Author Topic: Building a New Lathe  (Read 165742 times)

Offline vtsteam

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Re: Building a New Lathe
« Reply #275 on: June 07, 2015, 09:10:35 PM »
I had a little time today to work on the lathe. I driled and tapped the aluminum stepper mount end bracket and temporarily bolted it in place so I could work on the leadscrew and leadscrew bearings.  I'm waiting for arriival of 2-1/2" long socket flat head screws by mail to permanently mount the bracket.

The Acme leadscrew stock was turned down at the ends, and the cast bearings were bored to fit. i clamped them in position to make sure I had the length right, and to check clearance to the carriage, and measure for location the half nut.

That was it for the day.



« Last Edit: July 11, 2017, 03:25:32 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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RobWilson

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Re: Building a New Lathe
« Reply #276 on: June 08, 2015, 02:42:27 PM »
Loooookin mighty fine Steve

Your castings do turn out well  :clap: :clap: :clap:  , I have some ally casting to do later this month  :ddb: 


Rob

Offline mexican jon

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Re: Building a New Lathe
« Reply #277 on: June 08, 2015, 05:52:24 PM »
I had a little time today to work on the lathe. I driled and tapped the aluminum stepper mount end bracket and temporarily bolted it in place so I could work on the leadscrew and leadscrew bearings.  I'm waiting for arriival of 2-1/2" long socket flat head screws by mail to permanently mount the bracket.

The Acme leadscrew stock was turned down at the ends, and the cast bearings were bored to fit. i clamped them in position to make sure I had the length right, and to check clearance to the carriage, and measure for location the half nut.

That was it for the day.





I'm loving this thread  :thumbup: I get a little disappointed when I sign in and there isn't an update to read  :( Keep up the great posts and the excellent build  :bow: :bow:

P.s. Do you not think your clamps need a little bit of the love and care that is being lavished on the lathe  :lol: :lol: :lol:
People say you only live once ! I say thank F@*K can't afford to do it twice.

Offline vtsteam

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Re: Building a New Lathe
« Reply #278 on: June 08, 2015, 06:15:37 PM »
Thanks Rob! :beer:  You're going to be happy as a clam (as my New Orleans grandmother used to say) casting again!  :thumbup: :clap:

Jon thanks kindly, :beer: I hate to put it off, too -- it's not like the winter anymore and so many things I need to do before the next bout of cold weather, but I'm going to try to work on the lathe a little every other day between chores. Half nut looks to be the next needed part on the lathe.

Haha, agree totally about those clamps, poor things. I remember buying 20 of them for $1.50 each in 1972 when I was building a 27' catamarran to sail the coast in. Never did finish that boat, but I still have the clamps. They've been everywhere, including the bilges of the houseboat, holding things tgether in the rain. They're covered in not just rust but that and layers of epoxy, etc. You're right, they deserve better. Maybe one day the'll get dunked in washing soda, electrified, re painted and oiled -- straightened where necessary, too. But they still work well, have a deeper reach all around than my nicer cast iron C clamps, so they suffer everywhere......terrible case of tool abuse.  :whip:
I love it when a Plan B comes together!
Steve
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Offline S. Heslop

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Re: Building a New Lathe
« Reply #279 on: June 08, 2015, 07:43:11 PM »
It's already looking real professional and sturdy. Can't wait to see what you've got planned for the headstock.

Offline vtsteam

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Re: Building a New Lathe
« Reply #280 on: June 08, 2015, 10:24:35 PM »
Simon, I have a "sorta kinda" idea in mind for the headstock but it will probably boil down to just working it out in PineCad 3D.

In other words putting pieces of scrap wood together right on the ways to see what is going to fit, accept the wings of the carriage without interference, cover the stepper bracket,  at the right height, accept the roller bearings, room for pulleys, and with slides, and look beefy enough, etc. That will then be the pattern.

Not sure if I will cast it in zinc or iron -- kinda depends on how much metal it will take (limited iron crucibe capacity) and whether all my iron gear is in shape. My iron sand got waterlogged and I have been spreading it out on plastic sheet in the sun trying to dry it out.

But, I gotta do the half-nut first so I can get the carriage working on the leadscrew. No point casting the headstock until I have the means to bore it..
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Building a New Lathe
« Reply #281 on: June 09, 2015, 01:49:57 AM »
Simon, I have a "sorta kinda" idea in mind for the headstock but it will probably boil down to just working it out in PineCad 3D.
:lol: that was very good!


