Simple lathe tool ??'s

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MarkinMI
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Location: Northern, Michigan

Simple lathe tool ??'s

Post by MarkinMI » Mon Nov 05, 2007 4:53 pm

I've been doing some reading and trying to get an understanding of what the various tools are for a lathe. So I'm in need of some simple explaination or maybe even a picture so I can visualize them.
I've read posts suggesting the use of a "CATHEAD" and a "SPIDER" in some lathe applications. One person says he makes his own as they are simple and easy to make. I've looked in the Enco catalog and find niether of those things listed. So my simple question is: What are they and what do they look like?
Also, I have a 9" South Bend lathe. I'd like to get some collets. Can you tell me what size collets that lathe takes? (if someone has an Enco catalog, maybe even tell me what page they are on and which ones)
Thanks! :)

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millman5
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Re: Simple lathe tool ??'s

Post by millman5 » Mon Nov 05, 2007 5:49 pm

MarkinMI wrote:I've been doing some reading and trying to get an understanding of what the various tools are for a lathe. So I'm in need of some simple explaination or maybe even a picture so I can visualize them.
I've read posts suggesting the use of a "CATHEAD" and a "SPIDER" in some lathe applications. One person says he makes his own as they are simple and easy to make. I've looked in the Enco catalog and find niether of those things listed. So my simple question is: What are they and what do they look like?
Also, I have a 9" South Bend lathe. I'd like to get some collets. Can you tell me what size collets that lathe takes? (if someone has an Enco catalog, maybe even tell me what page they are on and which ones)
Thanks! :)
I have no idea what a "CATHEAD" and a "SPIDER" may be....... Need more detail.
To use collets you need some sort of a collet chuck. here is an example for a 14 X 40 Grizzley lathe http://www.grizzly.com/products/h5948 There are many different designs of collet chucks/closers. A collet chuck will limit you to fairly small dia. Especially on a 9" SB lathe. If I'm not mistaken The SB also has a screw mount spindle. In my opinion the least favorite spindle that can be had for making chuck changes easy.

You might want to consider a 6" 6 jaw scroll chuck for your 9" SB lathe. It will be more universal in its usage. It will hold work almost as secure as a collet.
If it works Don't fix it....

440roadrunner
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Post by 440roadrunner » Mon Nov 05, 2007 6:26 pm

My understanding of a cathead is this:

It is not necessarily a specific tool, but rather manufactured for the job. My understanding is that it's a sleeve which you can fix/ setscrew/ clamp to the work, and use then as a bearing surface which can be used with your follower or steady rest.

My understanding is that this would provide a bearing surface, or I guess even a tailstock center for irregular shafts or even tubing.

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MikeC
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Post by MikeC » Mon Nov 05, 2007 7:14 pm

440 is correct on the cathead. It's just a cylinder with setscrews, usually three (for triangular or hex work) or four (for square, octagon or round work) in each end. The screws are clamped onto a part that is not round or is rough, so that it may be held in the steady rest. It can be zeroed out like a four jaw chuck to run the work true. Definitely a shop made item and one you may never need but once or twice.

I am just assuming the spider would be the opposite, a part to go inside hollow work to allow the tailstock center to be used. It could be designed to accomodate odd shaped parts as well. I have made such an item to turn tubing when a pipe center was not available by machining a step that would fit tightly in the tubing on round stock, then centerdrilling and cutting off a piece to stick in the end.

I think the collets for the Logan 9" were 3TC, a shorter version of the 3C. I think that's the same collets for a SB9. In addition to the collets, you'll need a holder that goes in the spindle nose, the drawbar that pulls the collets into place and a spindle nose protector, which screws onto the threads of the spindle and keeps them from getting ruined in case of a bump while running the collets. There should be tons of this stuff on Ebay for a pretty reasonable price. You don't want to buy new collet sets if you can avoid it. They can get really expensive.

As mentioned, the factor on which collets set to use is the taper of your spindle nose (3MT?), length of the spindle, and the diameter of your spindle hole (3/4"?). A quick search should tell you what you are looking for and Ebay should have piles of it.

Mcgyver
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Post by Mcgyver » Mon Nov 05, 2007 7:17 pm

a cathead is sort of a homemade 4 jaw chuck, where each jaw is instead two bolts in line in a steel ring. easier to understand with a pic, quick google didn't turn anything up. think if you needed to machine a big steel tube and needed tailstock centre support, you rig up a cathead inside the end of the tube.

