Sunday, November 4, 2007

Lathe Stuffs

I've been having an exciting adventure with my lathe. As described previously, it's a 'project' lathe. That is, it is a project simply to get it running! One silver lining is that I can't really hurt it. So I've been tearing it down to see how it works. First, there are a lot more individual parts than I thought. You don't see them until you really pay attention. Second, I know how the lathe works now. Previously it was abstract "this turns this" sort of general idea. Now I know precisely how it works, and I know what the parts are called.

While my lathe was made in 1939 or so, the Clausing corporation still has some parts available! Amazing. They were kind enough to send me a parts list. You can see it Atlas/Craftsman 12" engine lathe parts diagram 101.07383. I can use the part numbers to find suitable replacements on eBay.

Now, for the dirt.

I took the tailstock completely apart. Something very bad happened to it. I suspect whatever it was destroyed the hand-wheel and bent the ram screw. What's left is a well-intentioned bastardization. The worst part is that the culprit didn't have a left-handed Acme thread laying around (who does!) to make another ram screw. So he bored out the ram's left-handed Acme thread and re-cut a common right-handed thread. This means the tailstock works exactly backwards to every other tailstock on the planet. Fortunately, fixing this is relatively easy - I'll bore THOSE threads out and press in the appropriate nut. Now, the machinist did a commendable job of turning a large bolt to make a new ram screw - it isn't an easy thing to make. It sure looked like a lot of work - far more work than spending a few bucks on a left-handed threaded rod or a few more dollars on a new ram screw.

I took the backgear assembly apart too. I was not pleased - again, something rendered the backgears unusable - they wouldn't stay engaged. I saw another full assembly on eBay and bid on it, as a lark. To my surprise my low-ball bid won. Comparing the new assembly with the original, I can see my backgear shaft has been replaced, and badly. Instead of turning a replacement shaft, the person found a section of pipe... Now, the backgear shaft is indeed hollow and contains another shaft which is on an eccentric. This eccentric is used with a lever to engage the back gears when appropriate. The fit of the eccentric shaft within the section of pipe was poor to say the least which is probably why the back gears would not stay engaged. To add insult to injury, the pipe had a larger diameter than the original shaft. So the guy bored the gears to fit. Now they aren't even useful as backup parts. Terrible decisions.

I'm not comfortable running the lathe without all the safety equipment. I scored an Atlas spindle pulley guard on eBay to replace mine, which had been lost sometime in the last 70 years. Atlas made the Craftsman lathes so the part are generally interchangeable. It's a tight fit - the bull gear actually brushed up against it. In addition, the new large back gear is wider than the old one and crashes against a large washer that's beside the mating spindle gear. So I have two problems to address - but it looks like with some creative reordering of washers on the spindle, I'll be able to make this all fit.

So far I've spent less than $35 on eBay to get critical parts. I still have to buy the left-handed tailstock screw and nut but those shouldn't be too much.

The original purchase price was quite reasonable, I'll have this running for about half the price of a well-cared for lathe.

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