vertical movement if spindle
|8 forum posts|
i was wondering if i can get some advice -
today whilst chucking up a 14 inch piece of 1 inch dia round bar on a 4 jaw chuck i noticed that i have some slop in the vertical direction with no side ways movement.
chuck was on tight
all 4 jaws tight .
bar still moved about 15 thou with clocking close the chuck.
my think is that the bronze bearing holding the spindle is oval shaped - elongated in the vertical direction.
any ideas on how i can check that?
I pulled the spindle out to have a look see - no apparent wear - wear is fairly even. now need to get a c spanner to set spindle up again.
|Chris Evans 6||11/02/2018 09:07:32|
|1216 forum posts|
I am not a Myford user but have read many threads on refurbishing Myford bearings. A search should come up with something.
2799 forum posts
Is yours the Super 7 that has the tapered bronze bushing on the spindle nose end and a bit of a faff about to adjust the bearings at the other end while keeping just a gnat's clearance on the tapered section? I'm sure its been discussed at length on here before, and elsewhere.
So first thing to do would be to reassemble the spindle and bearings, all nice and clean etc and set the bearing adjustment just right and then take your measurements again. Be sure to have your dial indicator plunger contacting the actual spindle and not the chuck, just to make sure what you are measuring is the spindle movement and not chuck slop etc.
If it then turns out that you do have in fact an egg-shaped hole in the tapered bronze bushing I think your only option might be to buy a new one. They are not like the older and ML7 split white metal parallel bearings that can be hand scraped and have shims removed in order to take up slop.
|2993 forum posts|
If the axial position of the spindle has been too loose for a long time there may well be wear in the vertical plane due to cutting forces "lifting" the spindle. I do not know whether the "mobile ex Myford fitters" are still around who could scrape the bronze bearing for you. Using 2 C spanners to set the spindle is an easier way, but not essential.
|784 forum posts|
I can confirm that the bronze bearing can be scraped to the spindle as I had this done professionally some years ago. It would be prudent to renew the tail bearings at the same time.
Would it be necessary to scrape in a *new* bearing?
2799 forum posts
Yes it looks like Myford no longer stocks the bronze bushing so scraping may be your only option. Hell of a tricky job though on a tapered bearing worn one side etc with your measured .015" movement. Probably not a first-tme scraping exercise. Do you have access to another lathe and can turn up a new bushing?
Edited By Hopper on 11/02/2018 11:16:38
639 forum posts
Don't start scraping the front bush until you have tried properly and carefully adjusting the spindle bearings exactly as described in the Myford handbook. Metal removed in error cannot be replaced. (An official Myford handbook is essential).Take time to read the instructions carefully as the Super 7 bearing arrangements are a bit unusual. It is important to do the adjustments in the correct order. bearings starting with the preload on the pair of ball bearings at the rear end of the spindle making sure the bearings are located back to back.
It is worth obtaining a proper C spanner for a few pounds (an old Sturmy Archer bottom bracket spanner can be used even though the radius of the C is not quite correct).When adjusting the very small clearance of the front bearing I have found it useful to have the catch plate mounted on the spindle which give you something to get hold of and get an initial feel to see if the bearing is too tight or loose.
|Nick Hulme||11/02/2018 12:23:13|
|542 forum posts|
When scraping the front bronze outer bearing bear in mind that spindle alignment was one of the things that could be adjusted/corrected by scraping during a factory refurbishment, busk that job and your spindle might point anywhere
|8 forum posts|
thank you for the advice. will chase down a C spanner today. I have an original manual that came with the lathe.
Although it is a little difficult to read as the pages are plastic and almost transparent now as you can see through the page to what is written on the other side. I guess the idea was to not use paper as oils etc would destroy paper.
when i place something behind the page i can read it.
will come back to you with results.
cheers and thank you.
|Michael Gilligan||11/02/2018 20:10:45|
11464 forum posts
You might find this useful as a back-up, Garry
Interesting question by the way
659 forum posts
Garry, before "attacking" anything I would remove the chuck and use a No 2 Morse test bar or whatever you have direct in the spindle then repeat your test with a dial gauge to see if you get the same or similar result. If there is 0.015" movement you should be able to see this without a clock ! I feel there is something more fundamental going on here ?
Be interesting to see what you do find out
2799 forum posts
No need for an expensive test bar. As suggested earlier, grab the bar in the chuck and use it to lever up and down, but make sure the dial indicator plunger bears directly on the headstock spindle behind the chuck. This way, you are sure you are measuring spindle movement and not chuck slop etc.
|1449 forum posts|
If you haven't bought a C spanner yet, if you have ER collet chuck then an ER 25 spanner will fit - ER 32 is a bit big but will do.
|Ian Hewson||13/02/2018 21:36:02|
|187 forum posts|
Simple enough job to make a couple from plate.
