Chinese Lathe CO6230A

[Davo J]

That question has been asked many times over the years, but no one seems to know the answer.
If you search for cat head you will get a lot of hits from gun builders, as this is what the usually call them. That is if your talking about a circular piece with 4 threads in it, to centre the barrel in the out board end of the spindle.

Dave

[DaveH]

Gerry.

Don't know if this will help.

http://www.projectsinmetal.com/a-rear-spider-nut-for-the-grizzly-g0602-lathe/
 
DaveH

[John Hill]

That threat on the end of the spindle can be useful. 

I made an indexing attachment which screwed in there locking a change gear to the spindle but what I would really like to do is use that thread to push on the draw bar to eject a tight taper rather than banging on the spindle.

[GerryB]

G.Day Guys
Thanks for the information.
I do not know if i have got this right but the threaded tube in the  info. seems to be threaded on the outside where as mine has an internal thread with a shoulder. see photo.
If i make a suitable 'Cat' chuck it will be sticking out from the end of the tube,which may be ok.
GerryB

[Davo J]

That link made me look twice as well, but it is a smaller lathe and a different set up.
Mine has the same internal thread and I have seen a lot with cat heads threaded into them, mainly on the gun smith sites.
They usually stick out past the end of the spindle about an inch and have the 4 threads tapped in from the sides. Being an extension off the end will let you be able to keep the gear cover on the end, instead of having to remove it.
With the threads/bolts for them, I have seen where guys have drilled into the end of the threads/bolts and made up brass tips similar to a mushroom shape, to be pressed into them to save marking your job.

Dave

[GerryB]

G.Day Guy's.
Well as they say one thing leads to another.
I had just received from the USA a set of three milling cutters,called the Little Hogger Mill Set.
Just the job only in my enthusiasm i forgot to take note of the size of the Shank which is 3/4".so did not order a holder to suit.
Now my mill holders only accept shanks up to 5/8",
So select a suitable piece of MS and start turning a Three Morse Taper and drill and tap for the Draw Bar.
Now comes the crunch,how am i to secure the item when reversed, in order to bore out the end to accept the Mill Cutter.
What i needed was a Draw Bar assy fitted in the Head Stock.
I had a Draw Bar fitted to the Mill so removed it and weighed up the pros.etc in order to fit it to the Head Stock.
First find a suitable piece of round MS which i just  had.
Set it up in the three jaw and begin to machine and cut a thread 1.5mm pitch.
I realise that the thread is quite fine for the dia,so i cut the thread to a loose fit so that if swarf should get in the thread when fitting it will not cause the thread to seize up so easily.
I also imagined that when left in place for a long period it would be prone to be a little hard to remove so i cut two slots to accept the spanner supplied with the Clarkson Autolock.
I set it up to bore the hole required for the new milling cutters and bingo,all was perfect.
So now i have the milling cutters i wanted and found a use for the thread in the end of the Head Stock Shaft.
I am now in the throws of designing a suitable 'Cats' Head.
GerryB

[Fergus OMore]

Hi Gerry,
               I've been trying to find details of cat head chucks but so far, without much success.
That is not quite true, because  I have the Holzapffel books on Turning and Manual Manipulation which has a drawing of one in use.

For those who don't know who Holzapffel was- and want to read it all, I commend it for Christmas, and next one and so on.

So, Gerry, with the aid of modern technology-- fingers crossed!

[GerryB]

 
G.Day Guy's,
Sorry,but i forgot to inform you as to what were the two different ends in the last photo.
Well when i measured the length needed for the unit i had machined to take the Draw Bar i had a little over 1 1/2" to cut off.
Not the one to waste anything i enviseged that maybe in the future i will wish to hold some other unit in the Morse Taper and that the length of the Draw Bar is too long so i cut the 'off cut' to two sizes,like big washers  and that is what you see either side of the finished threaded plug (for want of a better disscripsion)
GerryB

[Fergus OMore]

I sent TWO copies of the Holzapffel page.
Can you confirm receipt please?

[GerryB]

G.Day Norm.
Yes i have received the two copies you sent me but the trouble is i cannot relate them to the making of a suitable 'Cat Chuck'
Have another look and maybe you can put me in the right direction.
GerryB

[Fergus OMore]

Regarding cat heads generally, these are pretty crude affairs and  could be made out of a bit of piping with 4 or more securing bolts- and probably held by an other chuck( perhaps a 4 jaw).  In a bygone era- and in today's woodworking on the lathe, the odd shaped object could be secured with wooden wedges! It still goes on but daft modern engineering books seem to have lost sight of them.

