New to me Central machinery 8 x 12

I picked up a used 8 x 12 Central Machinery lathe.
Tag says 07 model ...
Guy i bought it from said he only made watch or clock parts or something ......
machine is not wore....
it's not scratched or dinged up it just look like it's been sitting in a basement for a long time paint looks like it's new.
Most of the tools are still in the plastic so fella didnt do much with the lil thing....
This is my first mini lathe...
I've been Machining for 20 years....
So the machining aspect is not my issue...
I've got the lathe setup on the table that I made and I'm now going over it with my ol trusty interapid test indicator.....
I put a dowel in the 3 jaw Chuck and I can get about .003 run out which I understand or am I'm hearing this is typical , normal or in tolerance...
I need it better !!!!
That is pretty normal for an inexpensive 3 jaw in general HF or otherwise. pull the chuck and indicate the inside the spindle bore. I bet its around .0005 - .001. My 8.5x18 barely moves the needle on my Last Word indicator. I use it for small stuff so I set it up with a 3C adapter and a 3C closer. Its under .001 all day long. If that's not good enough make an adator plate for a 4 jaw or for a pull back chuck.
so I took the chuck apart today deburred ,cleaned it up, took a stone to it and just made it slick as could be.....
reinstalled and I'm still .oo3 out of round
Could be the boss for the chuck was not cut in place. It could also be the chuck is off that much. Might also check it with different size gage pins just to see. Not only do inexpensive scroll chucks tend to be off they tend to be off by different amounts at different diameters. Again, go with a collet adapter, collet chuck, or 4 jaw if you want better.
not to mention out about the same horizontal in 4inches or so toward chuck.
That may be easier to fix. The head stock is just bolted to the bed , and the bottom is pretty rough. Could jus tbe a burr or chip in there. If not its dead easy to shim.
I guess the confusing part is when the chuck was off I put the test indicator on the adapter and swung it and I can't get a half thousandth of variance anywhere....
Well that pretty much confirms it. Its just a cheap 3 jaw scroll chuck then. .005 isn't uncommon. .003 is pretty good.
Bearings maybe ?
I don't think so. You might be able to feel .003 slop in a spindle by shaking it. They are just a grease lubed bearing though. Unless its different from the 7x10.
I've been reading post after post after post and videos on YouTube and all kinds of stuff on this lathe and I figured I would start my own post to get some insight I plan on doing quite a bit of threading with the lathe as soon as I can figure out how to engage the half nut :) and change the change gears I'm use to a big mazak I don't think I've ever changed, change gears before ? :)
:)
Any input would be greatly appreciated
Thank you

You are so going to miss your QC Gear Box. LOL. The half nut and engages the drive screw for both threading and turning. It does not have its own threading drive like bigger lathes often do. You are going to be swapping gears all the time. I suggest that one of the first things you make for it are long shoulder bolts with knurled thumb heads to make taking the cover off to change gears easier and faster. To go from turning to threading... yep. Change gears. MANUALLY.

The next thing I suspect you will miss is having a power cross feed.

Probably one of the first things you should do to the carriage is build a set shims so you can tighten the screws down tight on the sandwich plates and have very little movement. Just enough so it still slides easily.

I have a 7x10 converted to 7x16. Very similar machine.
 
P.S. It will single point thread, but make sure you always use the same engagement mark on the dial. For most jobs I prefer to use a die drive sleeve in the tail stock. That could be the third thing you make for it.

Or I suppose the first. It would make turning those shoulder bolt cover screws easier. LOL.
 
Man I appreciate it you guys have been a lot of help I think my back is broken from working on the tree house but I'm in here messing with this lathe now ....
Before i read these posts I found the socket head cap screw for the thread dial and it was loose I just tapped it with my palm and manually move the handle and it started turning I'll check gear mesh here in a second.....
You guys are a lot of help I appreciate it.
 
Bob la londe... ..
You are correct!!!! I am lost without quick change gear box... !!!
This gear "stuff" is french to me ....
I did chuck up a 12" x 1.625 dia piece of 7075 between centers ...
Just experimenting with speeds n feeds ...... damed if i didnt end up hand feeding the material...
This is probably gonna get some giggles but ive machined for a long time.
Started in a job shop on a Bridgeport mill like 20yrs ago ....
Got into tool and die ...
Used machines from Blanchard grinders to charmilles wire and plunge EDM ...
Last "job" i had was making parts for a large steel mill ....
I was married to a 6in lucas boring mill ..... got tired of watching the "big dogs" make all the money so i utilized a passion or hobby of mine and started prototyping a part at a buddys family ownd shop.
Qualified the first part sent some emails and received my first QTY order from a Vendor in the biz....
that was 2012 .....
Ive made a pile of different parts since..
My design my work....(well first part is my work) :)
I dont have to work for big dogs any mo... :)...
What ive run into is finding an open machine to tear setup down just to run a few ops on latest "idea" and end up taking 2 months to get a proto just to test !!
Ive got 3 sons so my evenings and weekends are no longer mine....
Hence the reason i picked up this little lathe .... hopefully i am able to get my protos ready in a week or quicker and move more parts .....
Shew...... that was alot...... :)

