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  • I'd always thought it was to reduce the chatter you can get with any form tool as more of it is engaged. I can't say I've had any trouble just plunging on an SC4 but I'm not exactly making gauge-perfect threads for inspection.

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    • A tool that is getting dull can still cut with sufficient pressure but eventually (at the worst possible time) will dig into the workpiece and cut much deeper than intended.

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      • Maybe that is it. I am using a cheapo chinese threading insert. Maybe I should try grinding my own HSS.

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        • Originally posted by DennisCA View Post
          Maybe that is it. I am using a cheapo chinese threading insert. Maybe I should try grinding my own HSS.
          If you have a diamond hone you can hone the edge of a carbide too. It makes them weaker but the will cut better if you keep the angles correct.

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          • Been working on a simple carbide grinder actually, but not ready yet, and now I wonder after seeing Stefan Gotteswinters latest videos if a slow speed one is better, or if I should have both. This one runs at 2800rpm.

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            • Originally posted by DennisCA View Post
              Maybe that is it. I am using a cheapo chinese threading insert. Maybe I should try grinding my own HSS.
              At least the ones I have (cheap chinese threading inserts) are sharp enough until you bump them against something.

              Too high cutting edge has same or worse effect than dull edge so double check that and rather set 0.1mm too low than 0.1mm too high.

              I had also problems of "sudden deeper cuts" before I installed the DRO to my lathe. Old and sloppy lathe is not super consistent how much the crosslide moves and heavy vibration for example is quaranteed to move it around.

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              • Originally posted by DennisCA View Post
                Been working on a simple carbide grinder actually, but not ready yet, and now I wonder after seeing Stefan Gotteswinters latest videos if a slow speed one is better, or if I should have both. This one runs at 2800rpm.
                I prefer to grind carbide and other high hardness materials at real low rpms (50-150) with wd40 or other light oil applied on the diamond wheel....no dust, splatter can be contained very efficiently and good control of the process. The standard approach usually is towards a high rpm dry wheel (cbn or diamond grit) for quick touch up. Works just as well, but tends to fling dust around. Both low and high rpm will do the job, but my personal preference is towards the lower end.

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                • Are the low RPM ones any good for situations where you need to do more material removal, such as re-profiling a carbide blade for scraping? Like going to a smaller radius.

                  I do like the idea of going slower and using lubrication to prevent dust.

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                  • Originally posted by MattiJ View Post
                    I had also problems of "sudden deeper cuts" before I installed the DRO to my lathe. Old and sloppy lathe is not super consistent how much the crosslide moves and heavy vibration for example is quaranteed to move it around.
                    I would like a DRO on my lathe as well. Though it seems it's the compound that's the real problem on mine. And the nut on the cross slide is worn and needs to be replaced, probably same story on the compound but I have not been able to figure out how to disassemble the compound.

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                    • screw the threading (geddit?!), what about the cats? Those must be special Scandinavian cats to like the snow. Love the picture of the 2 jumping at each other, I'll have to show that to my kids.

                      Don't know if you do this when threading, but I take spring passes every few DOC changes and especially before checking for fit/ measure. I find that helps alot on my smaller lathe. Also don't forget to get the cross slide back to zero by dialing it past and then back to zero in the same direction to take backlash out of the equation. I'd assume that you do that as a matter of course, but doesn't hurt to mention just in case.

                      As for me, all I did yesterday was add a bigger battery to my rear helmet light. It's a $2 cheapy and the battery wasn't lasting 2 rides, so dug around in my bag of salvaged li-ion batteries and wired up one that wasn't too big. Plus lots of zipties.

                      edit: daughters loved the cats
                      Last edited by mattthemuppet; 12-03-2019, 07:30 PM.

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                      • Originally posted by DennisCA View Post

                        I would like a DRO on my lathe as well. Though it seems it's the compound that's the real problem on mine. And the nut on the cross slide is worn and needs to be replaced, probably same story on the compound but I have not been able to figure out how to disassemble the compound.
                        If you have clearance in the feed screw / nut threads, then the slide can move forward, deepening the cut. That can happen from the cutter being "sucked in" by the cut, which can happen if the cutter has a positive rake and sometimes with a neutral rake. (It is rare with negative rake). That is the "effective" rake, including any rake that may be due to inclination of the toolholder in the toolpost
                        1601

                        Keep eye on ball.
                        Hashim Khan

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                        • Probably what happens, I need to make some new lead screw nuts for this lathe. The screws seem to be fine but the nuts are worn. Just another reason to get the Deckel running again... Hopefully I am soon there...

                          I also found another Deckel FP2 for 700 euros or so, + shipping a few hundred more I guess, but it has no tables and no vertical head and no accessories. And I think it lacks the Y-axis lead screw, it is disassembled from the rest of the machine.

                          I am pondering if I should buy it as a spare parts machine, I'd keep the horizontal spindle and the gears and shaft as spare. Disassemble it and sell the components online as spares, they seem to fetch money. Real issue is lack of space, and putting out lots of money on a non working machine,

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                          • Originally posted by mattthemuppet View Post
                            screw the threading (geddit?!), what about the cats? Those must be special Scandinavian cats to like the snow. Love the picture of the 2 jumping at each other, I'll have to show that to my kids.
                            Just ordinary cats. Most cats to me don't seem to mind the snow, as long as they don't have to be out long. These are young cats, their first winter, so they are naturally excited to see snow.

                            There was also a video:
                            https://i.imgur.com/H35sg3o.mp4

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                            • The well known South Bend and Boxford instruction book 'Know your Lathe' recommends putting the tool a little above centre (obviously diameter dependent). They don't give the reason but it means there is a component of force outwards to push the cross slide out to take up the slack. The relative inward and outward forces depend on tool geometry.

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                              • Honed the trepanning tool in my Akurate hole cutter - looks like this but somewhat cleaned up! Stuck some 16 gauge steel on the mill and cut me a lug-less back for the dial indicator in my carriage stop. Much sharper edge on the tool but it still doesn't seem that keen on cutting steel. Relief in all the right places too.

                                Got the brush holder mounted on the side of my mill finally. The what now? Long story. I've been trying to mount a digital scale on the side of the mill but have it encased so it doesn't die the first time the fly cutter comes out to play. Because it's been so well planned and not at all evolved as I go the rectangular tube had to have a slot cut out the front to attach the head. That's now covered by a brush-style draught excluder. Just have to clean all the chips out and get the scale back in there and see if it plays!

                                Went with the rather unorthodox - but effective - method of clamping the aluminium F channel to the rectangular tube, drilling a 3.6mm hole and then roll-tapping both parts M4. I figure that since they were tapped in-place the threads must be in-sync and so things like them jacking apart or being out of sync shouldn't be a problem. Unlike some of my previous attempts, these are perfectly in line.

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