Myford ML7 headstock restoration: bearing scraping, testing and spindle alignment
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- čas přidán 5. 09. 2024
- I have tried to document the steps I take when restoring a Myford ML7 headstock. Usually there is also additional work needed to be done, like replacing damaged parts (for example the bullwheel and mating gear in the backgear system because of missing gear teeth, which is very common) as well as "cosmetics" ie. a new lick of paint (with the usual prep work.. normally starting with cleaning and de-rusting).
The video here is more about the different steps that in my mind is a "must", ie. scraping the bearings for good contact and surface quality as well as alignment, testing the latter in both planes and setting up the headstock correctly in alignment with the bed. There are tests described for these steps in available literature e. industry standards and references like Schlezinger as well as Myford specific documentation (they have their own accuracy chart with (quite "stiff") tolerances..)
All in all, this video is "alignment and measurement" oriented and focus on this, which in my eyes is a very important aspect to cover and should be understood and applied as part of any restoration
Nice Jan. I'm about 2 weeks away from the headstock.
The bed surfaces are progressing well at the moment.
Sounds good! It is a bit of work, but rewarding to see how it progresses
I can follow the vertical corrections and shim compensation. I don't understand how horizontal correction is done. Because cutting forces do apply some side load, there must be wear in that direction also.
Once there is wear side-to-side, wouldn't it take an excessive amount of material removal to move the spindle bore down to expose fresh side bearing material? Maybe some side gap is simply disregarded? Treat the bearing halves sort of like V blocks, with enough lower and upper contact to control spindle position?
Hmm.. to my knowledge/experience (which isn't all that great all thing considered) this is also "scraped out". At least, I have managed to get the bearings to cover radially. That said, an ideal bearing like this shouldn't cover 100% or be exactly circular. The theory, as far as I have understood it, requires you to scrape segments/pads and/or make the inside into 4 (or more) flats. On these small and soft bearings I don't bother with this (and I think Myford didn't either).
Top videos you make, not to mention the work, which basically deserves a lot of respect 👌👍. I also have an ml7 and I'm also scraping the bearings, I have the problem that I can't play the side of the spindle get minimized, maybe it's due to my spotting process or I have to go down further?! Can you tell me which spotting color you use? best regards Sven
Thnks for the nice comments! Regarding the spotting color, I normally use a product called Canode, which is water soluble, usually the blue color as well as a yellow contrast color. However, you may use other products/colors.. not really of importance as long it gets the job done ie. makes the high spots stand out so you can see and hence scrape them. Not sure what is the problem in your case, but if you have used the template spindle and only get it to spot in the middle, it is probably to shallow, yes. Then you have to go deeper. If you have an email or use messenger we can discuss further there
yes by e-mail is better, where can I find your e-mail address? Kind regards Sven
@@svenhoftmann7663 jshaugjord at gmail .. or a PM
Complex restoration! Do people retrofit these with tapered bearings ?
Just what needs to be done :)
Not that I know, Myford offers a replacement kit for the now no-longer-sold white metal bearings. This consists of a similar constructed bearing set, ie. parallel and spilt, in bronze with a hardened spindle. The Myford Super 7 that was designed after the ML7 has a different spindle/bearings, where the front bearing is a conical sleeve ie. tapered.