A little background, for those readers who haven’t been reading this blog since the inception of written records (somewhere in 2009):
Just before I head out to Colgate University to install some woodwork, I decided the timing was about right to deal with a niggling issue I have had with the Wadkin table saw since I bought it, namely that the sliding table is not flat: it is bowed upward slightly in the middle. This is unfortunate. For cross-cutting around about the 90˚mark, this is no issue, but for ripping or acutely angled cuts, the bow or bulge upwards at the middle of the sliding table causes stock which I am ripping to be tilted up slightly. It is slight, but it means the rip cut face has the unfortunate characteristic of not being 90˚ to the adjacent face, necessitating additional steps after sawing put things right.
I just want the saw to perform the basics well, and in this case it has been letting me down.
Additionally, the detent positions in the sliding table for the mitre fence are severely worn, and the pivot hole location, which accepts a BSW (Whitworth) 1/2″ x 12TPI pivot bolt, has been heli-coiled -and not very well – so it is not a precise location any longer. As a result, none of the detent positions (there are three: 90˚, 45˚ and 30˚) actually produce accurate mitre cuts. Also, there are too few detent positions in the first place. I would like to have more, if they can be done accurately.
Because of the sliding table bow, the linear bearings for the table cannot be properly set, and thus the table runs with more slop in the middle position, which is exactly where you would want it to have minimal play, since that is where most of the cutting takes place..
Finally, the cast iron support beam for the sliding table is a ‘fugly’ casting which bothers me on an aesthetic level. so I have wanted to have that casting machined clean so it doesn’t look like it was cast by a couple of fellows who had spent a little extra time in the pub at lunch, if you catch my drift.
I’m more concerned generally with how a machine works, than how it looks, but if I have the sliding table off for machining work, then it makes sense to deal with the ugly casting issue at the same time.
In the past I have had machines with non-flat table castings, like my old Oliver 166 BD jointer, and I had a machine shop in E. Hartford CT do the grinding work on the two tables and fence for that machine, however, through that experience, and others, I have found that the shop doesn’t follow the instructions I give them, and haven’t been too friendly when the overcharge for services was their own fault and not mine, so it left me with a slightly bad taste in my mouth.
Also, Blanchard grinding, which is the norm in N. America at least, is not my top choice for correcting a distorted surface: rather, it is single-point planing.
As Wayne Moore put it in his 1970 publication Foundations of Mechanical Accuracy (p. 17) the acknowledged ‘bible’ on the topic,
Single point planing is how many machine surfaces on higher-end european woodworking and metal working machines are created. On the Wadkin, it was used for the table edges at the very least. Typically, on machine tables like those found on jointers and planers, and usually shapers, the planing is done in the direction of stock movement so as to leave the surface with very slight ridges, which allow for easier transport of the wood over the surface.
Shockingly, on some high end machines these days, like a Martin shaper, for example, the table surfaces are just ground whereas they used to be planed. It’s a cost-cutting measure to grind.
Trouble is, finding shops with single point planers for machine table work is tough: these machines are comparatively rare birds. I had, in fact, largely dismissed/abandoned the idea of getting the table planed, and instead had devoted quite a bit of time to the design of a sliding table made from Mic-6 aluminum tooling plate. This idea had its plusses and minuses, the chief-most among the drawbacks was the cost, which would likely be at least half-again what I had paid for the saw.
While humming and hawing over this matter for a good couple of years, I happened to be researching the topic of replacing cast machine ways with linear slide rails, which more than a few people have done with their Bridgeport mills so as to get around the cost and difficulty of machine and scraping everything back to spec. I then found a video of a guy who had his Bridgeport mill’s saddle re-planed, by a guy up in New Hampshire who had a planing mill which he had modernized and reconditioned. Here’s a link to the video that caught my attention. After the intro, which is definitely worth a view, if you jump ahead to the 7:52 mark you can see the planing machine and watch it work. Around the 13:00 minute mark you can see the metal planing most dramatically.
A bit of digging around and I had obtained the contact info for the fellow in NH, named Rees. I spoke with him and his son Fitz, who are both involved in the business. Rees is retired but his favorite machine to run happens to be the planer. I explained my Wadkin situation to him and, a month or two later, he came to my shop with his son to take a look at the Wadkin and inspect.
