myford drilling of centre

[New_Guy]

its good to hear you found the problem now you know whats wrong you can try and avoid it or at lest compensate it i wouldn't go out and get a new lathe you have a quality lathe that works for you and another project have you got an adjustable boring head? sounds to me you could maybe do it all on the lathe and you have a mill thats great don't let it phase you maybe take a few afternoons to plan out what to do and carefully give it a try

also that wear happens to all lathes yours is 30 years old its no surprise there was a big talk over on PM about wear on lathes sparked form a box way Raglan lathe the conclusions were that box ways were far easier to fix, stayed very accurate in the middle channel and that on all used lathes the tail stocks usually have/cause the most wear both to the bed and to the ram we use them so much and most dont have wipers it just happens with out us knowing it you are luck to have a Myford i bet if you fix this it will last another 30+ years with out any problems

 

[Blogwitch]

Frazer,

Have a look at my signature line.

I was getting myself really worked up when it came to machining mine, putting it off all the time, but eventually it got so bad, something had to be done.

There are few different solutions that people came up with in my post, and looking at it, maybe my method was the long way around the job, but for me, it was the right way for me to go. I am sure that one of the other methods would have had just the same good results.

After it was all done and dusted, I sat there looking at it and thinking, 'what was all the worry over'. A few hours of fine precision working saved me loadsa money and gave me loadsa satisfaction.

You have nothing to lose, the tailstock looks to be of no use as it is. If you make a rat's a**e of it, you have lost nothing other than a few hours of your time and a bit of material.

I honestly wish a few of you lads with problems such as this lived a little closer, I would come across and do the job for you. I have done it for a few people who have mini lathes, they brought them to me, but a Myford is just a little too large to bring over. But if it is worn in the same place mine was, then there is no reason that I couldn't do it with just the tailstock here, using the bedway slides and ram for reference points.

We will discuss it if we get to meet at Harrogate.


Bogs

 

[fcheslop]

Hi Bogs, just read and re read the tailstock post I don't see any problems machining the tail stock as you did yours but don't have a decently large mounting plate but as per your signature will have a go in the near future.The scary part is its my only lathe and my backside will be phutting penny washers.Correct me if I'm wrong the Myford clamps the tailstock spindle from below so this should be OK to lock the test piece for clocking in on the mill unless it'll go on the cross slide or vertical slide.Think the first job is going to be to give it a good looking at .Most of my kit is now getting past its sell by date and accuracy is becoming an issue the mill was bought in 1984 and has done a lot of work despite being a cheap Taiwanese import that was much slagged of in the press at the time by you know who and at the price of the new ones is hardly worth rebuilding but the Myford is a different matter so any help is appreciated .Time at the moment is not a problem spending larges sums that may be irreplaceable is if you get my drift.Looking foreward to meeting up on Saturday just keep an eye out for the overweight bearded guy cutting the straps on those bloody haversacks they wear and IL follow the sound of the high pitched Bogs victims we should meet up eventually or ill see you at security awaiting an escort from the boys in blue.
regards and best wishes Frazer

 

[New_Guy]

you dont have an angle plate big enough? make one just go to your local fab shop and ask if they could do you a small job for cash of a case of beer then take home your welded angle plate and machine it true you could even machine a key way so your tailstock slots in and then it wouldn't need much clocking

 

[fcheslop]

Thanks for the advice, have given it a couple of coats of looking at and think but not yet certain that it can be mounted on a My ford vertical slide using the cam lock holes clocked in then after bending my partner in crimes arm up his back borrow his tail stock and use this with a between centres boring bar the reason I'm looking this way is that i wish to re bush the rear of the tailstock where the handle runs as well as the front might as well kill two birds at the same time.
regards frazer

 

[New_Guy]

sounds like an idea

 

[fcheslop]

Hi all ,Back on this problem again re bushed tailstock as per Bogs article the machine is now within 1thou when checked in all directions and the tailstock sits 1/2 thou high with the barrel fully extended.I was going to post pics in another thread but still learning how to use photo shop etc.The machine will still not drill a parallel hole and the smaller the drill the worse the problem but when centre drilling using a clock as best as possible only get 0.0003 deflection .When drilling the hole the drill bit is widthdrawn approximately every 1/32.I have to say that it now definitely starts a centre drill a lot better and drills the larger holes to a far better degree of accuracy but just cannot find the problem with the smaller sizes any help will be appreciated before either it goes to the skip or I end up in the nut house.
regards Frazer

 

[fcheslop]

just tried drilling ten pins all 1/8 OD with a 1/16 hole using different tailstock chucks and two different chucks on the headstock all pins 1inch long when measuring at the max run out all the pins have a wall thickness of 17 to 19 thou.Gone right back to basics checked /blued of tail and headstock tapers all OK rechecked alignment and for twist all OK rechecked machine level every thing to within 1thou. Running out of ideas [ranout].
regards Frazer

 

[lordedmond]

have you tried using a collet chuck 1/8 dia is a bit small for a normal 3 jaw chuck

 

[Blogwitch]

Frazer,

I know it might sound silly, but I don't think you have mentioned if your three jaw has any runout in it.

