Mini Lathe adapter questions

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Mainebowlman

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I just received my new Wilton mini-lathe from Amazon. I'm impressed with what it has for the price ($99 including shipping): a 2/5 hp variable speed motor (no belt changing), faceplates, live center, spur center, knockout bar, etc. Both centers even line up perfectly!

I can't believe that I can now get out of the shop in the cellar and turn pens, Harry Potter wands, and bottle stoppers OUTSIDE on the back porch!!!

Enough with the gloat.

Question: Is there any problem using an adapter for the 3/4"/16 tpi mini-lathe thread so I can use my regular 1"/8 tpi Supernova chuck OR with getting an adapter from a #1 MT to a #2 MT so I can use my Jacob's chuck and pen mandrels on the mini-lathe?

Thanks in advance.

Jack (in the Mud)
 
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JimGo

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Jack,
That's a pretty nifty set up, especially for the price! You'll have to post a review once you've had it for a while. Not sure about the adapter; I assume it will work, but not sure about the consequences (e.g., may be more prone to slipping if you are turning something heavier than a pen). But, if you won a Supernova chuck, you probably know a LOT more about turning big stuff than I do!

Good luck!

- Jim
 
M

Mudder

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Jack,

I friend of mine has an old rigid lathe and when I go over to his house I bring my PSI #3418 adapter. It works pretty well but you got to make sure you get one that has the inner and outer threads concentric or you woll have runout. I went through 2 PSI's before I got a good one but their customer service was good. I think the price was around $16.00


<edit> Well I was close, it's $16.95, here is a link:

http://www.pennstateind.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=LA3418&Category_Code=

enjoy.



<2nd edit> Only drawback is that you will possibly wear the bearings out a little faster because of the weight of the chuck being further out from the headstock and your maximum stock length is reduced.

This is another reason thet I have Nova chucks.... All I need is another adapter and I can change from my jet mini to my DVR.

But at $17.00 this little thing is cheaper than a bunch more nova inserts [8D]

Hope this helps.

<3rd edit>

Sears sells a Jacobs chuck on a #1 morse taper and it also doubles as a holder for a buffing wheel Here is the link:

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00925354000

If you are really interested in the chuck drop me a line through the forum email as I think I might have an unused one in the shop from when I had a rigid lathe (where do you think my buddy bought his from [;)]) If I do have I'll give it to you much cheaper than sears sells it for (like 1/2 price of I'll trade you for some blanks) .
 

JimGo

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Jack,
If you're in the market for replacements, also check out Harbor Freight. I got a Jacobs chuck for about $12 I think.
 

Rifleman1776

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Adapters should be just fine. Mudders caution about wearing out bearings is not something I have thought about. My reaction is if that happens you do not have a very good machine to start with. A tip, find some nylon washers at the local hardware store the same size as your spindle. Put those on before screwing on the chucks or adapters. Will make removing much easier.
 

Fred in NC

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The nylon washers are a VERY good idea. Saves a lot of aggravation and possible damage to the spindle.

These washers can also be made from poly, such as lids from food containers. The center hole is easier to drill with a spade bit.
 
M

Mudder

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Originally posted by Rifleman
<br />...... My reaction is if that happens you do not have a very good machine to start with.......

Frank,

The bearings of the best lathe will eventually wear out.
Maybe not in your lifetime but they will go sometime.

It's one of those sad facts of life.........Now if you could build a machine that has all air bearings............................
 

Fred in NC

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".........Now if you could build a machine that has all air bearings............................" Actually it is not a new idea at all. http://www.newwayairbearings.com/

Some big lathes don't have ball bearings. The bearing is solid or made from sintered bronze or such. The spindle actually rotates on a thin oil film. Bronze bushings are widely available.
 

Mainebowlman

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Thanks for the feedback and info, everyone.

I've ordered a thread adapter and have contacted Mudder about his Jacob's chuck.

Will take it easy on the bearings, now that some of you have made me aware of that concern.

