Bad finish

[Michael GilliganParticipant @michaelgilligan61133]

An interesting experiment would be to remove the feedscrew and convert the topslide to lever feed.

[it might also come in useful sometime, as a slotting device]

I suspect that the finish would show a dramatic improvement.

MichaelG.

[EmgeeParticipant @emgee]

I agree with an earlier post that suggested stripping the top slide down, cleaning and lubricating then adjusting the gibs for slack free but smooth movement, rotating with the handle at consistent speed will produce a good surface finish. The same method works with a Unimat SL so should with the Emco 5.

Emgee

[FarmboyParticipant @farmboy]

I certainly agree it is essential to get everything cleaned and adjusted to minimise play, but I have also found it sometimes helps if you apply pressure with the free hand on the top of the slide to help counteract any tendency for it to move as you turn the handle.

Obviously you can then ony use one hand for turning, but it worked better for me on my Unimat SL which was really too small to comfortably work two-handed anyway.

Mike.

[JonParticipant @jon]

Im with Jason use two hands or fingers, nice and smooth continuous cut and feel for whats happening.

Op's picky its ripped, that can be numerous reasons why. What you can do is take a reverse cut dragging cutter as a cleanup cut.

Looks like 6082 T6 to me evident with continuous strings no chip breaker will cure.

[VCRParticipant @vcr]

Thank you all for your help. I am convinced that the problem is not being able to achieve a smooth and continuous movement. I will disassemble, clean, lubricate and reassemble everything with care. I've also been training my hands and it's a little better. Soon I hope to have a better result and a photo to post.

Vasco Reis

[Neil WyattModerator @neilwyatt]

On a mini lathe you can fit a short stub of allen key in a portable drill and use it in the securing screw of the top or cross slide handle to provide a slow, steady power feed for critical tasks. You may be able to rig up something similar for a Unimat.

[Peter G. ShawParticipant @peterg-shaw75338]

I agree with others who advocate using the fingers of both hands on the wheel rather than the handles. I actually use this method on the cross-slide as well. And on the leadscrew when I can't be bothered with engaging self-act, eg on a short section, or where there might be potential for an unfortunate collision.

On my lathe, I have discovered that the tightness of the 4-way tool post clamp can significantly affect the topslide. Too tight and the topslide becomes very stiff to move. Obviously there is some flexibility on my lathe causing this, but with the toolpost clamp correctly adjusted, it isn't a problem.

Another idea is to use a HSS tool with a slightly rounded cutting point.

Cutting in the reverse direction is, I believe, a combination of the above (HSS) idea and a blunt tip, it being sharper in the "wrong" direction.

Finally, I always use paraffin on aluminium for finishing cuts, especially as I have a quantity of electrical grade, ie almost pure, aluminium. For roughing, I don't bother too much with the paraffin, but using it I can get a very smooth finish. The downside is that it's smelly!

Regards,

Peter G. Shaw

[Anonymous]

No doubt the main cause of the poor finish on the taper is uneven feed rates. However, the finish on the parallel portion under power feed, while better, isn't perfect. It may be a trick of the light, but it seems to have light and dark bands, I'd expect the finish to more uniform. That implies that the cutting process is unstable. So it might be worth looking at the basic cutting parameters (insert type and height, depth of cut, feedrates, rigidity of the set up etc) before going to the trouble of powering the top slide. It ought to be possible to get a decent finish by hand feeding.

Andrew

[EmgeeParticipant @emgee]

Neil,

Vasco has the Emco 5 lathe so I believe he will need a socket rather than an allen key, also a smaller socket for the DB or SL.

Emgee

[Author]

Posts