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9:11 PM
June 9, 2010
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Wooly Mammoth
| | South carolina, USA | |
| Senior Member | posts 182 | |
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Tyler,
Don't know if this should go in the "Tips" forum or not. Please feel free to move wherever you think best.
Today while turning a 3" long piece of 3/4" drill rod – from Lowes, so ya KNOW it is ordinary drill rod and not something possibly hardened :), I began by cleaning up the longitudinal surface using very light cuts with a brazed carbide cutter and oil. Anyway, after a couople of light cuts, the surface had a wavy look to it. You could even feel it. Looked sort of like a 98% worn down rotary file. I triple checked the chuck – tight, and the toolpost bolts, also tight. I say "triple checked' because I double check them before turning the lathe on… section 36 of the Belt & Suspenders Society's manual of arms. :)
I wasn't taking deep cuts, but then wondered if I was moving the slide too fast down the ways. I repeated with a slower travel rate, and the problem seemed to disappear.
Got Harold Hall's lathe book the other day, but found nothing like this in there. So this beginner learned something. Hope this helps another confused novice – but remember, ya can't get more confused than da mammoth!
Note to the guys with tons of lathe experience… if I'm wrong about this, PLEASE tell me what my mistake is and how to correct it. I'm learning as I go and need ALL the help I can get.
– Don "Politically incorrect since 1947"
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8:06 AM
June 12, 2010
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Tyler
| | Seattle, WA | |
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How fast was your feed rate set for? If it's set really fast, you'll get a spiral cut just like you would if you were threading. As the part gets larger in diameter the feed rate needs to be set slower reduce the travel of the cutting tool along the Z axis (the Z axis is the axis around which the spindle rotates). I've done the same thing, but on a smaller scale. Instead of producing a wavy pattern I produced almost a thread pattern instead of a nice smooth surface. Like you mentioned, it felt like a file when I ran my fingernail along the length of the part.
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NOTE: I work full time and I'm attending college full time as well. So if it takes me a few days to respond, please don't take it personally. If it's urgent please send me a Private Message.
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9:52 PM
June 12, 2010
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Wooly Mammoth
| | South carolina, USA | |
| Senior Member | posts 182 | |
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The BGTs 'feed-rate' is my right hand on the rim of the handwheel, moving the saddle/crossslide/toolpost slowlyalong the ways … or maybe not slowly enough :):) Will just have to experiment more and practice, practice, practice! :) After all, metal lathes didn't have DRO or CNC for a long part of their history. Besides I get sleepy when you start talking about all those ZZZZ's :):) Keep it up, Tyler, and I'll have to learn something… :) [which I do appreciate despite my twisted humor.].
– Don 'Politically Correct' means never speaking the truth!'
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1:11 PM
June 16, 2010
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Wooly Mammoth
| | South carolina, USA | |
| Senior Member | posts 182 | |
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I might have stumbled on the answer to my 'wavy' lathe work… 'Whilst' :) perusing Harold Hall's book on "Lathework" I didn't find anything agbout my problem, but today while working on the 'spring center' project, when I supported the end of the bar with a center in the tailstock, took much shallower cuts, and fed the saddle S-L-O-W-L-Y down the ways, I had no 'wavy' finish. I would not have guessed that a 2 or 3 inch protrusion of 3/4 inch abrstock from the chuck could 'flex' like that without any tail stock support! I thought I was using a gentle touch on both the lead screw and the cross-slide feed, but guess not. A 'typical' beginner mistake? Hopefully others can learn from my mischief! :)
– Don 'Politically Correct' means 'protect the guilty' :)
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8:48 AM
June 17, 2010
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Tyler
| | Seattle, WA | |
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It can definitely flex. How do you like Harold's book? I picked up a lot by reading through it.
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NOTE: I work full time and I'm attending college full time as well. So if it takes me a few days to respond, please don't take it personally. If it's urgent please send me a Private Message.
- REMEMBER: You need to subscribe to your posts so that you'll receive an e-mail update when a member replies. You can also set your profile up so that you're auto-subscribed to all your posts. To set up Auto-Subscribe go to Profile > Personal Options > Auto-Subscribe to Posts.
- If you are having trouble posting pictures, be sure to visit the FAQ section of the forum for instructions.
- If you are having trouble viewing the forum posts, consider trying a different browser like Firefox or Chrome.
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8:57 AM
June 17, 2010
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Wooly Mammoth
| | South carolina, USA | |
| Senior Member | posts 182 | |
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Still digesting Mr. Hall's book as I go… may try a 'review' of it when I'm finished… like you said, Tyler, it seems to have a lot of info, but for me anyway, it seems to either gloss over or ignore some of the questions that a beginner with his shiny new BGT has. Or maybe I'm just not knowledgeable enough to appreciate it…
- Don If the 13 Colonies had 'gun control', we'd still be British subjects…. sigh, but I suppose we'd STILL have politicians!!! :)
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12:58 AM
June 18, 2010
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madreptillian
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Mammoth, it sounds to me like your experiencing a machinists worst enemy.. Chatter (followed by acid fingers lol) I could be wrong but however here are some things to consider.
1. Make sure your tool isnt hanging out.. make sure its as close into the toolpost as possible.. More overhang means more flex
2. Use a TAILSTOCK with a live center in it. If you machine far away from the chuck the metal has a chance to flex as there is tons of cutting force when you cut. – Example, If you only need to machine 1inch then have you metal protruding 1.200" out.
3. Speed and Feeds, Try increasing your feed and decreasing your speed.
4. I noticed you said your using a carbide cutter. The back of the packet the carbide came in will have the correct speed/feed/depth of cut. Carbides arnt designed to take light cuts (ok yes some are and they have approx 0.4 radius and these should be running extremly fast 3000+RPM and take light 0.005" cuts). The back of your carbide packet will tell you all the info you need. Is the tip your using designed for steel? Ally? Brass? Some things to consider. Example – Ally Carbide tips have a steeper rake and have a small nose radius where as a steel roughing tip has a huge radius and a less steep rake.
I hope one of these points helps! Let me know! Good Luck
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11:12 AM
June 18, 2010
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booze23
| | Toronto, Ontario, CA | |
| New Member | posts 19 | |
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This is a little off-topic here, but what exactly differentiates drill rod from, say, other round stock? Is it the alloy composition? Because I know that the metal doesn't come hardened before it is worked. Thanks.
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11:43 AM
June 18, 2010
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Wooly Mammoth
| | South carolina, USA | |
| Senior Member | posts 182 | |
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booze – my understanding and experience [both HIGHLY suspect :)] is that 'drill rod' is simply the American euphanism for the relatively soft and easy to machine iron rod commonly available in hardware stores here – it's not to my knowledge hardened in any way… I simply used the term to differentiate it from any other sort of alloy steel barstock that might be harder.
Mad Reptillian… thanks… sigh… I may have to re-think my 'slow speed for all' idea… Your detailed reply is exactly the sort of info this beginner needs, and so far haven't found lurking in books… sigh… and so far, the lathe books I've seen DON'T have centerfolds….. :) which might account for my short attention span. :)
– Don 'Fall six times, rise up seven' – Japanese proverb
[besides, I STILL think I'm smarter than the average drill rod... :) ]
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4:42 PM
June 18, 2010
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madreptillian
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Hey all good! We all had to start at the beginning Mammoth!
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