Hi all, I have purchased a myford super 7 that requires work(knowing that when bought) The classic problem of more wear near the chuck than tailstock. Now the wear on top of bed (where myford said they grind) is fine. The only wear seems to be the sides. I have read an article in MEW That states how to scape accurately with a jig and tool steel. Has anyone else done this? I have also bought the book by J A Radford thats states writings to ME But the section on converting to front shear running only isn't very clear (to me) Any Help or tips much appreciated. Cheers Colin
Hi Alan, Thanks for the reply. Do you think it's still worth a go? either that or i may use as is for now as i tested runout to be 0.00079" Over 4" and for what im doing for now will be fine and I'm not sure what original runout is although im sure it's less than that. I checked across face of chuck for the crossslide runout and this seems almost nothing although as standard it should take slight concave cut right? I suppose for the price it would be worth me sending away so i know i have a great lathe for many years to come. Cheers Colin
Colin Hi, although I'm no expert on lathes I did face a similar situation on my first S7 a number of years ago. In the end I used it as was for a few years and then bought a brand new Speed 10 (turned out to be a mistake as it was too small). I had some major concerns with my ability to get the shear absolutely parallel with the spindle leave alone to get the spindle to "look in" a few tenths. I felt confident that I could get them reasonably accurate as far as a constant width was concerned but the accuracy of the final result relied upon at least one of the shears being completely unworn from its' original machining. The problem here is that depending on the age of your machine some shears wear at the headstock end and others wear (much less) at the tailstock end, depending on which shear guides what.
After a couple of years use I found I could not get a reasonable compromise in saddle adjustment to provide a reasonable range of saddle movement. Tight at the headstock end and it would jam 6-8 inches out, adjust for this position and I would get some tool chatter close to the headstock. To be honest I never had a problem with the accuracy produced particularly as that is affected by other issues like tool push off, work support, spindle runnout etc. With a few years more experience now I'm sure that when my current S7 shows similar wear I will return it to Myford for a regrind. Unless you are doing some work which requires great accuracy I would consider using as is to get a feel for the rest of the machine you can then decide if it is worth the regrind or bad enough to take a chance on the DIY approach.
Yes, if you take a facing cut it should leave the end slightly concave, in practise anything from slightly concave to parallel is fine. If it faces convex you might have a problem if anything you faceoff needs to stand on a flat surface. If you are only facing shafts to length etc even that will rarely give you a problem.
I think this is the telling comment, I also always like my tools to be "right", then I know that any c*** ups are down to me entirely. However, this has proven to be an expensive policy and it has been proven to me many times that when you get to know your machine a good craftsman will turn out excellent work on a machine with much greater wear than yours. I have seen some superb work turned out on clapped out pre-war machines that you would not give shed room. Of course, I personally have also proven that a "clown" can produce crap work on a superb lathe.
In short, get to know the machine well by using it for a fair time. If it is reasonable and worth saving send it to Myford with some of your "hard earned". If it has other serious problems then have a go as you suggest or move it on and find another. The one thing about Myfords is that even fairly worn they have reasonable second hand value. The other possibility is that many older Myfords are broken for spares these days and beds rarely fetch a great deal of money. You might be able to get a bare bed to "play" with, leaving your own bed to go for a re-grind if all else fails.
Not sure if this helps at all but I would recommend caution before attacking a Myford bed with file and scraper.
Colin. I agree with what Keith said. My ML7 was a basket case when I got it, but I didn't mind spending money on it as it only cost a little more than 'free'. However I still spent 6 months using it and getting used to it first before embarking on a rebuild this year.
Mine had been through a hard life and was pretty well worn wih the bed thickness having worn between 0.001" at best to 0.008" at worst (from
0.500" nominal). The shear widths were less severely worn with 0.0025" off the front and 0.001" off the back.
I had it reground by Myford and picked it up last week,so still in the rebuild stages at the moment. They grind the top and the underside as well as milling the shears, and you have to watch your fingers on these as they are damn sharp - DAMHIK. There are some before and after pictures below.
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Despite this looking pretty bloody awful it still produced fairly accurate turning making jigs and fixtures for 'work' projects as long as I didn't want to move more than 8" up the bed. I have a scanned pdf copy of a factory rebuild on a Super 7 from an old issue of MEW if you want, mail for details.
Peter, why did you have to go and post those pictures of your beautifully re-ground ML7 bed. My S7 seems to have very little wear and works fine but my bed doesn't look anything like that and I WANT IT TO. SWMBO says you should feel guilty as there is now every chance that she will be denied something "essential" when I decide that my perfectly good bed just has to be sent for a regrind.
On a more serious note, did you have the saddle reground as well? Could you also let us know how easy/difficult it is to get the machine "set up" during the rebuild. Two friends of mine who have both done it tell totally different stories; one says it was a straightforward assemble and adjust while the other has some horror stories particularly with regard to facing after the rebuild. I'd be very interested in your experience which off course I hope will be all good.
The cost from Myford was £160 incl VAT to get the bed ground top & underside and the shears milled.
