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Wide radius cutting tool for lathe

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  • BCRider
    replied
    I'm wondering about the idea of just pushing/pulling through the length of tubing or pipe mentioned earlier by akajun. If you got a length of pretty close fitting PVC conduit and mounted the two ends to something and get someone to flex the conduit around in a barrel like "skipping rope" action while you push and pull the line through the conduit I bet it would come out the other end quite straight.

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  • jmarkwolf
    replied
    Originally posted by Paul Alciatore View Post
    Now there's an idea. Buy the tool, use it, and then sell it. Put it on E-bay for something like 50% of your cost and a one week auction. You may even get more than your money back.

    Hi Paul

    Ohio Mike suggested the same thing, and honestly, I'm leaning in that direction.

    As much fun as it is to think about how to fabricate the means for this and other tasks, if I always followed through with building the tooling, I'd never get my original projects completed.

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  • Paul Alciatore
    replied
    Now there's an idea. Buy the tool, use it, and then sell it. Put it on E-bay for something like 50% of your cost and a one week auction. You may even get more than your money back.



    Originally posted by Ohio Mike View Post

    Installing Maxline very soon. I was going to try to make something but life it short. I just ordered the tool and plan on selling it when I'm done.

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  • jmarkwolf
    replied
    Originally posted by Ian B View Post
    Do you have a milling machine and some way of rotating a piece of the delrin bar? With the tool & delrin axes at 90 degrees, plunge the side of a 1" end mill into the delrin, rotate the delrin once and a bit, job done.

    Ian
    I like this approach. I have a mill and a 10" rotary table and 1" end mills However to make the 7 rollers efficiently on one stick of delrin (cut them apart later), I think I would need a tailstock, which I don't have, to hold the "long end".

    I can't get very close to the rotary table due to the diameter of my spindle/collet chuck, etc., so making them one-by-one with minimal stick-out and no tailstock would be wasteful.

    Could probably fabricate a tailstock from big aluminum angle I suppose. Will give that some thought.
    Last edited by jmarkwolf; 03-01-2021, 08:30 PM.

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  • oxford
    replied
    Originally posted by Ian B View Post
    Do you have a milling machine and some way of rotating a piece of the delrin bar? With the tool & delrin axes at 90 degrees, plunge the side of a 1" end mill into the delrin, rotate the delrin once and a bit, job done.

    Ian

    You could also use a 1” ball end router and rig up some live tooling for the lathe.

    I could be nothing more than something held in the tool post with a hole through it the size of the router shank, a thrust bearing behind the cutter. Put the bit in the hole and power with a drill from the back. Feed in with the cross slide.

    Getting a router or die grinder attached somehow would also work.

    Leave a comment:


  • akajun
    replied
    Originally posted by Mcgyver View Post

    dial, dro, imo makes no difference...its just numbers. I've never bothered making a radius tool and after 25 years have done every radius this way with a DRO. But i get the DRO is slightly easier to read.

    I like idea of an indicator on the bed for the Z movement, vs slewing the compound around
    exactly, I just fed mine through a 8ft piece of 1" pipe, I pushed my son pulled, came out straight enough. Used a conduit bender with a long handle to make my bends.

    Leave a comment:


  • Ohio Mike
    replied
    Originally posted by jmarkwolf View Post
    I'm seriously considering installing Rapid Aire Maxline air compressor line in my shop.
    Installing Maxline very soon. I was going to try to make something but life it short. I just ordered the tool and plan on selling it when I'm done.

    Leave a comment:


  • Ian B
    replied
    Do you have a milling machine and some way of rotating a piece of the delrin bar? With the tool & delrin axes at 90 degrees, plunge the side of a 1" end mill into the delrin, rotate the delrin once and a bit, job done.

    Ian

    Leave a comment:


  • nickel-city-fab
    replied
    I would be tempted to grind up a form tool out of an old file or similar, and clamp that in one of my regular tool holders. Your lathe is plenty big enough for that if you keep the RPM's down and feed slowly.

    Leave a comment:


  • Bented
    replied
    I do it by using the coordinate position method mentioned above (-:
    https://photos.smugmug.com/My-First-...5B1%5D-640.mp4
    Last edited by Bented; 02-23-2021, 04:43 PM.

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  • 754
    replied
    Originally posted by Bob La Londe View Post
    My son installed Rapid Aire plastic aluminum tube in my shop for me, and he just straightened it by hand. Ours did not come on a spool It came in large coils. I think we went with 3/4 ID so maximize air flow. Its big stuff. We installed just shy of 200 feet of the stuff. We used 90s in inside corners in the machine room, but in the large shop areas we just curved it around the corner support beams and laid it on the horizontal wall purlins. Then we threw in a T and a drop line anyplace we wanted a manifold block. We bought some blocks, but towards the end of the project we just made our own.
    I use a similar design , and I cut steel with it., I use broken center drills to make the cutters.

    Leave a comment:


  • BCRider
    replied
    I've had good luck making pretty nice "look and feel" grooves like that using a round nose form cutter that is smaller than the final radius. Using a smaller cutter to hog out and then poke at the ridges avoids almost all risk of chatter.

    The amount smaller for the cutter vs final size only needs to be a small amount to make this trick work. For making the sort of rollers you show with a 1/2" radius I'd probably make up a roughly 0.45 radius cutter. As you get close to final depth it would only need a few touches on the ridges to get a pretty decent "close enough" size for the groove. And with a slight pull back to check the shape you're looking for a nice even .05 wide gap. It should be pretty easy to see where it isn't even just by eye and ease a little away.

    Such a cutter could likely be done in anything even a slight bit better than mild steel. You're only looking at cutting Delrin or similar and it only has to last a while. If you made the "cutter" up on the lathe as a fairly thick washer of around 3/16 thick with a relief angle cut into the edge it would be just fine. Then screw that to a piece of something like 1/2 x 3/4 to go into your BXA holder and you're good to go. If it gets dull after a few then loosen the center screw and turn it around to the other side. If the whole thing gets dull before you're all done then stone or grind the face back a little to freshen up the edge.

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  • gellfex
    replied
    Here's what I made for this purpose of making delrin rollers. Fits a 1/2" axa holder. Set the cutter to the radius and take nice light cuts. A 'plastic only' tool.

    Click image for larger version

Name:	inside radius cutter.JPG
Views:	375
Size:	53.2 KB
ID:	1930131

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  • Bob La Londe
    replied
    My son installed Rapid Aire plastic aluminum tube in my shop for me, and he just straightened it by hand. Ours did not come on a spool It came in large coils. I think we went with 3/4 ID so maximize air flow. Its big stuff. We installed just shy of 200 feet of the stuff. We used 90s in inside corners in the machine room, but in the large shop areas we just curved it around the corner support beams and laid it on the horizontal wall purlins. Then we threw in a T and a drop line anyplace we wanted a manifold block. We bought some blocks, but towards the end of the project we just made our own.

    Leave a comment:


  • eKretz
    replied
    Indicator or DRO are both better than dials for me because they're easier to read quickly. I tend to focus on efficiency and getting things done quickly - a bad back will do that to you. The less time I need to spend stooped over (bad back and 6'3", wonderful combo) the better.

    Leave a comment:

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