Andrew Tinsley | 24/08/2017 12:21:36 | ||
1817 forum posts 2 photos | Does the centre height of the ML7 vary significantly? If not can someone tell me what it is precisely? Obviously a nominal 3.5", but is it really so? I have yet to reassemble my ML7 (easier to renovate all the bits and pieces before reassembly!). So it isn't too practical to measure my lathe yet. Thanks, Andrew. | ||
Swarf, Mostly! | 24/08/2017 12:49:08 | ||
753 forum posts 80 photos | Hi there, Andrew, Here is a drawing that I have posted before in previous threads: It is part of Figure 21.2 of Geo. H. Thomas' book, 'The Model Engineer's Workshop Manual', page 240 in my copy, 1st edition. (sorry about the big white space at the bottom of the scan - I ought to have cropped it!) GHT recommended that lathe owners (well, he actually said 'ML7 owners' but ... ) should measure their own machine and make a customised version of the drawing for their own lathe. I measured mine by mounting a precision ground bar in a collet and measuring with a height gauge from the lathe bed to the upper surface of the bar, then subtracting half the diameter of the bar. My measurement was 3.497", though maybe I really ought to write that 7 as a suffix. Best regards, Swarf, Mostly! | ||
Howard Lewis | 24/08/2017 13:03:20 | ||
7227 forum posts 21 photos | Swarf Mostly, Did you take account of any eccentricity when the bar was in the chuck? Or did you centre it in the 4 jaw first of all? My 3 jaw gives about 0.005" T I R eccentricity; the 3 jaw (well abused) on a pal's Raglan gave 0.036"! Obtained these figures whilst making Centre Height Gauges to ease tool setting, (Neither of us uses QCTPs) Howard | ||
John Haine | 24/08/2017 13:24:02 | ||
5563 forum posts 322 photos | If you have any runout, either chuck a bar and skim it so you have a concentric bit to measure on, or take several readings at different chuck positions and average. I have measured my S7 in the past but it was so close to 3.5 I just assume that and never have an issue. | ||
Andrew Tinsley | 24/08/2017 14:13:29 | ||
1817 forum posts 2 photos | Thanks everyone, It looks as if I assume 3,500" I will not be far out. Andrew. P.S Thanks Swarf for the detailed drawing, I do have GHT's book, but I can't remember the drawing. maybe time to read it again! | ||
Swarf, Mostly! | 24/08/2017 16:26:14 | ||
753 forum posts 80 photos | Howard, I made my measurement with the bar held in a Myford Patent 2MT collet. That gave me sufficient accuracy for what concerned me at that time. I used a scriber blade in the height gauge - if I had used a dial gauge, previously zero'd on a known block, I could have checked for any eccentricity in the bar. Very few of the more exotic instruments in my 'Metrology Department' have been purchased new - the height gauges seem to have been previously visited by the workshop gremlin that eats scriber clamps! Andrew, As I wrote in my post, the scan I posted is but a small part of GHT's Figure 21.2. It is at the bottom right-hand corner of the figure. Best regards, Swarf, Mostly! Edited By Swarf, Mostly! on 24/08/2017 16:27:09 | ||
ega | 24/08/2017 17:54:43 | ||
2805 forum posts 219 photos | I recall being told by a former Myford fitter that the tailstock bases were made in varying heights so that the height of the tailstock centre could be made to correspond with the headstock centre. This suggests that the answer to the original question is "yes"
| ||
Andrew Tinsley | 24/08/2017 18:43:03 | ||
1817 forum posts 2 photos | Thanks Swarf and ega, You are quite correct as usual! It is indeed in GHT's book. Isn't it wonderful, how one can miss such an obvious figure in Gorge's book? Although I must have read it from cover to cover at least a couple of times, I somehow managed to miss it! Ega, I think you are probably correct about the varying height, I seem to remember someone at Myford's told me something similar. I don't know how it came up, as you can see from the above, my memory isn't the greatest! It is probably why I asked the question, because I had this niggling doubt, probably that long forgotten conversation trying to surface. Thanks all, Andrew. | ||
Andrew Tinsley | 24/08/2017 18:43:04 | ||
1817 forum posts 2 photos | Thanks Swarf and ega, You are quite correct as usual! It is indeed in GHT's book. Isn't it wonderful, how one can miss such an obvious figure in Gorge's book? Although I must have read it from cover to cover at least a couple of times, I somehow managed to miss it! Ega, I think you are probably correct about the varying height, I seem to remember someone at Myford's told me something similar. I don't know how it came up, as you can see from the above, my memory isn't the greatest! It is probably why I asked the question, because I had this niggling doubt, probably that long forgotten conversation trying to surface. Thanks all, Andrew. |
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.