Mini lathe chuck change out

Find a friend with a bandsaw
My parting experience on my lathe with 3/4 hot rolled ended with me looking for holes in my roof, after I changed my shorts.
Jamming the lathe is not the worst thing that can happen.
I was thinking of a riot shield during the operation , lol
All jokes aside I will proceed with caution. All my friends come to me for tools.
I might have to get as close as I can with the parting tool then suffer with the hack saw.
 
Just be aware that a 4 jaw chuck is a relatively heavy chuck and needs a powerful motor to turn it, the LMS 4 jaw chuck that I have was bought from a member here (Roycess , may he rest in peace) who could not use it due to the smaller HF mini lathe that he owned, it is working alright on my LMS lathe but it still takes a few seconds longer to come to full speed or to a dead stop.
LMS is the best source of info for you as you already know, the LMS chuck I have is also sold with or without a back plate.
the 4 jaw i got, K72-125 VEVOR was exactly the same size and weight, exactly the same registration, drilled 2 holes to match up the 3 hole bolt pattern and it worked like it was made for it
 

Attachments

  • IMG_6183.mov
    6.2 MB
just some feedback, the Vevor 4 jaw is still working great and it is nice to be able to take a part in the lathe chuck and transfer the chuck to my indexing head and back again not having the worry about zeroing it each time.

I also have an er32 collet chuck on its way on a slow boat from China. all will interchange between my lathe and indexer.
 
I'm curious, how long does it take to swap chucks with the flange type set up on many of the small import lathes?

Is it a fussy operation or pretty straight forward?

All of the lathes I've used had threaded spindles.
 
I'm curious, how long does it take to swap chucks with the flange type set up on many of the small import lathes?

Is it a fussy operation or pretty straight forward?

All of the lathes I've used had threaded spindles.
not long, 3 nuts to remove and reinstall with new chuck and mine will be within .002" tap with a soft blow a few times to get it perfect, of course the 4 jaw does not need that. I do install in the marked clocking.
the registration keeps them very close to centered.
 
I have only recently found reason to use the 4 jaw Sanou K72-80 4 jaw that I bought a year or so ago. Ironically it was to turn a faceplate for a job I am doing with a part bigger than either chuck. Lathe is a Vevor 7 x 12 and the supplied chuck is the standard 3 jaw centering K11-80? Anyway when I unbolted the 3 jaw and stuck the studs in the K72-80, it matched right up with the register on the spindle plate and the bolt hole pattern on the spindle plate. Most of the 3" chucks have the same mount, a 55mm register recess, a 66mm bolt circle, and three or four or sometimes 6 bolt hole pattern. Easily duplicated.

So if you need to make a backplate for a larger chuck that does not share that bolt pattern, you will need to make one side match the spindle plate on the lathe and the other face match the new chuck, and then it should also work for most other chucks the same size. You might also need some day to make a face plate for oversize turnings that won't mount well to a chuck.

To do that, Mark center. Mark 66mm bolt circle. formula for space by straight line between hole centers is HoleCenterDistance = BoltCircleDiameter * sin(180/n) where n = number of holes. If there are 6 holes, three are for a three hole mount and 4 are for a four hole mount, with one hole being shared. You have to calculate and mark the three hole and four hole bolt hole distances separately except of course for the shared hole. So let n be 3 for the 3 hole pattern, and let n be 4 for the 4 hole pattern.

The easiest way I have found, since I am a linux user, is open a ternimal and call up Python and work in the python environment. So I go
Python3 [ENTER]
import math [ENTER]
math.sin(math.radians(180/n))*d [ENTER] # (d is bolt circle diameter, n is number of holes)
and... it spits out the distance to measure in a straight line from one hole center marked on the bolt circle, to the next.

Measure and mark carefully. Centerpunch, then center drill, before going for the money shot. Now, set your part aside. Something else you got to do, first.

The registration recess is extremely important. A properly fitting one allows NO play and will hold your plate perfectly concentric to the spindle. This allows you to take it off and for instance move it to your mill to do a feature, maybe to your rotary table, then return it to the lathe and still be up tight and outta sight. A little slop and you will wish you had just paid $80 and waited 2 months for shipping from China. So, you have to machine the recess. Right? Wrong.

