Interesting and counterintuitive to me

On 12/03/2017 04:36 PM, snipped-for-privacy@whidbey.com wrote: ...

Can you explain? Waves arriving at the interface are partially reflected back onto themselves, cancelling out by destructive interference. Did I get it?

Interesting. In industry, there is an old method of vibration damping that involves letting parts slip against each other. I don't know if that's going on in your case, but it's something to consider.

Something else to keep in mind is a long story, but the short version is that Reed-Prentice once had a young engineer who decided that he could reduce headstock vibration by doubling the thickess of the head casting(s). It turned out that it made vibration worse.

If it's an AA/Sears 109-21270 your next problem will be spindle deflection.

There was some of that as well as the waves just having trouble crossing the interface. I don't understand it very well. I'm gonna have to spend some time learning about it. My goal was to just make the bed into a stiffer beam. I understand how to do that. It's all pretty easy and Machinery's Handbook has all formulas. Eric

On Monday, December 4, 2017 at 7:18:13 AM UTC-5, Jim Wilkins wrote: if it's an AA/Sears 109-21270 your next problem will be spindle

If it is an AA Sears lathe , the first problem was spindle deflection.

Dan

And the second problem was spindle bending, right at the bottom of the nose-thread relief.

It wasn't too difficult to bend back. I belted the lathe for speed and still use it for polishing, and for drilling small deep holes like axle grease passages, which don't have to stay precisely centered.

Since I have another lathe it might get a shop-made solid 1/2"-20 spindle with the end pointed to turn or grind between centers. The

1/2"-20 mount Jacobs chuck I usually leave on it is very nice for odd-sized small work and filing or sanding close to the jaws.

-jsw

Good thing it wasn't THAT Sears lathe. It's the Atlas made version. The 101.07301 In any case I have made a new spindle. The new spindle allows use of a Royal 3C spindle nose insert and 3C collets. I swapped the original plain bearing headstock for the Timken tapered roller bearing type. I still have lots more to do. I have yet to mill the underside of the ways so that the ways become a dovetail way like Hardinge uses. Before I do that I need to figure out how I am going to modify the carriage so that it will work with a dovetail way. Eric

Wow. This is going to be a Whidbey lathe when you're done. d8-)

Ooh! I like it! The "Whidbey Lathe". That's a great name ED, thanks. Now I need to design a logo. Years ago I bought 4 magazines (I don't remember the name right now) that have the plans in serialized form for how to make a quick change gearbox for the Atlas 6 inch lathe. So that's part of the planned improvements. It's a long term project but I'm gonna want something new to play with when I retire. Eric

I thought about keeping mine when I got my SB 10L, but shortly thereafter I bent the spindle nose, like many other people did.

An editor friend at American Machinist, who made flying model airplanes, wanted it. So, having plenty of resources as an editor d8-), I turned a new spindle on the SB from a piece of O1 drill rod and had it heat treated at a friendly shop.

The editor I gave it to, Bob Hatschek, used it for years, and I was told it worked great. If I had to buy the barstock and pay for the heat treatment, I probably wouldn't have done it. It would be too easy to warp it when quenching if I heat treated it with my meager facilities.

That's what makes this hobby fun.

My thing has always been learning old-time toolmaking methods. That's partly because the lathe, which I inherited, came with a bunch of toolmaking tools, and partly because I had to research a lot about it for writing my sections of American Machinist's 100th Anniversary issue in 1977.

I must get back to it soon, after I catch up with all of the home-repair jobs I left idle until I retired.

have the plans in serialized form

You might stop by your lawn equipment dealer and see if they would let you pick through their scrap bin. The little riding lawn mowers have a 6 sp eed transmission that could supply the gears for the gear box. The local d ealer has thrown out a couple of them.

Dan

I need specific gears Dan. But that's OK. I'm partway through a device for making gear cutters. The device is called the "Eureka" and it automatically backs off the gear teeth while the blank is spinning on the lathe. I've done the hard part which is making the spindle with the eccentric diameters. After I make the gear cutters making the gears themselves will be easy. I've cut spur and worm gears before so I know. Eric

Are you using Ivan Law's method of faking an involute or some other?

-jsw

I had a quick look at one of the lawn tractor transmissions. There are 10 gears and no two alike. If you change your mind and let me know what sizes you need , I will check and let you know what sizes are in the transmissions.

Dan

Not long after I got my 9" SB 'A', I saw one of the atlas lathes for $500.00, it was literaly beat to sh*t. The owner noticed me looking at it and kept pestering me to make an offer. He wasn't too pleased when I said I could probably re-sell it for two dollars as scrap.

Keep in mind that we're talking about two different lathes here. The little Sears 6" lathes, for which I made a spindle, were barely real lathes.

But Atlas made a decent box-way (flat-way) lathe for Sears that actually was a pretty good little machine. I don't think I ever saw one, but I ran a 10" Atlas at the shop I had invested in, and there was nothing wrong with it.

The box ways versus V-ways issue really was a matter of the manufacturing capabilities of the manufacterer. With good construction, either one could deliver good performance.

When I worked at Wasino we sold a smallish machine that guaranteed 50 millionths turning accuracy. It really would deliver it, and it had box ways. It was one of the most accurate lathes in the world.