Ok,so I've bought me a DTI,however thats fine for round bar material but...
Square block material hows that aligned? same procedure for round bar?
Cheers :wink:
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Ok,so I've bought me a DTI,however thats fine for round bar material but...
Square block material hows that aligned? same procedure for round bar?
Cheers :wink:
Hmmm,no answers as of yet.
The only way I can think of centralising a square block is drawing a diagonal lines across its corners and finding the center,then slip it in the chuck.
Stick a center in an arbour on the tailstock,offer up the tailstock to the workpice and adjust the center mark on workpiece to align with center.?
Pretty much. You need to ensure the DTI is dead on centre then compare opposite faces by rocking the chuck for a minimum readingQuote:
Square block material hows that aligned? same procedure for round bar?
It is easier and more accurate if you trap another lathe centre between the tail-stock centre and the centre-punch dot, then set the DTI on the trapped centre (alternatively make yourself a wiggle centre like this - http://www.frets.com/HomeShopTech/To...glycenter.html)Quote:
The only way I can think of centralising a square block is drawing a diagonal lines across its corners and finding the center,then slip it in the chuck.Stick a center in an arbour on the tailstock,offer up the tailstock to the workpice and adjust the center mark on workpiece to align with center.?
[edit] There are some real gems on Frank Ford's site, well worth reading.
Bill
Thanks for that,Bill.
Will have a look through that site.:clap:
As mentioned above, here is a picture of the operation.
This can be used to centralise any pop mark in the four jaw.
Using two centres, one in the tailstock, and one between the tailstock centre and the pop mark. Then use your clock on the centre that is suspended in the middle.
http://i202.photobucket.com/albums/a...s/rotbore6.jpg
You should find all good centres have a centre location in the small end, even ones with tangs on, and everyone should have two centres with their lathe, one for the tailstock, one for the spindle. Don't try to use a 'live' centre for the middle one.
Hope this explains it OK.
Bogs
Thanks Bogs.
No need for a big rod then. :wink:
Was going to email the bloke and ask him where he found his big rod. lol
Thats Bill, John, another techniqe to add to the list...A picture is definatly worth a thousand words
Ain't it just. :wink:
This was shown to me about 40 years ago, and I took the shot during one of my builds, about three years ago.
People do have a tendency not to look to the past, but look around for modern marvels to solve a problem.
I used to go around boot sales looking for old engineering books. A 20p book from the past has solved many of my problems up to now, and will carry on doing so into the future.
Try it sometime, you will be amazed at what you can pick up, information wise.
There is very little new any more in setting up machinery and jobs, most are old ideas, brought up to date, and charged big bucks for.
Oldies but goodies.
Bogs
Very true that Boggy.
As the old saying goes...you cannot teach an old dog new tricks..or words to that effect. :wink:
We are well into the future and yet we're still riding round on four wheels that was born in the fourth Millenium BC. lol
That's Mr Tandard to you, young whipper-snapper :LOL:Quote:
Very true that Boggy.
The Hardinge HLV-H (Frank has a Sharp copy) tail-stock weighs about 35-40kg (about the same as whole of your clarke lathe) and, with 50 odd square inches of base, tends to 'stick' to the bed, making it a right b******d to move - So, you don't move it unless you have to, that's why Frank's has a big rod ;)Quote:
No need for a big rod then. :wink:
Was going to email the bloke and ask him where he found his big rod. lol
http://www.mycncuk.com/forums/attach...2&d=1237608237
I just use a DTI?
Why the question mark?Quote:
I just use a DTI?
I was wondering what I was missing. Why pop the centre and use a pair
of centres when you can use a DTI? I have a few minutes I will set up a bit
of square and try and make a video if anyone wants to see it.
We're all eye's...well I am anyway.Quote:
try and make a video if anyone wants to see it.
I set up a chunk of square, actually took longer to find a bit than
to set it up. The video is really crappy, I know what's going on cos
I was there;-) Holding a camera and doing something is too difficult
for me.
You should aquire a tripod then.:smile:
I did try with a tripod, the lathe has a window behind it and all you could see was the sillohette of the gauge;-)
What it needs is a flexible, but lockable, arm to mount the camera on.
Seeing the marking on a DTI isn't easy if the picture shows much of whats going on. I did a video of a gear that
had runout, to show the people who supplied it, I used a 4" face gauge so you could see it. I don't think I can use
the big gauge to set a square as it probably won't clear the corners.
So your using the corners as a means to centralise the block?
