Mini Lathe Saddle Plate Fix


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I tend to be a bit of a Jack-of-all-Trades. Some of the interests I have are woodwork, metalwork...

This will be a quick Instructable on how to fix the saddle plates on the CJ0618, or similar, mini Chinese lathe which has been poorly assembled. There are other similar videos etc on the Internet describing this same problem. From the research I have done on many of the mini lathe brands they are built on the basic CJ0618 and seem to come with or without problems. It seems to me that the more you pay for these mini lathes the less problems you'll find when you get it.

In my case I bought a cheap Chinese mini lathe (the cheapest I could find at around AU$600 from the Aus Amazon) and expected to find faults. I did. One of the faults is how the saddle plates have been installed.

I will show you how I fixed these up

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Step 1:

There are 2 saddle plates located under the carriage, one under the front way and one under the back way. I have drawn an arrow on the image to show you where they are.

These saddle plates are there to stop any upward movement (chatter) of the carriage and are supposed to be set to just off tight allowing you to crank the saddle backwards and forwards along the ways easily.

If you look carefully at this image you will see that the plate (front and back) is not flat under the way. It's running at an angle along the sharp edge of the way. You'll see in the images to come that it is scoring a line down the length of the plate which will just get deeper and deeper as you use the lathe and you will need to keep re-tightening the plates.

REMOVE the two saddle plates -

You'll need to take the tail stock off and the lead screw. Then also remove the apron so that you can get at the 3 bolts holding the front saddle plate (they are behind the apron). Loosen the 3 bolts in front and the 3 bolts at the back. Then the whole carriage will slide off the tailstock end. Watch carefully how it's all come off so you can reassemble it.

NOTE: Reassembling the apron back onto the carriage needs a bit of adjustment so that the assembly clears the rack gear on the underside of the front way.

Step 2:

Sorry I didn't take more pictures of the underside of the removed carriage, but it's pretty straight forward. The two saddle plates are clearly visible and can now be removed.

As you can see there are only 3 bolts holding down the plate and if you look at the exploded diagram of the lathe in the manual you receive (a very poor paper copy - I downloaded a far better manual I searched for and found online) you will see that there should be 2 x 5mm grub screws in the front plate and the same for the one behind. As far as I know the more costly models have all the right parts but these cheap ones have skipped this step.

You can see the score marks already taking place on these plates and I only moved the carriage a few times when I got the lathe.

So what we have to do now is quite simple - to drill and tap 4 holes and put in some 5mm grub screws.

(I sent these pictures with my review after I got the lathe plus other comments on the other faults and I see the lathe has been withdrawn from our Amazon)

Step 3:

As you can see from these images the holes for the grub screws are on the same line as the other bolt holes.

What the grub screws are doing is providing an adjustable level for the plates to correspond with the level on the underside of the ways so that the 6 bolts can be tightened allowing the tiny sliding clearance needed for the carriage to slide on the ways.

The way the plates were held didn't allow for the 6 bolts to be tightened properly and they could work loose from any chatter of the lathe.

Drill out the 4 holes for a 5mm tap (I drilled a 4.5mm hole and then a 5mm tap)

When you put the saddle plates back onto the saddle keep the bolts loose.

Slide the saddle back onto the ways (you can now also put the lead screw back in. Now adjust the saddle plate bolts and grub screws so that the plates are flat under the ways - Now tighten the 6 bolts to so that the saddle can slide on the ways. Adjust the grub screws and bolts till you get this right.

Put the apron back on watching that it does not rub on the rack gear. Put the tailstock back on and - have I forgotten anything? - I think that's it.

Note - I saw some pretty good and clever upgrades to these saddle plates that others have made in brass etc but for now, I'm happy that the slides are working well for me.

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    2 Discussions

    None
    Cnc971

    7 months ago on Step 3

    Hi Garth,
    Interesting that you would modify the saddle plates to include the grub screws for adjustments. I had the grub screws on my lathe when I got it and found I was often adjusting them and the plates themselves are subject to minute movement as they are not flat on the underside of the saddle but supported only by the grub screws and cap bolts. My solution was to remove the grub screws And test fit the plates with strips of various thickness brass shim stock till I got it just right, no play and no drag. That was 10 years ago and I have never had to redo it. I have also used shim stock to better align various other parts of the lathe.
    Cheers

    1 reply
    None
    GarthKHCnc971

    Reply 7 months ago

    Thanks for the comment and your ideas of sorting this out.