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Discussion Starter #1
O.k, as you know I started of with this little guy here:

http://pirate4x4.com/forum/showthread.php?t=723470&highlight=

After using it for a bit, I relized that it would only work well for radii 1" and under. So, the search was on to find a design that would allow me to make dies in the 1 1/2" to 2" range on a 9" x 17" logan lathe. I found that there is little info available about making a concave radius tool for 1" and over. After looking around on various sites I came across this thread that had just what I was looking for.

About halfway down the page is the one I based mine from.
http://www.offroadfabnet.com/forums/showthread.php?t=1694


Scrounging through the scrap bin the following material was gathered for the build.

Cold rolled steel:
1 ea. 1/2" x 4" x 5" long flatstock.
2 ea. 3/4" x 1 1/2" x 2 1/2" long bar stock.
1 ea. 7/8" x 2 1/2" x 6" long bar stock.
1 ea. 1 1/2" dia. x 1 3/4" round bar stock.
1 ea. 1 1/2" dia. x 1 1/4" round bar stock.

Stainless steel:
1 ea. 5/8" x 7" long round stock.

Misc.
1 ea. 3/4" x 6" long shoulder bolt.
2 ea. 3/4" id x 7/8" od x 5/8" long bronze bushings.
2 ea. 5/8-11 jam nuts.
2 ea. 3/8-16 x 1 1/4" long socket head cap screws.
3 ea. 5/16-18 x 1" long socket head set screws.

1 ea. 3/8" square m.2 tool steel blank.


Started off by having a .375 square hole wired out in the center of the shoulder bolt.



The set screw to hold the tool bit in place was originally going to come down thru the top of the bolt, but when it was being tapped, the tap broke so it goes up from the bottom.



Parts coming together.



Frame welded together.



Holes bored, bushings pressed in and shoulder bolt in place.




continued.
 

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Having not done it before, I asked one of the toolmakers at work to show me how to grind the tool bit. There is not much to it.

Roughing it out on a regular wheel.



Sensitive content, not recommended for those under 18 Show Content


Finishing on a wet diamond wheel.



Tool bit in place.



 

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Having not done it before, I asked one of the toolmakers at work to show me how to grind the tool bit. There is not much to it.

Roughing it out on a regular wheel.



Sensitive content, not recommended for those under 18 Show Content


Finishing on a wet diamond wheel.



Tool bit in place.





Cool, looks good. Why did you make the bit square so close tollerence? Atleast thats what it looks like. Any variation in size and ofcourse another wont fit.
 

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With the main frame complete, it was time to come up with a handle. Originally, the handle was going to be removable to access the tool bit set screw. With that not being a concern anymore it is pressed onto the bolt head.



A "ball" was needed for the other end of the handle, and not having a working ball cutter yet (another thread coming), this is what I came up with.




This lathe uses a single large "T"- slot on the compound to mount the quick change tool post to, so a full size T-slot nut was milled so that the cutter could be attached to the lathe.





Mounted on the lathe.



Note: a .385 thick spacer was needed to bring the tool bit up to the chuck center line.


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looks good but WTF wheres the damn shots of the radius it cuts.
when/if i make one im going with the second link you posted, it looks easier to make and does internal and external radius.
 

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Discussion Starter #6
The completed cutter.



With the cutter assembled it was time to try it out. A piece of 3" stock was chucked up and the edges and center center lines are marked out.



To set the cutting bit depth, you measure from the center of the shoulder bolt to the tip of the bit. (in this case it is .500" for another 1" die)



Line up the bit on the center line.



The tool "should" be swung from right to left but I do both and haven`t noticed any ill effects. Depth of cut is dependant on the machine. As for this one, 30 thou. is about all it wants to do without chattering really bad. Softer material may yield different results.

 

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Found a video that helped me visualize a couple things and it helped me understand how I would set the tool up a lot easier than a written explanation could. http://www.youtube.com/watch?v=c-G2FV67g4c

Nice work!

edit: damn. went to youtube to find a video to see it "in-process" and the first one that came up was yours. How weird is it that I posted it at the same time as you.
 

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thats preaty sweeeeet. your going to cut more on that die correct? i would think you want almost a 180* cut out in the die.
 

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Sorry for the long post, had to get the kiddo`s baths and supper.

Cool, looks good. Why did you make the bit square so close tollerence? Atleast thats what it looks like. Any variation in size and ofcourse another wont fit.
Well, I told the wire guy at work that I wanted a .375 square hole for the bit and thats what he gave me. It is a very close (probably .0005) slip fit, so much so that I had to knock off the corners on the bit to get it to fit.
The bit was left long in case it ever needs to be reground or repaired.

looks good but WTF wheres the damn shots of the radius it cuts.
when/if i make one im going with the second link you posted, it looks easier to make and does internal and external radius.
Here you go.











Found a video that helped me visualize a couple things and it helped me understand how I would set the tool up a lot easier than a written explanation could. http://www.youtube.com/watch?v=c-G2FV67g4c

Nice work!

edit: damn. went to youtube to find a video to see it "in-process" and the first one that came up was yours. How weird is it that I posted it at the same time as you.
Sorry about that, I`m an incredibly slow typer.

Thanks to all for the kind words.
 

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O sorry must have missed that part. how thick material you plaing on bending with it? what you making?
 

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did you have a reason for making it so far off the compound? it seems like an awful lot of leverage on it.
 

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Discussion Starter #15 (Edited)
300 sniper


Well, thats kind of a compromise. In order to turn bigger pieces
( approx. 8.5") the carrige needs to be set back from the chuck because it will not fit under the stock being machined. It is actually pretty ridgid once it`s positioned correctly, I just lock the carrige in place and snug up the gib set screws on the compound. If and when I get around to making dies for the bender, the cutter can be mounted to the QCTP on the 16" lathes at work.
 

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Cool, looks good. Why did you make the bit square so close tollerence? Atleast thats what it looks like. Any variation in size and ofcourse another wont fit.
I know this is an old post, but HSS bars are precision ground. Any (quality, not chinese) 3/8" bit will be .375 +000/-002. Even a brazed carbide would be interchangeable.
 
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