A spider is a spacer the fits between the three jaws on the chuck, acts as a parallel to the chuck body so you can face thin stuff.

I haven't seen a cathead available commercially but I've seen spiders. Both are simple home built apparatus however so unless time=money (a business) I think most guys make them

edit OOOOPs, I'm wrong on the spider, been calling it that incorrectly for years. :oops:
Last edited by Mcgyver on Mon Nov 05, 2007 7:26 pm, edited 1 time in total.

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Lew Hartswick
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Post by Lew Hartswick » Mon Nov 05, 2007 7:17 pm

I just made a "cathead" for use at the chuck end to avoid installing a 4
jaw chuck (it's a monster) . They are normally used at the tailstock end
along with a steady rest to handle odd shapes. The one I mead can be
seen at: http://home.earthlink.net/~lhartswick -look at the entry labled
"cathead" (what else) :-)
...lew...
Oh ps. a "spider" is used behind an object held in a chuck to "index" it to
the chuck face. ie. keep the back face parallel to the chuck face.
..l..

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MGREEN
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Post by MGREEN » Mon Nov 05, 2007 8:42 pm

MarkinMI,
Click this link to see a short video of a cathead that I
made for a particular freebe job.
The set screws bear down on the out of round
workpiece inside of it, and the screws are adjusted to
get the outside surface of the cathead to run true with
the center axis of the lathe, which then allows the steady
rest to keep it located so that work can be performed
on the "free" end of the part.
If that's clear as mud, then the video should clear things up.
http://s34.photobucket.com/albums/d140/ ... CF0507.flv
Mike Green

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MGREEN
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Post by MGREEN » Mon Nov 05, 2007 8:44 pm

Here's a stillshot of the cathead.
Image
Mike

geraldvowles
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Post by geraldvowles » Mon Nov 05, 2007 8:56 pm

I'm about a year into home machining and I kind of figure that I'm far from ready to start getting involved in accessories that are so specialized that I'd have no choice but to make them myself. I've still only tried a very small percentage of commercially available tools and accessories and have my hands full. The exception to that is learning to grind HHS tool bits and get better at setups (clamping). Maybe because I used to be a teacher, I worry about the problems that most often come with taking on the "fancier" stuff right away without having a good basic foundation of knowledge and skills to build on. I think that's why apprenticeships were (maybe still are?) based on years rather than weeks or months. Then again, I could be slower so don't just take my word for it. :roll:
I'm not meaning to be negative by the way.
- Gerry
A Legend in His Own Mind

Jose Rivera
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Location: Vallejo California

Cat-head

Post by Jose Rivera » Mon Nov 05, 2007 11:11 pm

Nice looking cat head there !!

A cat head is used when the material needs to by supported by the steady rest but the material is not round enough to set the steady rest right into the part.

The part may be hexagonal, a forging or any other non perfectly round shape.

The cat head will be inserted into the part and then the steady rest will have a round surface to do it's work.

Is more complicated than just that, since it needs to be indicated to run true.
If the cat head wobbles then this will be transfered to the machined surface.

I have used very large cat heads used for machining large ship shafts forgings during my apprenticeship and got my journeyman's medals doing that.

These shafts where anywhere from 7" to 13" in diameter and from 12 to 60 feet long.

Without a cat head is impossible to machine something not round to start and specially so long.

Those shafts weigh as much as 26,000 lbs.

The lathe was an American with a 58" chuck (would swing 58") and the bed was 65 feet long with three large steady rests.

Right after finishing machine tool classes a the Long Beach City College, the first night at work for Jorgensen Steel they put me on this lather and the two guys on night shift had a ball with me.
I had only run 10" South Bends at school.

Ohhh ! the good old days !!

After about five years I started to get skittish handling such large and heavy parts and moved on to better pastures.

I still would run that machine if I had to.

Now I seat on my behind mostly staring at the monitor, but spend about 50% of my time in my home-machine shop.
The only big part now days in my life is my behind :-)

Skeeter5000

This is a spider that I made

Post by Skeeter5000 » Tue Nov 06, 2007 12:21 am

Her is a picture of a spider that I made. It is a simple chuck for the spindle to support and help center a long shaft and to keep it from whipping.

This is for the 12 x 36 HF lathe.

Image

Image

I am not a machinist, but did make this.

:D

Jose Rivera
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Being a machinist

Post by Jose Rivera » Tue Nov 06, 2007 12:34 am

Hey !

Nothing wrong with that !!

Who said that being a machinist and been creative did not go hand and hand ?

I may even steal your idea and make me one ! :-)

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