Re: Have a Bridgeport Milling machine...


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Posted by David Sherman on Thursday, May 08, 2008 at 12:30:39 :

In Reply to: Re: Have a Bridgeport Milling machine... posted by Doinco on Thursday, May 08, 2008 at 11:26:09 :

Jet, Grizzly, Enco, Harbor Freight, etc are all pretty much the same machine. I got a 12x36 for $1300 new 10 years ago and have used it for a variety of projects. It doesn't have the rigidity of the heavy old cast iron machines, but for the most part that just means you can't take such heavy cuts, which isn't a big deal. The accuracy has been fine for everything I've wanted to do. I recently bought a "Victor" lathe that weighs about 5000 lbs, but haven't figured out how to get it into my basement shop, or whether to store it until I can build a better shop. It doesn't help that my main storage shed got smashed by the snow last winter.

Anyway, I think you can probably find a good old American lathe just as cheap as a "Jet" type machine. With some of the really old lathes, you have to change the speeds by shifting belts and changing pairs of gears manually, which is a hassle. I have one of those flat-belt driven ones from about 1920, but have never set it up yet. I bought it only because it has a very long bed and came with good Armstrong tooling. The bearings are tight but the ways are rusty. The previous owner had rigged it up with an electric motor driving an automobile transmission hooked up backwards, which in turn drove the flat-belt drive pulley. The back gear still works, but to change speeds other than that, you use shift the transmission via a shift lever that was bent around in a strange direction to make it more convenient.

An older American lathe with a geared head would probably be your best bet at this point, but the Taiwanese one has served me well for many years and I definitely wouldn't call it "junk". For production work, a heavier machine would be better, but for making the odd repair part or pulley, it's fine.

Personally, I think horsepower is overrated in all shop tools, both woodworking and metalworking these days. If you're doing production work where the number of parts made per hour is crucial, horsepower is important, but for hobby, restoration, or prototype work, the setup time is always far greater than the actual time spent cutting, so it doesn't hurt to cut a little slower. All the workpiece and tool on a lathe cares about, for example, is how deep the cut is per revolution. Faster spindle speeds definitely mean it takes less time to remove the required amount of material, but that also means that in addition to a more powerful motor, you need a coolant pump to flood the tool with coolant and you need a much more rigid machine in every way to handle the stresses and keep down vibration. Similar considerations apply to woodworking tools like planers, jointers, and shapers. If money is no object, or speed of production is vital, I guess there's nothing wrong with unlimited horsepower, but if finish and craftsmanship are the only issues, you can save a lot of money, plus the expense of wiring and of moving very heavy machines, by scaling down somewhat in power and weight.



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