Announcement

Collapse
No announcement yet.

thin brass 7mm tube - how best to cut to length?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • thin brass 7mm tube - how best to cut to length?

    The tube I have to cut has ID of 6mm and OD of 7mm. I need to cut square pieces on the order of 3/16" long, then debur them. The pieces must be square, but some chamfer on the ends is acceptable.

    I tried chucking it in the lathe and cutting it with a Dremel with abrasive wheel. I was quite surprised at how poorly that worked. I was able to make one part but sure wouldn't want to make 20 of them.

    If I were to look for a saw blade that had 3 teeth in a half millimeter thickness it would need some astronomical number of teeth per inch.

    What is the actual way to cut this tube? (BTW the tube came to me with raggedy cuts on both ends.)

    metalmagpie

  • #2
    Maybe a tubing cutter with a 6mm mandrel inside the tube. Just big enough for a slip fit, not press fit. You could possibly turn a 3/8" bar on the lathe to under 6mm with a shoulder for a stop and put the cutter wheel on a single knurling holder and do them on the lathe. You would want the mandrel 1/2" long or so, to provide support under the cutter, and for the cut off part.
    Last edited by Toolguy; 07-27-2021, 08:23 PM.
    Kansas City area

    Comment


    • #3
      I would use my jewelers saw with a 2/0 (56TPI) blade.
      For actually squaring the ends, a sheet of 400-grit on a piece of glass.
      https://www.firemountaingems.com/res...ia/charts/771x
      25 miles north of Buffalo NY, USA

      Comment


      • #4
        I would mount the tube in a collet, extend the tube about 1" into a live center, measure from the live center end the 3/16", lock your carriage, then use a very narrow and very sharp HSS tool to cut them off.

        Comment


        • #5
          Just to throw something out there,,,,,What if you plugged or capped one end, pored it full of melted wax, then cap the other end and let the wax harden , then cut it to length. I assume some waxes are harder than others. just a crazy thought. Then melt the wax from you prices.
          _____________________________________________

          I would rather have tools that I never use, than not have a tool I need.
          Oregon Coast

          Comment


          • #6
            Harbor freight has a small cutoff saw that reloaded use. Google making 300 blackout out of .223. The utube videos will show the cutoff in use.
            You might try a de burin game tool also used in case trimming.

            Hal

            Comment


            • #7
              Originally posted by Hal View Post
              Harbor freight has a small cutoff saw that reloaded use. Google making 300 blackout out of .223. The utube videos will show the cutoff in use.
              You might try a de burin game tool also used in case trimming.

              Hal
              Thanks, Hal. I have used one of those HF saws for years (occasional use). But it recently gave up the ghost and their new model appears to me to be quite a bit more cheaply made. Plus, the blades they sell for those are fairly coarse and would leave huge burrs. Anyway, that reminds me I have an even older HF "chop saw" which converts an angle grinder to a cutoff saw. The grinder that's in it is totally shot but maybe one of mine could fit.

              Anyway, a tiny chop saw is a great idea.

              metalmagpie

              Comment


              • #8
                Originally posted by Toolguy View Post
                Maybe a tubing cutter with a 6mm mandrel inside the tube. Just big enough for a slip fit, not press fit. You could possibly turn a 3/8" bar on the lathe to under 6mm with a shoulder for a stop and put the cutter wheel on a single knurling holder and do them on the lathe. You would want the mandrel 1/2" long or so, to provide support under the cutter, and for the cut off part.
                The mandrel is to limit the internal burr?

                Comment


                • #9
                  Originally posted by lugnut View Post
                  Just to throw something out there,,,,,What if you plugged or capped one end, pored it full of melted wax, then cap the other end and let the wax harden , then cut it to length. I assume some waxes are harder than others. just a crazy thought. Then melt the wax from you prices.
                  Jeez, now I wish I'd never sold my two pounds of Cerrobend ..

                  Comment


                  • #10
                    Could try some Thinbit cutoff inserts. They go down to .025 wide. Picture of 14 pound Cerrobend blocks. It does melt at 158 degrees F if I remember correctly so might be limited.

                    Click image for larger version  Name:	Thinbit.jpg Views:	2 Size:	156.3 KB ID:	1953475
                    Last edited by Ridgerunner; 07-27-2021, 09:10 PM.

                    Comment


                    • #11
                      Originally posted by metalmagpie View Post

                      The mandrel is to limit the internal burr?
                      The mandrel is to support the tube and give the cutting wheel something to push against. You would have clean, square ends right on length.
                      Kansas City area

                      Comment


                      • #12
                        Originally posted by nickel-city-fab View Post
                        I would use my jewelers saw with a 2/0 (56TPI) blade.
                        For actually squaring the ends, a sheet of 400-grit on a piece of glass.
                        https://www.firemountaingems.com/res...ia/charts/771x
                        Exacto makes a small saw, but I would re- vist the lathe. Grind your parting tool extra thin at the end. Maybe .025 wide. My guess is your tool has too much presure to make a clean cut.


                        Click image for larger version

Name:	0016104_x-acto-mitre-box-and-razor-saws.jpeg
Views:	275
Size:	28.6 KB
ID:	1953481
                        Last edited by Fasturn; 07-27-2021, 09:40 PM.

                        Comment


                        • #13
                          A dental saw might work for something like this. Blade is just 0.02 mm (0.0008") thick.

                          https://www.denmat.com/ceri-saw-post...h-1-blade.html

                          https://www.ebay.com/itm/12317362523...MAAOSwbEZbFkJ3

                          Click image for larger version

Name:	s-l1600.jpg
Views:	271
Size:	133.7 KB
ID:	1953483
                          http://pauleschoen.com/pix/PM08_P76_P54.png
                          Paul , P S Technology, Inc. and MrTibbs
                          USA Maryland 21030

                          Comment


                          • #14
                            One more way on a mill. That's 6mm round, but you get the idea. Also a much smaller saw blade.

                            Click image for larger version  Name:	20210727_185941.jpg Views:	0 Size:	2.59 MB ID:	1953485
                            Last edited by Fasturn; 07-27-2021, 10:06 PM.

                            Comment


                            • #15
                              You want to cut the tube from inside to outside , for maximum support
                              Put it in a 7 mm collet and extend the tube 1/4" beyond the collet and then using a internal cutoff tool , go in and part it off .
                              The collet acts with maximum support for the cutting forces. If the tool has a slight lead angle it will part off cleanly and leave a burr on the tube in the collet
                              That can be cleaned with a 400 grit paper block , and ready to move the tube out 1/4" again.
                              The Boring tool can be made from drill rod.
                              Your shank should be .200 diameter and the disk ( Before trimming ) about .25.
                              Here is a photo showing a similar tool . do the inside (.200 diameter )shank first !.. then face to get the thickness ! ( .010 ? )
                              Then grind back and finish with a Dremal to get the cutting edges shown .
                              The Dremel parting tool puts a nice relief behind the cut edge that allows easy stoning. The tool would then be .225 and fit in the bore
                              Click image for larger version

Name:	P3250060.JPG
Views:	239
Size:	621.1 KB
ID:	1953495
                              Click image for larger version

Name:	P3250038.JPG
Views:	241
Size:	758.6 KB
ID:	1953496
                              Click image for larger version

Name:	P3250043.JPG
Views:	257
Size:	744.5 KB
ID:	1953497
                              Since its Brass you are cutting, you do not need heat treatment
                              Another advantage is the part will fall onto the shank of the tool for easy retrieval.
                              and it will be free of burrs
                              Rich
                              Green Bay, WI

                              Comment

                              Working...
                              X