Here is a list of all the postings Mike Donnerstag has made in our forums. Click on a thread name to jump to the thread.
|Thread: Myford S7 Cutting Barrel Shaped Cylinders|
I’ve just chucked up a bar that gives me around 10” from the bearing as leverage to check bearing play and found the following movement:
vertical: 0.0012” TIR
horizontal: 0.0016” TIR
I’ll search for previous bearing adjustment posts to see if this is ‘normal’
For interest, is it still possible to obtain Myford headstock spindles? I can’t see them on the Myford site, and I’d expect them to be £100s.
Edited By Mike Donnerstag on 30/05/2020 16:02:16
The lathe is from around 1982. The saddle bears on the outside of the two shears (wide bed).
Hopper: I don’t know much about the use the machine had been put to prior to my owning it, but I think your suggestion of a previous owner threading using a die-holder would account for that bed wear.
Measuring again, apart from the last 2 inches of the bed, the bed width across both shears shows no more than 1thou of wear (not bad at all!), according to my digital calipers (the only micrometer I have is 0-1&rdquo. This includes the visibly worn area on the top of the front shear. The final 2” measures 1.5-2thou above that, which accounts for my initial wear measurement of 3.5thou.
Slightly off-topic, but where did you get your small red magnetic indicator stand?
Or, is it an expensive Noga? My magnetic stand is quite large and the dial gauge on top is even larger. For that reason I tend to use a sensitive dial test indicator in the toolpost whenever possible, but I do need to buy a more compact magnetic stand to make setting up easier. My Batty in the magnetic stand is pictured below. I don't use it much as it's just too bulky and a pain to set up.
Edited By Neil Wyatt on 30/05/2020 22:02:03
Hi Hopper, can you tell me which articles you are referring to, and I'll look them up.
Apologies all - I'm struggling to keep up with all of the information, but I'm formulating a plan for today:
Gray: below is a photo of the measurements showing the difference from the unworn end of the bed in thousands of an inch. This only shows the thickness difference. Somewhere I have a photo showing the width difference. I know there is an unexplained very worn area on the front of the front shear that I've posted about before, but I'm fairly convinced this is not influencing anything.
Edited By Mike Donnerstag on 30/05/2020 10:48:21
Many thanks for all your posts and sorry for the confusion with the readings - I only have metric indicators, hence the conversion.
Gray: the test bar has been ground to 0.671", though I will double check its accuracy later
I set up the headstock bearings to the best of my ability a few months ago, having made a peg spanner as a little lathe project. However, as I'm no expert and I'm learning as I go (and doubt many things I do!), I'll do the bearing setup again, following the instructions to the letter and take further measurements after.
I printed a Myford alignment test sheet, and my tests have shown the spindle to be quite outside of tolerances, as follows:
As such, I don't think I can trust the accuracy of my spindle taper.
Do you have think the bearings may be worn, or need adjusting?
Unfortunately I don't have any engineering friends from whom I could borrow a level. Do you have any recommendations for one that I could purchase? I noticed that RDG have unnamed (Chinese) levels from about £52, or Moore and Wright for £144. Nice tools, thought I'd probably only use them once!
Is there anyone anywhere near Lincoln who could perhaps lend me a level?
|Thread: Myford Lubrication... yet again!|
I realise this subject has almost been done to death but...
The Myford oil gun is currently £80 incl. VAT. I have also read that even that gun leaks oil over time, or needs a cloth between it and the nipple to seal properly. This has led me, and I’m sure many others, to pursuing other options.
I have no end of oil cans and grease guns of varying qualities, but nothing that has really worked on the Myford nipples without significant leaking around the gun before the oil even got anywhere near the nipples. So far, I’ve had to remove the nipples to oil many areas, and the rest have been oiled with a grease gun, but the majority of the oil ended up all over me. There must be an easier way that doesn’t break the bank!
I understand that, without modification, the nipples need a high pressure to dislodge the sprung ball. I have a good oil can and tried attaching a very short length of hose to seal around the can spout and a nipple removed from the machine, but even though I pumped hard, no oil got through the sprung ball. I’ve read that some have used syringe needles, but I assume as this doesn’t force oil into the machine, many areas are left dry.
I noticed that several have mentioned using a Reilang oil can (around £31). These seem to be very good quality and very nicely designed tools, but are they able to oil the Myford nipples?
I've also noticed that the PressParts oil/grease gun (£17) has been recommended. Can anyone tell me whether this has provided a long-term solution, without modifications?
I also read many articles that mentioned Guy Lautard’s grease gun modification, but I’ve been unable to find his article online.
It would be interesting to find out how other (frugal) Myford users lubricate their lathes.
|Thread: Myford S7 Power Cross Feed Apron Adjustments|
Many thanks KWIL. I've tightened the LA58 after adjusting the 'cam' LA55 to ensure the leadscrew doesn't move when the half-nuts are engaged.
|Thread: Myford S7 Cutting Barrel Shaped Cylinders|
Continued from above...
