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Member postings for Mike Donnerstag

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
09/06/2020 15:42:41

Unfortunately they're all for an ML7, and I have a Super 7 with power cross-feed. I have just saved a search, so at least I should be notified if a good one comes up.

Just for interest, did you notice who the seller is??

Mike

09/06/2020 15:22:28

Just a correction to my previous post: the price by Myford for a bed and saddle regrind is £660 +VAT = £792. They are quoting turnaround times of between a fortnight and 2-3 months due to having skeleton staff and relying upon the engineering firm they use.

Mike

07/06/2020 12:30:18

Thanks Martin, - that's interesting. I'll find out what they can offer, though as mine has gearbox and power cross feed, both of which are working well, I expect the part-exchange price of a reconditioned lathe of similar spec to be very high, probably well over £4k, as the non-part-exchange price is £6418 incl. VAT!

It sounds as if you got a real bargain back in 2016.

Also I have to admit that, although it's frustrating at times, I'm quite enjoying doing work to improve my own lathe.

Mike

06/06/2020 15:42:19

Thanks Hopper - that makes sense.

I'll contact Myford on Monday about the regrind.

06/06/2020 14:34:30

Having mounted the saddle on parallels on the milling table and squared it up with reference to the unworn edge (where the gib adjusting screws are), I found that the wear in the back edge is asymmetric. I was hoping to just mill the 'hump' out of the middle.

I zeroed my DTI at the inboard (headstock) end. This rose to around a thou in the middle (the hump), but moving to the outboard (tailstock) end, this dropped to minus three thou! The fact that the wear is asymmetric led to me abandoning the milling so far.

Any idea why the tailstock end would be more worn? Is this normal?

I'm increasingly leaning towards a full bed and saddle regrind. I understand this is £660 at Myford Ltd. in Mythalmroyd. Anyone out there who has had this done by Myford Ltd? I did read the MEW article, though this was done at the original Myford in Nottingham. Any idea how long the lathe would be out of action if I had this done?

03/06/2020 12:15:43

Thanks Dave - you've definitely assessed the way I'm feeling very well indeed! I do tend to persevere to the point of frustration, and there is a lot of information to take in! I used to work in IT as a programmer and I changed career as I was 'burnt-out' from constant troubleshooting and fault-fixing, under pressure from management. While I love learning new things, such as engineering, I'm realising how difficult it can be when there's nobody to watch over what I'm doing and tell me, "Jeeesus!! Don't do it like that!!! Do it like this...". This forum is a godsend though.

I got to a point yesterday when I felt like screaming, "Help!". It would be great to have someone local come and have a look to give advice, though living in the sticks (Lincoln) doesn't help.

I feel fairly confident I could take a very light pass on that back edge using the milling machine, though I think I'd be scared of the inside corner and the face that mates with the top surface of the bed. If I had some skill with the scraper then perhaps I could finish that inside corner by hand. I realise from what I've seen and read about scraping so far that it is a bit of a black art, with a fair amount of skill and understanding needed to do it well. So… does anyone have any good places to start with learning about scraping techniques? Or even scraping projects, like a small surface plate? I’m sure I could dig out a lump of cast iron and have a go.

Mike

03/06/2020 09:32:51

I have a Sieg SX3 milling machine. Is this something I could do on the mill, or do you think it should be ground?

02/06/2020 22:04:39

Hi Martin,

I actually live just south of Lincoln.

Mike

02/06/2020 18:23:29

Martin: I did see your post about the carriage gib strip. In fact, it prompted me to remove the leadscrew, saddle and apron again today in order to check. I found that the gib strip had a convex and a concave face and it was the concave face that was in contact with the bed. I notice that it can simply be reversed, so that’s what I’ll do when I reassemble.

Another reason I removed the apron is to replace the two bushes supporting the rack pinion assembly. Unfortunately, Myford sent the wrong part, confusing the LA41 and LA42 bushes. So, there won’t be any progress for a day or two.

I tried running a dial gauge against the front vertical face of the front shear, attached with a magnetic stand to the saddle. However, I couldn’t get consistent results. Further investigation showed the saddle surface that runs against the back shear was convex, resulting in the saddle rocking against the rear edge of the bed. Surely that can’t be right? Or is it??

Anyway, after many days of investigation and frustration I have given in! I just don’t have the experience, the measuring tools nor any scraping skills to go any further at this point. For that reason, once I’ve installed the new bushes I’ll reassemble the lathe and I’ll just have to live with any remaining inaccuracies. I’ll try to get hold of a precision level in the meantime, but in due course I’ll get the bed and saddle reground by Myford. If only they were still in Nottingham and not Halifax!

Mike

01/06/2020 22:57:48

To summarise the situation so far as I understand it...