In my own modest little workshop, I've got an independent 3 jaw chuck as well as a little 4 jaw and I have watchmakers chucks that have recessed rings to nip round thin discs. If you plough your way through a lot of ancient British stuff( 1950's), you will find things like slotted face plates to hold exactly what you want to hold-- awkward shapes-FIRMLY. Moving on a bit( sorry to bore some), watchmakers used glue mixtures of rosin and shellac to do this.  You know odd castings hold very well in a bit of piping with the space filled with car bodge to hold everything in place. You don't run around and tell your critics how you did it-- because they might have a more elegant solution- to what is dead simple

Hope that helps a bit

[Fergus OMore]

I continued my search and simply Googled 'Cat Head chucks' and this came up on HomeShop Machinist where a firm was using a simple bit of piping and screws to hold an awkward shape to rotate in the fixed steady!

As as sort of addendum, Robert H Smith's Advanced Machine Tool Work is available FREE on the net as well as a reprint by Lindsay Publications.

On my copy page 6-28 there is a a write up on the cat head and diagram on his excellent but dated book.

As we - were on about tool and cutter grinding- there is an excellent set of maths on page 8-13 about getting clearances in grinding.

For those who dont know how to set the height of the grinder to grind tool angles- this is IT

578 FREE pages - now that's a bargain.

[andyf]

To prevent the outboard end of long stock which passes through the spindle flexing and flailing, , I just use a simple wooden V block fixed to the bench. Once something starts flailing, it rapidly gets worse, but a V block seems to be enough to prevent this, and wood leaves the surface relatively unscathed.

Andy

[Miner]

Fergus,
Thank you for posting that, There's a lot of great information in that. Very much appreciated.

Pete

[Fergus OMore]

Agreed about 'Smith' but I am wondering about Holzapffel and wondering whether these so classical books are also Freebies.I suspect that they are. OK, I'm hogging Gerry's posting but Gerry is is building a tool and cutter grinder so does he know what a Goniostat is? I ran a copy off  about a recent copy that someone from  the Society of Ornamental Turners site had made.

Hope Gerry approves?

[GerryB]

 
G.Day Each,
'Goniostat'! not a recognised word.
I have a couple of Mates who 'Cut' Gem Stones for something to do and they use a gadget that angles the unit at various angles in order to face the stone which is being cut according to its crystal layout.
I think we are going off on a tangent away from the 'Chinese Lathe' issue and may loose some of the Guys interested in the original issue.
So i am asking politely to refrain from heading off in different directions and to keep to the original theme.
GerryB

[GerryB]

G.Day
 Each,
Well i hope its a good day for you,its 37oC at the moment so its too hot
 to go into the oven(shed)
Also i tried yesterday to send this post but nothing seemed to happen
when i hit the 'Post' button.
Now i realize that the server could be having problems,but why do i
loose every thing including the attached photos?
Any way here goes again.

I did scan the various leads given me as to the 'Cat head Chuck' issue
but had no luck,maybe i was not doing it right.
So i decided to make a suitable unit to do what i needed,not too
difficult,actually quite easy.

I fount a suitable piece of MS 2" X 4".
Chucked in the Three Jaw and reduced an inch at one  end to 42mm,then
cut a thread 1.5mm pitch.
Removed and tasted in the Head Stock for fit,perfect.

Re chuck and bore out the centre to a suitable size.
When setup to bore i placed a stop on the Bed Rails to stop the cutter
1mm from the face of the Chuck.
I did not want the cutter coming into contact with the Three Jaw
Chuck,also it prevented Swarf building up in the Chuck and made a nice
wall to keep the Suds in play during the boreing.
Once i had finished boring out to a suitable size i reversed the item in
 the Three Jaw and cut off the 1mm blank from end.
GerryB

[GerryB]

Sorry Gentlemen but i am having problems including Photo's with my Posts.
GerryB

[GerryB]

I have reduced the size of this photo so here goes.
It is the first set up of reducing the Dia to 43mm and then cutting the 1.5mm tgread.
GerryB

[GerryB]

It would seem that i will have to set up each Photo individually at the moment as it will not accept more than one at a  time.
The second Photo shows the set up for keeping the Boring Tool from coming into contact with the  Chuck.
I have secured a Saddle Stop on the Bed Ways.
GerryB

[GerryB]

This one shows the set up for Boring

[GerryB]

And cutting off the 1mm end.

[GerryB]

Now i decided that i would use an Adjustable 'C' Spanner that i have so its on to the Mill to cut some slots.
I know that i could have just drilled a couple of holes suitably placed and used a Tommy Bar but then what would i do with my nice Adjustable 'C' Spanner?No do not answer)
I also decided that i would use 4 6mm Alan Cap Bolts for the adjustable Claws (well it is a Cat Chuck)
I found 4 suitable bolts and decided to fit Copper Pads to the ends that are in contact with the work so as not to mark the item being held.
Of cause you do realise that it only supports an item and rotates with the same,not like a Fixed or Traveling Steady.
There is also plenty of room to fit other Claws.
I envisaged using 1/4"x40tpi which would help in setting up to Thous of an inch.but that may come later.
The last Photo shows the completed unit so it now waits for the Barrel set up for which i built it.
GerryB