Gallery, Projects and General > How to's

Chip formation.

<< < (2/3) > >>

Pete W.:
Hi there, Matt,


--- Quote from: mattinker on October 29, 2013, 02:35:02 AM ---I'm surprised there isn't more response to this. I think that the most difficult thing to learn is speeds and feeds without calculating! Especially with unknown metals!

Matthew

--- End quote ---

Well, rebuke accepted!   :bow:   :bow:   :bow: 

I did read your post and I did watch both videos.  I found them very interesting but I didn't comment because I'm not currently in a position to try things out for myself.

Getting the new roof on the workshop is absorbing all my time at the moment - I'm just itching to get that job done and get back in there and making some chips!!   :drool:   :drool:   :drool: 

mattinker:
Forgiven!

Regards, Matthew

Meldonmech:
Hi
         Very interesting video presentation, now you have digested the basic theory of metal cutting tools, I feel it is important   for you to carry out some experiments for yourself and record your results. A repeat of the experiments in the video would be a good start.  Next I would suggest you try similar experiments on brass and aluminium, using the designated cutting speeds and cutting tool angles from engineering tables. This is not too lengthy a task and will provide you with invaluable experience, and records that you can refer to in the future.  At a later date you could introduce other variables like feed rate and depth of cut, recording the surface finish. The Theory of Cutting Tools is a vast and deep subject, but if you need information regarding uncommon materials for Model Engineers, it can be found on the internet, just Google your requirements.
                     
                                                          Good  Luck        Cheers David

mattinker:
David,

I've been hit and miss machining for too long. I found this very interesting, common knowledge to some, but clarifying. I particularly liked the angle of the tool compared with butter and the angle of the knife spreading! I'm not sure about what you mean about  " if you need information regarding uncommon materials for Model Engineers, it can be found on the internet, just Google your requirements." "unknown metals" in my workshop are pieces of metal that I've gleaned along the way that I can't identify, there aren't many that I don't recognise, part of my work is steel construction. I don't really see myself as a Model Engineer, I don't make models! I build machinery for theatre and television, most of my machining is pretty basic!

Regards, Matthew

vtsteam:
For me the top angle of the tool and the chip appearance (greyed on top, shiny under, etc) were new.

Most places I've read or found online in the last ten years seem to rake the top in a positive direction for steel, general purpose. Except where threading, where it's mostly neutral -- presumably to give a true profile when grinding to the thread form.  Also I've seen recommendations for neutral rake on top for brass, becaus it's "grabby".

But in the video, he says almost the opposite -- steel benefiting from a neutral to negative rake, soft materials benefiting from positive rake. Also, he doesn't seem to recommend a "dust" cut for finishing.

So, quite a bit for me to think about and try out for myself (as soon as I finish the never ending task of sorting out my shop).

I'm wondering if some of the differences are due to the proliferation in our hobby of very small and light lathes -- maybe its due to the inability to plow through with much negative rake compared to industrial machines, like the one in his demo.

Navigation

[0] Message Index

[#] Next page

[*] Previous page