My mill with fly cutter

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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Sandman north
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My mill with fly cutter

Post by Sandman north »

OK so don't tease me I don't have a real mill.... Oh but to dream !

I have a mill drill with the round column, when using the fly cutter the trailing edge is also in contact giving me a rub where I don't really want it !

See the picture

I am presuming because my head does not tilt this is a problem I cannot correct. I Just put some new bearings in the spindle OMG it is quiet now.

Look foreword to any suggestions
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armscor 1
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Re: My mill with fly cutter

Post by armscor 1 »

I shimmed the column to the base, trammed it about a thou over 5" radius giving me forward cut only and just touching on the trailing edge.
Bit of mucking around but can be done.
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NP317
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Re: My mill with fly cutter

Post by NP317 »

Suspect your flycutter geometry. Is it ground with proper clearance?
And if that anvil is one of the good ones, that top surface is forged onto the base, and hardened!
Let us know what you learn.
RussN
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BadDog
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Re: My mill with fly cutter

Post by BadDog »

Based on the horn, I suspect that is an ASO.

If it's the head out of alignment, running it the other way will prevent the drag on the following side, which would then be the leading side.

If it's improper geometry causing it to rub, that's an easy issue to fix.
Russ
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Sandman north
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Re: My mill with fly cutter

Post by Sandman north »

Thanks for the replies I never thought of shimming the column.... if I shimmed the one side I could run it in one direction .....oh a tilting head would be so much easier.

I get a drag mark in either direction of travel now.

Thanks
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BadDog
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Re: My mill with fly cutter

Post by BadDog »

In both directions, that points more to deflection. Possibly from application of an improper tool geometry. If there were no flex at all, it would take very near perfect alignment to have trailing marks in both directions. But reality is that there is always flex, it's just a matter of degree.

With that "both directions" information, assuming the machine is up to the task (not loose, DoC and feed in range for machine, etc) I would be looking hard at cutting edge geometry. Check clearance first, make sure it's not rubbing. If it is, you lost before you start. Next, cutting edge nice and fine, perhaps honed to a fine edge? Then consider cutting edge length. For example, on a light machine, you don't want too much edge in contact at once (ex. too fat a radius). If that looks good, and general cutter geometry looks good, then reconsider if you are overshooting on DoC and/or feed rates. Try less. And if all else fails consider increasing rake, which will depend on grind geometry. At least that's my thought process sitting at my desk.
Russ
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Sandman north
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Re: My mill with fly cutter

Post by Sandman north »

Something I just thought about this is in my vice on the bed.

Would I be better to clamp it to the bed and not in the vice?

Thanks
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BadDog
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Re: My mill with fly cutter

Post by BadDog »

I suppose that depends on the vise. Fly-cutters aren't meant for much stock removal, so loads are generally small, and a decent vise holding something relatively rigid (this easily qualifies) is generally going to be ok. Then again, the part is relatively tall, so I suppose a less substantial vise (comparatively) could be allowing movement. But not my first thought.
Russ
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pete
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Re: My mill with fly cutter

Post by pete »

If that was a decently built anvil it will have a hardened working surface which makes flex anywhere in the machine and cutting tool even more likely. Light cutting or marking on the back side of the fly cutters rotation is completely normal on heavier and more rigid machines than a round column mill. It took me a few hrs of playing around just to see if it was possible, but using a few tricks I figured out I did manage to get my Bridgeport clone trammed in within .0001" over a 20" radius in the X axis, and by moving the table in and out the same number over about 12" in Y. It still showed very light marking on the back side of the cut. The larger diameter of the fly cutting tools radius is the more leverage there is and the tool itself will flex. Then there's also the unavoidable spindle bearing clearance. That alone probably allows at least a half thou of change on something like a 4"-6" tool tip radius.

I also use my mill to machine wood and have what's basically a 3" diameter 3 tooth face mill designed to be used for wood. Even with light cuts of maybe .005" and razor sharp tool tips it still shows it's dusting off probably a few 10ths after the leading side of the tool leaves the wood. With a round column mill, shimming the column so the head is purposely tilted for fly cutting might take a lot more than that .001" If you can figure how to get an indicator tip into the correct position against the upper part of the head while not being attached to the machine itself, zero that out and then take a light cut with a fly cutter in any material and you'll see just how much the whole head deflects. I can guarantee it will be a whole lot more than most might think.

I wouldn't be embarrassed with only having a round column mill, any mill is better than none. I'd love to have a new condition Hardinge HLV-H or a Monarch EE. Instead I've got a 500 lb. light weight Chinese lathe. :-( A Youtube producer by the name of George Britnell https://www.youtube.com/user/gbritnell/videos who's also a long time member on many of the model engine forums used a round column mill for many years and produced some extremely complex exterior shapes to closely replicate full size engine castings using what were basically manual input cnc moves to exact pre calculated X,Y,Z coordinates. I believe he's changed mills now, but he has to be one of the better model engineers in the world by anyone's judgement. And everything he's made with that round column was to the highest standard. A bigger, better mill just makes things a bit easier that's all.
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Harold_V
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Re: My mill with fly cutter

Post by Harold_V »

Sandman north wrote: Wed Mar 10, 2021 6:46 pm I get a drag mark in either direction of travel now.
Ever wonder why that is?
If you don't develop a cross-hatch pattern, it's because the head ISN'T perpendicular to the table travel. That's exactly what you should be seeing.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
armscor 1
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Re: My mill with fly cutter

Post by armscor 1 »

Agree Harold but when refacing a cylinder head you need to achieve an acceptable finish without cross hatch and not making it excessively concave, difficult task.
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BadDog
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Re: My mill with fly cutter

Post by BadDog »

That's what I meant about a perfectly rigid machine (and tooling). Getting the dual pattern going both ways, unless that round column mill is exceedingly high quality (doubtful considering what I've read about alignment problems), I think it would likely only make a pattern like that if there was substantial deflection so that the machine is effectively/actively pressing the cutter into the work. If it's cutting fairly freely, it would seem to me very unlikely that it would develop the dual pattern. On my mill, I have to apply some nontrivial effort to aligning to get a nice cross hatch pattern, and even a tiny offset one way or the other gets a one way single leading pattern, and the other way gets a trailing wipe pattern.
Russ
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