I did NOT get the saddle reground and fitted by Myford as this IMHO was excessivly costly at £360 + VAT so £423 in total. However the plan is to do this myself ( it definitely needs it now) as I bought a surface grinder last year. I'm in the process of milling up a fixture to hold the saddle on the grinders mag chuck, then I just need to fit the replacement spindle bearings on the grinder and I will be able to get on and do it. It's basically just reducing the height on the clamping surfaces to match what has come come off the bed and then scrape the running surfaces back at bit and grind a step in the underside shear clamps to suit. Figures from Myford say to aim for 0.0015" clearance using no more than 0.008" of shims.
When I went up to Myford I spent a while chatting with the fitters inside the factory about how they tackled this and got the cross-slide to 'look in' for facing. The approach it from two areas, the first being to adjust the angle of the headstock casting over by means of the 2 pressure screws located at the ends of the front shear face under the headstock (if you ever wondered what those holes & screws were for!).
The second stage involves finding which side of the saddle is the 'fast edge' and slightly scraping this to get a very small taper along the face. The fast edge will be the verical face that either runs on the inside of the front shear or the outside of the rear shear, Myford say it can vary and be either one. You can check it by looking at the wear on the saddle and finding which face is worn and hence does the guiding. Its the fast edge that guides the saddle and the gibs then adjust the running clearance to match this.
I will be taking some pictures and documenting the process as I go along, but there is already a bit of a cheat-sheet for this. Some time ago in MEW there was a feature which followed a Super 7 through the refurb process at Myford, and Myford have reprinted this entire feature and will send you a copy if you ask:)
When I have done the grinding and start building it back up again I will be on the scrounge for an MT2 test bar to borrow to finish the setting up. If anyone wants to volunteer the loan of one I shall glady take them up on it! If ayone has a master dummy face plate this would be useful too but I fear this is one of those unobtanium things.
Peter, thanks that is brilliant and has answered several questions that concerned me. I'm sure that many of us would find your final record of the rebuild extremely useful. I found your comments about getting the saddle aligned properly particularly enlightening. Sorry to say that I have not got a test bar to loan you I'm afraid it is one of those things that I keep looking at but haven't yet found an unallocated =A335 (currently on offer with Chronos) to buy one. I'm sure someone will have one though.
I must admit that I envy you a surface grinder, the more odd things I do the more uses I can see for one. I'll have to start saving the pennies again and put it on the list after a larger mill. Thanks again for the excellent info and good luck with your rebuild.
Thanks also to ghowe for an interesting link which I hadn't previously found. Plenty of reading and thinking to do now.
Hi All, Many Thanks for the excellent and helpful replies. I am still torn on what to do.
I have looked at the shears and saddle and it appears the inside edge of the back shear will have no wear at all as nothing runs on it. So this said i should have a datum to work from for parallel and thickness of shears. I shall use as is at present as suggested and get a feel for the lathe.
Im sure i can put more errors into a piece than the lathe does! This lathe is really old as it still has the old style clutch. perhaps i will use at moment and then save up and have it done. I am working on a full repaint and general tidy up first anyway.
I hope to build a few little engines to start with but as the cyliners are only 2" long max the errors should be fine anyway. Just read your article Graham. Very nice. This gives me the confidence to give it a go myself in a few months time. My saddle bears on the same surfaces as you show except the carriage wraps around the back of the front shear. I take it this shouldn't take any wear though? Cheers Colin
Peter, Thanks for the offer on the article but my myford parts list arrived today with this article in it! I am going to give the job a go my self if the measurements reveal not huge amounts needed. The top of the bed is in tip top condition with hardly any marks. It's the hardened bed according to the cream coloured paint. I have to get myself an accurate calliper or micrometer and do a survey on the bed. If i do go for it i will post results on here. Cheers Colin
If it helps, I have an MT2 test bar you could borrow. The only thing I found was that it is rather short with only about 4 or 5 inches (from memory) available to dial against (a Chronos item) but it seems OK.
As a matter of interest (or boredom in my case) I managed to manually regrind my Super 7 bed myself. I bought it cheap with the intention of shipping it to Myford but figured that I would try to grind it myself and if that failed, Myford could have it.
The saddle guide was on the front sheer and so the rear of the rear sheer was relatively untouched and provided a reasonable reference surface. I set the bed up on the mill and ground the rear face of the front sheer to get that true to the rear of the rear sheer. I then manually ground (using a number of diamond hones) the other faces. It was bloody hard work that took more hours than I'd care to remember but the results were, though I say it myself, superb. My advice? It can be done but unless you have unlimited time, patience and arm muscles, spend the £160 and get Myford to do it! I also spent some hours 'mapping' the profiles of each sheer to understand precisely where the wear had occurred. Overall, the maximum runout was about
3 thou' on the sides of the sheers and 2 thou' on the top faces. That's a lot of metal to remove handrolically.
Mark
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I missed something there. What does the variety of paint have to do with whether on not Myford's hardened the bed. Or did they change colours at the time they went over to hardening the beds?
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