|Neil Lickfold||13/02/2018 21:45:48|
|446 forum posts|
I would take the spindle out, and then put bearing blue on the spindle,(remove the felt oiler, but remember to put it back in for final assembly) . And see what the bearing blue looks like and where it touches etc. Then go from there. Scraping takes a while to get right and experience learnt in scraping is a good skill to learn anyway. I did mine many years ago and still have a spare S7 tapered bush that I have never used yet, lol I did the scraping and refit while the bearing was on it's way out here. an easy way to monitor the scraping is to put a #2 morse taper inthe spindle and leave it there. Then get a test bar, or make one on another machine etc, then as you blue and scrape, set the test bar between centres and run you indicator along the front and across the top to see where you have to take away the material. This is assuming that the tailstock was in the correct centre line position of course. Between centres, you can aslo check that the tapered section of the spindle shaft is round and concentric as well. If not, it can be lapped, or sent to a machine shop and have them cylindrical grind and make the taper concentric to the inner #2 morse taper and round again. It all depends how good you want the end result. Making parts to a roundness of 0.002mm should not be any issue if the refurbishment of the spindle is done correctly.
|Brian Wood||14/02/2018 10:54:20|
|1608 forum posts|
You don't need to pull the felt out, there is a small hex head grub screw just below the spindle exit which is there specifically to let you push in hat pin or similar through the felt to trap it in place. It is a right pain trying to shove it back down from the open bearing against the pressure of the spring and hold it there while you wrestle the spindle back into place. There have been cries of help before on this aspect when people have removed the spindle without knowing that essential trick
|Billy Bean||14/02/2018 11:12:05|
|174 forum posts|
Currently speaking to Myford about a new Connoiseur lathe.
They advise that they can supply spares and advise on problems so may be worth sending them an e-mail.
EDIT - e-mail address is ---- email@example.com
Edited By Billy Bean on 14/02/2018 11:15:12
|Martin Kyte||14/02/2018 13:46:27|
|1302 forum posts|
Set up the spindle as below.
Do your clocking test with the chuck removed and something with a 2 MT in the spindle. This eliminates any movement caused by the chuck and or it's mounting.
If you are still worried blue it as described by Niel Lickfold above. That will accertain if the bearing bush is oval.
Myfords fit new bushes in the lathes that they refurbish and I was informed that these days they don't scrape them. Give them a bell to see if they can supply a new bush if you need one.
Spindle setting up is as follows.
1. Power Down
2. Remove all belt tension.
3. Remove Chuck
4. Rotate RH collar one complete turn. (top towards you).
5. Rotate LH collar one complete turn. (top towards you).
Spindle should be completely free of front bush.
6.Loosen allen screw on collar at end of spindle.
7. Using the Allen key tighten collar as tight at it will go by hand.
8. Back off LH collar one complete turn + a bit (top away from you)
9. Rocking the spindle by holding the spindle nose tighten the RH collar by hand (top away from you).
10. When you feel resistance to movement stop.
11. Collar should be just tight enough that spindle can just be moved by hand holding the nose.
12. Do up the LH collar by hand (top towards you).
13. With the crescent wrench on the LH collar tap the end smartly with a 12oz hammer.
14. With the lathe running slowly (lowest direct speed) put the oil gun in the front oil cup and pump until oil issues from the front bearing.
Hope this helps.
|8 forum posts|
firstly - apologies not responding earlier - working to pay for my hobby..
got onto to the job this morning after review comments and suggestions.
Findings on disassembly:
RH collar was ever so slightly loose - it looks to me that the spindle had moved forward a tad.
so i continued the disassembly, cleaned everything, reassemble as per your instructions, put the 4 jaw chuck back and measure the slop again.. amazingly no slop...
checked the main bearing whilst disassembled - no apparent wear in any one spot. wear appears even all around.
so i am thinking the not so tight RH collar was the cause allowing the spindle to move forward.. although it does not explain that i only had vertical movement not horizontal.
I am taking this opportunity of this pause in my project to have the slides ground as the carriage has always been tight towards the right. Adjusting the carriage gibs to be tightish near the gap meant i always had to turn the handles harder when moving the carriage past a certain point.
it appears the previous own did a lot brass work (still finding shavings in odd places from time to time), maybe a clock maker. anyway lots of wear at the gap on the slides.
so will have slides, cross slide etc ground and reset to parallel..
there is a business, MTA, in Mona Valve that has done hundreds of myfords over the years.
thank you all again for excellent responses to my dilemma.
following the instructions outlined by Martin and others I have
|norm norton||17/02/2018 10:35:58|
|75 forum posts|
Excellent description of the sequence Martin. Vastly better than the Myford Manual.
I just did the job yesterday before reading your list and wish I had it to hand at the time! Although I have done it twice before it is like re-inventing the wheel as I stare at the Myford Manual to remember what on earth I did last time. This time I wanted to put back the Vee belt in place of a Linked belt.
However, I have a query. The bit that Myford make confusing is the tightening of the collar to 'push' the inner races together - the manual is not clear in describing by how much this collar must be tightened, but does say that too much and the ball races are over loaded. That makes sense to me as the outers are held apart by a spacer so the inner faces cannot bear up to each other. Yesterday I put a DTI on the spindle nose to measure longitudinal end float and tightened the collar to leave about 0.0002" play (two tenths).
Are you saying that hand tightening with the Allen key as a lever will never put too much loading on the bearings? I don't disagree with this view but I am inclined to leave space for an oil film.
I do also wonder if this adjustment of the inner races should be done when the outers are temporarily clamped together, but obviously with the spindle taper well free (one turn) of its seat.
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