Member postings for Darren Keats

This is a still from the recent video:

Firstly the half nut is full of crud and needs a good clean. The block on the right, retained by two Phillips head screws and bent washers is loose. I am assuming this is some sort of gib strip and needs to be adjusted so that the half nut slides smoothly up and down. At present the half nut is waving about up down and sideways it all needs disassembling, cleaning and the putting back together with the gib strip properly adjusted although I can't quite see how the adjustment is made, presumably a couple of allen screw on the right hand edge. The whole thing is a fine example of poor engineering (sorry).

Once that is done the guide on the left needs adjusting so that the lead screw just bears on it so that it prevents the leadscrew deforming when the half nut is engaged. Although again I can see no easy way to make such an adjustment.

Good Luck

John

yes i agree ,it needs disassembling, but im not confident on getting this adjusted correctly

It might be worth looking at the support bracket at the right hand end in case it is adjustable, as with one half nut the leadscrew may just have been lifted out of place.

Brian G

If you want a fine feed for ordinary turning, the changewheels need to be selected to maximise the reduction ratio between Mandrel and Leadscrew.

For the C2 or C3 mini lathe this would entail a 20T driving a 80T which is compounded with another 20T to drive a second 80T on the Leadscrew. This will give an overall reduction of 16:1 so that for each revolution of the chuck, (with a 1.5 mm pitch Leadscrew ), the Saddle would move by 0.09375 mm or 0.00370 inches. For a 16 tpi Leadscrew the movement would be 0.0039 inches per revolution.

Direction of travel will be decided by the setting of the tumbler reverse, (or direction of motor rotation )

Howard

**LINK**

Hi Darren

If you look at picture 29 it only shows 1 half nut.

Cheers Michael.

This is what should be happening

Check that the top half of the nut is moving down like the lower is moving up.

Also try it when the lathe is running slower and make sure the carriage lock is not done up.

Edited By JasonB on 13/01/2021 17:12:03

Check that the top half of the nut is moving down like the lower is moving up.

Also why have you got it running so fast if it is for feed, would even cut a very coarse thread at that rate.

You need to check the geartrain/change gear set up behind the left cover.

1 with lathe unplugged, first release quadrant to free change gear mounted to leadscrew from any other gears in the train.

2 turn the change gear on leadscrew manually to check leadscrew rotates, if so, engage carriage feed lever to check for expected movement forward and reverse - if carriage is not moving then investigate for correct movement of half nuts (by peering at right end of carriage with a torch to confirm that the half nuts move together and apart to clasp the leadscrew).

3) if that checks out alright, check that the change gears you expect to have in the train can be made to mesh correctly and check by rotating chuck by hand to confirm motion all through the gear train to the leadscrew - if not look for change gear mounting issues or potential damage (grub screws or nuts to tighten etc)

4) check operation of tumbler reverse jockey wheels - correct engagement etc

5) if all the above is Greek to you, download this manual....

g0765_m.pdf (grizzly.com)

Edited By Martin of Wick on 13/01/2021 14:36:51

this is a very useful download for someone like me who needs to identify what parts are called, appreciate this👍🏻 And to everyone else who is trying to help me 🙏🏻👍🏻

When engaged the wheel won't work and vice-versa.

The half nuts are adjustable in several ways, there is also a hidden grub screw that controls how closely they mesh (Incidentally Ian Bradley suggested such a screw as an upgrade for the S7).

Neil

Either the lever is not engaging the half nut ( not adjusted correctly ) or the half nut is worn

Edited By John Rudd on 13/01/2021 11:17:31

Is the answer in the word "lift". The lever should be pushed down to engage the leadscrew.

Keith

get a complete unit from Axminster or the spares supplier already mentioned may have a suitable one but check first..

Edited By JasonB on 29/12/2020 07:02:00