# I picked up a few machines.



## Geerbangr (Jun 21, 2017)

First off I'd like to say hello to all. I have zero experience operating a metal lathe and a mill. I play around with cars in my shop and always need something machined in one fashion or another. I have a friend I kinda rely on that helps with some things for me but like everyone else I get tired of asking him to do things for me. 

So after watching Craigslist for a while and opting out of buying anything from HF I found these two machines. 

OTMT OT252700

27.5" belt lathe

Enco  20" mill/drill

These machines are supposedly brand new.  

I started cleaning the lathe up first. It appears to be in nice condition. It was still covered in cosmoline I guess. I can post a picture of my lathe and then maybe start asking questions I have about operating it with success.  If anyone has experience with one of these elcheapo lathes like mine and have corrected any issues the lathe comes with please feel free to share with me.


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## DAT510 (Jun 21, 2017)

Welcome to HM. Looks like a nice lathe to start with.


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## Geerbangr (Jun 22, 2017)

So I have some questions I'm wondering about with this lathe. It came with a stack of spare gears and zero tooling nor a manual. 

Everything seems to work well on it that I've tried. Different speeds, carriage runs manually and auto feed. I don't not see a way to reverse the lathe. 

I've waded through YouTube videos looking for some answers on how and what with to get started using this machine. Tooling seems to be preferential to ines personal taste. What would be decent cutting bits to purchase for a beginner? I'm not looking for bits to cut parts for the space shuttle, just bits to get started learning how to properly use the machine. 

The other thing that eats at me is the backlash in a few of the controls. Some of the videos I've watched claims backlash to be inevitable in lathes due to tight tolerance causing the machine to bind up. How much backlash is too much and how much is not enough? I do understand it is a low level machine so maybe I'm being to picky.


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## DAT510 (Jun 22, 2017)

To start here's a link to the manual.  http://www.otmtmachines.com/images/manuals/87-115-949.pdf

The gears are most likely your threading gears.

With regards to backlash, all machines will have backlash. Depending on the types of screws and thrust bearings, some will have more others will have less. Acme threads typically used on manual machines will have more than the ball screws typically used on CNC machines. For example my manual lathe has ~0.005" backlash on the cross-slide.  I can adjust it by tightening the split nut and and the nuts on the lead screw.  But as I tighten them up the friction to turn the lead screw also goes up along with the wear on the screw and nut.  So it's a balance. Accuracy while machining is maintained, by always machining (cutting) in the same direction (in or out, right or left) as you were when you set the zero on you dial.

There are some good YouTube video that show how to work with backlash, much better than I can describe with words.

Here's an example of just one of them:  




As for lathe cutting bits, you could go with a pre-ground set of HSS bits. HSS works better with lower power machines. Pre-ground will get you started with bits ready to cut, while they can be resharpened on a bench grinder. There are also soldered carbide and insert carbide bits.  Little Machine Shop and Grizzly Industrial both have some less expensive sets that are good for starting out.

Hoped this helped.

Continue to ask away, there are lots of talented machinist on this site that will be happy to answer your questions.


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## Geerbangr (Jun 22, 2017)

Thanks a lot Dat!!!


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## brino (Jun 22, 2017)

Hi @Geerbangr,

Welcome to the site!

That lathe is about 3 times bigger than my first metal lathe (Sears/Atlas 109).....and looks to be in much better condition too.

For cutting bits, I use almost exclusively HSS and sharpen them myself.
It is a personal choice, and there are some great discussions here:
http://hobby-machinist.com/threads/lathe-cutting-tools.59874/
http://www.hobby-machinist.com/threads/how-to-grind-a-hss-turning-tool.52581/

It might not have reverse, many hobby-level machines do not.
If in does have reverse and the chuck mounts on a threaded spindle nose, be careful, it could unscrew during use and ruin your day!

Be safe and have fun!

-brino


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## Geerbangr (Jun 22, 2017)

I think I'll get started with hss bits. So the maximum tool size for my machine says 1/2". Would it be fair to say that 3/8" bits would be the best all around size to use?


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## Geerbangr (Jun 22, 2017)

Another question of concern. My tool post has 3 bolts down each side. That let's me set up 2 bits at on time, correct? That way when one bit dulls I can rotate the tool post and resume working with the other bit, correct?

Also, is it common practice to utilize all three bolts to hold the bit tight? With that knowledge I can figure out how short of a bit I can use. My plan is to run hss bits.


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## RandyWilson (Jun 22, 2017)

You can fit four tools in the tool post at once.  This is so you can have four different tools set at the same time.  Tool height is important. The cutting edge needs to be at the centerline of the work.   With that type of tool post, you adjust the height with shims underneath the bit. Using 3/8 rather than 1/2 would mean adding an extra 1/8" of shim under the tool. And you will quickly learn why we spend multi-hundred dollars on quick change tool posts.


