-I've seen a few videos from Mr. Gelbart, he's a good source of shop knowledge and a pretty sharp old man. In this video he's made good use of a water jet. I used to design the welding fixtures for two trucks, several about 20 feet long. I used the tab-and-slot approach for joining large/heavy plates together with some degree of relative accuracy over the length. Spindles, reference holes/pins, and swing-out sections could all be employed without a lot of expensive machining to the fixture. There are some down sides to using a water jet but it was the best choice for what I was designing.
When I was doing it, if felt similar to a way I had been doing it in the past but not quite. Watch the direction when you start the coil, it's gotta be ccw, I tend to naturally want to do it cw.
-I wouldn't consider this a horrible idea but it does depend upon how aggressive the cut is and how thick the cut-off wheel is. Flexing the wheel from the side can be risky as they aren't made to work like this. When an abrasive wheel lets loose it's too fast to react to and is about guaranteed to let some blood loose, maybe in your face. Not a fan of using diamond wheels on steel as they're somewhat expensive and can get clogged easily (there is a dressing stick for this). Some folks like using diamond wheels, my preference is just my opinion. Would strongly recommend a wheel guard around the abrasive wheel, safety glasses, a dust mask, and even a face shield for when the exploding wheel happens. Other than that.....I used thin abrasive wheels to cut out large chunks of hardened tool steel when there were engineering changes and still prefer that to just grinding or using carbide cutters. That's what abrasive wheels were made for provided you work safely within their limitations.
I use cutoffs often on angle grinders....you mean you use on your bench grinder as done here? I did consider the pros of using abrasive wheels since they're cheap and will cut through anything but thought the diamond wheel was cheap enough to be worth a try....I have installed one and did a test cut w/satisfactory results. I know they make screw-on cutoff/grinding wheels that can take side loads and aren't grinding-wheel thick so that would've been my choice...despite not being able to make thin cuts. I don't know what makes these steel cutting diamond blades different than tile blades or if they're less likely to gum up w/steel...
-Not on the bench grinder. I used them now and then in a surface grinder. In a previous life I was a tool and die maker. Either from engineering changes or needing to repurpose an obsolete component I would have to carve out/off relatively large chunks of hardened tool steel before grinding to precision dimensions. Grinding off large chunks isn't fast or fun so I would mount a thin cutoff wheel in the surface grinder to speed up the process. You can simply make intersecting cuts to remove a corner but what if you had a 1" thick plate that required the thickness reduced by 1/4" or more? Many hours of grinding and wear out at least one grinding wheel in the process? I'd use the abrasive cutoff wheel to make a series of slashes (imagine a hair comb) to depth so I had a series of standing ribs. I'd then used a brass drift and a hammer to break off the ribs. Now go back with a regular wheel for the surface grinder and go to the precision dimensions needed. This works well with hardened steel, not so much with unhardened/soft steel. You're only limited by your own imagination when milling, turning, grinding. Oh you're also limited to how safe your imagination becomes too. I really don't like grinding with the side of a wheel. The thinner the wheel the greater the risk of exploding that wheel. It's scary and too fast to react to.
-They'll cut through most materials until they get gummed up or glazed. Aluminum, plastic, composites, aluminum-bronze alloys (Ampco), and a few other materials are notorious for clogging abrasive wheels. Ever seen a bench grinder with bits of aluminum stuck to it because some idiot tried grinding aluminum? Abrasives work provided the pores aren't clogged or the wheel isn't glazed. Even an India stone can get clogged with particles (shiny surface) and won't work properly until the pores are cleaned out, which is why you use most hand stone wet instead of dry.
-It's all about the particle size, the matrix they're bonded in, and what material is being abraded. Using diamond/CBN abrasives in the jig grinder works great on hardened steel but I'm not a fan of using them anywhere else. That's just a personal opinion perhaps formed when diamond/CBN tooling was expensive. Other folks like using them and my opinion/preference doesn't make their opinion/preference wrong for what they're doing. I balance my choices based upon cost, availability, and previous experience. You'll do the same for your choices.
-That depends upon what the target is. They don't pulverize very much in skin but do in bone. Imagine your face....
-The danger of impact may be diminished when they don't go very deep in your skin but still present a danger with what they introduce into your skin. Abrasives create some nasty infections with the carried metal particles when deeply imbedded and don't readily wash out. I've had infections that I battled for a couple of weeks that limited the use of my hand at the wound site. Tetanus and blood poisoning are possible. Infection can even begin at the fingernail cuticles for some if exposed to the "spray" of sparks. Everybody has different levels of susceptibility to the heavy metal alloys. Gambling with your immune or respiratory system can have bad consequences so be safe. An old friend of mine had to occasionally grind beryllium-copper (BeCu) alloys for EDM electrodes at work. He developed reparatory problems by age 50 that will stay with him for life. I'm still spitting out aluminum-oxide particles from all those years of surface grinding.
-Shapes of cutting tools for the lathe are only limited by your imagination and how well you understand tool geometry. Having a particular shape/feature ground into the cutter means it's always the same, foolproof, and done in one cut. This is not only convenient but it greatly speed up the machining process. I fully encourage you to explore what creating your own lathe cutting bits can do for you. Hope this helps.
I'm repurposing a T-nut that I had to shorten about 3/8". I decided against grinding to avoid grinding dust so decided to face it to length. My lathe is small (6x18) and not very rigid. I had a b***h of a time getting it done. I don't know if interrupted cuts are generally difficult in small machines or if the alloy for this t-nut was hard enough to make it extra difficult. At some point, as the material was warming up, I could see the material move (carbide insert) instead of cutting...I was forming beads on the surface instead of cutting. It got hot enough to get sparks going. The chips/dust was also extra itchy...almost like fiberglass. I also didn't bother to dial it dead center since the nut is rectangular (square chuck) because I was facing it I figured it didn't matter much but it did seem to make the interrupted cuts worse
-With smaller, less rigid machines you have to take smaller cuts. Hope you didn't try taking all 3/8 in one pass.