1) The bearings have been adjusted according to the manual and Malcolm's notes. The lathe is cutting perfectly round, at least according to my vernier micrometer

2) The wear in the lathe bed alone is nowhere near enough to cause the extent of 'barrelling' that I am experiencing

3) This therefore points to lathe bed twist and/or headstock alignment

Having had inconsistent results doing a similar thing as before, but this time with a thicker bar held solidly in a four jaw chuck, I'm going to try measuring with my DTI and the precision ground test bar tomorrow.

Gray: I'll check the test bar for concentricity first, as you suggested. This is something I haven't done as yet.

I'll also try the 'Rollie's Dad's method' of removing twist from the lathe bed.

If the problem does point to the headstock being out of alignment with the bed, can this be adjusted without removing the gearbox or other ancilliaries?

Mike

Thread: Myford Lubrication... yet again!
01/06/2020 22:10:23

Has anyone changed the oil nipples on top of the gearbox with oil cups, as mentioned in David Haythornthwaite's article? Do you know if I need to remove the gearbox cover to press the nipples out?

Many thanks,

Mike

31/05/2020 20:30:09

The Pressparts oil gun is great, though I’ll have to make a bespoke nozzle to fit the cone pulley nipple.

Regarding the two nipples on the cover of the gearbox, I’m thinking of replacing these with oil cups as in the Myford Lubrication article. Has anyone done this, and do I need to remove the gearbox cover to press these out?

Mike

Thread: Myford S7 Cutting Barrel Shaped Cylinders
31/05/2020 17:41:43

Blimey - I can hardly keep up with all the information! Many thanks everyone.

blowlamp: I can confirm that a turned bar is indeed round, definitely to within a tenth of a thou (0.0001), as measured by my Mitotoyo mic.

Although the above test has confirmed that the bearings are good, I've readjusted the front bearing (leaving the rear bearing preload alone) to be ever so slightly 'tighter'. I'll post the results of the spindle movement using a bar in a chuck as a lever as before.

31/05/2020 07:31:41

Hopper: Instead of a flat file, I ran a small flat slipstone over the scarred-up front shear. So far at least, I don't think that area is to blame for the barrel shape, but I'll do some more testing today. I'm determined to get to the bottom of this and thank everyone who has posted so far for their help.

Regarding the stress on the bed, one thing I intend to try is to see how the bed reacts when the nut pressure on the right hand end is released. I'm still wondering if the problem is a combination of headstock misalignment and bed compensation.

Mike

30/05/2020 19:54:47

Niko: Interesting. So, only just under my own measurement. I think I’ll assume the bearings are adjusted okay and try something else, such as doing a test-cut between centres.

Mike

30/05/2020 18:25:03

Niko: I was using a bar held in a chuck, giving 10" of leverage from the front bearing, with all my might! Not that I'm all that mighty! wink I got between 0.03mm and 0.04mm on my metric gauge.

Here is my setup:

img_0543.jpg

Anyone: Is this what you would expect?

Just to reiterate my questions stated earlier:

  1. What radial movement they would expect at the spindle nose, using a bar held in a chuck as a lever?
  2. How do I measure the spindle end float (axial movement)? Do I need to use some kind of lever against the bull wheel for example? I understand this should be 'measured' as zero.
  3. Is it possible to obtain a 'new' spindle, if I deemed that mine needed replacement?

Edited By Mike Donnerstag on 30/05/2020 18:32:00

30/05/2020 18:08:40

Martin: Apologies - I had only given you half the information! I've updated the photo in my last post with ALL the information that Myford gave on assessing lathe beds.

According to the document, the allowance in thickness is 5thou.

Mike

Edited By Mike Donnerstag on 30/05/2020 18:27:11

30/05/2020 17:53:07

Having spent the last few hours searching to no avail, can anyone tell me:

  1. What radial movement they would expect at the spindle nose, using a bar held in a chuck as a lever?
  2. How to measure the spindle end float (axial movement)? Do I need to use some kind of lever against the bull wheel for example? I understand this should be 'measured' as zero.

Most of the ME threads I have been reading about setting up Myford bearings say how sensitive it all is, and several people have complained about end float resulting in the spindle locking up under an axial load, e.g. tailstock drilling. Mine runs nicely despite some fairly heavy tailstock drilling I've done recently, with no excess noise, no chatter and no locking up. I'm loathe to mess about again with the bearings unless I really need to.

Many thanks,
Mike

30/05/2020 17:42:17

Martin: The maximum wear on the bed, according to Myford, is given below, which is indeed 5thou, not 0.0005" (1/2 thou):

myford factory rebuilt - bed regrinding.jpg

Mike

Edited By Mike Donnerstag on 30/05/2020 18:07:09

30/05/2020 15:56:11

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.
Mike

Edited By Mike Donnerstag on 30/05/2020 16:02:16

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