Rees was initially skeptical that a woodworker would want a woodworking machine set up more precisely, but when he checked over the table on my saw he could confirm that the bow was more than insignificant, and he also said he could deal with repairing the pivot hole and detents for the mitre fence.
So, yesterday, the right moment had arrived, and I pulled the sliding table and its support beam off of the Wadkin:
The saw now without its sliding table looks a bit diminished to be sure:
The angle brackets to the left and right which carry the table were also removed later so they could be inspected at Rees shop. I noticed that the surfaces under those brackets were single-point planed, though the brackets themselves were simply rough-ground.
I was surprised to find that, with a straightedge on the bottom surfaces of the sliding table, where one of the linear rail assemblies mounts, was very flat, while I was expecting it to be concave:
Checking with the straightedge along the (in the above photo) left side mounting position for the rail, however, found a result which was concave, as expected. So the table bow was not uniform, seemingly concentrated towards the sliding table edge which runs along the blade.
Also, with the linear rail assemblies off the table, I found that the assemblies themselves were not straight along their lengths:
Each linear rod carrier was bowed a bit more than 1/16″, the gap totaling more than 1/8″ at the middle:
I’m not sure that bow really matters with those parts, as the mounting bolts will hold the rails in a straight position, but it was curious nonetheless.
With some help from a friend, I got the sliding table and support beam loaded in a rental truck and arrived to Rees’ shop a little after lunch. He lives in a rural area, up a dirt road. The view at the shop door revealed a clean space, a good sign:
He had various pieces of equipment, most of which were quite old, like this Brown and Sharpe universal milling machine:
Here’s a look at the planing mill, with the sliding table laid down for some preliminary inspection:
We flipped the table over and Rees checked the top face along each edge only:
The weird thing was that the inspection did not show the table edges to be as bowed as they had appeared to be in the shop when it was examined using a Starrett 48″ straightedge. Rees was also puzzled, since he had also looked at the table when it was on the machine and had seen the bow. We then checked up the support beam, and found it to be decently flat too along the linear rail mounts.
This was one of those unaccountable moments, kind of like where you hear your car making a strange noise so you take it to a mechanic, whereupon it does not make the strange noise. It is quite possible in this case that the weight of the casting itself was causing the sliding table to un-bow slightly when laid, giving the impression that it is flatter than is actually the case.
Anyhow, Rees will do further inspection and will plane the top and underside of the sliding table, along with a re-do of the mitre gauge mounting and positioning locations. The support table looks like it will not need work, so it will just have the casting edges cleaned up.
Possibly, further inspection will reveal more clearly the location of the table bulge – when it was face down on the planer’s table it definitely was not presenting a dead flat surface, as it spun easily on a high spot. But the good news appears to be that the table rework will not be as extensive as initially imagined, which means the work will take less time, will affect the finished height less, and will cost less as well. So, that’s all good. Rees should be able to turn this around within a week – and he is excited to tackle the work, which in itself is becoming a rarity among those who do the mechanical arts.
Here’s a look at the back of the planer, which dates from 1905 or so:
The front carriage, which you can see has been re-scraped:
I’ve been in several shops where you can see an abundance of old ‘arn (“old iron”); the difference with Rees shop equipment is that it has been scraped and aligned and selectively modernized, but he has held off on the usual tarting up you see with a lot of older machinery, where the parts have been painted all shiny, and brass pieces buffed to a sheen, and new bearings put in, but the important stuff, the alignments and flatness of surfaces, has been left out. It’s like cleaning up an old engine and repainting it, buffing the valve cover, etc., but not actually rebuilding the internals properly. There’s a lot of ‘restored’ equipment out there like that – because it is the low hanging fruit, so to speak, anybody can do it, and gives the most ‘wow’ factor to the average person looking at it.
I guess I like Rees approach better – I think he has the priorities right – where the machines he has work really well, and as intended from the factory, but he couldn’t give a damn about the paint or the buffing of hand wheels, etc.. All the same, I will probably attend to the paint on my saw at some point, but it won’t be this round. I look forward to getting it’s geometry back to where it (hopefully) was when the machine left the factory sometime around 1970.
I’ll follow up with anther post in the near future. Thanks for dropping by the Carpentry Way.
Post II in this thread can be found here.