-They're different cutting conditions than continuous cutting in all machines. Larger, more rigid machines take the interrupted cut in stride. Smaller machines tend to stumble, bog, or just don't yield a pleasant cut. Interrupted cuts with carbide is asking for a chipped/shattered edge because carbide doesn't like the hammering shock of an interrupted cut. I've posted about this several times.
-Cheap T-nuts from China aren't heat treated and are fairly soft, a good quality T-nut will be heat treated and more difficult to cut.
-Good observation, remember this so it will serve you in the future. Even unwanted results go into the experience memory to learn from.
-Stage 1
-Stage 2
-Fun isn't it?
-The top edge of your cutting tool has to be at or slightly (.01-.02) below center when doing a facing cut to the center. For a facing cut from the center back out the height of the cutting edge is reversed just like when boring.
-Hex stock sure is available in a few different materials but not HSS. Why would you want HSS in a hex shape? There are ways to do this but I'd need to know what you're going to do with it.
-No, never felt the need to make or use one. If I had a block needing an off center hole I'd use the mill to locate it. This tool may work well but it depends upon how accurately the center punch was laid out. I suppose it would be ok to make/use this but I don't see the point unless you have nothing but a lathe to use for boring holes. There are also toolmaker "buttons" for locating holes in a 4 jaw.
yeah, I think this might be more for those w/o a mill. I could see it being handy to drill quare holes on stock that doesn't have perfectly square faces to rest on to w/o busting out a sine plate. It also allows the user to do multiple operations w/o repositioning, (facing, drilling/boring), though all those are possible in a mill, a quick change may make tool changes faster on a lathe if a mill is not equipped w/a quick tool system of sorts.
-Agreed.
-It's always about either accuracy or speed. They are often mutually exclusive, accuracy/speed is a relative thing that depends upon the allowable tolerance. They're both rabbit holes. For greater accuracy in hole location on a lathe consider the "toolmaker buttons" I mentioned. They take more time to set-up but there's that accuracy/speed thing again.
-A mill can also easily create two sides square to each other, provided that the head is trammed and the vise is parallel/perpendicular to the axis. Lathe can do this too but with a great deal more fiddling about. The work to be done kinda dictates which/both machine to use. Pro's and con's to both machines and I feel they compliment each other. Then there's also the surface grinder.....
-Quick change is what I prefer, being semi-retired means time is seldom an issue for getting the job done. I do still read and appreciate the contributions to this thread. My comments are not a critique or the last word in machining either. Hope you're doing well.
no 'offense' taken, keep chiming in...I didn't think 'redundant if mill' despite the obvious.
With all things China, you're usually looking at which middle man will provide the same product with the lowest ROI to them. There's certainly a price tag with QC from China but the markup can be ridiculous at times. Obviously the guy's time will never be recovered but it does provide an invaluable educational series for people running into issues & is applicable to most/all lathes, not just lathe shaped objects
-I've made several posts regarding things imported from China, most of them unfavorable. I also feel that part of that low regard for imports from China is due to the buying public. China can make about anything the West can and of the same quality but capability often has little to do with how poorly made products arrive here. Things are made to a price point and the average consumer usually has no idea what they buy. Most consumers feel all things they can see are equal except the price tag numbers. This is exactly what the importer hopes for and the nature of his/her game. If the consumer were better informed they might see/know why something is a poorly made product but most only concern themselves with whether it looks nice and then look at the price tag. The same is true for expensive status objects that fail to perform. Most of the consuming public evaluate by things they easily understand and avoid research to learn what they don't understand. There are also unethical practices by the Chinese but that's another topic altogether.
-Can't be certain but if there's cutting going on when he reverses the direction of travel then this could be considered an indication of play in the saddle as it shifts when reversing direction. Cutting in ONLY one direction would be better when checking for taper.
I look at harbor freight as the 'classic example' of this. I've been going into that store for 20+ yrs and have seen the progression from 'one time use' tools (if you were lucky) to their now 'life time' hand tools. They could've kept selling the one time use **** (and there's still plenty on the shelves) and stayed small but they constantly phase out line ups and they seem to take customer feedback seriously (as reflected by their user rating system online). People love to hate on HF but the proof is in the pudding as I've seen them grow and become the new 'SEARS' for tools.
-Retro-fitting the controls or ball screws on an "old" lathe with bed wear would be a nice exercise but almost pointless, like putting lipstick on a pig.
The control kits aren't too bad or expensive...For instance, it's roughly in the price region as a quick change (if doing single lead screw). The ballscrews may be too much work and I probably wouldn't want them on a manual machine w/o some way of increasing friction to prevent them from backing. I do agree this starts getting into 'love of the game' restomod territory trying to save old iron from being recast into chinese mini lathes.
I have seen a 100 tooth saw 7 1/4 saw blade bolted to piece of turned bar thru the spindle thru hole used as an indexer on the outboard end of the spindle. They used a section of bimetal hacksaw blade to catch the tooth for the next indexing on a rod that was clamped onto the head stock. Teeth were counted and marked with a marker before hand for the indexing positions. and a drill rigged to the tool post used to drill a hole.
-Yep, seen some "creative solutions" too. Would also like to see how your example kept the chuck locked in. The saw blade was probably a better solution than the scribed line trick. It's always about how close/accurate do you need to be.
the guy's double indexing jig at the headstock end does 360 degrees, also very clever:
I originally saw that procedure shown in a very early edition of HSM magazine and they used a weight and cord wound around the spindle to keep it in place against the stop.