in its viscosity or some other property?

    PhilM

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  2. Hi PhilM,

    the differences between the machinist's level and a carpenters level comes down to four things, as far as I can tell:

    1. The base of the machinist's level is scraped to a high standard of flatness

    2. the bubble vial in the machinist's level is very precisely machined and shaped and is of ground glass. Cheaper levels have vials of plastic or bent glass

    3. the vial in the machinist's level is configured so that the bubble moves more quickly across -i.e., the bubble is less curved internally than the one in a standard builder's level - and this makes it more sensitive

    4. on the machinist's level, the bubble is sized so as to fall exactly between the inscribed marks, rather than more vaguely occupy a space between the lines as in the builder's level. The marked divisions on the machinist's level are precisely calibrated.

    Of course, that extra precision comes at a price! I was fortunate to be able to borrow that level from the local machine shop. I'd like to get one some day though.

    ~Chris

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  3. Nicely done. Your methods look good, and the proof is in the cut. If your base is twisted I bet its not by much. Have you faced anything wide yet?

    Like you I did not believe that twist could have any ill effect when I first got into one of these machines. Having seen the positive effects of removing twist from a base I am inclined to believe it is a necessary condition to remedy, but by no means the only one. I have adjusted 4 166 jointers, 3 16"s and a 20", and each one had its own issues to be worked out in order to run right. Glad you are back to making shavings.

    -Will

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  4. wow talk about finicky!!! But you did inspire me to give my jointer some loving.

    quick question...ive got the Hammer A3-31 jointer/planer combo...the knives are disposable and really thin and flexible. i was wondering if there was a way to be a cheap skate and somehow hone the blades to get some more life out of them?

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  5. Hi Chris,

    Great work, glad you got it tuned up and ready to go. Sorry to hear that you had such a hard time with the bearings and that Lynn couldn't help you.

    Looking forward to reading about you tearing into the new coffee table project.

    Dan

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  6. Will,

    thanks again for your input. I agree that removing twist from the base is a necessary first step. in this case, the bases were leveled to one another but the bridge had a slight twist in the middle, and I wasn't about to strip it all down and take the bridge for machining. Maybe one day, maybe not!

    Nick,

    I'm familiar with that machine. I would say it is not worth bothering with trying to re-hone blades in cutterheads set up for that system. There usually is more than a little re-honing necessary, for one thing, it is difficult to keep the honing/sharpening perfectly parallel over the length of each blade, and since the knife position can't be altered in the head there is a high possibility your final cutting arc will not be even across the knives and the jointing will not be as good. It's disposable tooling, plain and simple. I might add, in theory at least, your time is money, and the advantage to those quick change knives is less machine down-time and time out of your day setting the knives into place. How long would it take you to hone knives versus how much do the new knives cost?

    Dan,

    the tearing into that coffee table has just begun, and that thread will be getting going soon. I'm still not quite finalized on the design. Thanks for your comment!

    ~Chris

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  7. Hi Chris,

    I don't really have any machinery (wouldn't be cost effective for me), but I am fascinated with the old ones (not bikes!) for some reason, so I appreciate your posting your efforts to tweak/tune/restore. There is immense satisfaction with being able to confront and fix problems that arise with most things, rather than have to rely on someone else (brain surgery, etc. excepted), and I think there is immeasurable benefit from having the knowledge to do so. And I'm sure you've learned that while it takes time, it is really not very difficult in most cases. Having the knowledge to use and fix one's tools is almost a necessity to consider oneself accomplished, but in any case, adds richness to the path we follow.

    So not only can you inspire others in your woodworking, you can impress with your mechanical genius too!

    Steve

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  8. Thanks Steve. I think the only way to really know a machine is to take it apart and put it back together. Not knowing how to tune and repair a machine is akin to having chisels which you don't know how to sharpen (or won't sharpen). Sadly, many woodworkers I have come across seem to prefer to remain almost willfully ignorant of their equipment (for what reasons I can only guess at) and continue using that equipment even when it is clearly out of adjustment and working far short of its true capabilities. I could tell you some stories, but I will save that for later!

    ~Chris

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