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  • internal boring.

    I find this video fascinating. I wonder what the smallest internal threading is possible in metal in a home shop environment?
    https://www.youtube.com/watch?v=78XYpr2Vnvg

  • #2
    The video doesn't give any indication of scale but from https://www.phorn.de/en/exhibitions/...105-with-eg35/

    Some new high-performance versions of Horn’s 105 Supermini are set to be unveiled at AMB 2016. Featuring a new coating, a new substrate and a new microgeometry, this equipment will set new standards for boring out holes of between 0.2 mm (0.0079") and 6.8 mm (0.2677"). By introducing this equipment, Horn are responding to the wishes of its customers who are having to contend with higher and higher percentages of stainless/high-alloy/inhomogeneous steels and want to accelerate their throughput. Suitable for hole diameters of between 0.2 mm (0.0079") and 6.8 mm (0.2677"), the 105 Supermini tool system offers more than 1500 cutting insert versions for many different machining tasks.

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    • #3
      As tool size gets smaller you run into the problem of not having enough "feel" or movement resolution to prevent breakage. It can be done with CNC. That's the limitation.

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      • #4
        Originally posted by plunger View Post
        I find this video fascinating. I wonder what the smallest internal threading is possible in metal in a home shop environment?
        https://www.youtube.com/watch?v=78XYpr2Vnvg
        I would be willing to bet that I can make it down to 2mm thread on a decent manual lathe with DRO. After that I have no idea, probably would need more than decent lathe, microscope and something more than ordinary means of setting the tool height. Not to forget 200 usd worth of tooling to break and way too much time..

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        • #5
          Beautiful tooling, but still makes my blood boil.
          I have used phhorn tooling many times. It is the best there is.It is super expensive German made toolingThe times That I have used these tools,they were the ONLY off the shelf tools that would do the job.I have been running lathes since 1954 and making parts similar to thos shown in the video.What makes my blood boil is how little,the designers know about machining difficulty and cost. Their is probably $2000 dollars worth of phhorn boring tools shown in this short video. Most of these are one use tools. When they are dull ,throw them away.The attitude of most designers is,hey if I can draw it ,Why cant you make it.Rant over Edwin Dirnbeck

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          • #6
            Originally posted by Edwin Dirnbeck View Post
            Most of these are one use tools. When they are dull ,throw them away.The attitude of most designers is,hey if I can draw it ,Why cant you make it.Rant over Edwin Dirnbeck
            Sometimes works for hobbyist advantage as you can grab used PH HORN solid carbide boring bars 1-3 dollars per piece from ebay and (attempt) to sharpen them.

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            • #7
              ph horn regrind

              Originally posted by MattiJ View Post
              Sometimes works for hobbyist advantage as you can grab used PH HORN solid carbide boring bars 1-3 dollars per piece from ebay and (attempt) to sharpen them.
              Yes good idea. Pay attention to the phhorn boring bar holders. The shank of many these bars are oval shaped. This provides great rigidity and puts the cut edge right on center.Edwin Dirnbeck

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              • #8
                Originally posted by Edwin Dirnbeck View Post
                Yes good idea. Pay attention to the phhorn boring bar holders. The shank of many these bars are oval shaped. This provides great rigidity and puts the cut edge right on center.Edwin Dirnbeck
                That is going to be my next prob..project as I have some ph horn boring bars on the post. 5 mm minimum bore and 15mm reach so nothing extreme.
                Sold as a resharpened, time will tell how good.

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                • #9
                  I have many similar Micro-100 solid carbide boring bars (round shank with flat), some "tiny". I touch them up as required on a diamond wheel. No issues.
                  Last edited by lakeside53; 08-26-2017, 11:05 AM.

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                  • #10
                    Originally posted by Edwin Dirnbeck View Post
                    ...What makes my blood boil is how little,the designers know about machining difficulty and cost. Their is probably $2000 dollars worth of phhorn boring tools shown in this short video. Most of these are one use tools. When they are dull ,throw them away.The attitude of most designers is,hey if I can draw it ,Why cant you make it.Rant over Edwin Dirnbeck
                    I agree. I'm certain that part of it is not knowing/understanding the difficulty of producing certain parts but it also has to do with the notion that,
                    because we have machines capable of working to very tight tolerances, we should make everything that tight. There's no doubt that CNC machinery
                    makes it possible to work to very close tolerances when necessary but anybody who has been in the machining game for very long knows that not
                    everything needs to be super tight. Making parts that are more precise than they need to be to function correctly are going to cost more money.