The action of a small drill trying to drill a component with an elliptical motion will give almost the same results as you are getting.

The thin drill will follow the elliptical motion, even if you have centred it. A more rigid drill will stay on centre much better.


John

 

[fcheslop]

Hi lordedmund, tried collet chuck and even just a plain drill chuck the baffling thing is the run out is near constant on all pins, now been on with this for 2 days in total and still no better looking decidedly dodgy for some anatomical components :big: just so frustrating this has always been a problem with this machine .I am going to try the tailstock on another ML7 to try and find out if it is the tailstock or something else just at the stage of not seeing the wood for the trees but convinced its something simple but what.
Hi Bogs, run out about 3 thou at 1/8 chuck jaws parallel
regards Frazer

 

[lordedmond]

If its always been a problem, then it must be a fault with the basic setup of the headstock, bed and tailstock

what does a morse taper test bar indicate in the headstock ( no chuck fitted )
the same test bar can also be used in the TS


Stuart

 

[dparker]

Hello All: I have had the same problem with deep drilled holes wandering off center also. I improved the problem by doing the pecking thing and cleaning the bit off with a toothbrush and cutting oil each "peck" (it did help quite a bit). One thing I did not see mentioned was the point of the drill bit being right in the center of the drill. I took some time and sharpened the bit (granted, quite a bit larger than 1/16" dia) and tried to make sure that both cutting lips were the same length, this improved the problem somewhat more when both lips were cutting. I could be just fooling myself and your mileage may vary but good luck, a interesting thread and I will attempt to apply the helpful answers in my shop also.
don

 

[fcheslop]

Hi Stuart , The machine has been checked with Morse test bar and wound in ,then checked with a between centres test bar,spindles both ends have been clocked, max wear on bed ways is 2 thou all other measurements have a max run out of 0.001 as set.The machine will turn a 18inch bar to within 2 tenth parallel and will bore a hole true enough that I cannot measure the err. I have had my test bars recently checked and they are within 2 microns and this is the tolerance I made them to when i used to work in precision engineering .The problem has only become a nuisance in the last few years as I no longer have access to precision machines[looks like next job some where with decent kit] and at the moment I need to make some very small parts for an engine 1/16 bore and 1/16 stroke daft I know so I have found some hypodermic needles and am currently thinking of using these for the cylinders and pistons previously they would have been sparked. The next job on the lathe to find out where the problem lies so I am going to try the tailstock on another machine To be honest this has always been a problem on this machine and never seems to improve and is peeing me off to put it politely and would love to bin the machine if I could but don't know what small machine to purchase to run along side it .Thanks for the advice keep it coming we might just hit lucky.Think I will have to start making larger models maybe even as big as Poppin :big:
Regards and Thanks to all Frazer

 

[billmac]

Myford series 7 tailstocks get their side to side location from the two inside edges of the bed. Unfortunately the wear on these faces can vary down the length of the bed so that the tailstock can be aligned straight at one point but not in other places. I assume that you have adjusted the base of the tailstock to make the best of this situation which is an unfortunate design feature. A few degrees wander in the pointing of the tailstock can cause a drilled hole to wander a lot further out, particularly for deep holes and smaller bores. To check this, look for angular free play, after you have adjusted the tailstock as well as possible.

 

[fcheslop]

Hi Bill, Thanks for the advice this has also been tried and the bed tested and is parallel to with in 2thou.Just going to live with it for now as life's to short but will try and eliminate tailstock today or tomorrow then work from there as a the moment I just don't know for certain where the err is coming from and am becoming a bit like the fufu bird :big:.Thanks to all for the help will post if/when i find the problem.
regards Frazer

 

[fcheslop]

Hi again.tried the tailstock on another ML7 and it drills a 2inch deep test hole bang on centre so hope fully this proves the tailstock and my repair ?.Next will try to find out if the problem is in the headstock is it vertical or horizontal err by marking the collet and piece then seeing which way its wondering when drilling but not certain yet how I am going to test the spindle in relation to the bed if you get my drift.lt will be nice to actually find something obviously wrong ha I wish
regards Frazer

 

[lordedmond]

bet its the vertical alignment of the headstcok bearings as you have now eliminated the TS so it can only be the HS


try putting your test bar it the mandrel and using a hight gauge from the bed way as you know the bed is OK

Stuart

 

[fcheslop]

Just to say thanks to all for the advice.Stripped and checked headstock on machine no problems found the hole machine has now been totally stripped and checked and the max run out is 2 thou but still wont drill true.As i have said before this machine has always had this problem but from time to time it nark's the hell out of me.Going to start looking to replace or buy another to run along side it any advice on a small but accurate machine gratefully accepted but not a Myford :big:
regards Frazer

 

[lordedmond]

for the cost of a phone call why not ring Myford up , they may be able to zero you in as to the problem with your lathe. the sales man is Malcolm and the sen fitter is Brian

don't be put off with the term salesman Malcolm knows these lathe inside out

as you have checked the thing from top to bottom and found no errors , your job will have given you the correct methodology to test out the lathe, Sorry I have no more ideas to help you sort out the problem

Stuart

note they shut at friday lunch for the weekend