changing nose

[Swarfing]

Guys

I have a Vernier TV-280 lathe (Metric) that has an A1-4 short nose mount. I need to replace the 160mm 3 jaw as it is knacked (scrolls worn, jaws worn, inner slots worn. I'm having real issue with suppliers not understanding this mount no matter how simple i explain. It is metric, common as muck in the rest of Europe but not here. It has 2 circles of bolt holes and the inner ones are M9 outer M10. The foot print of this mount is the same as an D1-4 so i believe i could use the same backplate arrangement with the cam lock pins removed? not a problem as long as i have a chuck that i can drill through the front and miss the scrolls?

I can not get any of the suppliers to confirm if a standard D1-4 chuck has holes that go from front to back yet all the pics i see show what i believe to be the case. Could somebody with a D1-4 mount with screws showing on the front around the spindle hole confirm whether these holes go all the way through (some chucks don't i know already). The taper on the spigot is the same and the circle is same.

My other option is change the mount to a D cam lock mount but do not know if this is possible without replacing the whole spindle....Please help getting fed up not being able to make swarf 

[Davo J]

I have a D1-4 mount but all my  studs screw in from the back. I would need to be a small chuck to have holes all the way through to miss the scroll.
A back plate mount might be better for you to mount a chuck?

Dave

[bambuko]

I feel some sympathy with the suppliers because they must be perplexed by your question ...
The pics of chucks with bolts from the front that you see are for the "front fitting chucks" - this refers to bolts used to fix the chuck to a backplate. There can also be "rear fitting chucks" were the backplate is bolted to the chuck from behind. These bolts have nothing to do with the studs used to fix backplate to the spindle. The studs used for fixing of the backplate (and the chuck) to lathe spindle are screwed into the backplate from behind. That is, assuming that you use backplate - you can also get chucks with rear ends made to fit directly to lathe spindle without needing backplate, but they are prohibitively expensive.
So in your case, assuming that you want to modify D1 backplate with studs to suit A1 spindle, the only thing you have to is to remove backplate from the chuck and than remove cam lock pins and add four threaded holes on correct PCD to accept whatever studs you desire. There is no need to drill chuck body at all!
Alternatively, you might be able to get backplates from people like Rotagrip.
Here a pic of what I am talking about:


Your new chuck registers on diameter K, and the studs to fix to lathe spindle are screwed onto backplate from the left.
So you fit the chuck to backplate and backplate attaches the chuck to the spindle.
Of course D1 will only have one row of studs (unlike A1, which has two) but it doesn't matter - one lot should be enough.

Hopefully I understood your question better than the suppliers you talked to? and this info helps, but if you need more - shout.

Chris

ps the pic shows backplate for DIN 55027 chuck, but this doesn't matter - the principle is the same for all.

[Swarfing]

Don't worry i have not just relied on my description but sent them the nose data. Look at the link below and what i have is the top one. I did think about mounting up a standard din chuck but the i would have to worry about two lots of bolts when changing chucks which i do frequently. My lathe only has a 27mm bore down the spindle so to get the mounting holes to miss the scrolls is not really an issue. It is all catch 22 with need a working lathe to work a chuck for the lathe i'm working 

http://www.lathes.co.uk/latheparts/page10.html

[bambuko]

That's the whole point - you don't need to miss the scrolls ... and that is what I was trying to explain. Obviously haven't done good enough job. I am not sure that I understand what your problem is ...
Buy a chuck, buy a semi-finished backplate, fit the backplate to your spindle, turn register diameter (to suit the chuck you have bought), fit the chuck to thus finished backplate and Bob is your uncle.
At no point does it involve drilling a chuck, or missing scrolls, or am I missing something?

Chris
EDIT - I think I get it - it's the inner circle of chuck fixing bolts that bothers you? If so, just don't use them

[Swarfing]

Chris the A1 mount relies on bolts through the chuck straight through the back plate and into threads in the nose.

[bambuko]

You are indeed correct - it uses bolt not stud.
I can see your problem now.
Did you talk to Rotagrip (link in my previous posting)?
They are selling A1 chucks.

Chris

BTW A1, D1 etc are imperial in origin not metric (even if your French friends decided to bastardise it by using metric bolts ...)

and that's what you want (or something very similar):



be prepared for £500  

[Swarfing]

Oh yes i saw these hence why i'm trying desperately to go they way of my thoughts. There are quite few different variations but the Europeans (excluding the UK) stuck to the basics in metric form. The d1-4 mounted chucks should have enough meat for me to bolt to the centre circle the same as the one i have. I really need somebody that has these screws on show the same as this one http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=290512794733&ssPageName=STRK:MEWAX:IT (bare in mind i only need an 160mm chuck) to confirm if they go all the way through.

Thanks

Paul

PS the lathe cost me less than that ;-)

[bambuko]

What about getting something like this:



than you can fit any plain back chuck rear mounted to this backplate?