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## Geerbangr (Jun 22, 2017)

RandyWilson said:


> You can fit four tools in the tool post at once.  This is so you can have four different tools set at the same time.  Tool height is important. The cutting edge needs to be at the centerline of the work.   With that type of tool post, you adjust the height with shims underneath the bit. Using 3/8 rather than 1/2 would mean adding an extra 1/8" of shim under the tool. And you will quickly learn why we spend multi-hundred dollars on quick change tool posts.





I think reading between the lines it's not s good idea to use shims under a bit? Does a quick change post always keep the bit on the centerline of the work piece? 

Would a wise investment be to purchase a quick change tool post? Is so which quick change would be suitable for my machine?


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## RandyWilson (Jun 22, 2017)

In that situation, shims are a necessity. It's not that it's a bad idea, just that it can be time consuming to set up.  In a typical operation, you'll use one tool to true up the end, another to do the turning, a third to chamfer the ends making them purdy, and a fourth to part off the completed piece.  That's a lot of screwing around with bits and shims. With a QCTP and enough holders, you have all your common cutting bits already set up and adjusted. Changing bits is as easy as flipping a lever, picking off the last tool and holder, then dropping on the next one.


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## Geerbangr (Jun 23, 2017)

Alright you guys are awesome and the info given is much appreciated.  It looks  like a quick change tool post will be the first item I need to gather. 

My lathe is a 10" lathe if I'm reading it properly. So what is a decent brand quick change and what size should I buy? I see several options out there. Pickup one that 10" is in the middle of the area covered or 10" at the highest end or 10" at the lowest end of range? 

All of my bits should be 1/2" bits since the machine is designed for 1/2" bits?


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## WoodBee (Jun 23, 2017)

Geerbangr said:


> Alright you guys are awesome and the info given is much appreciated.  It looks  like a quick change tool post will be the first item I need to gather.
> 
> My lathe is a 10" lathe if I'm reading it properly. So what is a decent brand quick change and what size should I buy? I see several options out there. Pickup one that 10" is in the middle of the area covered or 10" at the highest end or 10" at the lowest end of range?
> 
> All of my bits should be 1/2" bits since the machine is designed for 1/2" bits?


Geerbangr,
The easiest way to start in my opinion is:
- Buy a reasonable set of preground hss tools (as mentioned before in this thread)
- search for a set of shims to get each tool on centre with your current toolpost. Every reasonably flat piece of metal stock is acceptable, sheet metal, snips of soda can, etc.
- keep the shims with the tool. If you want to use the tool you can simply put it in the toolholder with its appropriate shims.
- locate a pdf of "how to run a lathe" on the internet and read it (a real paper one may be a more comfortable option if you can find one)
This book by south bend is a widely adviced "beginners guide to turning"
- find yourself some scrap metal and make "paper weights". Start using your lathe, it is the best way to find out what you need to know and need to have. The only other tools you really need to start is a bench grinder (and maybe a lapping stone) to sharpen your cutters and a few measuring tools (set of calipers and a good scale)
- read on this and other forums, ask questions if you can't find the info you are looking for.
Look on YouTube, there are some great channels for beginners: that lazy machinist, toms techniques, mrpete222 to name a few. Once you get the hang of it, you will find a lot more channels with good metalworking info on YouTube. It is quite an active community!
Learn!

I am sure in time you will add a lot more to this list, but at least you will know what you want and need most.
Maybe you start grinding your own tool blanks (in my opinion a good skill to have), or maybe you decide to join the people who use carbide inserts tooling.
I see a good quick change toolpost in your future, but read around on the different forums about them. You will spend quite some money before you have a set with a good number of toolholders, so you might as well be sure you buy the one you want.
Also I know a calliper is not the proper measuring tool for precision work. In time you will need at least one accurate micrometer (number depending on the size of your work), but you don't need one to get started. Look around, good brand ones in good condition can be found used for reasonable prices.

Start making chips and have fun, that is probably the best thing you can do to get started!

I hope this will help some,
Peter


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## Geerbangr (Jun 23, 2017)

Thanks for the advice Pete!!


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## brino (Jun 23, 2017)

by the way, there are several different revisions of the Southbend book "How to run a lathe" here:

the 3rd edition: http://hobby-machinist.com/resources/sb-how-to-run-a-lathe-3rd-ed-pdf.2890/
the 15th edition: http://hobby-machinist.com/resources/sb-how-to-run-a-lathe-15th-ed-pdf.2891/
the 27th edition: http://hobby-machinist.com/resources/sb-how-to-run-a-lathe-1966-27th-edition-56-pdf.2909/

I have not opened them all to look for differences or find one that is scanned clearly...I'll leave that to you.

