Numptie newbie questions

[AdeV]

I have a couple of Q's, one which just bugs me, and one is a question about making stuff...

Q1: Why aren't lathe dogs counterbalanced? Surely, you always want them to run in balance, so rather than having to counterweight the drive plate, surely it'd make more sense if the dog was properly balanced?


Now, making stuff..

Q2: My as-yet "not here" lathe has, according to the info on lathes.co.uk, an awkward and non-standard chuck mount:

Unfortunately the spindle nose was not an industry standard type but formed with a bolt-on flange - three 17/32" holes on a 4.75-inch pitch-circle diameter - so making chuck replacement a slow and tedious business.

I'd like to convert it to use a D1-4 (or similar) camlock, because that looks like a nice way to change chucks/faceplates quickly, easily and accurately; and there should be a wide variety of options, wheras I bet trying to find an Edgwick chuck, faceplate or drive plate would be a tedious job.

Would the conversion simply be a case of machining up a suitable adapter to bolt to the Edgwick and a camlock backplate? Or is it even easier than that, requiring just the drilling & tapping of a machinable camlock? I've googled without much success for a suitable camlock "back", any ideas where I could get one from?

Sorry for the numpty Qs... but I'd rather ask idiot questions than remain an idiot.

[bogstandard]

Ade,

What you are contemplating is surely feasible, but getting the bits might be a problem.

Unless you can find someone breaking a suitable mount lathe, then it would be a matter of making say a D1-4 mount yourself.

Bob Deere (deere_x475guy) has made one fairly recently for fitting onto his rotary table. I am sure he could give you the ins and outs of that exercise.

http://madmodder.net/index.php?topic=1350.0

If that would be too much to attempt, then maybe one of the larger screw fixings would do you. Boxford springs to mind.

A few lathes use that standard and things such as ready made chuck backplates are very cheap, around 15 squid for a 6" one, whereas the last  one I bought for my D1-4 mount cost me over 40 squid. Making an adapter mount in Boxford standard would be a fairly easy affair, if you have the wherewithall to do it.


Bogs

[AdeV]

Thanks Bogs, for the comprehensive reply. And the pointer to the thread, which didn't come up even when I searched ?

I think I could make the mount myself, if I understood how it actually worked. It would probably behoove me to go look at an actual camlock mount & chuck, so I get some idea of what I'm trying to achieve...

A screw adapter would certainly make sense, albeit (maybe?) at the cost of spindle capacity. Also, am I right in thinking that it's pretty unwise to run a screw-on-chuck lathe backwards? On account it may unscrew itself?

Thanks again, I will owe you  if you keep answering my questions 

[bogstandard]

Ade,

It is not surprising, but I have never heard of the lathe you are about to receive, so I wouldn't know about spindle bores etc, or whether the lathe has reverse or not.

What you have to think about is that a threaded nose has been with us almost since the beginning of engineering lathe time, and has stood the test of time rather well.

My previous lathe was an Atlas, which had the same nose thread as a Boxford, and that stood me in good stead for many years, and it had a normal 3MT up the spout. The only time I needed to run in reverse was when screwcutting metric threads, and so it never had any speed on it, as I was using the back gears.

On the other hand, I am now using D1-4, and it is a true pleasure to use, less than a minute to change a chuck, and you can go from full wack fwds to full back without having to worry about the chuck coming loose. Also they remount very accurately if you have taken the trouble to mark up your chucks on the optimum location, plus of course, even on a smallish lathe like mine, it has a very useful large spindle bore size.

I am sure if you could wake Bob up from his hibernation, he could give you all the details you need to know.


Bogs

[DeereGuy]

Hi all, I am at work and don't have much time to reply.  AdeV I will try to help you out as much as I can.

[AdeV]

Hi all, I am at work and don't have much time to reply.  AdeV I will try to help you out as much as I can.

Thanks Bob, it's much appreciated 

I don't have the lathe yet (next week - I can barely contain my impatience...), once I have that I should be able to start thinking of dimensions, etc.



An unrelated question for anyone: In the picture of the lathe, it can be seen with the 3-jaw chuck clamped in the 4-jaw. I didn't check when I looked @ the lathe to see if it was clamped in hard or "just nipped up" for transport. Ordinarily, if dialled in properly, would it actually be safe to run a 3-jaw in a 4-jaw? My gut says "no"... but I wonder if someone got bored with changing chucks all the time & came up with this as a "wizard wheeze"...

Pic showing 3-jaw in 4-jaw:

[NickG]

Looks scary to me! The lathe looks a really nice sturdy bit of kit though. 

[bogstandard]

Ade,

It certainly can be used that way, and is often used for producing a lot of the same offset components.

Once you have set up the first one in the three jaw and set up the four jaw for doing the offset, rather than having to set up completely over and over again, the three jaw is just slackened off and a new part to be machined fitted.

Also, if you are using say hex bar, it can be difficult to hold in a four jaw, so mounting it into a three jaw first overcomes the problem.

I hope that explains it OK


Bogs

[AdeV]

Nick - it looks even sturdier in the flesh  I knew (logically) it was a big 'un when I bought it.... but (like the Lister CS's) I was slightly surprised about just how big! Lucky I have plenty of room really...

Bogs - that's an excellent explanation, and makes perfect sense. I guess the rotational masses would demand a slow speed - those chucks aren't light - especially if the 3-jaw is off-centre. I must admit, I'm not sure I'd have thought of that as a work holding solution, had it not been set up like that already.

[sbwhart]

Some chuck have a safe maximum speed stamped on them.

Cheers

Stew

[NickG]

It looks very similar to a Lang we have at our club - massive!

[Krown Kustoms]

I have been threatening for a while to buy a 9 x 22 lathe, I was also debating on holding my 3" 3 jaw in it, I have seen it done recently and looks pretty sturdy.
-B-

[bogstandard]

When using a setup like this, if you have any common sense, use it.

If it looks, or you suspect it is going to be unsafe, then walk away from it, and find another way to do the job.

Holding chucks within chucks is an accepted practice, but only within the obvious safety limits. Start at a slow speed and gradually work up, the machine will soon tell you when the out of balance effects are being reached.

Then stay well under that speed.

I personally wouldn't trust doing a setup like that on something like a mini lathe.


Bogs