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Fly Cutters

This topic has 5 replies, 5 voices, and was last updated 23 February 2012 at 00:36 by Michael Cox 1.

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22 February 2012 at 20:42 #38104
Wannabewelder
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@wannabewelder
Query regarding F/C in MEW181 & 187
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22 February 2012 at 20:42 #85498
Wannabewelder
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@wannabewelder
Hi

I want to make myself a flycutter and have been looking at the two articles. I found both of the articles interesting and, in general, easy to follow but I have a couple of (I hope not too idiot) questions that I'm hoping someone more knowledgeable than me can assist with.

In the tangential tool flycutter article in 181 it appears to me (photo 2) that the slot in which the tool is mounted is not "square" with the flat base of the body in which the tool is mounted; yet as far as I can see there's no mention of of the tool slot not being square in the text. Am I missing something? I have to say I don't understand why the cutter is "tangential" Help please?

In the TC insert flycutter in187 only one insert is used; why? I would have expected two to be used in the interest of balance and faster cutting.

Finally, for a newbie, which of the two would be the best for ease of manufacture and operational performance?

Regards

Wannabe
22 February 2012 at 21:22 #85501
M0BND
Participant
@m0bnd
Yes, why is it 'tangetial' and not 'perpendicular'? It's not like the lathe tangential tools that we know of (not that I understand any way).

For my machines at home I have a standard fly cutter with wimet braised inserts and HSS tools and use these due to the size and rigidity of the machine I have. Depending on your setup and cash flow will depend on which type you go for.

The tipped version – quick to change but expensive!

HSS version – cheaper but grinding the correct geometry on the tool must be somewhere handy!

The shear size and spindle speed will determine the balance issues that you may be concerned with and unless you are running faster than 2000 – 3000 rpm, I wouldn't worry.

Hope this helps!!

Andy.

Edited By M0BND on 22/02/2012 21:37:46
22 February 2012 at 22:38 #85506
Robert Dodds
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@robertdodds43397
Wannabe,

Its not easy to define the exact motion of the "tangential" tool. In so far as it cuts on the end of the the tool like the lathe tool being marketted at present by the Aussies, you could construe it as tangential I suppose.

The apparent incline of the toolbit is, I would suggest, nothing more than shadow on the photo.

As far as which would be easiest of the two versions 181 is not particularly beefy and if you needed a bigger version you would need to spend time adjusting those angles to get the neccesary clearance on the tool edges.

187 is perhaps more adaptable to particular needs but relies on having a ready supply of toolbits whereas £10 will get you up and running (toolbit included) if you buy one off the shelf from one of the several online traders.

As MOBND suggests balance is unlikely to be a problem unless you are running at super high speeds More relevant is the ability to keep two tools so aligned that they take equal shares of the cut and load on the spindle. This is seldom easy to achieve and most are happy to get by with just one cutting edge going round.

At the end of the day the choice must be yours. Do you want the challenge of making one or have you a job in mind that requires flycutting and then material factors may also influence you choice of cutter.

Hope this helps rather than confuse

Bob D
23 February 2012 at 00:24 #85522
chris stephens
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@chrisstephens63393
Hi Wannabe,

Rather than call this a "tangential" tool I think the other name commonly used ie "diamond" might, in this case, be easier to understand. The cutter has on its end a rhomboid or diamond shaped face and it is this face that gives the clearance, and apparent angle, that you wondered about

A friend pointed me to another "tangential" fly cutter over on another forum, it is a different design but very neat looking, and it uses a round cutter, take a look at;

.http://www.homemodelenginemachinist.com/index.php?topic=15491.0

chriStephens
23 February 2012 at 00:36 #85523
Michael Cox 1
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@michaelcox1
The term tangential arises because the long axis of the cutting tool is approximately tangential to the arc described by the tip of the rotating tool.

The alternative tangential fly cutter mentioned by Chris Stephens that is describedc in HMEM suffers from one problem in my experience. In most flycutting the tool is cutting intermittently and the hammering cause the cutting tool to slip in the holder unless the motion is restrained by a positive stop.

Mike
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