Back to the questions :)
Freakin gears....
My "Tub" gear is a 100 tooth .....
When tryin to get a decent finish my speed was fine but my feed was to fast
Rather than change the gears AGAIN i just hand fed....
Nice finish !!!
And part is true!
Less than .0003 runout and straight !
I guess what I'm asking is throw me some gear combinations I've got some charTs that I pinned up on the wall in front of the lathe.....
I still can't make heads or tails of this dang thing..
I will be cutting a lot of aluminum mostly .750 to 1.5 dia
Some 304 SS
Im using inserts on kenmetal holders ...
(Mostly)
I need to cut a 8x.075 thread ....
There's about 48 gear combinations I can find for that thread.....
Im not doing something righ.....
I'm pretty sure I've got, a, b c, d e and F the tub gear figured out.....
I don't care if you got to draw me a picture in crayon ....
For the Love of All That is Holy just tell me what gear to put where :)
That metric thread will be on some pretty soft mild Steel....
And which two gears am I needing to change too slow my feed when cutting aluminum and wanting nice finish ...
Let say 1.5 dia alum.....
high speed semi slow feed .... ?

Tired
Brain dead ....
Tbanks again guys.
 
Oh, and if its like my 7x10 its got a universal brush motor for the spindle, so very little low rpm torque even in low gear.
 
You said "I've got the lathe setup on the table that I made and I'm now going over it with my ol trusty interapid test indicator.....
I put a dowel in the 3 jaw Chuck and I can get about .003 run out which I understand or am I'm hearing this is typical , normal or in tolerance...
I need it better !!!!"

I hope I am not misunderstanding what you are saying but I will try to help with my limited experience with the Central Machinery lathe. I have a 7 x 10 I have used for @ 5-6 years and it was never consistent with the centering of stock in the jaws usually 3-4 thousandths out. When needed I would shim between the jaws and the stock to center my work. Eventually I replaced the 3 jaw with the 4 jaw independent chuck for my lathe from Littlemachineshop.com and suddenly life became much better. It was important for me to center my work every time I chucked it up and so it was worth it to use a 4 jaw independent and take the time to gauge the work to adjust to exact center. If this aspect is not what you are talking about, sorry, I am just an amateur.
"When in doubt I go ahead and step in, they will understand I am a greenhorn"
 
Last edited:
Wayne
You are spot on.
I have looked at the 4 jaw from LMS ...
Ive never "liked" having to shim work piece ,(on lathe) so a 4 jaw maybe something i pick up soon ...
 
I bought the four jaw from LMS for my lathe of the same type. I'm certainly no expert either but I understand if one needs spot on use a 4 jaw or a collet. I also bought the ER32 collet chuck. As budget allows I'll be getting the collets.


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When I actually turned threads on mine I always just looked up the gears from the chart in the manual. Then I'd take a scratch pass and check it with a thread gage. If you didn't get the manual with the lathe its no big deal. Since its a current model you can probably just download it directly from the main HF website. If the manual is not available there is something some folks do not know. HF has (or atleast had) and on=line database of manuals. Its not formally organized except for by directory and model group, but if you send an email to their support staff they can provide a direct link. If you look at the URL for your manual you can quickly figure out how their on-line database is organized.

ER 32 collet chuck? Now that sounds interesting. I am using 3C with a closer in both of my small HF lathes, but ER 32 will hold larger stock than 3C. I'll have to look into that.
 
Hey guys .....
Thought I would get back in here with some more questions :)
I ended up picking up a 44991 mill with rotary table, forward reverse setup .......
Guy was starting a biz making somethin and decided he wasn't gonna make any money ..... so he listed it for sale and I ended up with it .. for 4 C notes .... :)
The 2 machines have actually surprised me........
Fairly accurate.... Lil machines... I thought $400 was good for the mill...
Ok..... so I got tired of trying to calipar / and or scribe to next location.
So I ordered one model #5012 , 12" readout.....
https://littlemachineshop.com/products/product_view.php?ProductID=5012

NOT my first order from them ... but this one was little unexpected I guess I'll say.....
I know I can cut the flat bar that the slider rides on
But would rather not.....
I've decided to add a 2" piece of 7075 in place of the left side, little red table end ..... made of plastic ..... uhh....
The hardware I received is ..... well it's not user friendly...
Some there is TOO much of .....
Some not enuf ......
I don't have or maybe I dont Understand how the or what the slider reads off of ?
Any input or help would be great !!!!!!
Also ......
No "instructions" (not that I would use them anyway....)
Provided
I understand the basis behind it ....
As far as mounting and such.....
Oh ya....
I took x axis handle off an seen those open , dry as hell "bearings" please tell me there is better bearing available or I'll just get one from bearing place.....
Thanks again ....

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