Hopper: Yes, pretty borderline wear it seems. The lathe is a post-1972 wide-guide version. Regrinding may well be the answer if I need greater accuracy.
Not done it yet: Wouldn’t bringing the tailstock into play just add to the number of variables contributing to the problem? Or, would it definitively isolate the issue to the bed, thereby proving that the headstock alignment is not to blame?
JasonB: I could try taking a heavier cut, though I’m expecting chatter at the outboard end to confuse the measurements.
Michael Gilligan: You may well be right about the lathe bed just being worn, with a regrind the only way to increase accuracy.
I will try the MT2 test bar suggested by Graham Meek and turning between centres suggested by Not done it yet. If that doesn’t help identify the issue, I’ll have to decide whether to live with the inaccuracy, or to stump up for a regrind. Actually, the dismantling, transport and subsequent reassembly and alignment scare me more than the cost, which is within my budget.
Just an idea: If the problem is due to bed wear, would it be worth checking and adjusting the flatness of the saddle gib strip to ensure it is bearing on as much of the front shear of the bed as possible? That way, perhaps it might skate over the bumps instead of diving into the hollows?
Firstly, I'd like to thank everyone who replied. I expect all of you have a greater engineering knowledge than I. I did a little toolmaking on my violin making course during 2012-2016 and have only been doing more at home since then, firstly in a severely limited way with a Myford cross-slide fitted to my woodworking lathe (!), then with the Myford S7 I bought at the start of last year, and more recently with the purchase of the Sieg SX3 mill.
I knew the Myford was an old lathe with an unknown amount of wear, but I thought it was a great price (£1500) for one with a gearbox and power cross feed. It’s from 1982-ish, so the saddle is already ‘wide-guide’. I’ll try to reply to everyone separately below, so please excuse me repeating myself, and apologies for anyone I've missed!
Pete Rimmer: The idea of compensating for an out of line headstock makes complete sense to me. If the axis is pointing towards the back right corner of the lathe and the front right foot is raised to compensate, in my mind at least this would explain the barrel shape. Just an idea: would an iron casting such as a lathe bed spring back to its original flatness, or thereabouts, confirming this? If so, I could see what happens when I slacken the two nuts at the right end of the bed.
Unfortunately, I don’t have access to a machinist’s level, but if there is anyone on here who could help, in the Lincolnshire area, I would be eternally grateful. Having said that, it seems that not everyone is in agreement that it would help identify the problem.
Graham Meek: I’ve been using a freshly sharpened piece of 3/16” HSS held very solidly in a tangential toolholder made by a very capable young chap who is head of the engineering workshops at Newark college. He has given me a great deal of help, that is, until he fell off his push-bike and broke his hip at the start of the year! Anyway, I made sure the depth of cut was the minimum necessary to remove metal from all the way along the shaft, between 1 and 2 thou. The tool cut very sweetly with no chatter on the mild steel bar (not sure whether it was leaded for free-cutting, but it cut well). The cutter was sharpened with no radius, but has retained its edge during the eight or so test cuts, giving consistent results.
I’ll try the ‘test bar test’ tomorrow (I’ve been solving lockdown relationship problems today – my own relationship that is - very tiring!!) using the (probably Chinese) 11” (including taper) MT2 test bar from eBay recently. It’ll be interesting to see what this shows. I’ll keep you updated on my findings.
My overhaul so far has really only covered the carriage. The bed wiper felt was completely missing when I purchased the lathe, so this was the first job I did last year, as well as removing, thoroughly cleaning and oiling the saddle. The underside of the saddle is quite scored. More recently I replaced one of the apron bearings, which was so bad it leaked oil from the apron sump. Apart from adjusting the bearings and giving the whole machine a good clean and oil, I haven’t touched the headstock.
I have completely ignored the tailstock so far in my setting up since replacing the apron, as I considered its alignment to be just another variable to contend with and confuse issues further.. though more on this below.
(By the way, I have your handwheel dial fitted that I purchased from Steve Tracey – great design and a fantastic bit of kit!)
Martin Kyte: I haven’t noticed any rigidity problems with the ER40 collet chuck, going by the lack of chatter. The cut has been very light; no more than 2thou.
Blowlamp: I’m coming to the conclusion that it may well be just bed wear that I’ll have to live with, until I dismantle everything and have the bed reground, which seems to be worth considering. The lathe is from 1982 and therefore already has the ‘wide guide’ saddle, hence my taking the measurements from the full width of the bed.
I have absolutely no experience with metal scrapers, even though I do own several blunt ones. Without someone who knows what they were doing, I’d be afraid of doing more damage than good.
To be continued...