Not sure if I will cast it in zinc or iron -- kinda depends on how much metal it will take (limited iron crucibe capacity) and whether all my iron gear is in shape. My iron sand got waterlogged and I have been spreading it out on plastic sheet in the sun trying to dry it out.

My first lathe had a headstock/tailstock and all but bed made out of "special alloy". Alloy and plastics on all the wrong places. Some ideas were fine and finish was good but 1/4 of the elastic module of the steel and 1/4 of the quality lathe.

Pekka



Offline vtsteam

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Re: Building a New Lathe
« Reply #282 on: June 09, 2015, 09:14:19 AM »
To be honest, Pekka, the zinc alloy would probably have higher properties and be better for the purpose than cast iron. Check the properties for za-12, including tensile strength and damping. If I cast it in iron, it would be more a matter of using my big furnace and melting iron once again for the fun of it -- and coming full circle in using so many different fabrication methods and materials on this one project.

The problem with most commercial die cast zinc alloy products is that the material and method were chosen to minimize cost, by using very thin sections and high speed production methods. Zinc alloys are so strong and easiy injection molded into thin webs that such are the norm. It's possible to find machine tools with 2 mm sections and complex webbing in ZA because it can be formed and used this way. You'd never be able to do that in iron, it doesn't have the tensile strength or easy injection molding capability.

ZA cost saving is not a priority in a home-shop built small lathe -- I'm only making one, and it's easier to just cast a thick section than a thin web. The cross slide on my lathe is 25mm thick ZA by comparison. It's stronger, stiffer, and more vibration absorptive than an equivalent thickness cast iron, part -- both are overkill, however, because of the need to be able to bolt accessories to the table through either Tee slots or tapped holes. So it doesn't really matter from a design standpoint, the thickness is determined by practical fastener depth requirements.

For the headstock, I'd say ZA has the edge, because of tensile strength requirements around the area of the bearing housings, and in general torsion on the whole at the center height for cutting and the pull of the drive belts, plus vibration damping qualities, re chatter. I'm sure both will produce good headstocks if properly sectioned, but if i were just to stack up materials properties for the same headstock sections, I'd say ZA would be better.
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Building a New Lathe
« Reply #283 on: June 09, 2015, 03:43:06 PM »
I have packed that lathe away to resist selling it to anyone, because it is that bad.

I have become so allergic to any zink alloys that it might influence on my views, but that lathe is soo bad. Maybe I should take head stock away and take some photos. The casting don't look even as thick than economy cast iron. If it were solid it might have fared better.

Also slides were this wonderfull zink alloy.

I don't think that ultimate strenghth is issue here, but I wish it were more rigid. Turning iron metals with it was like trying to peel rotating wiener with a carrot. Turning tool had to be razor sharp or piece was escaping at front of it. Like everything was flexing.

Wish they would have had sense to build it right, it might have worked better.

That said,  you don't need to wring out every gram of it and cut all the corners, therefore I believe you are going to succeed.

Pekka

Offline vtsteam

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Re: Building a New Lathe
« Reply #284 on: June 09, 2015, 09:36:59 PM »
Well Pekka, this is new territory for me, too. Maybe I won't like the zinc for some reason or other, down the road. In which case I'll just replace the part with another one in iron, or whatever. That's the nice bit about being your own manufacturer, customer, and customer service department! No arguments.

I did have only one part in zinc alloy on the Gingery lathe. I lookied at it about a month ago and it appeared as good as it was when cast 13 years ago. And a very high wear part at that: the half nut.

It's amazing how tough that has been. I see more wear on the steel ways and slides than on that half nut. I wonder how many miles of leadscrew thread have passed through it? And sometimes at pretty high pressure, with swarf. That toughness is one of the things that impressed me and got me thinking about using some alloy on this newer lathe. We'll see how it works out in practice.  :beer:
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #285 on: June 13, 2015, 05:11:09 PM »
Waiting a couple days for a call back from the sand and stone delivery guy, so at a halt on th4e cistern, so back on the lathe!

I made a pattern and cast the half nut using a piece of threaded rod smoked with a candle as a core, and casting in a steel arbor.

« Last Edit: July 11, 2017, 03:27:01 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline mattinker

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Re: Building a New Lathe
« Reply #286 on: June 13, 2015, 05:14:21 PM »
Looking good Steve, the ZA alloys are great!

Regards, Matthew

Offline vtsteam

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Re: Building a New Lathe
« Reply #287 on: June 13, 2015, 05:15:57 PM »
Zinc and sand eat end mills, and the only carbide ones I have are too big for this, so it was mostly hacksaw chisel and file for this one, though I did have a carbide lathe tool to turn the rim. Anyway, here's the nut cleaned up some. The core left the thread prints.



