Smart and Brown Lathe Crosslide Screw Renewal

[Stilldrillin]

That will do nicely Darren.....   

David D

[CrewCab]

Nice one Darren .......... impressed² 

as for the concrete .............



just a thought      ........... I know it's more expensive but it's but far less stressful on the knees mate

CC

[John Hill]

CC, too right, those concrete helicopters are wonderful machines.  In the hands of someone who knows what they are doing they can produce an almost gloss surface which seems to have high resistance to oil staining.

[Darren]

John, you ain't wrong mate, my knees are suffering, wet cement ain't too kind to skin. 

[John Hill]

Darren, wet cement is caustic and best kept off your skin if you dont want housmaids' knees and hands!

[Darren]

Now that I have my rotary table set up and ready to use it's time to cut some curved slots in the anti backlash nut....

Not having used a rotary table before this fool set up a dial gauge in the mill spindle to center the RT....you wouldn't credit it would you?
When I realised what I was doing I felt so dumb...!!!

If the work is correctly centred on the RT then that's it, cos the RT is used "off center" cos that's what it's for  

Anyways, there was no need for any real precise work here so the area to be cut was marked off with a pen by spotting through the old nut.



Four holes were drilled to help the milling cutter out a little.



Then it was milled with no drama or anyfink.....



Job done



Well that wasn't very exciting, maybe the next bit will be, can only hope eh?

Sum of parts made so far



Now to the fitting of these parts to the lathe. The two nuts needed to tighten together whilst at the same time they both ended up in the correct orientation. Otherwise there would be no point in having them at all.....bit like the originals, prob not original cos they were way out in this respect.

Either one of the two nuts needed to be faced/shortened until they met as described above, I chose the round one cos it's a darn site easier to do than the other one...  



Now fitted, the round nut is just ahead of this one just inside the slide. It's held from turning with a small keyway shown earlier in this thread.



The two nuts meet together with the outer nut in the position shown above. As things wear the outer nut is turned clockwise to take up any slack. As you can see I have set it so that I can gain maximum adjustments over time....

Next to finish the other two locking SS nuts off and we should be almost done.....

[Stilldrillin]

VERY nicely done Darren! 

Not having used a rotary table before this fool set up a dial gauge in the mill spindle to center the RT....you wouldn't credit it would you?
When I realised what I was doing I felt so dumb...!!!
If the work is correctly centred on the RT then that's it, cos the RT is used "off center" cos that's what it's for  

Not the least bit dumb!  

You should always know where the centre of the r/t is, so you can pace out from that datum point for your hole positioning etc.......  

David D

[Darren]

Gotcha....

Now I need to work out how to find the centre of the RT cos what I was doing last night would never have found it. But it did prove that the spigot I made was truly centred on the RT itself.

Mind you, I'd have been a bit worried if it wasn't......

[Stilldrillin]

Gotcha....

Now I need to work out how to find the centre of the RT cos what I was doing last night would never have found it. But it did prove that the spigot I made was truly centred on the RT itself.

Mind you, I'd have been a bit worried if it wasn't......

Hold finger clock in spindle.

Rotate, to clock bore or centre spud of r/t.  

[bogstandard]

Darren,

Just to give you a litle tip.

It is not always necessary to centre the RT or the job.

Say you want to drill 12 equidistant holes around a plate and you already have a centre hole in the plate, and you are not after perfect thou accuracy. Just mark on the plate where the first hole is to go, mount the plate into the RT centre using whatever is necessary, a bolt held in the chuck is favourite. Then just position the marked hole under you cutting bit and drill away, then just rotate the RT by the number of degrees required, and drill another hole. As long as the centre of the job is on the same centre as the RT, and you have placed the position to be drilled under the cutter, then every hole after that will be on the same PCD as the first. No need to centre the RT.

The job you have just done would be a good example of use of that method.


Bogs

[Darren]

Thanks John, that's pretty much how I did it this time.

There's nothing like practical exp, I'm sure it will all become much clearer as time goes on...

[Darren]

Stuck the two nuts in a hex collet holder and drilled six 3.5mm holes in each. Next job to make some small Tommy Bars....is that the right name?



Back on the lathe, a little stiff at first but soon freed up with a couple of turns backwards and forwards.




I now have a half metric lathe that will be much easier for me to get on with  

Oh, and got rid of some slop of course. Now have to let it bed in and see how it goes.....

[Stilldrillin]

Darren,
Those are 2 sweet looking locknuts..... 

That machine`s looking good inside & out! 

David D

[Darren]

Thanks David,

If I'm honest the cross slide unit is a bit rough all round. Someone has also chewed it quite a bit at one end with a hacksaw by parting off work. The cross leadscrew ( Y?) was badly worn, hence I renewed it.

But it cuts straight and leaves a good finish despite it's roughness.

Fortunately the cross slide and tailstock came from another machine and I just added them to my sliding turret and lever cross slide tooling to give me more options.
The rest of the lathe is in fairly good condition.

I have found that since I actually started to use the dials on the mini lathe to gauge the depth of cut I was getting better results. I like to work in metric but couldn't really get on with the imperial dials of the Smart and Brown. So now hopefully I will find it a little easier to use with the metric screw conversion.

We shall see....fingers crossed there will be an improvement.....