Author Topic: Chip formation.  (Read 10580 times)

Offline mattinker

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Chip formation.
« on: October 27, 2013, 08:06:28 AM »
Hi,

I just found a video that explains clearly chip formation, the thing I find the most difficult as an amateur. The sound is pretty lousy and the intro music atrocious!

     


Regards, Matthew
« Last Edit: October 27, 2013, 11:59:09 AM by dsquire »

Offline vtsteam

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Re: Chip formation.
« Reply #1 on: October 27, 2013, 10:55:35 AM »
That's a very interesting presentation, Matt. I tend to do things because I've read that's how they should be done, or through experience with what seems to work or doesn't work. But it is seldom that we get an explanation of WHY something is occurring so we get the physical basis to understand it.

It's kind of like the difference between simply following recipes..... and understanding ingredients so you can write your own recipes.

This video helped me understand the ingredients and how they work.

I don't mind the silly music or the presentation -- I learned something, and he explained it very well and quite thoroughly. The information and concepts will stick with me.

Thank you for pointing this one out!   :thumbup:  :beer:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

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Re: Chip formation.
« Reply #2 on: October 27, 2013, 11:07:03 AM »
Thanks for the link Matthew - interesting video, (and interesting style !)

Andrew
Andrew Mawson
East Sussex

Offline sparky961

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Re: Chip formation.
« Reply #3 on: October 27, 2013, 07:32:34 PM »
Great explanation of chip formation.  Thanks for sharing the link.

Offline mattinker

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Re: Chip formation.
« Reply #4 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

Offline Pete W.

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Re: Chip formation.
« Reply #5 on: October 29, 2013, 04:44:16 AM »
Hi there, Matt,

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

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: 
Best regards,

Pete W.

If you can keep your head when all about you are losing theirs, you haven't seen the latest design change-note!

Offline mattinker

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Re: Chip formation.
« Reply #6 on: October 29, 2013, 05:31:15 AM »
Forgiven!

Regards, Matthew

Offline Meldonmech

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Re: Chip formation.
« Reply #7 on: October 29, 2013, 12:33:07 PM »
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


Offline mattinker

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Re: Chip formation.
« Reply #8 on: October 29, 2013, 05:51:59 PM »
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

Offline vtsteam

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Re: Chip formation.
« Reply #9 on: October 29, 2013, 07:34:59 PM »
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.

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline mattinker

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Re: Chip formation.
« Reply #10 on: October 31, 2013, 06:42:25 PM »
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

David,

I realise that I didn't thank you for your suggestions and good wishes. My reply was inadequate. I had a bad day!

regards, Matthew

Offline modeldozer

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Re: Chip formation.
« Reply #11 on: November 05, 2013, 02:23:51 PM »
Very informative, thank you for sharing.

Abraham

Offline mattinker

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Re: Chip formation.
« Reply #12 on: November 05, 2013, 02:46:05 PM »
Abraham,

i'm glad it's useful, I've been seeing "chips" in a new light, as a consequence I'm getting better finishes and more precission.

Regards, Matthew

Offline S. Heslop

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Re: Chip formation.
« Reply #13 on: November 06, 2013, 06:35:01 PM »
I was just drilling some big holes on the drill press today when I remembered this vid. I noticed the chips had stopped being the nice curly sort and became the ugly wobbly ones as the drill I was using got bigger. So that prompted me to reduce the speed to get the nice ones back.

I've always had trouble with grabbing when drilling steel on the drill press but I had no problems at all going by the chips. Well, until I got to about over 16mm diameter when I couldn't slow the thing down any more.

But yeah that's a good video, thanks for posting it.

Offline mattinker

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Re: Chip formation.
« Reply #14 on: November 07, 2013, 12:37:45 AM »
I'm glad you liked it!

That's an interesting application of the gleaned information! Pillar drills have a tendency to be too fast. A solution to the speed problem can be to add a jack shaft.
http://forum.ih8mud.com/merchandise-storefront/617689-rogue-drill-press-reduction-kit-1-2-1-4-ratios-available.html
I couldn't find the fifties article I was looking for, but a big washing machine pulley on a jack shaft might be an interesting project.

Regards, Matthew