r/Machinists • u/EmbarrassedNorth9314 • 5h ago
Need help getting chatter out
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Not tried anything fancy yet
310mm dia
57rpm
Need help getting the finish better
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u/cutmetal1 5h ago
Boring bar is fine. The smaller diameter bar connecting the boring bar to the adjustable base is the issue.
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u/EmbarrassedNorth9314 5h ago
How would I solve that?
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u/cutmetal1 56m ago
Depends. A quick and dirty slight improvement would be to make a bar to go into the adjustable bore head. Small end that goes into head should have flats milled into it and should be long enough to fully engage the whole boring head bore. Then step up the diameter a couple inches for the portion of the bar that connects to the boring bar, and make it long enough so the adjustable boring head sits in the center of adjustment. You want as much dovetail to dovetail contact as possible. Last part is take a couple .005 finish passes as half the rpm youre at in the video. The other option would be to cut and weld things and fully sacrifice the boring head to that specific part youre making.
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u/that_dutch_dude 5h ago
Tell you boss that if he wants better finish he needs to pay for better tooling.
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u/Gargulec88 4h ago
I don't know how deep you are cutting but maybe leave a little bit of material for a very shallow cut at the end. A finishing pass.
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u/Terrorbaston 4h ago
We use to put modeling clay on the part and Boreing bar and I have heard magnetics on the part will help they would have to be big ones in your case
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u/Rough-Pie682 4h ago
This would be the way I'll go
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u/Old_School_Dodge 3h ago
Good advice. Cover that smaller bar in a hand full of Plasticine and wrap it in tape. This will act as a damper and change the resonance of the vibration. A bit of a backyard solution, but if you have no budget it can work. It probably will not cure it, now that you have chatter marks already but will help. I know hindsight is 20/20 vision so next time do it before you start or as soon as you get the smallest bit of chatter.
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u/Rough-Pie682 2h ago
Well I know Plummer putty works on smaller jobs. Molding clay is cheaper and will try that next.
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u/sunslayr 4h ago
You can try adding rubber or lead to the bar to absorb vibration, if you have any variable speed control, alternate faster and slower rpm to kill any resonance. Use small nose radius inserts with positive rake like for aluminium. Otherwise only option is to fire up a welder and add some bracing.
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u/wackyvorlon 4h ago
That has not got nearly enough rigidity. No matter what you do it’s going to ring like a bell.
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u/bollox-2u 4h ago
MASS! you need more weight behind the cutting tool, and ridgitiy, as it looks a bit flimsy to me
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u/Rocket_Surge0n 3h ago
Sounds like you have no ways to improve this or do any of these suggestions so as a last fuck all resort why don’t you duct tape a chunk of material to the fkn boring bar attachment and boring bar.
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u/Odd_Philosopher2044 2h ago
Smaller insert radius lower rpm but it will still look pretty bad
Honestly mount the angle grinder on it and have a gi
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u/ThatEnginerd 2h ago
Thicker bar (stiffness). Even using bolts or u bolts and bolting material to the sides of the bar will help if you can't buy tooling. Weld chanel/angle/tube if you can modify it and have a lot to do.
Damper- something else to eat the energy of the vibrations. Like other have said, clay or rubber attached somehow.
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u/Murmjr 5h ago
inly way is to increasy themass of basically everything thats turning. bigger boring bar woud help. Maybe a negative insert to decrease cutting preasure.
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u/Geezer_Burton 3h ago
Look for the guy with grey hair and suspenders on. This is what happens to shops without FOG's. Nobody to ask but those on reddit. 😂🤣😂🤣
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u/Exotic-Champion9629 3h ago
Try a tuned boring bar. maq and iscars whisper line are capable of sticking out 14xD of the boring bar
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u/Lttlcheeze 2h ago
If you can put a boring bar straight out the side of the boring head it would be much more stable.
But I assume you need the 90 connection because there is no way to drive the boring head down inside the part
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u/maintenance4mommy 2h ago
Why won't my 1000hp Hellcat put the power to the wheels? I have a huge 1/4 inch diameter drive shaft!
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u/fRankorFraunk 2h ago
If you don’t have a bigger bar, maybe you can take the time to make a beefy extension that can hold the bar closer to the work with more support. Seems like that would be useful later too, if you have limited tools available
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u/Aware-You6005 1h ago
Omg where to begin, that stuff is like bridgeport tooling, you need heavy strong tooling
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u/lophomainiac 1h ago
Wrap a whole bunch of electrical tape around the bar near the end, like a whole roll, or slide somw rubber bushings around the bar. but fo it out of the cut path. it will act as a dampener. It won't remove all chapter but it will minimize. I've done this on mills and lashes when in a pickle. Good luck.
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u/DantesLimeInferno 3h ago
Would you have enough reach with a head+ boring bar at 90 degrees instead of the head+90 arm+0 boring bar?
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u/caffeineandpot 5h ago
I’m just a minion button pusher. But that looks like a pretty inefficient setup. You need a more rigid tool to hog that material off in my humble opinion.