The thrill of victory........

[myxpykalix]

AND THE AGONY OF DEFEAT!!!!!!

8149

I am trying to cut out (1.5") rings to stack 2 to make a round box then i will make a lid. I don't have a 3" endmill to preglue the pieces and when i get to the last revolution of the cut out it breaks. I was leaving a skin on the outside but both times it catches and kaboom!

I was using a .5" endmill with a .1 cutdown per revolution. How is the best way to cut a ring out without destroying it? My .25 endmills aren't as long.

[rb99]

Just a thought...

Could you cut a plug the size of the inside, then cut the inside first, put the plug in the center, then cut the outside? The plug would stop the ring from vibrating and give it support.

Another thing to try is making tabs that are the full height of the ring. They would be manually removed after.

RIB

[myxpykalix]

makes sense, i'm glad i thought of it....lol

[cabnet636]

i have had to learn alot about deep cutting lately and have mucked up my share of bits and material, i have found 4" long bits of 1/2" for hogging and 1/2,1/4 and 3/8" ballnose for carving. the first cut is to remove much of the perimeter material so the final profile cut will not have massive vibration, if project were say 12" diameter then i would do an offset say .125 inches out and remove 2.5" of say 3" thickness then come back and remove the .125 down to 2.8 inches. once this is done profile my interior and slip some 1/2" stips into the cut space to help eliminate vibration when returning to cut the exterior out. many times it is not the bit but the collet nut that is the culprit!

jim
8150

[stevem]

Climb cutting.

[magic]

I have put dogs around the part - moved the cutter a quarter rev around the perimeter then moved the dogs. Especially on metals.

I've also got in there an held parts by hand.

[butch]

Jack
I have done what Richard suggested on a couple different projects with very good results. I made a plug slightly shorter than the tube I was cutting then put a cap on with a screw to hold the pipe (item being cut) solid. Also cut at about 1.0 ips.

[myxpykalix]

I was going to try what richard suggested and also thought i might leave a skin on the bottom of both the inside and outside of the ring and take it over to the jointer and skin it off that way.

[knight_toolworks]

ok I am the king of this. I have been hollowing boxes out 2.75" deep. I have used the 1.75" .5 downcut endmill from centurion. there is just enough to go 3"
the sides of the box are about .25" thick. I cut at 1ips between 8k and 12k rpms and .5" per pass.
there are several ways to do this. do a offset cut on the outside and a full depth cleanup pass. leave tall thin tabs on the inside. say .25" wide and tall. then do a cleanup pass as the last cut to remove them.
cut the discs out put them in a ring holder and then just cut the inside out.
check out out thin these are.
http://s154.photobucket.com/albums/s266/knighttoolworks/ALO/

[myxpykalix]

Sure looks like you are a master at this, question is are you a jedi master? OK obe wan you need to go into a little more detail on your instructions. lol

The only reason i was making a "ring" was because i couldn't cut deep enough to make a 2.5 or 3" box out of one solid piece. You seem to have mastered that and even though my box was round I should be able to do the same thing.

I don't fully understand your instructions though. I don't understand about leaving tabs on the inside and some of the other instructions. But thanks i will study your pics better to glean more info.

[knight_toolworks]

if you can leave a bottom on it it would be far stronger.
sorry I am good at doing it terrible and describing it.
so you can do it all at once. the trick is to do the inside cut with two different toolpaths. the first is a inside profile cut to the depth you want say 2.75" this saves a lot of problems and keeps things accurate. if you do it all with a pocket cut shavings can jam and cause the sides to blow out or deform.
then you do a pocket cut to clear the inside out. you use a smaller pocket then the inside say 1/2" smaller.
you can use a straight bit they work ok. but I like the downcut better.

8151

8152

[knight_toolworks]

I forgot I cut the boxes to size first. so doing the outside first or bandsawing it may be best.

[rb99]

You could also cut a groove in a spoil board the size of the finished ring.

Then cut 3/4 of the ring from the top down.

Flip the piece over and fit the finished ring in the groove.

Hold the piece in place using clamping (on 1/2 of the top, and to the outside.)

Then cut the center out.

Change the clamp to the inside and the inside top half and finish the piece.

RIB

[mitch_prest]

what type of wood are you using... it may be the wood is just not suitable to what you are attempting

m

[knight_toolworks]

I have done it with so many different woods from mdf to pine to soft maple walnut to bamboo plywood tropical hardwoods and plywood. as long as you have the outside cut and then hollow it it is fine. I bet I have made 300 hollow boxes so far.