Moving the corners would be to complicated for me;-) I set up the flats.
What if we have 3"x1" block :smile:
It will only be a 3" x 1" block twice per revolution, the other two times it will be 1" x 3"Quote:
Originally Posted by GeorgeD
.
It's also √10" now and again.
Mr S got a couple of inches of 1" diam EN36 going spare?
Think so, check tomorrow, it's dark now and that workshop is bloody haunted.
.
Had another go with a camera, not a very good video. I usually set up
a lot faster and don't talk bollocks while doing it;-) I will have to have another
go, I can't understand why it was so dificult.
http://www.youtube.com/watch?v=2CJNEyy3QiY
Thank you.
I thought that was excellent, mind you I am a computer programmer ;-)
It is possible to set a bar up in a 4 jaw chuck to 2 thou easily or 1 thou with a bit of care using no specialised equipment at all.
Works on square, round or rectangular all the same method.
First thing to remember when using a 4 jaw independent chuck is to forget it has 4 jaws and tell yourself it has two sets of 2 jaws even to the point of marking opposite jaws with a different coloured marker pen.
On the front of a 4 jaw chuck is a series of concentric rings these are guide rings so you can line opposing jaws up using the rings for a guide, some of the cheaper, smaller chucks may only have 3 or 4 rings on, widely spaced.
There is no reason why you can't remove the jaws and turn some intermediate rings on with a Vee shaped tool.
Now put your piece of material in the chuck, we will assume it's square although the operation is the same for square and round and only slightly different for rectangular.
Using opposite jaws just nip the work up trying to get the ends of the jaws in the same position relative to the rings, this should get you within a post code of centre.
Now take any lathe tool and turn it round in the holder, blunt end out. This is your secret weapon, everyone has one of these but mat not have a dial gauge or other expensive toys.
Now with one face of your square bar vertical wind the blunt end in until it touches the bar and note the reading, if you can, zero the dial, now retract, turn half a turn to the opposite jaw and wind in to get a reading.
If you are dead lucky both readings will be the same, chances are they will differ by 10 thou or so. In which case work out the low side, that's the side you have had to wind in more and you will need to slack this jaw off a tad and tighten the opposite one up.
Repeat taking the readings on these two jaws, forget the other two, until the reading is the same on both sides.
Now deal with the other two jaws, this is easier as you know what the reading should be from the first two unless it's rectangular and you will have two different readings.
Sounds a bit long winded but believe me it takes far longer to type this than do it, after a few goes it's easy to get to a thou by this method, if you want better then break out the DTI at this point.
The main thing is to remember to just work on a pair of opposite jaws, beginners make the mistake of trying to work all 4 jaws at the same time which together with inexperience causes untold problems.
lolQuote:
I usually set up
a lot faster and don't talk bollocks while doing it;-)
Try using two chuck keys to centralise,saves alternating between jaws.
To be honest I'm thinking the centers approach to this will be much easier,until I get the lathe then I won't know?
:wink:
Whats the name of those hollow tubes that you insert into the chuck for protection of the workpiece? ie supposing I want to turn the end of a threaded rod from 10mm down to 8mm I need to protect the thread from damage,whats the insert called?
I think there is no one 'right' way, it all depends on the job. The centres approach works ok if you are trying to centre a flat end face but might not work if the item has any shape on the surface. JohnS' approach works well and i use it, especially if you want to reduce square to round or the surface finish is so poor that a DTI would give fluctuating readings. A DTI approach works well in most circumstances but involves a little more setup effort in getting the DTI out and in position, and is the only truely viable approach when you want to centre a bore in the chuck irrespective of the external shape and particularly when the bore isn't central with respect to the outside edges.
soft brass shim, or even thick paper will do the jobQuote:
Originally Posted by GeorgeD
Nope,that brings up all manner of shims except the name of the item I'm looking for.Quote:
soft brass shim
Can't find the youtube vid where the bloke propely named it befoe he used it on the lathe.
Oh bugger,I only need a soft metal tube near enough the diameter of the threaded rod then use a slitting saw to slice it tdown the middle. tsk!:rolleyes:
I don't know about tubes, I always cut up an aluminium soft drink can into strips with a pair of scissors, to put between the jaws and the job to prevent bruising.
Bogs
Would a collet be any good? (5C type etc)
I suppose its name is that of a collet since its a sleeve with a slit in it,made one out of a bit of 15mm copper piping...very easy to do. :whistling:
Hopefully my new toy turns up tomorrow,can't do any weldin today...its hissing down here. :mad: