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CAMCOMPCO
Guest
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 Posted: Tue Nov 28, 2006 2:02 pm Post subject: Cutting internal Keyway |
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Hi all,
I am trying to cut a 2 inch internal keyway into some CRS and am having
some trouble. I have an Atlas 7" shaper and have ground a bit out of
tool steel (kiln hardened after grinding). The issue is that I get
deflection because of the tool being a bit over 2 inches long. What's
happening is that the keyway is being cut just fine at the beginning of
the hole but is deflected down to nothing by the time the cutter gets
to the other side of the hole (2" further). I am using 1/2 inch tool
steel and thought that it should be strong enough to not deflect. Do I
need to make the cutter out of 3/4 inch steel? If so, how would one
cut a keyway into a 5/8" hole (2 inches long)? Should I make my cutting
tip smaller (width), right now it is .25" wide (the width of the keyway
I need.
Any help would e greatly appreciated.
I had one idea, that was to anneal a file, cut it, drill holes in it,
make a new clapper attachment to hold the file with screws through the
holes I made in the file and file away the group....in effect,
converting the shaper into an automatic file...just seems like I should
not have to do that.
Thanks again
John |
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Karl Townsend
Guest
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| Posted: Tue Nov 28, 2006 2:02 pm Post subject: Re: Cutting internal Keyway |
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| Quote: | I am trying to cut a 2 inch internal keyway into some CRS and am having
some trouble. I have an Atlas 7" shaper and have ground a bit out of
tool steel (kiln hardened after grinding). The issue is that I get
deflection because of the tool being a bit over 2 inches long. What's
.... |
I cut keyways this long and longer all the time on my Bridgeport vertical
slotter. Not as rigid a unit as yours. But, I use HSS for the tool bit -
better. The deflection force in the tool bit is a constant, i.e. it doesn't
change from the start of the cut to the end. What changes is the length of
the ram in the shaper, or how far out it is from the support. I suspect you
may have something worn/loose in the shaper itself.
Karl |
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Tom Gardner
Guest
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| Posted: Tue Nov 28, 2006 2:02 pm Post subject: Re: Cutting internal Keyway |
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"CAMCOMPCO" <JCPUBLIC@CAMERONCOMPONENTS.COM> wrote in message
news:1164717776.519480.79050@n67g2000cwd.googlegroups.com...
| Quote: | Hi all,
I am trying to cut a 2 inch internal keyway into some CRS and am having
some trouble. I have an Atlas 7" shaper and have ground a bit out of
tool steel (kiln hardened after grinding). The issue is that I get
deflection because of the tool being a bit over 2 inches long. What's
happening is that the keyway is being cut just fine at the beginning of
the hole but is deflected down to nothing by the time the cutter gets
to the other side of the hole (2" further). I am using 1/2 inch tool
steel and thought that it should be strong enough to not deflect. Do I
need to make the cutter out of 3/4 inch steel? If so, how would one
cut a keyway into a 5/8" hole (2 inches long)? Should I make my cutting
tip smaller (width), right now it is .25" wide (the width of the keyway
I need.
Any help would e greatly appreciated.
I had one idea, that was to anneal a file, cut it, drill holes in it,
make a new clapper attachment to hold the file with screws through the
holes I made in the file and file away the group....in effect,
converting the shaper into an automatic file...just seems like I should
not have to do that.
Thanks again
John
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How about a broach? |
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k.pearson
Guest
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| Posted: Tue Nov 28, 2006 2:02 pm Post subject: Re: Cutting internal Keyway |
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On 28 Nov 2006 04:42:56 -0800, "CAMCOMPCO"
<JCPUBLIC@CAMERONCOMPONENTS.COM> wrote:
| Quote: | Hi all,
I am trying to cut a 2 inch internal keyway into some CRS and am having
some trouble. I have an Atlas 7" shaper and have ground a bit out of
tool steel (kiln hardened after grinding). The issue is that I get
deflection because of the tool being a bit over 2 inches long. What's
happening is that the keyway is being cut just fine at the beginning of
the hole but is deflected down to nothing by the time the cutter gets
to the other side of the hole (2" further). I am using 1/2 inch tool
steel and thought that it should be strong enough to not deflect. Do I
need to make the cutter out of 3/4 inch steel? If so, how would one
cut a keyway into a 5/8" hole (2 inches long)? Should I make my cutting
tip smaller (width), right now it is .25" wide (the width of the keyway
I need.
Any help would e greatly appreciated.
I had one idea, that was to anneal a file, cut it, drill holes in it,
make a new clapper attachment to hold the file with screws through the
holes I made in the file and file away the group....in effect,
converting the shaper into an automatic file...just seems like I should
not have to do that.
Thanks again
John
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John,
In my experience, the complete key to getting a shaper bit to not push
away is the shape of the cutting edge. It has to have enough rake to
bite into the stock. It also has to be sharp. Even a little dullness
(use a magnifying lens to look for a line of light along the cutting
edge - if found = dull).
You can go to a smaller tool, but that will take longer and have to be
resharpened more often. Sometimes it works better to do a small tool
for a way, then switch to a larger tool and repeat until at depth. If
moving from side to side to create the final width, try to take the
same amount of each side of the key.
As to how much you can cut - if it stalls, it's too big. You'll know.
If you don't take enough per cut it will push out and chatter, dulling
the tool and making it hard to get back into the cut.
I spent 30 years watching and working with some master shaper
operators (they would hold tenths and often make complex pieces faster
and more accurately than the CNC guys could). It all came down to
very carefull control of all the angles and clearances of the
cutters.;
Karl Pearson |
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