You can bolt the plate-to-be to your spindle plate and turn it, yeah. But how do you check for fit? The only way is to take the plate off and turn it around and see if it fits! The problem is obvious. Let's say you have half a thou more to go because it doesn't quite fit. Then, somehow, you have to turn the plate back around and somehow get it perfectly exactly right on the money where it was when you started turning the feature. Good luck with that. And so, what you want to do is turn a disk with a raised register just like on the spindle plate. Just turn the jaws around and extend them to the limit, and cut a piece of 3/4" thick aluminum to barely fit. Turn it down and face it, center drill it, and lay out a circle representing the register feature. You just turn to within a few thousandths (I always do my actual work in inches. Metric is for sissies and my lathe handwheels are graduated in 62.5 gradations equaling a thousandth, with a full turn being 1/16", very handy!) with a slight chamfer on the outer edge, and keep trying to fit one of your chucks to it. You want it nice and snug fitting, not one molecule of play, but not a force fit. A very slight taper is actually the proper way. The registration recess depth should be 5/32" or 4mm. The registration disk on the mating part should be 7/64" high or 3mm. You don't want it to bottom out! Stick with those standards and you will have maximym interchangeabilityness.

So yeah, make a nice disk, bolt holes completely optional, but with the registration circle standing proud by the specified height and at the specified diameter. Start with it a thou or so over spec diameter and test fit, keep carefully shaving material away and fitting, until you got it. Now you have a dummy that you can use to check the REAL face plate or back plate that you are making. Bolt it up, tap it in, tighten the bolts good, and make chips. Turn your registration recess 5/32" deep and 2.165" diameter. Okay okay, a hair less than 55mm so you can sneak up on a perfect fit. Use the dummy you made to check the fit as you go. Be sure to surface your plate nicely and you may as well put both the 3 bolt and 4 bolt hole pattern. Also any other feature you think you might want. When you got it good, unbolt, flip it around, and you should have a perfect fit. There. You got a face plate! To make it a backplate, just add the features to match the chuck or other device you want to mate up to your spindle.

For a mini lathe, yeah the proper backplate and faceplate material is cast iron. Big deal. It's a MINI lathe, after all. 3/4" aluminum will work just swimmingly, You are probably only dealing with a 500w motor, after all. If you want to use CI or steel, go for it. Whatever blows your skirt up. Aluminum is dead easy to machine on these machines so I use it a lot. You can if you want. You don't have to. I can do whatever I want so don't bother trying to aluma-shame me. Waste of keyboard strokes that you could put to better use.

Like I said, I have to make a part too big for a 3" chuck and I am to cheap to buy a nice 5" one, so I am making essentially a disposable faceplate all jigged out for the part I got to turn, which is a left side plate for a vintage Penn 209 reel. I want to put two REALLY BIG magnetic brakes in it and use it for night time surfcasting, and the ancient and thin bakelite side plates require a bushing to distribute the load, and there simply is not room since the magnet holder must be extendable up into the spool end recess, and 1/2" diameter N52 is the smallest that I calculate will work for these big ol reels. So, aluminum sideplate, milled, drilled, and tapped for two threaded mag knobs, as well as the spool end bearing knob. If possible I will implement a replacement for the original clicker. There is a little extra room from removing and tossing the idler gear and worm drive gear as well as the rest of the yankee levelwind frippery which reduces cast distance by a good 10 yards. Later I might do a stainless steel version but for this prototype I will use 6061. Aluminum part, aluminum faceplate. Later I will made a solid frame, turn a few upgraded parts including high speed gears, and a new right side plate to house it all. And yeah, a really kewl handle, of course. I may use these custom faceplates again, or maybe not, but they will get saved and not repurposed.

I just made the registration fitment dummy today.
RegistrationFitmentDummy.jpg


Tomorrow or the next day I will mount the new gonna-be faceplate to the spindle and turn and burn, and with this dummy I can fit it to the spindle by proxy without taking it off the spindle and losing location.

Yeah, I got a fancy pants dial indicator and mag base, but Papa just don't roll that way.
 
Back
Top