Scraping the night away

I’ve been trying to sort a problem out with the website which means that I can’t upload photos. Hopefully I’ll get it sorted out soon but in the meantime I’ll just have to do without.

I was brought up with Smart and Brown lathes; my dad has had a Model A for around 50 years and a 1024 VSL for around 20 years. It wasn’t therefore a huge decision what I would look for when I started to put my workshop together a few years ago. The lathe I bought (unseen off ebay) was a Model M Mk2 which was a very nice 4″ swing tool-room lathe from the late 1940’s to the end of the 1950’s.

It looks better blurred...
It looks better blurred…

It was in a pretty poor state and I think it was a long time since it was a cossetted tool-room machine. Undoubtedly shifted to some unswept corner of the maintenance shop to turn spacers on. I made several other posts about the assessment and strip-down but the most significant matter was the slide-way wear. There was 0.010″ over the length which is quite a lot!
I had wondered about grinding and looked into the costs, but it didn’t seem to be a perfect solution. True it would be a lot quicker than scraping but I could see the possibility of knock-on problems. I wanted to keep the original position of the head, which provided the correct clearance arrangements with the feed drive gears at the rear. One grinder I spoke to suggested that they had ‘shaved’ gears to get over this problem. It just didn’t seem like the right answer. Whatever I did I was going to have to re-establish the original height of the saddle once the work had been completed to ensure that the half nuts still centered on the lead-screw, the feed shaft within the apron, and the main traverse gears had the correct clearance with the rack.
So, to cut a long story short, I decided to scrape the slide-ways using a hardened rail sitting on part of the original head location face and the end of the tail-stock slide as a guide. With a clock stand moving along that whilst clocking the front way, I was not only able to see the initial wear but it gave me a basis from which I could start the work, so that I could start to scrape the worst of it out and establish a reasonable state of parallelism before moving to the next stage.
Months of intermittent scraping have followed. A bit here, a bit there. A few weeks ago, I had arrived at the point of being within 0.001″ over the slide-way according to the clock and so I went to blueing the rail and using it directly on the slide-way to establish a better flatness.
Getting there...
Getting there…
Still further hours but at last the front slide is now ‘good enough’ to sit the rail on to start to do the opposite way. There’s a lot of work to come and this is why I haven’t tried to finish the front slide perfectly. When the rear slide is done, then I’ll use a precision level on my datum faces (under the head) to set the bed horizontal and then use some ground V blocks which span the two slide-ways to establish not only the angular alignment to the head face but to ensure, using blue under the v blocks, that the alignment is achieved with faces on the same plane, not just parallel. It’s almost inevitable that after I’ve scraped the rear way, that the two faces will be parallel but not on the same plane. The process to align will mean that at least one of the ways will have to be completely re-scraped again.
Anyway, months of intermittent work ahead but the first stage is complete.

3 thoughts on “Scraping the night away”

  1. Ah scraping. Done it a few times myself. Seems like a never ending task. Gets to the point where I say bugger it–that’s good enough. So in my case–factory perfection is never achieved–I have to be content with the fact that it’s better than when I started. Each time I have found myself involved in this, I lust for a Biax power scraper—but none ever magically appears.

    Probably the closest machine to compare yours to in the US is the Hardinge HLV-H– but they have a hardened steel bedway, and the carriage has a synthetic material (name of which escapes me at the present–brain fart) on the large flat underside.

    One thing that is done quite often over here is to machine, then grind the bedways and guide surfaces of the carriage, and restore the centerheight with brass plates fastened to the surfaces of the carriage.

    But I’m sure that you know all this, from your family’s history in the machine tool business.

    I see that you are in Devon–I have a friend who lives in Dalish, and we face time once a week and swap lies for a couple hours. Like your Dad, and yourself, he is a craftsman in his own fields, but has never been a motorcyclist.

    Herb Kephart

    1. Hi Herb
      I’ve also yearned for a biax scraper, but I think I spent a lot of time pussy footing around the first slide-way. I think it can go faster. Too much measuring when I had a lot to come off. This side I’ve already been a bit more sensible and have just kept on it when I knew I wasn’t going to run the risk of going too far. 0.010″ is a long way to go.
      I actually went to look at a Hardinge… a TL which was quite a small lathe built in the 1940’s I believe. It was a beautiful lathe with hardened strips on the ways; it had a more conventional slideway arrangement than the HLV-H. I was looking because I saw how much work I had got to do on my lathe. I kept finding that I needed a lathe and instead I had a lathe project. The TL was nice, but worn and even though it had some of the nice Hardinge details which make screw cutting so easy, it too needed work and I thought better of it. Hardinge had a factory in Exeter, which is fairly close to me (40 miles) so apparently there are a few around here. The Smart and Brown Model M Mk2 that I have will be a great little machine when I’ve finished it. I’m planning to use turcite on the underside of the saddle and scrape that in at the end. I’ve just got to keep disciplined and I’ll get there.

  2. Hello from Australia I have the same lathe I was regrind the bed but this.made me.think twice do you have any other photos of measuring and.correcting.

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