MadModder
The Shop => Tools => Topic started by: Pete. on June 08, 2014, 04:11:37 AM
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I bought a ML7 bed purely as a scraping project. I've got the bed flat to half a thou, just working on the headstock end now to bring it down level.
I never owned a Myford and reading up I see that some use the inside ways to guide the saddle, and others use the front and rear ways like most other types of flat-bed lathe.
How can I tell which type I have and which of the inner ways does the work on the narrow one?
Since this bed is heavily scraped it's probably 7 or 8 thou lower overall.What adjustments are there for the saddle gibs, especially the underside of the ways?
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Basically, the answers to your questions have been answered- and answered over the years.
One was very recent here when I mentioned Turciting the saddle. The reason- or one of the reasons is to compensate for the possible misalignment of the leadscrew when a marked reduction in thickness of the bed is created by scraping. However, you will almost certainly hit the problem of having to compensate for the saddle which will be worn as was the bed. You are going to have do both together. Whether you pad the saddle with metal or turcite or use a liquid plastic is obviously your choice.
So moving back to the bed, you will certainly have severe wear on number 1 shear about 6" from where the chuck should go. You'll have to correct this before playing with narrow and whatever guides.
What you should find( I've done several beds) is that number 4 shear is an 'air fit' and has never been used in anger. I've found mill marks here. So you can bear off Number 4 to correct number 1!
As for the central gib, all the experts on Myford have hit problems because the inner guide on the saddle assumes a convex curve. So you can choose your correction to either Jack Radford's methods or Martin Cleeve's. My take is that it is a lot easier to add an adjusting gib to bear on number 4 shear than scrape and or build up the inner guide- which if you think about it will have a worn shear.
And that, basically, is that.
Norman
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I have no saddle Norman, just a bed I bought for scraping & alignment practice. I've no intention of building a working machine from it, didn't even purposely but a ML7 bed it's just what came up for sale locally. The guy I got it off had bought a scraped bed that the scraper had 'guaranteed to within a thou' - my expectations are much higher than that!
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Why has this got a sticky?
Anyway Norman, you were spot-on with your estimate of the wear on the shears. No1 is (was) worn 6 thou at between approx 4-6" off the gap. No4 shows machining marks along most of it's length, a bit faded opposite the worst wear on 1 so I''ve used it s a reference. No3 shows no appreciable wear measured off No4 and I haven't checked No2 yet.
So far I've rough-scraped No1 so it's down to about a thou and a half variation. Tomorrow evening I expect I'll get it to within a few tenths all along then I'll work on No2.
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It's two fold! One, I'm glad to help somewhat and I would thank you for giving me an opportunity to exercise my somewhat worn memory.
I wish you further success - and look forward to reading the next episode.
Cheers
Norman
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Pete, though it's for practice, it would be neat to make something of it afterward, not even necessarily a lathe.
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Ah, possibly - who knows. I hadn't thought that far ahead :)
Here's the wear along the front - quite significant. Measured in tenths of a thou with zero at the far right out of shot.
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Not my old scrapper is it.
Its the old one where tail stock locates on the inner side flats with underside clamping.
Saddle on outer vertical flats top, side and bottom that will need to tie up with what has been done.
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Don't think it's yours I got it off a guy in Medway.
I now have the front and rear shear parallel to about four tenths. Miles better than the 6 thou it started with.