                    That video does demonstrate that it's possible to work internally on some pretty small parts but one thing that can be a big issue with parts that small
                    is chip clearance. The fact that the parts in the video are open sided means there are no issues with buildup but on a "real" part that small clearing
                    chips could be a big deal...
                    Keith
                    __________________________
                    Just one project too many--that's what finally got him...

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                    • #11
                      Much program editing would ABSOLUTELY be needed

                      Originally posted by LKeithR View Post
                      I agree. I'm certain that part of it is not knowing/understanding the difficulty of producing certain parts but it also has to do with the notion that,
                      because we have machines capable of working to very tight tolerances, we should make everything that tight. There's no doubt that CNC machinery
                      makes it possible to work to very close tolerances when necessary but anybody who has been in the machining game for very long knows that not
                      everything needs to be super tight. Making parts that are more precise than they need to be to function correctly are going to cost more money.

                      That video does demonstrate that it's possible to work internally on some pretty small parts but one thing that can be a big issue with parts that small
                      is chip clearance. The fact that the parts in the video are open sided means there are no issues with buildup but on a "real" part that small clearing
                      chips could be a big deal...
                      You a right . The programing shown in the video would destroy the tooling in seconds. In the video all chips are broken and expelled almost instantly. In a solid workpeice you would need to cut for a few seconds, rapid out of the hole about 4 inches , blast it with HI PRESSURE COOLANT for a few seconds and repeat and repeat.Often ,that doesn't work and you need to withdraw more and put in program stops and MANUALLY REMOVE CHIPS. This gets really bad when the designer specifies the stringiest stainless steel there is.Edwin Dirnbeck

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                      • #12
                        I have internally threaded a .159 diameter hole for .500 with a shop made bar from 01. It was for a 10-32LH thread.

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                        • #13
                          On my Monitor, I had to both make a square thread shaft and Nut to hold scale dimensions.
                          The tool bit was made from HSS and hardened. I have some photos for your observation.
                          The shaft is .140 ( 3.5mm ~) in diameter and the thread OD is .171 (4.4mm~). The Pitch is .0312 (32TPI) , which means the thread land is .0155 and the groove is .0157. The thread depth is .016" (.4mm) The main problem is that the tool can be no more .139 wide as it has to retract out of a .140 hole . Since the thread is .016 deep , I made the thread depth .017 and that gave me a shank diameter of .122 ( 3.15mm~) The Brass nut has two threads, the internal square thread and the external "V" thread for the retainer nut.
                          In making the tool, I turned the tool to .176 first, then reduced shank diameter (.122) and left a short length at the end.
                          That allowed me the gradually face the tool end down to the .0157 required width with ease !
                          Then all it take is to remove most of the material with a Dremel Tool and then give front relief.
                          I think this could be done even smaller . all work was done on a 10" Boxford lathe (without optics )
                          Rich








                          Sorry for bouncing the photos around , I am trying to get use to HSM's photo inventory ..a little complicated
                          Rich
                          Last edited by Rich Carlstedt; 08-26-2017, 10:23 PM. Reason: deleted duplicate photo

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                          • #14
                            Not quite on such a small scale, last year, I bought a dozen Piccolo mini boring tools, solid carbide and titanium nitride coated and a shop made holder for £35 including postage on eBay. When I see them now, they are £10- £15 each. They will start in holes down to 5mm and reach about 12mm, I was very lucky to get them.
                            Piccolo are made by Iscar, I believe.
                            Last edited by old mart; 08-27-2017, 08:34 AM.

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                            • #15
                              [


                              Sorry for bouncing the photos around , I am trying to get use to HSM's photo inventory ..a little complicated
                              Rich[/QUOTE]
                              Not familier with your money . Is that a large coin.I have never heard anyone use hss in its softened state. Did you anneal a piece of hss and machine it or can you buy it in its soft state. If so how does it machine and how did you harden it. Did you source it out. Very nice work Rich.

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