Fixing the Mini Lathe Saddle - Still Hand Scraping - Part 2

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Continuing to tune up the Chinese Mini Lathe, next job to look at is the lathe saddle.
I have had a lot of problems with surface finish and the tool cutting on the outfeed. In this series we're working through the various problems with the lathe saddle as it came out of the factory and working out how to improve its accuracy and rigidity.
In part 1 we looked at the problem, take some measurements and start to hand scrape the bearing surfaces of the saddle in order to start to bring it into truth.
Here in part 2 we identified a problem with the alignment of the saddle bed ways which we need to sort out before we can move onto the actual gib strips.
The fix applies to the following lathe models: CJ0618, Crenex 7"x14", Clarke CL300M, Warco Mini lathe, Sieg C2 and many other brands which are based off the Chinese mini lathe design. However the techniques could be applied to other makes, models and sizes of lathe and aren't limited to this particular model.
See part #1 here - • Fixing the Mini Lathe ...

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Опубликовано:

11 янв 2024

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Комментарии : 20

@mattholden5 5 месяцев назад

I'm pretty sure the next level of this rabbit hole is going to be about how steel work hardens from chiseling with a carbide scraper vs how grey iron remains supple after the same treatment. I think that's an extraordinarily useful rabbit hole to go down for the hobby machinist, even if they've heard the same lesson before somewhere else.Thanks for bringing us along on your journey.

@jardine1able 5 месяцев назад

Well done mate, that was really interesting, Happy New year to you and family. Looking forward to the next installment, Regards Mike from Cornwall.

@radboogie 5 месяцев назад

Thanks Mike! Happy New Year to you and yours also 👍

@richardcrook1320 Месяц назад

Measuring that needs a test indicator, not a dial indicator. They're more sensitive, and more accurate.

@russellhayward2359 4 месяца назад

You can also widen the bottom of the v groove, on the mill with an endmill, I have seen other RU-vid creators do the same thing, hope that makes some sense

@stephaniea9722 5 месяцев назад

I've never seen someone put so much effort into one of the cheapest lathes you can buy. Actually it's a bit inspiring to see. I hope to see you scrape the ways and cross slide too. I worry the ways might be out and twisted because the lathe isn't level. I've wondered about making a fixture to scrape the underside of the ways. In your case, you could probably replace the gibs with a gib that is meant to scrape. It could easily make the bottom surface coplaner.

@radboogie 5 месяцев назад

Thanks for the kind words Stephanie 👍 Whilst filming for Part 3 I came across some other issues that are going to require some way scraping, will be editing that one soon and hopefully will have it on YT in a few days time. I love the idea of a fixture to "auto scrape" the underside ways - nice thinking! It looks like my "under-ways" are pretty straight but there is work to do on the upper ways. Your idea could be adapted so that a single point tool (HSS) is attached to the saddle so that it touches the ways, then you could slide the saddle along the bed and it would act like a planer/shaper. Would need to make sure the rear end of the saddle was pulled upwards so it rode on the gib underneath and didn't rest on top, but deffo an interesting idea...

@stephaniea9722 5 месяцев назад

@@radboogie I saw the scraping technique on a video where someone built their lathe from scratch. You can preload it with a gib with a hole through it to hold a scraper. I saw a technique for making surfaces parallel by indicating the surface on a surface plate, then grinding down a few spots to just slightly above the desired depth by indicating (like 1/10th of a thou). Then you'd blue up and scrape or grind until that spot gets blue. By making a few of these reference spots you get a good visual cue of your progress. Looks like you'll need to make a straight edge for doing the ways. This all looks doable, makes me think that maybe it isn't too terrible to buy a cheap lathe and fix it up.

@joell439 5 месяцев назад

Flat is where it’s at 👍👍😎👍👍

@radboogie 5 месяцев назад

That's a great phrase Joel, I might have to steal that! 👍

@danbendeke220 5 месяцев назад

I really appreciated the "follow along". I have an old worn lathe that needs a little work and this was good inspiration. Where I live, Cast Iron is hard to come by as well. Not sure why? I do have a question. The scraper?! Can you DIY one or can you share where you get yours?

@radboogie 5 месяцев назад

Thanks Dan. Hand scrapers are also quite hard to find. I bought mine from @ImpracticalMachinist - he has a RU-vid channel and sells hand scrapers that he makes on eBay. You could also search for "Sandvik Coromant Scraper 620-25" - hard to find in the UK but might be easier to find in other countries. If you wanted to DIY one you can search eBay for "YG8 Solid Cemented Carbide Tungsten Steel" and buy the carbide as a flat strip. This can be cut up and ground (thought not easy to cut) and brazed onto the end of an old worn out file. HTH

@danbendeke220 5 месяцев назад

Wonderful information. Very much appreciated. I will check it out and see what is available. Best of luck with your channel and projects! @@radboogie

@mikemelbrooks 5 месяцев назад

I can't see why scraping the two shoulders achieve anything, on my Lathe they are only in contact with a metal plate, if I tighten the three bolts up on either shoulder they clamp the shoulder up completely.

@radboogie 5 месяцев назад

On my lathe the level of the shoulders is higher than the bottom of the bed way underneath the bed. So If I tighten up the gib bolts the gib will cant over at an angle like I showed in Part 1. I need to put shims between the shoulder and the gib and that means I need to get the plane of the shoulder parallel to the bed so the gibs make full and level contact with the bed ways and don't cant over.

@mikemelbrooks 5 месяцев назад

I see, i found my three bolts had worked loose, what I did was place shims inbetween the plate and the two outer bolts, and put a stud in the middle hole with a nylock nut on it in the center hole. I can then use the nylock nut to take up any play. If you just use shims you have no adjustment? I haven't used the lathe much since doing this. 🤞

@radboogie 5 месяцев назад

Thanks Mike. I intend to get the shims just the right thickness to take up any slack (famous last words) 😂 Have seen some people make a tapered gib that they can adjust with a screw, but that looks like even more work.

@stephaniea9722 5 месяцев назад

@@radboogie tapered gib would definitely be the way to go. Do you have any links to people who did that mod?

@radboogie 5 месяцев назад

Check out RotarySMP - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NkLtLUbPvzA.htmlsi=p_cbAifVa5aU0bph