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4

Need some lathe help,

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casca92

MURPHY:Was an optimist ,when compared to me
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#1
I have some 8.5 inch square x.25 thick with 1 inch holes in each corner have roughly 50 of these at no cost hardness unknown painted yellow on one side.

I have one bolted to an 8 inch face plate to cut a 6 inch circle out out the center. hand to cut each corner off with portable band saw so they could rotate and not catch bottom of table.

what tool should I use to cut center out of piece. this is first piece mounted so had to be cautious that i don't hit
one of the mounting bolt hold down. I am clear all the way around 6 inch circle and half way through piece.

It is taking way to long to go through .25 inches.

lathe is jet 9 x 20
started with grinding a broken drill bit to a point to make initial grove and it worked ok for awhile.
next tried 3/8 3 sided insert straight with some success
now working with .25 3 sided insert straight. with some success .
did try some HHS ground to fit groove but does not stay sharp long even with diamond hone ground on green wheel and finished on diamond wheel.
tried all speeds from 180 rpm up to 1100 rpm

so tell me what speed I should be using and suggest a couple of tools to use. MY PLAN IS TO BUILD SOME DUAL WHEEL ADAPTERS FOR MY 1985 HONDA 250 SX 3 WHEELER
 

DHarris

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#2
Do you have access to / or friend with a Plasma torch or a metal cutting band saw? You could rough cut to size then move to the lathe to finish turn the edge? (band saw would be best as it would not harden the edge like the plasma cutter would). You could do the same with your hand held band saw making straight cuts as close as possible so you are not making large skip cuts when you turn the part.
 

f350ca

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#3
A trepanning tool is what you need to grind. Basically a parting tool with the sides ground to fit the curve of the cut with a little clearance angle. Then plunge that into the face. As for speed, about 60 rpm would be 100 fpm, but I'd probably start slower.

Greg
 

T Bredehoft

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#4
I'm with Greg on that. Both the trepanning tool and the RPM, slower is better. If your lathe won't go below 180, you must use carbide. Any other tool, the heat will destroy.
 

Karl_T

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#5
You may not have it, but this job would go WAY EASIER with a rotary table on the mill.
 

casca92

MURPHY:Was an optimist ,when compared to me
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#6
Do you have access to / or friend with a Plasma torch or a metal cutting band saw? You could rough cut to size then move to the lathe to finish turn the edge? (band saw would be best as it would not harden the edge like the plasma cutter would). You could do the same with your hand held band saw making straight cuts as close as possible so you are not making large skip cuts when you turn the part.
tried the 4 x 6 band saw plate will not fit, unless stand up on edge. and using vertical band saw 1/4 is just to much ti try and twist tried both of those.
BUT IF THIS PROJECT WAS EASY WOULD HAVE ASKED MY MOM TO DO IT !
 

richl

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#7
Hole saw and drill/mill may work to get a rough hole started and than finished on the lathe. Hole saws are relatively affordable, something in the 3-5" range will get you started. The rest of the hole can be done with a boring bar...

Hth

Rich
 
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