-brino


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## Silverbullet (Jun 23, 2017)

Your lathe doesn't have the quick change gear box for cutting threads. But the pile of gears will make it cut most threads you might need. There may be a gear use diagram on the end door of the head stock. Start watching lots of YouTube , Mr pete2  , Keith Rucker, Abom ,lots of others . Mr Pete , Tubalcain is an x shop teacher. You would do well to start with his videos.
Welcome to the site , help is here if you ask.


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## markba633csi (Jun 23, 2017)

Interesting lathe I'd like to know more about it- not often you see a leadscrew with a crank handle on the end, mainly an English feature I think. 
Mark S.
ps looks like chips will accumulate down in the bed under the chuck, you'll need to vacuum under there with a crevice tool on your shop vac


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## Geerbangr (Jun 24, 2017)

My vacuum cleaner is my best friend in my shop, lol. I'm going to pick up a quick change tool post and a fistful of pre ground bits and start making chips once I get back home. Meanwhile reading up and watching YouTube videos on lathe operation.  

Can you guys suggest a decent quick change tool post for me?


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## whitmore (Jun 24, 2017)

Geerbangr said:


> My vacuum cleaner is my best friend in my shop, lol. I'm going to pick up a quick change tool post and a fistful of pre ground bits...
> Can you guys suggest a decent quick change tool post for me?



The Aloris QCTP clones are very popular (CDCO and eBay and other suppliers have 'em).   AXA or BXA series would suit your lathe size,
and those are standardized, easy to get extra holders in future.   Some measurement of the toolpost tee slot will
be required, you have to build or order a suitable tee nut with the new toolpost.  

Two dovetail-tensioning schemes are wedge and piston; I've used and enjoyed wedge-type.

There's another QCTP design that has adherents, known as Multifix <http://www.createtool.com/article.asp?id=41>.

A lot of Youtube videos of lathe work show the quickchange features in use.

No one else has said it, so I'll suggest getting some 1/4" HSS blanks; the grinding time to shape or sharpen  one is much less than
that for a larger chunk o'steel, and as a hobbyist you don't need to produce lots of swarf quick.    It'll be good to get in lots of
tip-grinding practice when learning.


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## BROCKWOOD (Jun 24, 2017)

Welcome aboard!  I am a newbie myself.  1 thing that I originally ignored when setting up my bench top lathe was mounting it solidly to the work table.  As the parts I wish to make increase in size, so does the vibration.  Now that I do have it securely fastened, I'm thinking on how to add a rollcage to further stiffen it.


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## DAT510 (Jun 24, 2017)

Regarding the QCTP..... Most likely you will need an AXA size tool post, but you will need to measure to be sure.  

If you scroll down on the page in the link below, you can see how to measure your lathe to insure you order the correct size QCTP.  The Important Dimension is is the distance from the Centerline of your Lathe, to the Top Surface of your Compound.  That will determine the Size of the QCTP.  Too Big and you won't be able to lower the tool holders enough to center the tool with the centerline of the lathe.  Too Small, and you won't be able to raise the tool holders enough.

http://www.shars.com/products/toolh...quick-change-tool-post-set-wedge-type-111-axa



Caution with the 0.6" dimension listed for "H".  As others have mentioned in other posts, it would require a very thin tool because of the inherent thickness of the bottom of the tool holder.  I'd say on the order of 0.8"+ to 1.75" maybe be a safer range.

I personally use a Phase II QCTP.  I've found them to be a bit more consistent regarding quality than the Unbranded Clones.  I purchased a new set that included 5 tool holders, on eBay for ~$200.  

From the picture of you Lathe, I can't tell how your current tool post is mounted.  There is a high likely hood you will need to do some machining to mount the QCTP to your compound.  In my case, my compound had a large treaded hole, much larger than the post/stud for the QCTP.  I ended machining a double treaded bushing, that screwed into my Compound, and which the post/stud of my QCTP screwed into it.  Other Compounds have Large T-Slots, to which the mounting base of the QCTP is machined to fit.


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## GLCarlson (Jun 26, 2017)

Re tool bits: quarter inch M42 or cobalt HSS. Anything bigger is both overkill and too expensive for that machine. Even 3/16 square is big enough, but quarter is cheap, widely available, and plenty large.

In a tangential holder (just search the forum on that).  A tangential only requires grinding on one face, with a  fixture- eliminates all the magical stuff about grinding 3 angles at once.

And, yes, do bolt it down (and level).


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## Geerbangr (Jun 27, 2017)

Thanks for all the great input fellas. I'm out of town working for another 3 weeks and can't hardly wait to get back home and get started making chips.


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