made some chips...

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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liveaboard
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Re: made some chips...

Post by liveaboard »

Last year I bought a box of cutters from the UK. almost all HSS.
horizontal cutter colection.jpg
These were in the box too; I don't have an arbor for any of them. One has carbide ends on the teeth.
What are they called and what are they for?
unknown cutters + parts.jpg
I made a lifetime supply of T-nuts today. It was a lot of work! Mostly 12mm, I made some 8mm ones too just in case I ever want them.
Tnuts lifetime supply.jpg
I set this air tight fiberglass weapons box on a stand to keep the mill tools in, the height is so that I can lift heavy things in and out without bending my back, like the rotary table or the vise.
treasure box on stand.jpg
I made a wooden holder for my mill tools, the horizontal cutter fit below. Wow, me getting organized; never thought that would happen!
treasure box inside.jpg
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Harold_V
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Re: made some chips...

Post by Harold_V »

liveaboard wrote: Fri Jul 09, 2021 1:42 pm These were in the box too; I don't have an arbor for any of them. One has carbide ends on the teeth.
What are they called and what are they for?

Shell mills. They are used much the same way one uses an end mill, just larger in diameter than those you can usually hold with a collet.
They are, in my estimation, well beyond their useful life. They've been sharpened many time, reducing the gullet to the point where they most likely would be troublesome taking any reasonable cut. They may still work fine for light passes, assuming they have been properly ground, however. So long as they've ground a proper secondary, so the heel of the grind doesn't drag in the cut. Note that as the periphery of such cutters is reduced, so too is the rake angle. They most likely no longer have rake, or it may well be transformed to negative, which lends to poor performance as well.

They are generally held with a stub arbor, one which has keys that engage the slots found on the back side of the shell mill. That ensures they do not spin on the arbor when under heavy load.

Note that some have the corners chamfered. That's often the result of the tips of the cutting edges having been damaged. The corners are chamfered to prolong the useful life of the shell mill. The chamfer also provides better heat dissipation. Large diameter cutters are often run too fast, damaging the tips.

H
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liveaboard
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Re: made some chips...

Post by liveaboard »

Thanks Harold.
I guess I should throw them into the scrap bucket... I'll let them sit for a while first, so they ripen up before I toss them,
pete
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Re: made some chips...

Post by pete »

There's also others around Mark, but do a Google search for Practical Treatise on Milling and Milling Machines. Brown & Sharpe produced that one. It's now over 100 years old but the information is still just as good as when it was written. Yeah different equipment than your Euro mill, it doesn't matter. The information, methods and techniques are still the same. Cincinnati also produced a great one but damned if I can remember the title right now. But it's also on Google Books. Detailed information about vertical cnc milling is almost easy to find today, with horizontal manual machines and larger diameter arbor mounted cutting tools that's tougher today. So your forced to go back to those older books. The set ups, gearing tables for helical milling, speeds, feeds are all good except there may be some in the older books where there speeds are for High Carbon tools and not HSS. If I recall the numbers correctly I think High Carbon cutting tools are roughly 40% of HSS.

It's pretty easy to sort out what a rpm table is for even if it's not specifically mentioned. If the tool diameter is even close to 100 ft. per minute in mild steel it's for HSS. Well under that then HCS. To use the same tables with carbide or replaceable tip carbide tools it's fairly safe in most materials to triple the HSS numbers, read the chip color and adjust from there. Some of today's carbides can go 5-6 times HSS or even a lot more. I have seen numbers as high as 1100 ft. per min in mild steel but that's for specialized carbide types and coatings. Completely unknown steels are where it gets tricky and you can burn up or chip even carbide pretty easy. I have some 1" plate I didn't understand what I was picking up as scrap used on Cat mining truck boxes. It's shock and abrasion resistant wear plate and almost for sure designated as one of the AR series of metals. Because of rigidity and what I've read about it since, I suspect it may not be machinable on my equipment or without ceramic tool tips. So sometimes even free material could end up being far more expensive than just buying the correct alloy. Highly rusted steels can also help kill your carbide tool life unless your initial cut is already deep enough to get well under it during the first pass. I now grind, flap wheel etc that rust off first as much as possible before it gets machined. And you REALLY don't want the rust chips or dust mixing with the way oil on your machine slides.
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Re: made some chips...

Post by liveaboard »

Free; we don't get that variety of material in Portugal!

The scrapyard 10 miles north charges the same price for old steel as the steelyard 40 miles south charges for new steel. The only difference is, I can buy small heavy pieces.
Anything other than mild steel is only available in Lisbon, 3 hours drive. They don't ship or deliver, and alloys or finished steel is very expensive too, 5x more than mild steel.

I bought the machinist handbook from Holland, I haven't received it yet.

I have some nice pieces of steel in my boat in Amsterdam, I bought back when steel was cheap. Too bad I never drive there anymore.
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