A narrower width tool and shorter length would help with chatter on the finish cut. A insert with molded in chip breakers and short peck for roughing. And why not put the part up against the collet? Constantly varying the speed while in the finish cut will also kill chatter. This isn’t the best production method but for one part it would work. I often do this with manual override when needed.
John retired in 1995 but found that if there was a slight relief in the center of the tool HSS and you cut only with the two corners then when the corners overlapped and there was no longer pressure in the center it would cut smooth, sort of like putting relief in the center of a cutoff tool with the edges cutting on the same plain, hope this helps! Joe
Your grooving tool looks more like a parting tool. Similar, but different geometries. Doesn’t have the side flank clearance of a grooving tool, so you’re rubbing badly as you’re transversing. They’re designed just for plunge cuts. You can use a full radius button tool for the majority of the grooving, then come back with the parting tool to square up the inside shoulders
More feed man. Many chatter and chip breaking issues can be solved by turning up the feed rate. In almost all cases, you don't set preload on an angular contact bearing. It's built into the bearing. When used in pairs or other combinations, you just torque them together and you're all set.
Well definately not on the SKF7005 super precision bearings that I have in my spindle. If i'd torque them to contact eachother it will bind and won't be able to turn. May be an exception but I assume there is a reason they (the manufacturer) give a preload and not a torque recommendation.
Turning of most alu alloys is really a pain because the only way to get the chips to break, is to feed crazy fast and have a decent DOC. Flood coolant also seems to help. When taking light cuts, there is no way to break the chips.. I've found that steel or stainless inserts break the chips the easiest and will leave almost as nice a finish as a polished alu insert. There are some grades like 6026, which are meant to be turned and will break chips easily. 7075 is also great for turning.
It can be difficult to make chips with those tools, regardless of speeds and feeds, especially in Alum and titanium, but softer steels too. The easiest way to make chips is to set your peck clearance low and peck more often ... Also, coolant helps a ton when trying to encourage breaking chips, believe it or not. Getting away from the part off style tool will help too, actual grooving tools have different clearance angles that encourage freer cutting and better chip control. Could also go to a turning style grooving, back and forth, that helps get the feed rates up there alot higher, which will of course help.
Tried out your painters tape and super glue fixture method today on some 1/16 thick aluminum and WOW that made cutting the stuff absolutely painless. Held great and all it took to remove was a sharpened paint scraper to get under the tape.
Get or make a set of expandable arbors...They are much easier than having to press a shaft and most importantly you can still take it out even if the part is left very delicate after machining!
I would suggest first choking up on your parts in the lathe to avoid chatter. Especially when the material is what is producing your harmonics. Not to mention the pin is just pressed in, which still has some wiggle room. Further out, greater tendency for chatter. (I think we all know this) For regular work, I always keep the stick out to 1/4" from the chuck + the part. I would go shorter if I didn't have tool clearance issues. Second, rough out as much as you can but leave about 60 - 75% of the tool width for finishing, or simply, enough for the tool to get a good bite and not deflect away. Third, when roughing, peck the grooving tool in, and then give it plenty of room to back off and not only break the chip, but allow to be ejected. When you can't get the proper SFM, then shallower pecks are a good solution. It's takes longer, but then you avoid the safety hazard, and you avoid the time used for cleanup. I like a good, radiused insert, with side cutting geometry so I can get a smooth finish for the floor of the groove. For this, I'd consult with whomever made the insert on best practice. I also bet that Sandvik tool holder accepts a square insert.
A little off topic maybe but I'm amazed at the clarity of the detail you are able to capture while machining. How do you do this? What camera or cameras do you use? Is this function of NYC CNC done by a professional filming crew? Do you edit? It would be awesome for us to see the technical and behind the scenes of the filming of your You Tube Channel. Many of us would like to see how y're are able to not only machine but the full package producing parts and a beautiful film. Your amazing! Thanks and never stop making these films they are a great teaching tool.
Shorter tool, higher speed, faster x feed (a bigger chip will break better) and you shouldn't feed sideways (z/transverse) with a square edge grooving tool, get a one with a 2-3 thou radius and it will feed much more cleanly and quietly, or use what you have but only feed inwards (x).