Tony Pratt 1: Whenever I've set up the bed in the past (only had the lathe since Jan 2019) I used the collar method, but then I found discrepancies when turning a shaft of a shorter or longer length, hence why I tested the bed by machining the whole length of the shaft today under power at the slowest gearbox speed.
Martin Kyte: I've been testing by machining a shaft, not a bore. I've adjusted the bearings in the past and haven't found a big problem there.
speelwerk: I bought a test bar recently, so I will see if that confirms what I found when machining the (unsupported) shaft
Pete Rimmer: What do you think may be twisted to make the barrel shape?
old mart: I intended to align the tailstock only once I was happy with the unsupported shaft.
I've been overhauling my Myford Super 7 and, having machined a 1" dia x 5" long test bar with 1" held in a collet chuck, I found (after many, many tests and adjustments) that it is cutting a barrel shape instead of a parallel cylinder.
I have adjusted the feet to ensure the ends of the cut are the same diameter, but having run the cutter from right to left each time using the slowest power feed, I found that the middle of the cylinder is consistently around 0.0015" (1.5thou) oversize. I ensured that the cutter was removing metal from the length of the bar on each pass.
Is this a common thing due to wear?
Would the wear be in the bed or the apron? Or both?
Does anyone have any workarounds for when accuracy is essential?
I should add that I measured the bed wear according to a recent article in MEW and it is just on the limit of needing a regrind, with 5thou of vertical wear and 2.5thou of horizontal wear across the full width of the bed.
Edited By Mike Donnerstag on 23/05/2020 17:16:55
|Thread: Myford S7 Power Cross Feed Apron Adjustments|
Just a quick update on this problem I posted last year. I removed the apron assembly (to replace several bushes) and found that the gib strip (LA7) was tight against the bevel of the half-nuts and the apron casting regardless of the position of the gib adjusting screws. I cleaned everything and checked that there was no burring to the gib strip, to no avail.
I remedied this by fitting a shim (cut from an old aluminium venetian blind, around 10thou thick) between the gib and the apron. The gib can now be tightened with the pan-head screws (LA8) and adjusted with the gib adjusting screws (LA9 and LA10).
Perhaps this was due to the half-nuts having been replaced in the past with remanufactured and slightly oversized items??
|Thread: Myford Super 7 (with gearbox) Leadscrew Removal|
Martin Kyte: Many thanks for that tip - something I'd read in the past and had forgotten until you mentioned it. I used a spark plug socket with some studding, washers and nuts and it worked a treat.
I gave Myford Ltd. a call this morning about how to replace the two bushes holding the rack pinion assembly (LA23), but unfortunately it seems that the technical people no longer take calls. I'm hoping this is down to being short-staffed due to the pandemic.
Does anyone know how to remove the rack pinion assembly shown below, in order to replace the bushes? Is it just a case of drifting out the pin holding the larger gear? Is it tapered?
Edited By Mike Donnerstag on 22/05/2020 10:31:08
Many thanks to everyone who posted so far. I managed to get the gear off the end of the leadscrew and carefully slide the leadscrew from the gearbox. There was no second grub screw but the gear was a tight fit. Having attempted to do it by hand, I used a puller to gently pull it off in the end. I also carefully stoned the leadscrew to remove any burring around the key slot, though I couldn't see or feel any.
Does anyone have any information on how I should remove and replace the two bronze bushes in the powered cross-feed apron? I'm hoping I don't need a press. Do you think they should just drift out and the new ones back in?
Thanks chaps - tomorrow I'll check if there is a second grub screw and use a puller to remove the gear, as you may be right in that the key may be stopping the leadscrew from travelling any further through the gearbox.
I'll let you know how I get on.
Clive: The leadscrew on the later gearbox Super 7s definitely does all the way through the gearbox. (It'd make my life easier if it didn't!)
Does anyone have any hints on replacing the apron bushes?
I have a Myford Super 7 with a gearbox. The lathe dates from around 1982, serial number SK151723.
I need to replace two bushes in the apron and I understand that to replace these I need to remove the apron, and to do this I need first to remove the leadscrew.
To this end, I've removed the gear quadrant, the gearbox cover and the grub screw from the gear at the left end of the leadscrew. I've also removed the bolts and dowels from the leadscrew bracket from the right end, which is now hanging down from the end of the leadscrew.
I tried using a brass drift to knock the leadscrew out of the gear below, but found that, even though it is moving, it is incredibly tight. I'm just wondering if I'm doing the right thing, and need some reassurance before I use more force! Also, if anyone has done this in the past, is it reasonably easy to reassemble once I've replaced the bushes? Also, do I need any special tools to replace the bushes?
A photograph of the progress so far is below:
|Thread: Bending 1/8" Steel Plate|
On silver-soldering again, if I am able to get the workpiece(s) up to a dull red heat, is that a good indication that I should be able to silver solder it?
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