I managed to break the chuck key tonight while using it to unscrew the 4-jaw chuck from the mandrel of my ML7, prior to fitting the 3-jaw chuck. Luckily I could extract the broken piece, and grind four new flats on the key, but I wonder what the recommended method is for loosening the chuck from its thread? The only thing that occurs to me is to use a bar across the jaws of the chuck but I worry about damaging the jaws.
Cliff Coggin Kent UK
Not much help this, but it shouldn't be that tight that the key breaks off. I Had one that was very tight on the threads, due to using a cheap backplate. No problem, lock the backgear, use a long lever, a few taps with the hammer, and bingo! chuck off.
Then a new backgear costs about £50.........
This explains why so many ML7s have teeeth missing from the backgear. I thought it was moving the lever into backgear when it is running, but it isn't....
I just use a short tyre lever between the jaws. If I can bend them it wasn't a very good chuck :-)
Grab the sides of one jaw with a large adjustable spanner and heave. Have the outer edge of the jaws roughly flush with the chuck body diameter. This provides maximum leverage and ensures that forces are not transmitted to the scroll or the scroll bearing.
This is pretty kind to the chuck but the back gear is still the weak point. If all goes pear shaped and you break a tooth at least you had the comfort that you used minimum force and broke it gently !!
jim
I quote the Myford ML7 manual:-
(11) When removing a chuck (or faceplate), do not 'yank' the chuck off with the headstock locked with the back-gear, but set the headstock for normal back-gear drive, and after placing a piece of hard wood on the lathe bed, pull the spindle round by means of the belt so one jaw of the chuck or slot in the faceplate strikes the wood sharply. The most obstinate chuck is released in this way, and a great deal of the load is taken from the back-gear teeth.
I have used this method once or twice and it does work. I must admit that my normal method is to use the chuck key with the back-gear locked, but I do find the 'Myford method' useful if the chuck has got itself stuck on as a result of interrupted cuts.
Mark Rand RTFM
I have been taught to NEVER use the chuck key to remove screwed chucks (Like Myford). I open the jaws enough to insert a short length of hardwood between the jaws (about 18 inches of 1 1/2" x 3/4" Jarrah) across the chuck, lock the spindle and give the end of the wooden bar a whack with my hand. The chuck comes loose every time and the wood will not bruise the jaws at all.
Charlie Stone (Western Australia)
Does it ever bruise the hands?
Mark Rand RTFM
Bruised hands will recover on their own; bruised jaws cost money.
Cliff Coggin Kent UK
How do you effectively lock the spindle? By putting on the lowest gear ratio?
The way I used to take screw off chucks of was (this was a 12" taper scroll chuck on a very old Ward lathe but I think the idea could be used on smaller with a bit of care)......
using a good strong piece of wood (I used to use a bit of 3" X 2") tighten the jaws onto it, and rest it on the rear slidway, then engage the slowest gear in reverse, there would be one almighty bang and the chuck would come off first time (although I did once manage to break the wood)
HTH
The Myford has a built-in spindle lock (found under the change wheel cover next to the spindle). And the force needed is not all that high, it doesn't bruise the hand at all.
Charlie
?????????? What model Myford ? I have owned 3 ML7's one C7 capstan and one S7. None of mine had a spindle lock. Just curious.
-- Regards,
John Stevenson Nottingham, England.
It is a Super 7 circa late sixties. A rod (about 3/8" dia) that is located with a ball and spring detent to stop it floating about is pushed into a hole machined in the spindle pulleys to lock it up. It is definitely original equipment.
Yep - my Super 7 had one too.
-- Steve Blackmore
There is one fitted on my ML7R too. I think the 'R' variant has a super 7 head and tailstock on a standard bed and fitted with standard saddle from what I can recognise.
Bob
By the time a piece of Jarrah gets to Britain, it probably costs more than its weight in gold!
It certainly wouldn't be used for bashing a chuck off a lathe!
In the days when things were done properly (i.e, before British Rail) Jarrah was frequently used by the "better" railways for sleepers, on account of its properties. Since they can't afford such sensible things nowadays, they have to use steel or concrete - the former a non-renewable-source material, and the latter prone to snapping! (If in doubt on the latter, take a close look at some of the present-day main lines - they are easy to spot :(
Dave.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.