I personally would have milled the groove with a woodruff cutter. Finish the part in one op. I also think if you had your pulley closer to the collet, and ran the sfm slower, you may have seen some reduced chatter. Also, believe it or not, the tool may have been too sharp, I've experienced that before. Polish it lightlybwith an ultra fine stone and give that a whirl.
John, there is actually a chart for how much clamping pressure you have vs input torque, at least for Kurt vises. A D688, for example, gets a little over 7300 ft lbs of clamping force, for 80 ft lbs at the screw.
I recently saw a video with someone using a cutting tool that had relief in the middle of it to stop vibration that ends did the cutting with relief in the middle
The chatter comes solely from the vibration of the part. If you clamp your part against your front end of your chuck our collet holder it will be less, but not dissapear. Clamp you workpiece (whatever workpiece you have) on the outer diameter and run it with a tailstock if possible. in this case your clamping setup makes the part at the larger diameter go wobble an makes it instable. Therefore your grooving strategy will also not work, even when you tweak your speeds and feeds. a parting tool needs to be "fed" properly, if your feed and speed is not correct your chip will not brake !! this is only to achieve with a good clamping or stability of your workpiece. "Quick and dirty setup" does not work in this case ! Use of a tailstock or clamping on the outer diameter will bring the stability you need. Take a parting tool and start in one corner of the pully, then move to about 75% of your insert witdh an continue with radial cut until the desired pully witdh. Leave a little material for rest machining and walk your contour once. Grooving and parting are the most underestimated machining workes on a lathe , mostly stabillity is the biggest problem !!
The lathe is good, feel the lathe flowing through you... I'd put a four jaw on a manual with round stock (or hell if you have a big enough block of square stock) centered and drilled then eccentrically drill the other holes. Then press the pin in and do the grooving operation, like you did. (Meanwhile on the manual lathe...)
Cut a puck (close to size)(I realize you said you didn't have round stock, so this is all moot, anyway), chuck it in the lathe, face the sides and drill the ID, turn a separate arbor to fit the ID (precisely), mount the faced pulley on the arbor, turn the OD, bob's your uncle.
can you talk about the measurable “roundness” on the tormach vs the lathe? the mill would take various x-y moves vs a lathe and i wonder exactly how significant that is for a single machine part.
DJ Delorie Wayne Rademacher you could peck it out with the parting tool and clean up with you left and right tools. I have the same tormach lathe and a doosan. I use the same tool in each. That insert is too wide for the Tormach. In the doosan it works fine--I can peck out and get a decent finish on the doosan on a pulley....and drill the holes, and pass it off to the sub for finishing.
I would’ve made the whole part in a lathe. You should buy a haas lathe very easy to learn to program. I personally work at pulley and gear shop and you could make this entire part easily and faster with a lathe. But I do understand you were working with flat material.
I'm surprised that you did the super glue with tape, because that would effectively mean you're relying primarily on the adhesive of the tape as far as I can tell. What Clickspring usually does for his parts (glued metal to metal) is to use a torch to get the stuff off easily.
Looks like the rpm on the lathe is too slow from my eye. Chatter looks like the pin might be flexing. There are also aluminum specific grooving and turning inserts that are up coated carbide 825-3275sfm Or about 412-1637rpm at .004ipr They are also usually designed to only go in the left and to the right or vice versa because of the relief angle.
For what you want to do with the pulley, you would have actually needed to make the diameter of the pulley smaller, about the thickness of the fishing line you're using. Else, your results will be slightly off. But I don't know how accurate you want to measure. Anyway, it's best to push as much stones as possible aside, that lie on your way ;)
So there is not a tool that you could have used on 770 to cut the x /z plain in a radial fashion instead of using the lathe . Wile i cant get fusion to work for me i am sure it can do the math . would be nice to have a mill one day lol.
your ideas on cutting with a parting tool are definitely not ideal especially if you use a idexable holder; take grooves out that are 1/3 - 1/2 the thickness of your parting tool within a pocket then go back and remove the remaining discs so you always have enough cutter engagement to take a truly radial cut and reduce the axial engagement of your parting tool. Really helps ease the conscience with process reliability. also indicate your drill concentric to you drill press and line up your predrilled holes for your drill press concentric to your spindle by hand (without the spindle running) to get more accurately placed manually drilled holes.