« Last Edit: July 11, 2017, 03:30:11 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #288 on: June 13, 2015, 05:59:55 PM »
Thanks Matt!  :beer:

And trial fit to the leadscrew -- it works!  Holding itself up here because the fit is very close since it was cast on the actual screw core rather than tapped.

« Last Edit: July 11, 2017, 03:29:46 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline Meldonmech

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Re: Building a New Lathe
« Reply #289 on: June 14, 2015, 06:39:11 AM »
Hi Steve,

                   The nut turned out well, I have never had the need to use a smoked steel core, but will give a go next time I am casting. Was the core difficult to remove?

                                                                           Cheers David

Offline vtsteam

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Re: Building a New Lathe
« Reply #290 on: June 14, 2015, 08:23:27 AM »
Yes David, It was fairly difficult to remove because it was well locked in by parts of the casting that had to be removed themselves, and it was zinc. But not because the casting adhered to the core. Once freed of the temporary fillets, it popped right out when tapped with a drift. But chopping away the zinc with a chisel was slow going, and it was difficult to get a grip on this particular part in a vise that could take a good hammer blow on the chisel.

There are quite a few smoked steel cores in the construction of a Gingery lathe, as well as permanently affixed arbors (no smoke) as in this one. This design half-nut is basically the same as used on the Gingery lathe, with a change in dimensions, and the use of a much coarser acme thread and bigger leadscrew. I did wonder how that might work out. But it has very well here.

A steel core can be removed when the bury is up to about an inch, when driving out lengthwise for a full hole, at least in aluminum. it gets harder to do above that length. The resulting fit is always very close.

A half section, as in a split bearing half, is much easier to remove, and a half casting like that is essential on a threaded piece for removal ...I would think. I've never tried to unscrew a full cast thread. Maybe it could be done....don't know.
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Building a New Lathe
« Reply #291 on: June 14, 2015, 02:02:25 PM »
That looks pretty good (and sounds a little laborous).

Pekka

Offline vtsteam

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Re: Building a New Lathe
« Reply #292 on: June 14, 2015, 02:53:23 PM »
Thnks Pekka! :beer: Maybe it sounds worse than it was -- I probably spent an hour on it.

Today I made a feed lever from a piece of scrap stainless and brass. The half-nut opens and closes. I just need to make a spring loaded detent to complete the carriage.

« Last Edit: July 11, 2017, 03:30:55 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Building a New Lathe
« Reply #293 on: June 14, 2015, 03:03:29 PM »
Looks really good Steve  :thumbup:

Don't let it get wet, that zinc and brass will fizz away and produce a nice (not so little) battery  :bugeye:
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Building a New Lathe
« Reply #294 on: June 14, 2015, 03:21:19 PM »
Nah, salt not fresh water! And I promise not to dunk it in the ocean.  :lol:

Or a lake for that matter. Aluminum and brass or bronze, bronze and steel, aluminum and steel, stainless and bronze all form galvanic couples in salt water, and yet are routinely used in combination on all kinds of equipment. And equipment a lot more exposed to the elements than this lathe will ever be.

Anybody out there using aluminum bolts for even your all aluminum projects? Even aircraft routinely mount aluminum with steel AN fastenings.
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Building a New Lathe
« Reply #295 on: June 14, 2015, 03:27:08 PM »
No salt in your perspiration then?
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Building a New Lathe
« Reply #296 on: June 14, 2015, 03:30:44 PM »
Andrew you can't be serious!

You really think a couple of brass handles and perspiration are going to seriously degrade this lathe......in how many years do you figure -- so I know when to start another one?
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #297 on: June 14, 2015, 03:37:23 PM »
Of course there's an even better reason not to get a lathe wet. And it doesn't even need a galvanic couple....the ferrous parts rust.

Of course we all try to prevent that with this other substance called oil. Works on brass and alloys too.
I love it when a Plan B comes together!
Steve
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Offline mattinker

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Re: Building a New Lathe
« Reply #298 on: June 14, 2015, 03:48:41 PM »
Anyway, it looks very nice! Sort of maritime!

Regards, Matthew

Offline awemawson

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Re: Building a New Lathe
« Reply #299 on: June 14, 2015, 03:51:10 PM »
loosen up Steve, it was a joke  :thumbup:

But you know, there are some engineers who know that they have 'rusty hands' and I'm sure it's that they perspire more salt.
Andrew Mawson
East Sussex