Chris

ps I would double check HBM chucks .... - sometimes it is genuinely cheaper to spend more  
Assuming that your budget extends that far, Vertex would possibly be better, and Bison (Toolmex) or TOS would definitely be better choice?

[Swarfing]

Chris i appreciate the sentiment but i have an independent for four four jaw that mounts directly to the nose already. If i could i wold love to change the nose for a D1 mount to make life even easier but without making one (which i still might do) are hard to come by. Because the nose is very flat against the machine i could afford to bolt the mount directly to the existing A1?

[bambuko]

...Because the nose is very flat against the machine i could afford to bolt the mount directly to the existing A1? ...

I am not sure I follow you?

...If i could i would love to change the nose for a D1...

I doubt it can be done easily.

...I can not get any of the suppliers to confirm if a standard D1-4 chuck has holes that go from front to back...

Even if it did, why do you assume that they would be on correct (for your purpose) PCD?
No supplier will get involved in your mods - the moment you start drilling their product, you are on your own.
D1 chuck you linked to (from RDG) is camlock fitted. It will definitely not have any bolts fitting it from the front through the chuck body.

...i have an independent for four four jaw that mounts directly to the nose already...
...getting fed up not being able to make swarf ...

If you have four jaw chuck, than there is nothing stopping you making swarf - you will just get more practice setting things up in four jaw 

Chris

[Swarfing]

I hear you Chris and your right in all aspects but if i want to keep the cost down then i have to do what i need to do. The PCD of the cam lock pins is the same as the old holes of the A1 if i was to go for a purpose D1 chuck (hence the need for the bolts to go all the way through). The link i showed before for the D1-4 chuck clearly shows bolts on the front next to the bore. What are they for if nothing to do with the cam lock pins? if they are for the cam lock pins then i have my bolt holes through the chuck? The other option is as you have pointed out is to spend the money. The reality is this is a high precision lathe which i bought and put back together on a shoe string budget. I've been waiting over five weeks to make some proper swarf with it and it just gets a bit frustrating.

Image of chuck in question is the 160mm

http://www.rdgtools.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww.rdgtools.co.uk%2facatalog%2f3_JAW_LATHE_CHUCKS.html&WD=8756841f25&PN=D-14_CAMLOCK__M300___COLCHESTER_STUDANT__MASTER_.html%23a8756841F25#a8756841F25

I pulled the back plate off the original three jaw tonight to see if i could do anything with it and who ever fitted it originally did a bad job. The holes were drilled through from the front of the chuck and they do not line up at the back with the nose properly. All for the bin..............

[bambuko]

...if i want to keep the cost down then i have to do what i need to do...

I definitely understand  

...The link i showed before for the D1-4 chuck clearly shows bolts on the front next to the bore. What are they for if nothing to do with the cam lock pins?...

They are nothing to do with camlock pins. Normally chuck is made in two pieces and these bolts are there to hold the two halves together. On chucks where you don't see them at the front, they are simply done from behind:
For example, bolts in the front:

Bolts (9) are holding together front (1) and rear (2) of the chuck.
This is an example directly mounted short taper spindle chuck. Bolts (8) could be replaced by camlock pins.

Or another example, bolts from behind:

Again, bolts (9) are holding together front (1) and rear (2) of the chuck.
This an example of plain back chuck, requiring backplate to fit it to the spindle.
Backplate, in this example, is fitted from the back using bolts (8).
Often/sometimes these bolts (8) are fitted from the front.

You will see from this (I hope) that PCD of the bolt heads you see on the front of the chuck in picture you have linked has nothing to do with your needs and is entirely at the discretion of the chuck designer. You might be lucky, but than you might not, plus you can't remove them anyway, or your chuck will fall to pieces   (unless you introduce another way of holding the two halves together?)

...this is a high precision lathe which i bought and put back together on a shoe string budget...

Yes this is very nice lathe indeed, I am envious  

...I've been waiting over five weeks to make some proper swarf with it and it just gets a bit frustrating....

I understand your frustration, but if I were you I would get on with using four jaw chuck, which I understand you have?

I pulled the back plate off the original three jaw tonight to see if i could do anything with it and who ever fitted it originally did a bad job. The holes were drilled through from the front of the chuck and they do not line up at the back with the nose properly. All for the bin..............

Why should it be for the  bin? Holes in the backplate are just clearance, just open them up. Location is provided by the spindle taper, bolts are just used to secure it on the spindle not to locate it.
I am not sure I understand you here?

Chris

[bambuko]

Hi Paul,
In case it helps you - I have taken apart my D1-3 chuck and taken photo:



This particular one secures rear half with bolts on the outside perimeter, so it should be possible to do what you were planning.

Chris

[Swarfing]

Hi Chris thanks for that and just to let you know I've made an adapter plate to fit between the back plate off the old chuck and my chuck from my old lathe. Interestingly i made it out of fibreglass and it works a treat. i will just have to keep my eyes peeled for a proper job. Your pic though does show that it would be possible to covert your chuck to an A1-3 mount.

Thanks for the help.

Paul