Jack (in the Sun...finally)
 
M

Mudder

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Originally posted by Fred in NC
<br />Some big lathes don't have ball bearings. The bearing is solid or made from sintered bronze or such. The spindle actually rotates on a thin oil film. Bronze bushings are widely available.

Fred,

What happens when the lathe is off?
How many revolutions before the oil spreads again and lifts the shaft?
I work as a quality engineer for a company that makes miniature precision components, linear and rotary motion assemblies.

Our gear hobbers use a bronze bushing to hold the taper center of the hob shaft. These are made out of oil impergnated sintered bronze bearings and I can tell you they wear quite rapidly. A typical life for this component is a little over 200 hours. On the other hand, our newer machine that uses ball and thrust bearings has a life of more than 1000 hours before a rebuild. The problem with the sintered bronze bearing is that when the machine shuts off for a removal of the cut gear and loading of a new blank the oil film is displaced and the shaft is rubbing on the bronze bearing on restart.

I have been studying the problem on and off for 4 years now and even with the best synthetic oils that I can get it still takes 11 revolutions for the oil film to "float" the shaft again.

Granted, I gave you an exterme example but unless you have a true air bearing, everything will wear out in time. How long it takes to wear out is another question
 

Fred in NC

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Mudder, if I understand you correctly, you are talking about a tapered bushing and shaft, and probably not in a horizontal position. Sintered bronze bearings, with an oil cup, and in a horizontal position, need less than one revolution for the shaft to be floating in oil. At least that is how I understand it . . .

Also, have you heard of Babbitt bearings? lathes and other machines used them until ball bearings became affordable.

I am not trying to say that any of these are better than ball bearings. Just info for its own sake!
 
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Mudder

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Fred,

I'm not going to debate you.

I'll tell you the facts of this application.

The hob shaft is 2.5" in diameter and is 18" long.
The hob weighs from 50-90 lbs depending on weather it is a spline hob, gear hob, or pulley hob.

It is a horizontal application.
There is an oil cup but it has little to no effect.
The hob and shaft are flooded with oil at startup.
The fit between shaft and bearing are .0002" maximum because of the gear quality that must be maintained.

The hob spins for 11 revolutions before the oil film will float the shaft.

There is only a very few applications that will allow the bearing to float in less that one revolution but it is hard to predict until you do the PV calculations and then have an accurate determination of the
coefficient of friction.

Sintered bronze bearings and bushings are generally not used in close tolerance applications with the exception of a few applications that have a full time pressurised oil flow to them. We do have one huge lathe in the shop that uses bearings like this and it have those bearings changed about every 6-10K hours of use.

Here is one curious question... Sintered bronze bearings are well suited to applications such as a fan. They seem to last and last without appreciable wear. Why is that?
 

Fred in NC

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Mudder, I am not trying to debate either, and I really appreciate your info.

I am not sure why bronze bearings last so long in fans. Maybe the shaft and fan are light in weight. A lot of light duty motors (read cheap) use plain bearings.

Best regards, Fred in NC
 

lkorn

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I am in the Marine repair industry and regularly overhaul LARGE diesel engines. These engines have pistons that are One Meter in diameter and weight several thousand lbs each. the conrod and crankshaft bearings are babbited. Before the engine starts, there is a "pre-lube" pump that starts the flow of oil throught eh gallery to protect the bearings and bein to float the shafts. Even so, bearings are inspected about every 12,000 hours of operating time. Usually they are worn enough to require replacement. In fact, I have never re-instaled one of these because even though it might be reusable, it wouldn't last another 12K hours and the cost to take the engine apart again far outweighs the cost of a replacement bearing.


Originally posted by Fred in NC
<br />
Also, have you heard of Babbitt bearings? lathes and other machines used them until ball bearings became affordable.
 
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Mudder

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Originally posted by Fred in NC
<br />....I am not sure why bronze bearings last so long in fans.....

The magnetic field and centrifugal forces tend to hold the shaft centered. If the blade is half way decent in terms of balance the thing will run for years and years.
 
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