Author Topic: reconditioning finally done - a Schaublin 70  (Read 1553 times)

Offline Mcgyver

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reconditioning finally done - a Schaublin 70
« on: July 18, 2022, 01:05:01 AM »
Pretty much done, phew! The idea was spare no effort in an attempt to achieve factory new accuracy and performance. Its a no small challenge given it was a wreck and Schaublin was arguably the finest maker of lathes. (There may be equals, but I can't think of a maker that surpasses them). It took over a year and many times I had to hold my tongue just so! I did everything on the this lathe, spindle regrind and made a new double taper bearing (ended up about 3/4 of a tenth TIR), lapped the tailstock, hard chromed and ground the quill, (2 tenths clearance, you can hold the TS vertically and the quill doesn't fall out), scraped and ground the slide rest, scrape the bed, scraped the headstock and tailstock into alignment to a tenth....every surface that touches another got worked on. Had to make many missing parts as well.

Really of sick of reconditioning at the moment....but nah, the biax isn't for sale...yet :). I even painted it which I usually don't do...but its a Schaublin so deserved it.

Here's a blog of sorts of the work.....not complete, but shows most of it.

https://www.metallum.shop/reconditioning-a-schaublin-70/












« Last Edit: July 18, 2022, 01:19:27 AM by Mcgyver »

Offline derekwarner

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Re: reconditioning finally done - a Schaublin 70
« Reply #1 on: July 18, 2022, 02:07:50 AM »
I found the Metallum attachment absolutely fascinating......and read every word relative to the images.....

Initally I had questions :Doh:  ...how do you?, ............then reading further :happyreader: just about every point was explained

I read your text......

 "Here’s my setup with the headstock casting warming on the plate, the bearing a nice and a digital thermometer to know what’s what".

I wondered about the linear expansion you mentions and the digital pyrometer......then concluded the accuracy of such instruments is not the point, but the absolute repeatablity is the critical unit of measure and work

Possiblly missed it, but what is your own acceptable % of cross-hatched bluing on a flat surface.....[eg, 60%.....80% of the flat surface with blue transfer, considering the viscosity of the bearing blue? - with a ?% of even pattern distribution over the total length of the flat bed?]

An example of this question, is the % distribution of bluing on the saddle top swivel is located more around the centre axis of the swivel, rather than the outer top boxed surfaces of the saddle

I don't know of too many any other machinist who could attempt, successfully complete & document such a task

Thanks for sharing  :ThumbsUp:

[in a previous life, I had the pleasure of supervising Technicians hand scraping :thinking: the Train and Elevation helical bronze wheel to the steel worm on the speed reducers on FMC 5" 54 Caliber gun mounts RAN Naval vessels  - their ability was far greater than mine, I simply recommended the final work be acceptable for approval - the bluing medium used was not Prussian blue, but a deep blue died viscus spirit ]

Derek
« Last Edit: July 18, 2022, 09:40:40 AM by derekwarner »
Derek L Warner - Honorary Secretary [Retired]
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Offline Jo

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Re: reconditioning finally done - a Schaublin 70
« Reply #2 on: July 18, 2022, 05:52:43 AM »
 8) Well done Michael. You did a much more thorough job on your than I did on our Schoey https://www.modelenginemaker.com/index.php/topic,10597.0.html

Which reminds me I still have to go back and make hundreds (it feels like hundreds  ::) ) of backplates and mount up the chucks for her :facepalm:.

Jo
Enjoyment is more important than achievement.

Offline Mcgyver

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Re: reconditioning finally done - a Schaublin 70
« Reply #3 on: July 22, 2022, 01:38:28 PM »
Thanks for the kind words.

Derek, I was asleep at the switch....sorry for not answering your question sooner.  Its probably 20-30 points per sq inch.  I almost always do the final bits by hand and have a light touch so there is very little deviation between hi and low.  Of course any readings will depend on how much blue so things are subjective.  I've got to the point where I just know when the work isn't going even going make a 10ths indicator hand flutter, then it sort of ceases to matter.  i.e. if the deviation is less than a 1/2 a tenth between high and low, I've kind of stopped worrying counting points.   My thought is, with a film of oil in there and such small deviation, you should be get near 100% bearing.  I did a lot more counting of points early on and still do some, as I gain experience it just seems less necessary and more something for defining a job, QA checks etc.

Plus I don't have a tough task master with clipboard inspecting !  :D

Offline steamer

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Re: reconditioning finally done - a Schaublin 70
« Reply #4 on: July 22, 2022, 09:59:58 PM »
Late to this party,  sorry

That sir is SAWEEEEEET!   I've lusted after one of those for some time.....

Nicely done!!

Dave
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Damned ijjit!

 

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